Vol. 30 No. 03 Jul-Sep 2021

Mariya Khalid                              BDS, FCPS
Mohammad Ali Chughtai           BDS, FCPS, MHPE, FFDRCSI
Sohrab Shaheed                         BDS, FCPS, FFDRCSI
Syed Nasir Shah                         BDS, FCPS

OBJECTIVE: The aim of this experimental study is to compare the dimensional accuracy of gypsum casts after repeated
disinfection in microwave at 900 Watts, 2450 MHz (5 minutes) and immersion in 0.5% Sodium hypochlorite (10 minutes).
Disinfecting casts is recommended to prevent cross infection but may cause dimensional changes. During fabrication of
prosthesis, a cast may get contaminated several times so there is a need of repeated disinfection.
METHODOLOGY: Sample size was 33 (11 in each group), calculated through WHO software for sample size determination
by using standard deviation of 0.16 at 95% confidence interval and 80% power of study. Impressions in irreversible hydrocolloid
were recorded of an acrylic cast fabricated for this study. The impressions were poured with die stone and were randomly
divided into 3 groups; Group I: Microwave disinfection, Group II: Immersion disinfection in 0.5% Sodium hypochlorite, Group
III: Control group. For Groups I and II, each cast was disinfected 7 times with 5 minutes interval between two disinfection
cycles, after every cycle anteroposterior and mediolateral measurements were recorded using digital Vernier caliper (accuracy
upto 0.01 mm). For group III, casts were rinsed with distilled water, dried in open air within temperature range of 28+/-2OC
for 10 mins followed by anteroposterior and mediolateral measurements. This procedure was repeated seven times for each
cast.
RESULTS: Anteroposterior and Mediolateral differences of dimensional change between and within the Group A, B and C
was calculated by One Way ANOVA. Inter/intra examiner reliability was taken into consideration at the time of study.
Mean dimensional change in the casts were insignificant through six disinfecting cycles. However, in the seventh cycle, a
significant difference (p=0.003) was observed in the anteroposterior dimension (0.03% dimensional change for Group A and
1.26 % for Group B whereas, in mediolateral dimension, dimensional change was 0.35% for Group A and 0.59% for Group B
(p=0.004). Dimensional change of >0.5% was considered as the cutoff value for casts to be considered as dimensionally accurate.
Casts disinfected through immersion disinfection did not produce dimensionally inaccurate casts in anteroposterior dimension
after third cycle and in seventh cycle in mediolateral dimension. However, result is significant only in seventh cycle. Microwave
disinfection produced dimensionally accurate casts throughout all cycles.
CONCLUSION: Microwave disinfected casts remained dimensionally stable compared to immersion disinfection.
KEYWORDS: Disinfection, microwave, immersion, dimensional stability, gypsum casts
HOW TO CITE: Khalid M, Chughtai MA, Shaheed S, Shah SN. Comparison of repeated chemical and microwave disinfection
on dimensional accuracy of gypsum casts. J Pak Dent Assoc 2021;30(4):235-242.
DOI: https://doi.org/10.25301/JPDA.304.235
Received: 13 January 2021, Accepted: 01 August 2021

INTRODUCTION
 Impression recording is the first step in fabrication of oral prosthesis.1 When a dental impression is recorded, it comes in contact with plaque, saliva and blood which may contain pathogenic microorganisms.2
When cast is poured against a contaminated impression, it also gets contaminated and becomes a source of infection for the dental personnel.3-4 Many studies have shown that pathogenic organisms were recovered from the casts.5-7 Up to 1991, washing impression under running water was a recommended practice.8 However, just washing impression does not remove pathogenic organisms causing Hepatitis
B,C and Tuberculosis.9 According to guidelines of infection control in dentistry, all prosthodontic items should be cleaned, disinfected and rinsed with an active disinfectant before sending them to laboratory.10
Irreversible hydrocolloid is the impression material which is widely used over the entire world.3 Alginate can be used in recording preliminary impressions, impressions for fabrication of temporary fixed dental prosthesis, study casts, impression of opposing dentition, orthodontic models, impression for fabrication of sports mouth guards and bleaching trays.11 Alginate is dimensionally unstable material, as hydrocolloids constitutes about 85 % water, they undergo imbibition in the presence of moisture and undergo syneresis when left dry.12 In past, different studies have been conducted to evaluate the dimensional stability of irreversible hydrocolloid using different disinfectants and different methods. The most common chemical disinfectants routinely used by dentists are alcohols, aldehydes, chlorine combination,
phenols, bisguanides, iodide combinations, and ammonium.13 Disinfection methods used for alginate impression material are
1. Spraying
2. Immersion
3. Incorporation of disinfectant in alginate by manufacturer
4. Mixing alginate with disinfectant
Each method has its own advantages and disadvantages. According to previous studies, spraying causes the least dimensional changes but is not capable of disinfecting all surfaces. On the other hand, Immersion is the most reliable method of disinfection as it comes in contact with all surfaces but produce dimensional changes15, especially if dental impression is immersed for a long period of time.4 High
level disinfectants cannot be incorporated while mixing impression material because of health hazards rendering third and fourth method not very useful. In most of the studies, chlorhexidine is incorporated while mixing alginate but according to Souza et al. AIDS virus and hepatitis B are deactivated by 2% Glutaraldehyde and 1% Sodium hypochlorite; however, these microorganisms are more resistant and are not eliminated with 0.5% Chlorhexidine.2
Keeping in mind the sensitive nature of alginate impression material, the suitable alternative is to disinfect dental casts instead of alginate impression as it is the cast on which prosthesis will be fabricated. Gypsum casts can be disinfected by spraying, immersing into a disinfecting
solution, by adding an antimicrobial agent to the plaster mix, by manipulating the plaster with a disinfectant solution16, microwave disinfection13 and autoclave disinfection.17 Different disinfectants used for disinfection of dental gypsum are formaldehyde, chlorine compounds, glutaraldehyde, phenols, iodophors18 and ozonated water.19 Immersion in sodium hypochlorite for 10 min at a concentration of 1:10 dilution (0.525%) is recommended for immersion disinfection.18 As previously mentioned, spraying does not provide effective disinfection whereas autoclave disinfection and incorporation of disinfectant while mixing plaster affects the physical properties of dental casts.14 Microwave disinfection of dental gypsum cast has shown to reduce the of bacteria on the casts after 5 minutes of microwave oven
irradiation in an ordinary household microwave oven set at 900 wattage.20 So, for the purpose of this study, disinfection methods selected were chemical disinfection by immersion method and microwave disinfection as both of them have proved to be effective in disinfection of gypsum casts.21 In case of microwave disinfection, there is no effect on the efficacy whether the casts are wet or dry at the time of disinfection.22 In addition to efficacy, another important requirement of disinfection is that it should not affect dimensional accuracy of casts23 so, now, there is a need to compare both of these methods in terms of dimensional accuracy
According to Stern et al, during the fabrication of complete denture, a need may arise to disinfect dental cast seven times.24 A dental cast can be contaminated when poured against contaminated impressions or during trial of the denture base prosthesis several times in clinic.25 This study was carried out to compare the effect of repeated microwave disinfection of gypsum cast to repeated immersion disinfection. Both of these disinfection methods have been studied separately and are considered acceptable in terms of efficacy and dimensional accuracy, however there is no study comparing these methods by repeated disinfection. This study was aimed to compare these two methods (microwave disinfection and immersion disinfection) and to determine the best disinfection method for the gypsum cast which produce the least dimensional changes.

METHODOLOGY
This experimental study using non- probability consecutive sampling technique was conducted in Prosthodontics Department of Sardar Begum Dental College and Hospital, Peshawar. Sample size was 33(11 in each group) calculated through WHO software for sample size
determination by using standard deviation of 0.162 at 95% confidence interval and 80% power of study. The three groups are:

Group I:
Gypsum casts irradiated in a microwave oven (Samsung,
Korea) for 5 minutes at 2,450 MHz and 900 Watt.

Group II:
Gypsum casts immersed in 0.5% Sodium Hypochlorite
(Haq chemicals, Pakistan) for 10 minutes

Group III:
Gypsum casts rinsed with distilled water, dried in open
air within temperature range of 28+/-2 degrees for10 mins
followed by anteroposterior and mediolateral measurements.

SAMPLE SELECTION

Inclusion criteria:
All casts poured in the impression recorded from acrylic cast.

Exclusion criteria:
1. A crevice or deficiency in the midline of palatal vault of impression.
2. An impression short in one or more regions of the sulci, especially around the tuberosities or the labial sulcus.
3. Tray flange showing through the impression material.
4. Impression material detached from the tray.
5. Impressions from incompletely seated tray.
6. Casts having broken, distorted and entrapped air at metal rod duplicates.
7. Any void present in the cast.
8. Cast fractured at the time of separation from the impression material
The above mentioned conditions act as confounders
and if included will introduce bias in the study
results.

Acrylic master cast:
An acrylic master cast representing edentulous maxillary arch was constructed in heat cure acrylic (FDS, Pakistan) using long curing cycle. Reference points (A, B, C) for measurements on cast were made on the acrylic cast by inserting metal rods in the approximate position of incisive papilla (A) and in the region of right and left second molar (B and C). A hole was drilled in the position of each reference point and a metal rod was inserted and secured in place with auto polymerized acrylic resin (Figure 1). The distance between points A and C was kept 40 mm, after polymerization shrinkage, this distance was reduced to 39.96 mm. The distance

between points A and C was kept 40 mm, after polymerization shrinkage, this distance was reduced to 39.96 mm. The distance between points B and C was kept 55 mm which was reduced to 54.66 mm after polymerization shrinkage.

Custom tray construction:
For the uniform thickness and distribution of impression material, a custom tray was constructed using auto polymerized acrylic resin (FDS, Pakistan) after application of 4mm spacer on master cast. Perforations were made in the custom tray (Figure 2).

Alginate impression material (Alginmajor, UK) was mixed according to manufacturer’s instructions using distilled water. Ions in different concentrations might be present in tap water which can interfere with chemical reaction of irreversible hydrocolloid27 , that’s why distilled water was used. Acrylic master cast impression was recorded in alginate and rinsed under tap water for 10 seconds. The excess water was shaken off and impression was poured with type IV gypsum (Dentamerica, Taiwan).
The cast was allowed to set for 40 minutes before removal. Casts were allowed to dry in air for 24 hours, as stone casts may take 24 to 48 hours in losing excess water and gaining enough strength to be handled without damage.28 After 24 hours, casts were randomly subjected to one of the groups by simple random sampling.
For Group I, cast was irradiated in microwave at 900 watt and 2450 MHz for 5 minutes. After 5 minutes, cast was allowed to cool for 5 minutes. Then, anteroposterior (AB) and mediolateral measurements (BC) were recorded (Figure 3) using digital vernier caliper
(Tianhe, China). Same procedure was repeated seven times.
Ame procedure was repeated seven times. For Group II, gypsum cast was immersed in 0.5% Sodium hypochlorite for 10 minutes. Then, anteroposterior (AB) and mediolateral measurements (BC) were recorded using digital vernier caliper. This procedure was repeated seven times.
                Figure 3: Anteroposterior and mediolateral dimensions measured on cast
For Group III, gypsum casts were not disinfected. Anteroposterior (AB) and mediolateral measurements (BC) were recorded using digital vernier caliper seven times with duration of 10 minutes between two readings.

RESULTS
  Anteroposterior and Mediolateral differences of dimensional change between and within the Group A, B and C was calculated by One Way Anova, While Paired Sample T Test was used to do Reliability analysis of measurements by rater 1 and 2.

ANTEROPOSTERIOR DIMENSION
Anteroposterior dimension between the points A and C was 39.96mm. Maximum percent dimensional change was 0.43 while minimum value recorded was 0.03 with the range of 0.4 in the Microwave disinfection Group A. Maximum percent dimensional change in the chemically disinfected Group B was 1.26 and minimum change was 0.20 with the range of 1.06. Whereas 0.45 was the maximum and -0.13
minimum percent dimensional change with the range of 0.1 noticed in the Control Group C (Table 1, Figure 4)

MEDIOLATERAL DIMENSION
 The Mediolateral dimension between the points B and C (BC) was 54.66mm. Maximum percent mean dimensional change in the Group A was 0.35 and minimum change was 0.16 with the range of 0.19. Maximum percent mean dimensional change in the Group B was 0.59 and minimum was 0.20 whereas 0.31 and 0.11 was the maximum and minimum percent dimensional changes with the range of 0.2 noticed in the Control Group (C). (Table 2, Figure 5).

INTERGROUP COMPARISONS
  Mean dimensional changes in anteroposterior and mediolateral dimension of the casts were insignificant through six disinfecting cycles. However, in the seventh cycle, a significant difference (p=0.003) was observed in the anteroposterior dimension and mediolateral dimension(p=0.004) within and between the groups. (Table 1 and 2). Mean dimensional expansion was observed inchemical disinfection group.
Maximum percent dimensional change observed in the Anteroposterior dimension between Group A and C was 0.02. While minimum percent dimensional change observed was 0.07 with the range of 0.05. Whereas 0.66 and 0.009 was the maximum and minimum differences in the Anteroposterior dimension among the Group B and C respectively with the range of 0.651.
Maximum difference of change observed in the Mediolateral dimension between Group A and C was 0.81mm, while minimum difference observed was 0.07. On the other side 0.147mm and 0.02mm was the maximum and minimum differences in the Mediolateral dimension
among the Group B and C respectively.
Paired Sample T test was applied to get the Inter and Intra rater Reliability analysis. Mean difference in the readings by rater 1 and 2 was 0.018 mm ±0.37 while 0.46mm ±1.61 in the Mediolateral Dimension. But, difference between the measurements by rater 1 and 2 was insignificant. Similarly Mean difference observed in the readings by the rater 1 at two different occasions in the Anteroposterior dimension was 0.52mm±1.6 while 0.06mm±0.34 in the Mediolateral Dimension. Similarly there was insignificant difference in the measurements observed by the rater 1 at two different occasions. This shows reliability of the overall results.

DISCUSSION
Cross infection control is mandatory in any field of medicine. Likewise, there is an increased chance of cross infection in dentistry as oral flora constitutes of a number of microorganisms which can be transported to laboratory via impression, casts and prosthesis.29
For this reason, disinfection of impressions and casts is considered very necessary to control cross infection.30 The impression material chosen for this study was irrerversible hydrocolloid because of its hydrophilic nature31 and sensitivity to disinfection procedures.32 Disinfection methods selected were microwave disinfection method and immersion method because of their increase efficacy against
most of the organisms.1,33 Acceptable methods to measure dimensional change are travelling microscope, measuring microscopes, micrometers, dial gauges and calipers.34 Digital caliper was used for the purpose of this study.
This study was carried out to compare the effect of repeated disinfection on dimensional accuracy of gypsum casts using microwave disinfection and immersion disinfection. It is difficult to relate the results of this present study with the literature since there are no available studies that compare the effect of repeated microwave and immersion disinfection on dimensional accuracy of gypsum casts.
When intergroup comparison was made, mean dimensional changes in mediolateral and anteroposterior dimension of the casts were insignificant through six disinfecting cycles whereas in the seventh disinfecting cycle a significant difference (p=0.003) was observed within and between the groups. This means that up to six cycles both microwave and immersion disinfection were acceptable in terms of dimensional accuracy but in seventh cycle there was a significant difference.
Cast expansion was observed in a study18 when cast was subjected to immersion disinfection in 0.5% Sodium hypochlorite for seven times. Our study also showed the same results. The reason for increased dimension may also be because of the dissolution of gypsum metal rod duplicates resulting in increased distance between reference points. According to Malaviya Neha, microwave irradiation causes loss of water as steam35 which may be the probable reason for the shrinkage of microwave disinfected gypsum casts. In our study, shrinkage also occurred in microwave disinfection group in anteroposterior dimension. According to the results of this study, casts disinfected through immersion disinfection did not produce dimensionally accurate casts in anteroposterior dimension after third cycle (percent dimensional change greater than 0.5) and in seventh cycle of mediolateral dimension. However, result is significant only in the seventh cycle of
Anteroposterior dimension (P value= 0.003) and in seventh cycle of mediolateral dimension (P value= 0.004)
In a study performed by Saleh26, when microwave irradiated gypsum casts and casts obtained by immersing impression in sodium hypochlorite were compared, there was a statistically significant difference (P < 0.05) of the overall dimensional accuracy of casts between the control group, sodium hypochlorite disinfection group and microwave irradiation group. The results of this study showed that casts treated with microwave irradiation present similar or improved dimensional accuracy when compared to the casts in the control group.26 Our study also showed the same results i.e.; microwave irradiation produced dimensionally accurate casts and there was statistically
significant difference between control, chemical disinfection and microwave irradiation group in the seventh disinfecting cycle. However, in our study, casts are immersed in sodium hypochlorite instead of impression and repeated disinfection was performed.
In a study conducted by Anaraki et al.36, there was no significant difference in dimensional accuracy of gypsum casts between case and control samples when samples were exposed to 7 consecutive rounds of 900 watts (W) microwave irradiation for five minutes each time. In our study, microwave disinfection gave dimensionally accurate casts throughout seven disinfecting cycles but a significant difference between chemical disinfected casts and control samples was observed in the seventh disinfecting cycle.
Kumar et al. studied dimensional stability of gypsum cast after repeated immersion in 0.5% sodium hypochlorite and 2%gluteraldehyde. The results of his study revealed that stone casts immersed in 0.525% sodium hypochlorite and 2% glutaraldehyde solutions showed significant linear dimensional change compared to stone casts in slurry (control group). Our study also showed the same results i.e.; casts disinfected through immersion disinfection did not produce dimensionally accurate casts after third cycle in anteroposterior dimension and in seventh cycle of mediolateral dimension. However, result is significant only in anteroposterior and mediolateral dimension in the seventh cycle. This difference may be because immersion time was 30 minutes in Kumar’s study as compared to 10 minutes used in our study.18
Goel K et al37 performed a study comparing microwave irradiation with chemical disinfection (using 0.07 % Sodium Hypochlorite) on the dimensional accuracy of gypsum cast. The results showed that there was no significant difference between the microwave irradiated group and chemical disinfection group. However, Goel et al did not study effect of repeated immersion and microwave disinfection. In our
study, repeated disinfection was performed according to which, there was no significant difference between the three groups upto six disinfecting cycles.

CONCLUSION
Microwave disinfected casts remained more dimensionally stable as compared to casts disinfected through immersion.

LIMITATIONS
1. A similar study with larger sample size should be designed.
2. A more precise measuring instrument will give more reliable results.
3. Another study should be performed with time interval between two disinfecting cycles of 24 hours so as to simulate the clinical situation more closely.
4. Another study should be designed focusing on the effect of repeated microwave and immersion disinfection on hardness, compressive and tensile strength of gypsum casts.

CONFLICT OF INTEREST
The authors declare that there is no Conflict of interest

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Tayyaba Saleem            BDS, FCPS, MME
Raheela Yasmin            BDS, DCPS, MHPE, PhD
Anbreen Aziz                 BDS, MHPE
Usman Mahboob           MBBS, MPH, FHEA, DHPE, Fellow FAIMER
Ahsan Sethi                   BDS,MPH, MMEd, FHEA, MAcadMEd, FDTFEd, PhD

OBJECTIVE: Present study was conducted to assess the perceived academic sources of stress among undergraduate dental
students and determine its association with gender, year of study, pre-university education and accommodation. This study
was conducted in dental section, Islamabad Medical and Dental college, Islamabad from July to November 2016.
METHODOLOGY: BDS students were asked to rate their perceived stress on four point Likert scale of modified version of
Dental Environment Stress (DES) questionnaire. Descriptive statistics were applied to find the mean scores and SD on all
items. Using SPSS v.21, Kruskal Wallis test was used to compare stress levels among different undergraduate professional
years and Mann-Whitney U test was applied to determine the association and stress sources and demographic variables.
RESULTS: A total of 172/200 participants responded (86%) to the survey. Overall stress in undergraduate dental students was
in moderate range. Majority of students (93%) reported that syllabus load was either stressful or very stressful (3.53±0.64),
85% students reported lack of relaxation time as stressful or very stressful (3.42±0.86) and fear of failing was reported as
stressful or very stressful by 82.5% (3.34±0.87). When stress scores of all classes were compared third year reported more
mean stress scores than other years (2.50±0.50). Females were more stressed compared to males with mean score of (2.37±0.39),
students living at home were more stressed than hosteilites (2.38±0.38) and those with GCE A-levels had higher stress (2.40±0.38)
compared to HSC background students. Academic performance was the most stressful of the five stress domains (3.07±0.74).
CONCLUSION: Syllabus load followed by lack of time for relaxation and fear of failing were the most perceived sources
of stress. Academic performance was the most stressful of the five stress domains and third year BDS was the most stressed
class.
KEY WORDS: Dental Education; Dental Students; Psycholofical Stress, Stressor, Undergraduate,.
HOW TO CITE: Saleem T, Yasmin R, Aziz A, Mahboob U, Sethi A. Perception of academic stressors among dental undergraduate
students. J Pak Dent Assoc 2021;30(4):228-234.
DOI: https://doi.org/10.25301/JPDA.304.228
Received: 14 January 2021, Accepted: 19 June 2021

INTRODUCTION
  tress is body’s reaction to physical, mental, or emotional stimuli.1Dental education is challenging and stressful experience, stress levels among dental graduates are higher than general population.2 Studies show multifactorial nature of stress that is associated with
psychological and physical effects in different phases of dental education. 3,4 The rapid increase in curricular content has steered attention of dental educationists for identifying and addressing the academic stress and stressors among their students. 5 This is the key to enhance quality of learning environment. 5 In addition, social factors such as accommodation or educational background with which students enter dental institution may also provoke stress. 6
Dental environment stress (DES) is usually reported to be caused by frequent exams, time limited course goals, clinical and laboratory assignments, patient handling, high performance expectations, financial status and insufficient relaxation time. 7 Stress symptoms may include tension, anxiety, fear, depression, fatigue, headache, cynicism dizziness, insomnia, impaired immune system and tachycardia. 8,9 When left unattended these may potentially transpire in burnout and suicide in some severe situations. 10                                                                Stress in dental students had been identified using different stress scales, including, “Dental Environment Stress Scale” (DES),11 “Maslach Burnout Inventory” (MBI),12 and “Psychosocial Stress Inventory” (PSSI). 13 Among these, DES is commonly utilized. 14                      Many studies have identified stressors among dental undergraduates, however there is scarcity of literature exploring stress sources among Pakistani undergraduate dental students, and explore its association with the demographic variables. Therefore, the aim of the present study was to explore perceived stress sources, stress levels and their association with sociodemographic factors of gender,                pre-university education system (General certificate of education (GCE) Advanced level or A-levels and Higher school certificate HSC, and accommodation etc.

METHODOLOGY
  A descriptive cross-sectional survey targeting all undergraduate students from first to final year BDS was done from July to November 2016 in dental section, Islamabad Medical and Dental College (IM&DC) Islamabad. The study targeted all students of BDS (N=200), those with known psychological issues, who did not give consent, and those who were not present on the day of survey were excluded. Ethical approval was obtained from the Institutional Review Board (letter no. IMDC/DS/IRB/50, dated 16th June 2016.). Al-Sowygh ZH modified “Dental Environment Stress” (DES) questionnaire was used The tool comprises of 41-items grouped under five stress-provoking domains i.e., personal factors, educational environment, workload, clinical training, patients, and academic performance with reported reliability of 0.89 with Cronbach’s Alpha.4 It was selected for the present study because it was developed for and used in a culturally and religiously similar environment. The DES Questionnaire was validated by ten faculty members of IM&DC to determine suitability for local use, suggested changes were incorporated
Students were approached in their respective lecture halls. Due permission from the Principal and respected faculty was taken by primary researcher (TS), who took verbal informed consent from students and explained questionnaire format. Data confidentiality was ensured by keeping the questionnaires anonymous. Stress domains were not disclosed to students in distributed questionnaire. This study utilized
Likert scale with four-point response against each item from 1: not stressful, 2: somewhat stressful, 3: stressful, and 4: very stressful Filled questionnaire were collected, a separate code was given, and data were entered and analysed in SPSS version 21

STATISTICAL ANALYSIS
  Frequencies and percentages were calculated for qualitative data including socio-demographic variables i.e., age groups, gender, living accommodation, pre-university education, and marital status. Internal reliability of all questionnaires responses was determined using Cronbach’s Alpha (0.87). In this study, stress was considered mild if it had a mean score of 1.99, moderate with a score of 2-2.9 and 3 or more was considered severe.
For all classes, means with standard deviations were calculated jointly and separately for the 41 items in the questionnaire. Mean stress scores and their standard deviation were calculated for all demographic variables and the “pentagon of stressors” (five stress domains)
consisting of personal aspects, educational workload, environment, clinical work, and patient associated factors, and academic achievement. Distribution of data was assessed with Shapiro-Wilk test which showed that it was not normally distributed.
Kruskal Wallis test was used to find association among the four BDS classes and their stressors on the four-point Likert scale. The ranking orders were analysed to determine the highest mean rank for study years, which was then related to the statistical significance. Dissimilarity in replies from the BDS classes were considered statistically significant. Significance in difference of perceived academic stressors with demographic variables and stressor domains was found with Mann-Whitney U test. The ranking orders were analysed to determine the higher mean rank for each demographic variable separately. A p-value of less than 0.05 was deemed statistically significant.

RESULTS
  One hundred and seventy two out of two hundred students participated in the study giving a response rate of 86%. The students were divided into three age groups, first ranging from age 18 to 21 years, second from 21-23 years and third group of age 24 and above. Majority of the students 56% were in the second age group, with a mean age of 21±1.6 years. Socio-demographic details of participants are presented in Table 1. As there were no married participants, further comparisons were not done with marital status.
Mean scores of highest stressors for all students who reported these items as stressful or very stressful, in the descending order were “Overloaded feeling due to syllabus load” 93% (3.53±0.64), followed by lack of relaxation time 85% (mean=3.53±0.64), “Fear of failing” 82.5% (3.34±0.87), “Clinical requirements” 81.3% (Mean=3.27±1.0), “late ending day” 75% (Mean=3.17, ±1.00) along with “examinations” 72.7% (Mean=3.13, ±0.98).

Minimum stress was perceived with “language barrier” 6% (1.4±0.6), “Availability of qualified laboratory technicians” 16.7 (mean=1.73±0.88) and “Inadequate number of instructors/teachers in relation to student” 18% (1.7±.95)

Mean scores for demographic variables revealed that females were more stressed (2.37±0.39) than males (2.25±0.356). Students with GCE A-level were slightly more stressed (2.40±0.38) than F.Sc. students (2.34±0.39) and those living at home with families were more stress (2.38±0.38) than those living in hostels (2.28±0.39).
Mann Whitney U test revealed following results for the socio-demographic variables under study. Female students were significantly more stressed from “clinical requirements (quota)” (p=<001), “competition of grades” (p=0.01), “transition from pre-clinical to clinical work” (p=0.01), “conducting procedures on patients with poor oral hygiene (p=0.01), “fear of being unable to catch up if left behind (p=0.03), “fear of not being able to join a postgraduate dental education program” (p=0.03), “insecurity concerning lack of employment positions” (p=0.03), “Responsibility of getting suitable patients” (p=0.03). A comparison of educational background was done
with DES, which revealed GCE A-level students were more stressed with “being treated as immature & irresponsible by faculty” (p=0.03) besides “lack of confidence to be a successful dental student” (p=0.04). However, HSC students felt more stress with “language barrier” (p=0.02) and in “getting relevant study material” (p=0.02).
Comparison of accommodation revealed that students who live in their homes were significantly stressed in “insecurity related to
professional future” (p=0.045), “insecurity of lack of employment” (p=0.004) along with “receiving criticism about work” (p=0.005). Students living in the hostels on the other hand reported “lack of home atmosphere in hostel” p<0.001 with statistically significant difference. Comparison of DES domains with demographic variables and item-wise DES mean scores which were calculated for
the four BDS classes along with the results of Kruskal Wallis test are shown in Table-2 and Table-3, respectively.

DISCUSSION
   This study evaluated various stressors perceived by undergraduate dental students and their association with demographic variables. Moderate levels of DES scores  (2.35±0.38) were reported by students. Elani et al in a systematic review reported a similar pooled mean DES
(2.34±0.23), whereas Poly et al. in a comparative study of dental and medical students reported similar mean DES (2.39±0.40) for dental and medical students (2.21±0.29).14,15
Three highest stress factors reported in this study were syllabus load (3.53±0.64), lack of relaxation time (3.42±0.86) and fear of failing (3.34±0.87). Tangade et al. reported fear of failing (3.07 ± 0.72), unemployment fear (2.73 ± 0.74), financial issues (2.71 ± 0.83), and lack of relaxation time (2.69 ± 0.95).16 Al-Sowygh et al reported assigned class work (3.52±0.79), late ending day (3.52±0.81) and Lack of time for relaxation (3.43±0.79) as most stressful factors.17 A local study reported, huge syllabus as the second most common stressor.18 Another study reported “late ending day” as major stressor for males, and final-year students.3 These results endorse the result of the present study, dental curriculum is inherently demanding, clinical work requirements and assigned academic load contribute to stress.15 Variation in highest perceived stressor in studies can be attributed to difference in daily working hours of many institutes and financial support from family for local students.
Present study identified that BDS classes reported significant differences in various stress items. “Late ending day”, “syllabus load”, “examination and quizzes” were more stressing for first year. These results are endorsed by a study which reported same stressors for their first- and second-year students, however “amount of assigned work” stressed their students more4 compared to examination and quizzes. “Lack of relaxation time” and “moving away from home” were main stressors for first year in another study.19 First year students of present study were more stressed about “Insecurity concerning lack of employment”, like a Malaysian study.20 Senior students have better knowledge of dentistry and information on various job opportunities in the market which could have reduced this stress in
subsequent years.
Third year BDS had significantly high scores for stressors associated to clinical training, these results are in accordance with previous studies.4,20-22 A shift from preclinical to clinical settings and application of procedural skills on real patients is demanding for third year students. Previous studies showed a similar trend with increase in stress levels from first year to the final year with stress peaking in the 3rd year.3,16,23 Conversely a Turkish study reported that clinical years were less stressed contrasted to preclinical years.24 This could be
due to syllabus load in addition to the atmosphere created by the preclinical staff, which may add to the overall stress for the students.
Socio-demographic aspects affect dental students. In this study female students were significantly more stressed, these results are in accordance with previous studies.20,25,26 This could be because females confess more to having stress or they may feel, and encounter added stress.27 Generally, males do not express their stress or cope with it. Living in a “patriarchal society” and fearing to fail their
duties Pakistani men rarely admit depression or stress.15
In Pre-university education system comparison total mean scores for the students of GCE A-level was slightly more (2.40±0.38) as compared to High School Certificate
HSC counterparts (2.34±0.39). Effect of pre-university education on stress levels has scarcely been reported in literature. However, some studies reported comparison of having or not having a previous degree with stress levels.27,28 One study reported insignificant difference in academic success of medical students from different pre-university education systems. GCE A-level students give extra study time and hence tuition fee.29 They also go through substantial documentation for equivalence before admission, these reasons could result in greater stress for them.
Dental curriculum is essentially didactic, students with GCE A-level are trained in critical thinking and active involvement in learning. This could explain why A-Level students are significantly more stressed than their HSC counterparts on “being treated as immature by faculty” and “lack of confidence to be a successful student”. Since A-level students were in minority in present study the results cannot be generalized to all A-level dental student population. Significantly higher stressors for HSC students were “language barrier” and “difficulty in getting study material”. This could be because two languages are still used in F.Sc. examinations and students are dependent on
didactic teaching strategies.
In this study the students who were living with families reported higher stress scores, these results are endorsed by one previous study.30 Conversely, other studies have reported that students living away from home were more stressed.16,31 Possible reason could be that more time and effort are required for commuting, there are added claims on student’s time by their families and friends, or the reason could be the feeling of “academic isolation”.28
Comparison in “pentagon of stressors” domains disclosed that major stress scores were reported in “academic performance”, and “workload”. “Academic performance” being the highest stress domain for final year, similar to results of previous studies.15,19,32 An Egyptian study reported academic pressures as second greatest stressful domain.33 Other studies reported it as either the stressful33 or incredibly stressful domain.4,20 First year students in present study perceived workload as the highest stressor, in contrast to another study which reported that the senior years were more stressed with workload.33 The clinical factors domain was third highest in present study, in contrast a West-Indian study found that this domain was most stressful.19 For clinical year students of this study the stress related to the
“personal factors” was higher, this result is supported by another study done in Egypt33 but is opposed by another study which reported that all classes were highly stressed by “personal factors”.34 Third year perceived “Educational environment” as most stressful domain, this result is endorsed by another study.19 Reason could be the shift to clinical situations, where students are not only assigned theoretical assignments, they also are required to work with teaching and support staff, and patients while practically
performing on real patients.
Students require protected time to relax, identification of the stressors will help formulating strategies to prevent stress build up and its negative effects. Formal student support programs including counselling cells and mentormentee programs can contribute to this and ensure an environment which reduces stress and promotes student well-being. The transitional phase of preclinical to clinical, needs to be addressed to support students for better self and patient management.
Inclusion of only one dental college along with not exploring effect on stress due to student’s personality traits were limitation of this study. Future studies need to be designed to conduct a comprehensive research involving multiple institutes to report more remarkable findings at national level. Student’s individual personalities should be considered in future studies on annual performance along with effect of implementation of stress coping programs.

CONCLUSION
   Syllabus load, followed by less relaxation time and fearing to fail were most stressful factors reported by the undergraduate dental students. More stress was reported by female students, those living at home and students with a background of A-levels compared to their counterparts. Academic performance is the most stressful of the five stress domains for students of all classes. Third-year BDS was the most stressed class. The study indicates that dentistry is stressful therefore dental students require training for stress coping. Recognition of stressors, awareness, student counselling, mentor-mentee programs need to be provided in institutes to help improve student wellbeing.

ACKNOWLEDGMENT
   The authors are grateful to the students who participated in the study and the administration if the dental section who supported the research.

CONFLICT OF INTEREST
   None declared.

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Muhammad Haider Amin Malik                                   BDS, FCPS

Nazia Yazdanie                                                             BDS, FCPS, MSc, PhD

OOBJECTIVE: To review the periodontal considerations associated with removable partial denture therapy.
METHODOLOGY: Using a MEDLINE search, for "removable partial dentures periodontal", a total of 712 papers from
peer-reviewed journals came in results. The MEDLINE search was made more specific by applying filters to the key phrase
with other key words such as "periodontal evaluation"(140), "direct retainers"(77), "non-surgical periodontal"(8), "surgical
periodontal"(180), "plaque"(249), "periodontal indices"(112), "tooth mobility,"(180) "periodontal maintenance,"(60) "splinting,"(198)
and "split major connector"(2). Both in vivo and in vitro studies on the Perio-prosthodontic aspects of RPD treatment were
included in the study pool whereas case Series and case reports were excluded.
RESULT: A total of 1206 studies were collected from the search engine. After applying the exclusion criteria and filtering the
duplicates a total of 95 studies were included for the narrative review.
CONCLUSIONS: Out of all the factors, recall and oral and denture hygiene have the utmost importance.
KEYWORDS: Perio-prosthodontics, removable partial denture, periodontal indices.
HOW TO CITE: Malik MHA, Yazdanie N. Perio-prosthodontics considerations in removable partial denture: the role of the
prosthodontist. J Pak Dent Assoc 2021;30(3):219-227.
DOI: https://doi.org/10.25301/JPDA.303.219
Received: 09 August 2020, Accepted: 12 March 2021

INTRODUCTION
   The relationship between periodontal health and restoration of teeth is intimate and inseparable. For restoration to survive long term, the periodontium must remain healthy so that the teeth are retained.1,2 Periodontics and prosthodontics share this interdisciplinary coordination in multiple aspects: treatment plan, procedures execution, outcome achievement and maintenance. To facilitate this collaboration, the Prosthodontist should appreciate the Periodontic implications of various restorative procedures.2-4
Fixed and removable prosthesis supported by oral mucosa, natural teeth or dental implants are provided to
patients according to their indications.5 There may be situations where systemic health, oral conditions, financial
constraints or time constraints preclude the use of fixed prosthesis in the patient.2 Due to oral tissue preservation, the Removable partial dentures (RPDs) are a best choice as an alternate treatment option.6,7 However, for most of the patients the fixed prosthesis is more desirable from a psychological point of view.6,8-10 Successful treatments by
RPDs require thorough insight on the effect and interactions of the RPD with the oral tissues.4 The purpose of this article is to review the dental literature regarding Perio-prosthetic considerations in RPDs.
Using a MEDLINE search, for “removable partial dentures periodontal”, a total of 712 papers from peerreviewed journals came in results. The MEDLINE search was made more specific by applying filters to the key phrase with other key words such as “periodontal evaluation”(140), “direct retainers”(77), “non-surgical periodontal”(8), “surgical periodontal”(180), “plaque”(249), “periodontal indices”(112), “tooth mobility,”(180) “periodontal maintenance,”(60) “splinting,”(198) and “split major connector”(2). Both in vivo and in vitro studies on the Perio-prosthodontic aspects of RPD treatment were included in the study pool whereas case Series and case reports were excluded. A total of 1206 studies were collected from the search engine. After applying the exclusion criteria and filtering the duplicates a total of 95 studies were included for the narrative review.

Pre prosthetic periodontal evaluation phase
    The periodontal examination of a patient for any type of prosthetic treatment is important for the prognosis and
success of treatment.11,12 The periodontal examination must include the status of Oral hygiene, status of bacteria accumulation, degree of reversible and irreversible damage to periodontal tissues, gingival biotype, functional and static occlusion and mobility of teeth. The objective at this stage is to diagnose any periodontal conditions that would either compromise the construction of the denture or compromise the prognosis for a successful therapeutic outcome.13,14 Overhanging fillings, open margins of existing restoration, over-contoured restorations, severely tilted teeth and furcation involvements increase the bacterial accumulation in the oral cavity. These plaque retentive features must be minimized or removed before proceeding to a definite prosthetic treatment. Likewise, immune status of host and response to previous periodontal and prosthodontic therapies is also important.2,3,14 Periodontal loss in young patients has poorer prognosis than the older patients because in the younger patients the disease has taken a more virulent course.
A quick assessment of the patient’s level of education and motivation of oral and denture hygiene is necessary as
it is critical to success of RPDs.3,14 This process of learning and encouragement should be a part of each appointment of the treatment and post treatment recalls.15 In RPDs there is more coverage of hard and soft tissue than FPDs therefore the Oral hygiene is even more crucial for these patients.16-18
Finally medical status of the patient must be evaluated. Medical conditions can either have a local implication on
the overall health status of the periodontal tissues or they can affect the prognosis of any restorative treatment on the
abutment teeth.19 Failure to appreciate any underlying systemic condition or any medication that can affect the
periodontium may cause serious setbacks and failures of the restorative treatment. According to Leyvee et al, abutment teeth with good periodontal prognosis have a 9.3 lower risk of tooth loss than the teeth with lower prognostic values.20

Pre prosthetic periodontal procedures Non-Surgical Procedures
    Routine non-surgical periodontal care has two basic components: Effective daily plaque removal by the patient
and Supportive periodontal therapy (SPT) every 2 to 6 months.21-24 Generally patients are not able to remove all the plaque from all surfaces of teeth throughout the day but a good immune system can resist detrimental effects of residual plaque.23,25-27 Being the most conservative and non-invasive periodontal treatment, Scaling and root planning (SC/RP) is also termed as the basic supportive periodontal therapy (SPT).28-30 This therapy can give the greatest level regain of the clinical attachment loss as compared to any other therapeutic technique.22,30,31 It also aids in an improvement in oral microbial composition which in turn, helps in reduction of pocket depth and also reduction in bleeding sites. It is cost effective and has minimal side effects in comparison to surgical techniques.24,32

Surgical Procedures
Surgical periodontal therapy is indicated in cases where2,33-35
1. Continued bone loss in a patient who has had SC/RP and is on a 2- to 3-month periodontal maintenance
schedule
2. The need for making more cleansable gingival contours.
3. The need to clean root surface that are in accessible non-surgically.
Though Surgical periodontal therapies help maintain a healthy periodontal status however they have their own biological costs. If health of periodontium is not maintained by a regular SPT, any type of surgical procedure may fail to give favorable outcomes.34,36,37

Effect of Removable Partial Dentures on Plaque
    RPD wearing has been associated with alteration in quantity and quality of plaque.38-45 Addy and Bates stated
that, whether a denture design is either close fitting or self-cleansing, plaque accumulation is higher with patients
that have poor oral hygiene.44 In a series of studies Ghamrawy E. et al have stated that plaque formation is enhanced on abutment teeth with increase proliferation of Spirilla and spirochetes than other bacterial strains.40-42 Thus special tooth brushing techniques must be advocated to patients wearing RPDs as they are at high risk of developing periodontal disease.41 Bissada evaluated gingival response to coverage by partial dentures.46 All the design features were similar for these dentures except the relationship of the gingival tissues to the palatal plate and the material of denture. The results of the study showed that the coverage of gingival areas by RPD without relief and the acrylic based dentures showed overt periodontal inflammation that is appreciable both clinically and histologically, whereas the areas left uncovered by denture were the least affected. Based on the results of this study a minimum distance of 5 to 6 mm away from the free gingival margins for major connectors was proposed. Similar observations were made in other studies on plaque accumulation due to RPD use. They concluded that a meticulous and persistent level of oral hygiene is required for patients wearing patients. They also stated that the denture design should simple and minimalistic, thus it should cover only those hard and soft tissues that are required.47-49
Wearing of RPD may promote the formation of plaque but if meticulous oral and denture hygiene is practiced by
the patient then it can be effectively control. In a study the authors demonstrated that just by teaching patients meticulous tooth brushing, plaque can be controlled.48 The hygiene measures that the literature supports includes; using special toothbrushes for proximal surfaces, frequent cleaning of the dentures and tooth brushing after each meal.41 Thus, it can be extracted from the literature that the wearing of RPD may promote plaque formation but the major factors are related to poor oral and denture hygiene.

Effect of Removable partial dentures on periodontal indices
     FPDs have a general repute of being a better treatment option than the RPDs amongst the less experienced dental
community and patients. This biased notion has been made due to several reasons.50-52
RPD is given in a patient that is not suitable for any fixed restoration either because of poor abutments and/or poor periodontal status of patient. Thus RPD wearing patients that have a compromised prognosis of remaining teeth, make a larger number.
Complications of FPDs are less reported by patients and less observed by the dentists because the periodontium has a better tolerance for abuse and trauma than oral mucosa. Thus if factors like oral hygiene, prosthesis design and case selection were to be kept constant, the clinical outcomes related to periodontal health would not differ both for RPDs or FPDs.51
If oral hygiene and denture hygiene measures are meticulously followed by patients, there appears to be no
correlation of poor periodontal indices and RPDs.51-54 However few studies have attributed RPDs with worsening
of periodontal indices of abutment teeth as compared to non-abutment teeth.50,55 The crux of this reported variation of result lies in the difference of oral and denture hygiene by the patient.52,56,57 It is recommended that Recall visits should be planned to intercept the development of periodontal pockets.58

Effect of removable partial dentures on tooth mobility
    Mobility of natural teeth can be physiological or pathologica.59 The clinical mobility of tooth is classified by
numerous periodontal indices which have different criteria of assessment and classification.60 One of the pathological causes of tooth mobility is periodontal disease. Periodontal disease causes the alveolar bone to resorb and minimizes the volume and quality of the supportive tissues of the tooth.61 Partial dentures are associated with increased tooth mobility of abutment teeth, which may be attributed to increase forces on abutments or dental plaque accumulation.62-64 Rigid Metal major connector directs less forces on abutment teeth than a non-rigid polymer based major connector.65 However care in planning and designing of RPD on a dental surveyor, selection of abutments and harmonizing occlusal contacts can decrease this harmful effect of RPDs on the natural teeth.38,61,66 If oral and denture hygiene are taken care of, forces from RPDs alone may not cause abutment tooth mobility.57

Effect of Components of removable partial denture on periodontal status of abutments
Direct retainer design
    Direct retainers vary in shape, origin and materials according to the suitability and requirement of partially
dentate situation.67 Direct retainers are considered to cause gingival recession and increase caries of abutment
teeth.68-74 However if retainers are placed according to survey line and well supported by rests, they will not cause any harm to periodontal tissue.67,75 Some studies have showed that precision attachments are less damaging to periodontium than the clasp type retainers; this may be due to better vertical loading of abutments teeth.74,76-79 For distal extension bases mesial rest with I bar retainers were proven to be more favorable for longevity of abutment teeth.72,73,75,76,78-82 For periodontally compromised abutments bar retainers in the clasp type retainers and non-rigid retainers in the attachments type retainers were found to be favorable for periodontal health of abutment teeth than any other types of retainers.66,73-75,78-83 Newer composite materials have comparable retentive and mechanical properties as compared to cobalt chromium clasp.84 Clasps made out of PEEK (Poly ether ether ketone) were found to have less flexural strength than cobalt chromium clasps.85, thus to achieve retention they would be made wider than cobalt chromium clasps, which may cause increase in plaque accumulation.

Major and Minor connector design
A basic design principle for removable partial denture is to extend the dentures on to supporting tissues and minimize the coverage of marginal gingival tissues.81 Marginal gingiva that is loosely attached to the alveolar bone is prone to stripping from contact with denture components especially the major connectors.76,81,86-88 This stripping is due to the lack of well supported occlusal rests or excessive coverage of components over the gingival collar.87-91 As a design principle a minimum of 4-6mm of distance should be kept between marginal gingiva and borders of Major connector.15,46

Denture Framework materials
Traditionally metal has been used for denture framework for RPDs but with advent of new materials various
non-metallic materials have been used for Denture framework such as PEEK . The advantage of PEEK over metal denture framework materials is that its modulus of elasticity closely matches to that of alveolar bone. In a study by Xin et al, it was shown that due to flexibility of framework made by PEEK, forces on abutment teeth were less than other metallic denture framework; however the forces on mucosa were increased specially in the distal extension bases. Thus for patients with poor periodontal status of remaining teeth, PEEK may be used as a denture framework but for distal extension bases it is not recommended.92 In another study, High impact denture resin was compared with cobalt chromium RPDs. There was no statistical and clinical difference in outcomes of periodontal health in both materials.93 However, Itoh et al concluded that rigidity of major connector is associated with decreased abutment mobility.65

Split Major Connectors
Stress breaking phenomena is of paramount importance in minimizing forces on abutment tooth. While various clasps are designed to disengage the abutment tooth during physiological movement of distal extension base; the Split Major Connectors or Stress breakers are designed to decrease torqueing forces to the abutment teeth during physiological movement of distal extension base dentures.94
Henderson and Steffen suggested a split lingual bar to redirect the torqueing forces on the abutment tooth.13 Photo elastic studies were done by Reitz et al. prove the efficacy of split major connectors in both maxillary and mandibular arch.94,95 For maxillary major connector he stated that the split palatal major connector reduced the forces directed to the distal-extension abutment and transferred to the regions underlying the denture base. For mandibular major connector he stated that95,96
1. In short distal extension bases , there is no significantreduction of force on abutments by use of split
major connector.
2. If the split of major connector extends to the midline, the stress on the distal-extension abutment is not only in            a more vertical direction but also has less magnitude.
3. In the long distal extension denture bases, the stress was increased on the alveolar bone.

Effect of splinting of abutments
Few in-vitro photoelastic studies suggested that at least two abutment teeth should be splinted in distal extension
bases for reduction of stresses especially when periodontal support in compromised.97,98 In some studies it was suggested that fixed splinting of abutment teeth should be done when attachment are used for distal extension bases.70,81 Splinting of abutment tooth is associated with less abutment movement than non-splinted abutments.77,99 Carlson reported that in addition to splinting of abutments the other main factors included denture hygiene and gingival relief for successful RPDs.98 No clinical study was found on this subject.

Effect of impression technique
Impression making is a fundamental step for establishing the attributes of the denture i.e. support, stability and retention. Impression making of distal extension bases must accommodate the function movement of denture base.
Stability of denture base and load sharing with teeth is directly related to amount of contact of supporting mucosa
with major connector.100 An in vivo study compared the functional movement of distal extension RPD bases made
by three different impression techniques; (a) an altered-cast impression, (b) an impression made from a border-molded custom tray, (c) an irreversible hydrocolloid impression in a stock tray. The altered cast impression had less movement of distal extension base in that can be clinically significant because mucosal support has an indispensable role of sharing the occlusal load with the abutment teeth in distal extension RPDs.101 A recent systematic review reported that there is not enough advantage of altered cast impression over one piece cast.102 This is because of lack of data to prove that altered cast impression is better than any other technique for distal extension removable dental prosthesis impressions. The article also emphasizes that there is need for more scientific research with larger sample sizes and longer performance reviews.

Periodontal Maintenance in recall appointments
Recall appointments are necessary for both periodontal and prosthetic maintenance for patients wearing RPDs.
However these are not well maintained in all the dental facilities especially where students’ work.103 Periodic recall
appointments aid in early diagnosis of a periodontal diseases or a prosthetic condition which are easier to control in the early stages.103,104 The frequency of these recalls depends on the need of individual patient, because of the variation in immune status, denture biomechanics and plaque control. Distorted or damaged components of dentures, Ill-fitting dentures, changes in occlusion, and signs of Parafunction and poor denture hygiene can render the RPDs useless or even dangerous. Thus a timely intervention can save undesirable trauma to the remaining teeth and soft tissues.58,105,106

Conclusion
Considering all the above stated literature, there are many factors of periodontal health in patients wearing removable partial denture, however the most fundamental factors are Recall appointments and Oral and denture hygiene which are usually ignored in most of the practices. Therefore, it is of utmost importance that the dentists must follow up with their patients and keep a record of their periodontal health because prevention is better than cure. The designing of the prosthesis must foresee the periodontal implication of the individual components.

CONFLICT OF INTEREST
None to declare

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86. Ao A, Wakabayashi N, Nitta H, Igarashi Y. Clinical and Microbiologic Effects of Lingual Cervical Coverage by Removable Partial Dentures. Int J Prosthodont 2013; 26:45-50.
https://doi.org/10.11607/ijp.3061

87. Ogunrinde TJ, Dosumu OO, Shaba OP, Akeredolu PA, Ajayi MD. The influence of the design of mandibular major connectors on gingival health. Afr J Med Med Sci 2014; 43:29-33.

88. Orr S, Linden GJ, Newman HN. The effect of partial denture connectors on gingival health. J Clin Periodontol 1992;19:589-94.
https://doi.org/10.1111/j.1600-051X.1992.tb00688.x

89. Lechner SK. Partial dentures and gingival health. 1963; 208: 1963- 966.

90. Ribeiro DG, Jorge JH, Varjão FM, Pavarina AC GP. Evaluation of partially dentate patients ‘ knowledge about caries and periodontal disease. J Gerondontology 2012;29:253-58.
https://doi.org/10.1111/j.1741-2358.2011.00460.x

91. Wright PS, Hellyer PH. Gingival recession related to removable partial dentures in older patients. J Prosthet Dent 1995;74:602-07.
https://doi.org/10.1016/S0022-3913(05)80312-9

92. Chen X, Mao B, Zhu Z, Yu J, Lu Y, Zhang Q et al. A threedimensional finite element analysis of mechanical function for 4 removable partial denture designs with 3 framework materials:CoCr, Ti-6Al-4V alloy and PEEK. Sci Rep 2019;1:1-10.
https://doi.org/10.1038/s41598-019-50363-1

93. Maninder, Rajesh. Comparative clinical evaluation of removable partial dentures made of two different materials in Kennedy Applegate class II partially edentulous situation. Med j ournal armed f orces indian 2015;71:306-12.
https://doi.org/10.1016/j.mjafi.2012.08.020

94. Bickley W. Combined splint-stress breaker removable partial denture. J pros dent 1969;21:509-12.
https://doi.org/10.1016/0022-3913(69)90072-9

95. Educ C, Dimensions N, Surg O, Jh K, Dimensions N. A photoelastic study of stress distribution mandibular split major connector. 1985;54:220-25.
https://doi.org/10.1016/0022-3913(85)90292-6

96. Caputo AA, Ph D. A photoelastic study of a split palatal major. J pros dent1 984;54:19-23.

97. Itoh H, Caputo AA, Wylie R, Berg T, Angeles L. Effects of periodontal support and fixed splinting on load transfer by removable partial dentures. J pros dent 1998;79:465-71.
https://doi.org/10.1016/S0022-3913(98)70163-5

98. Carlon GE et al. Studies in partial pental prosthesis IV. final results of a 4-year longitudinal investigation of dentogingivally supported partial dentures. Acta Odontol Scand 1965;23:443-69.
https://doi.org/10.3109/00016356509021764

99. Aydinlik E, Ph D, Dayangas B, Ph D. Effect of splinting on abutment tooth movement. J pros dent 1983;49:477-80.
https://doi.org/10.1016/0022-3913(83)90306-2

100. Fernandes CP GP. he significance of major connectors and denture base mucosal contacts on the functional strain patterns of maxillary removable partial dentures. Eur J Prosthodont Restor Dent 1998; 6:63-74.

101. Leupold J, Pfeifer DL. hree risen of vertical movement xtension removable partial impression techniques occurring denture during loading bases made by of. J pros dent 1992;65:290-93.
https://doi.org/10.1016/0022-3913(92)90332-5

Muhammad Haider Amin Malik                                   BDS, FCPS

Nazia Yazdanie                                                             BDS, FCPS, MSc, PhD

OBJECTIVE: To review the periodontal considerations associated with removable partial denture therapy.
METHODOLOGY: Using a MEDLINE search, for "removable partial dentures periodontal", a total of 712 papers from
peer-reviewed journals came in results. The MEDLINE search was made more specific by applying filters to the key phrase
with other key words such as "periodontal evaluation"(140), "direct retainers"(77), "non-surgical periodontal"(8), "surgical
periodontal"(180), "plaque"(249), "periodontal indices"(112), "tooth mobility,"(180) "periodontal maintenance,"(60) "splinting,"(198)
and "split major connector"(2). Both in vivo and in vitro studies on the Perio-prosthodontic aspects of RPD treatment were
included in the study pool whereas case Series and case reports were excluded.
RESULT: A total of 1206 studies were collected from the search engine. After applying the exclusion criteria and filtering the
duplicates a total of 95 studies were included for the narrative review.
CONCLUSIONS: Out of all the factors, recall and oral and denture hygiene have the utmost importance.
KEYWORDS: Perio-prosthodontics, removable partial denture, periodontal indices.
HOW TO CITE: Malik MHA, Yazdanie N. Perio-prosthodontics considerations in removable partial denture: the role of the
prosthodontist. J Pak Dent Assoc 2021;30(3):219-227.
DOI: https://doi.org/10.25301/JPDA.303.219
Received: 09 August 2020, Accepted: 12 March 2021

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Marium Azfar                                   BDS, MPH

Saima Qureshi                                 BDS, FCPS

Syeda Noureen Iqbal                      BDS, FCPS

Sadia Rizwan                                  BDS, FCPS

Imran Khan                                     BDS, MSc

Arfa Baig                                         BDS, FCPS

Khadijah Abid                                 MSPH, MSc, BS Hons

OBJECTIVE: The objective of this paper was to assess the awareness regarding oral aphthous ulcers and its risk factors among
BDS and MBBS students in private institute of Karachi, Pakistan.
METHODOLOGY: A cross-sectional survey was conducted at a private institute of Karachi Pakistan for the duration of six
months. Medical and dental students of age more than 18 years of either gender were enrolled in the study using non-probability
convenience sampling technique. Pre-designed proforma was used to collect data regarding demographics, history of recurrent
aphthous stomatitis and knowledge of oral aphthous ulcers and its risk factors. The knowledge score of 4 out of 6 was considered
as adequate knowledge. SPSS version 25 was used to analyze data.
RESULTS: Of 150 participants, the mean age was reported as 22.94±1.65 years (range: 21-25 years). In those 150 participants
46 were males (30.7%) and 104 were females (69.3%). Overall mean score of knowledge was 4.35±1.29. Wherein 73% had
adequate knowledge regarding oral ulceration and its risk factors. The dental students had significantly higher proportion of
adequate knowledge regarding oral ulceration than medical students [p=0.024].
CONCLUSION: Overall students had good knowledge of oral ulceration and its risk factors, wherein knowledge of dental
students was better than medical students.
KEYWORDS: Oral ulcers; Recurrent Aphthous stomatitis; awareness, oral ulceration, risk factors, eating habits
HOW TO CITE: Azfar M, Qureshi S, Iqbal SN, Rizwan S, Khan I, Baig A, Abid K. Awareness regarding oral aphthous ulcers
and its risk factors among BDS and MBBS students-A cross-sectional survey. J Pak Dent Assoc 2021;30(3):215-218.
DOI: https://doi.org/10.25301/JPDA.303.215
Received: 25 November 2020, Accepted: 25 May 2021

INTRODUCTION
The most frequent type of ulcers occurring in the oral cavity are aphthous ulcers also known as recurrent aphthous stomatitis. It is a degradation of the epithelium that contributes to the formation of underlying inflamed conjunctive tissue.1 Almost 25% of people around the world suffer from oral ulcers and estimated point prevalence is 4% globally.2 It is prevalent among both genders but predominantly affects females and teenagers.3,4
Stress, family history, infective agents, allergic conditions, hormonal disturbances and gastrointestinal diseases are the most common etiological causes of oral ulceration, but the causes of recurrent aphthous stomatitis remain unknown and vague.1 However, literature showed that stress (54.8%), was the common cause of recurrent aphthous stomatitis followed by nutritional deficiency as 25% (i.e. micro-nutrient deficiencies including iron, folate, zinc, B1, B2, B6, B12 deficiencies) and food stuff (16%).2,5
Dental as well as medical graduates can play an important role in educating the patient, friends, families and communities regarding prevention, diagnosis and treatment of oral ulcers.6-8 Statistics regarding how well dental and medical students are aware of oral ulcers is unavailable. One research found that only 56% of dental students were familiar with the true etiology and therapies of oral ulcers and 64.2% of the dental students had experienced recurrent aphthous stomatitis which was prevalent among female students.9
There is lack of information available on the awareness of oral aphthous ulcers among medical and dental students
in Pakistan. The purpose of the current study is therefore, to explore level of awareness among students. The study
will help students learn about the disease diagnosis, its etiologies, therapies and prevention strategies.

METHODOLOGY
   A cross-sectional survey was conducted at a private institute of Karachi Pakistan for the duration of six months. Sample size of 150 was estimated on Open epi sample size calculator using proportion of knowledge regarding true
etiology and therapies of oral ulcers among dental students as 0.569, absolute precision as 8% and 95% confidence level. Medical and dental students of age more than 18 years of either gender were enrolled in the study using non-probability convenience sampling technique. Participants who did not give consent were excluded from the study.
This research was approved by ethical review committee of Sir Syed College of Medical Sciences (Ref#SSCMS/College/Principal/Dental/20001161).
Study was initiated after taking verbal consent from all the eligible participants. Pre-designed proforma was used to collect data regarding demographics and history of recurrent aphthous stomatitis. Second section questionnaire included six questions regarding knowledge of oral aphthous ulcers and its risk factors. The knowledge score of 4 out of 6 was considered as adequate knowledge. The questionnaire for knowledge assessment was designed by the research team itself. The validation and reliability of the questionnaire was checked by applying reliability analysis which gave the value of Cronbach’s alpha as 73%.
SPSS version 25 was used to analyze data. Numeric data such as age and knowledge score were presented as mean
and SD while categorical data like gender, education background, experience of oral ulcers knowledge questions
and adequate knowledge was presented as frequency and percentage. Chi-square was applied to see the association
between knowledge level and effect modifiers like age, gender, experience of oral ulcers and education background.
A p-value<0.05 was taken as statistically significant.
Of 150 participants, the mean age was reported as 22.94±1.65 years (range: 21-25 years). Of 150 participants
46 were males (30.7%) and 104 were females (69.3%). Majority of the participants were dental students (n=81, 54%) and 69 were medical students (46%) respectively. Of 150 participants, 57 had experienced oral ulcers (38%)
and 93 had no experience (62%).
About 88.7% of the participants claimed that they knew about oral ulcerations. Almost 71% said spicy food is risk
factor for oral ulcers, 74% said smoking can cause oral ulcers and 69% considered stress as a risk factor. Of 150 participants 64% said family risk history is a risk factor for oral ulceration and 68.7% said type of toothpaste can play a role in occurrence of oral ulcerations. (Table 1)
  There was statistically insignificant difference in proportions of adequate knowledge with respect to age
(p=0.247), gender (p=0.262), and experience of oral ulcerations (p=0.194). The dental students had significantly
higher proportion of adequate knowledge regarding oral ulceration than medical students [p=0.024]. (Table 2)

DISCUSSION
   A total of 150 students taken part in the study and responded back. Most of the participants were females and this reflects the dominancy of female students in medical and dental college. Out of 150 students. 88.7% of the students
knew about oral ulcerations and 11.3% did not have idea of oral ulcerations. Similarly, in a previous research 85% of
the responders knew about oral ulcerations.9 In a research by Rathod et al it was found that 44% of the students had
history of oral ulceration.10 In our research, the experience of oral ulceration was low in all students (38%). Whereas
in previous researches, the experience of oral ulceration was high among all students.9,11,12
Some researches had showed that incidence of oral ulceration is highly correlated with diet.13,14 In previous researches of oral ulceration associated with diet have shown, that fried items and spicy foods are the potential risk factors for oral ulcers.15,16 thought that spicy food intake is the reason of oral ulcerations.9 In our research we found that 71.3% of the students knew that spicy food is a risk factor for oral ulcerations. This statistics highlights that Pakistani people usually consumes more spice in food on daily basis, and spicy food can influences the health outcomes like oral ulceration.17,18 Previous researches have also shown that stress and family history of risk factors of oral ulcerations.1,19 In current study, we found that most of the students knew that stress and positive family history of oral ulceration are risk factors of ulcerations. Hence, this is important for students to know which kind of food should be avoided and to manage stress in order to prevent ulceration.16
In our research, most students knew the form of toothpaste could cause oral ulceration (69 per cent). However, previous literature has demonstrated that students have limited understanding of toothpaste ingredients. This can be troubling, since it is important to know the product you use to brush your teeth every day because whatever you consume, it should be safe enough. Herlofson et al20 has demonstrated that tooth paste containing sodium lauryl sulphate is one of the main cause of oral ulceration. In a similar research, it was revealed that 30% of the students did not know whether sodium lauryl sulphate is present in their toothpaste or not and 63.3% did not know about the chemical composition of the toothpaste.9 Another research reported that 72% of the students did not look at the chemical composition of toothpaste and they choose toothpaste on the basis of brand and price.21
The relationship between oral ulcerations and smoking is not fully cleared. However, the highest prevalence of oral ulcerations was observed among young individuals especially university students.22 A hospital based study also revealed that tobacco users had less chances of oral ulcerations as compared to non-users.23 The literature on the “protective effect” of tobacco use, particularly smoking, on aphthous ulceration has been heavily debated, especially in terms of a possible underlying mechanism. It’s been suggested that smokers’ oral mucosa has further keratinization.22 Keratinization prevents the oral tissues from bacterial penetration and trauma. Multiple compounds are ingested systemically from cigarette smoke, and one of these absorbed constituents that encourages keratinization may be hyperkeratosis, which is usually confined to the mucosal region where smokeless tobacco is kept. While hyperkeratosis is a premalignant disease, it is conceivable that it protects the oral mucosa from aphthous ulcers by providing a local protective impact. There is also debate about whether nicotine, which is found in cigarettes, or one of the tobacco product’s constituents, causes the defensive effect.18,24 Nicotine is more systemically consumed in cigarettes than in nonsmokers, so the former may have a lower defensive benefit than the
latter.18,24-26 In our study we found that 74% of the students thought that smoking can cause oral ulcerations. This shows that only 26% of participants had correct knowledge and were aware that smoking had protective effect on oral ulcerations.
In our study, most of the students were adequately aware of oral ulceration and its risk factors (67.3%) and high
proportion of knowledge regarding oral ulceration was observed among dental students. This study would be help in
designing educational intervention for students mainly for final year students who are going to deal with patients

CONCLUSION
     Overall students had good knowledge of oral ulceration and its risk factors, wherein knowledge of dental students
was better than medical students.

CONFLICT OF INTEREST
None to declare

REFERENCES

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2. Patil S, Reddy SN, Maheshwari S, Khandelwal S, Shruthi D, Doni B. Prevalence of recurrent aphthous ulceration in the Indian Population. J Clin Exp Dent. 2014;6:e36-40.
https://doi.org/10.4317/jced.51227

3. Amadori F, Bardellini E, Conti G, Majorana A. Oral mucosal lesions in teenagers: a cross-sectional study. Ital J Pediatr. 2017;43:1-6.
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4. Queiroz S, Silva M, Medeiros AMC, Oliveira PT, Gurgel BCV, Silveira É JDD. Recurrent aphthous ulceration: an epidemiological study of etiological factors, treatment and differential diagnosis. An Bras Dermatol.
2018;93:341-46.
https://doi.org/10.1590/abd1806-4841.20186228

5. Edgar NR, Saleh D, Miller RA. Recurrent aphthous stomatitis: A review. J Clin Aesthet Dermatol. 2017;10:26-36.

6. Ahamed S, Moyin S, Punathil S, Patil NA, Kale VT, Pawar G. Evaluation of the oral health knowledge, attitude and behavior of the preclinical and clinical dental students. J Int Oral Health. 2015;7:65-70.

7. Petrauskiene S, Mushayev H, Zemgulyte G, Narbutaite J. Oral health awareness among international dental and medical students at Lithuanian University of Health Sciences: a cross-sectional study. J Oral Maxillofac Res. 2019;10:e3.
https://doi.org/10.5037/jomr.2019.10403

8. Liu H-Y, Chen J-R, Hsiao S-Y, Huang S-T. Caregivers’ oral health knowledge, attitude and behavior toward their children with disabilities. J Dent Sci. 2017;12:388-95.
https://doi.org/10.1016/j.jds.2017.05.003

9. C LP. Knowledge , experience and risk factors for oral aphthous ulcers among BDS students: University of Nairobi; 2009.

10. Rathod U, Kulkarni S, Agrawal V. Prevalence of recurrent aphthous ulcers in dental student: A questionnaire based study. Stress. 2017;180: 80-83.

11. Kaimenyi JT. Oral health in Kenya. Int Dent J. 2004;54:378-88. https://doi.org/10.1111/j.1875 595X.2004.tb00015.x

12. Kaimenyi J, Guthua S. Occurrence of ulcerative oral lesions at Kenyatta National Hospital, Nairobi, Kenya. Afr J Health Sci. 1994;1:179-81.

13. Du Q, Ni S, Fu Y, Liu S. Analysis of dietary related factors of recurrent aphthous stomatitis among college students. Evid Based Complement Alternat Med. 2018;2018:2907812.
https://doi.org/10.1155/2018/2907812

14. Challacombe SJ, Alsahaf S, Tappuni A. Recurrent aphthous stomatitis: Towards evidence-based treatment? Current Oral Health Reports. 2015;2:158-67.
https://doi.org/10.1007/s40496-015-0054-y

15. Ma R, Chen H, Zhou T, Chen X, Wang C, Chen Y, et al. Effect of bedtime on recurrent aphthous stomatitis in college students. Oral Surg Oral Med Oral Pathol Oral Radiol. 2015;119:196-201.
https://doi.org/10.1016/j.oooo.2014.10.014

16. Shi L, Wan K, Tan M, Yin G, Ge M, Rao X, et al. Risk factors of recurrent aphthous ulceration among university students. Int J Clin Exp Med. 2015;8:6218-223.

17. Safdar NF, Bertone-Johnson E, Cordeiro L, Jafar TH, Cohen NL. Dietary patterns of Pakistani adults and their associations with sociodemographic, anthropometric and life-style factors. J Nutr Sci.
2013;2:e42.
https://doi.org/10.1017/jns.2013.37

18. Yang K, Li Y, Xue Y, Wang L, Liu X, Tu R, et al. Association of the frequency of spicy food intake and the risk of abdominal obesity in rural Chinese adults: a cross-sectional study. BMJ Open. 2019;9:e028736.
https://doi.org/10.1136/bmjopen-2018-028736

19. Senusi A, Higgins S, Fortune F. The influence of oral health and psycho-social well-being on clinical outcomes in Behçet’s disease. Rheumatol Int. 2018;38:1873-883.
https://doi.org/10.1007/s00296-018-4117-y

20. Herlofson BB, Barkvoll P. Sodium lauryl sulfate and recurrent aphthous ulcers: a preliminary study. Acta Odontologica Scandinavica. 1994;52: 257-59.
https://doi.org/10.3109/00016359409029036

21. Fernandes F, Groisman S, Toledo E, Sampaio F, Verbicario R, Ricardo H, et al. Habits and knowledge about toothpaste of students from Legiao Da Boa Vontade (LBV). J Dent Health Oral Disord Ther. 2015;3:00076.
https://doi.org/10.15406/jdhodt.2015.03.00076

22. Abdullah MJ. Prevalence of recurrent aphthous ulceration experience in patients attending Piramird dental speciality in Sulaimani City. J Clin Exp Dent. 2013;5:e89-94.
https://doi.org/10.4317/jced.51042

23. Mohamed S, Janakiram C. Recurrent aphthous ulcers among tobacco users- hospital based study. J Clin Diagn Res. 2014;8:Zc64-lc6.
https://doi.org/10.7860/JCDR/2014/10368.5145

24. Mohammed MEA, Brima EI. Cytological changes in oral mucosa induced by smokeless tobacco. Tob Induc Dis. 2019;17:46. Article ID PMID 31516489
https://doi.org/10.18332/tid/109544

25. Sawair FA. Does smoking really protect from recurrent aphthous stomatitis? Ther Clin Risk Manag.
2010;6:573-77.
https://doi.org/10.2147/TCRM.S15145

26. Motamedi MR, Golestannejad Z. Use of pure nicotine for the treatment of aphthous ulcers. Dent Res J (Isfahan). 2015;12:197-8.

Marium Azfar                                   BDS, MPH

Saima Qureshi                                 BDS, FCPS

Syeda Noureen Iqbal                      BDS, FCPS

Sadia Rizwan                                  BDS, FCPS

Imran Khan                                     BDS, MSc

Arfa Baig                                         BDS, FCPS

Khadijah Abid                                 MSPH, MSc, BS Hons

OBJECTIVE: The objective of this paper was to assess the awareness regarding oral aphthous ulcers and its risk factors among
BDS and MBBS students in private institute of Karachi, Pakistan.
METHODOLOGY: A cross-sectional survey was conducted at a private institute of Karachi Pakistan for the duration of six
months. Medical and dental students of age more than 18 years of either gender were enrolled in the study using non-probability
convenience sampling technique. Pre-designed proforma was used to collect data regarding demographics, history of recurrent
aphthous stomatitis and knowledge of oral aphthous ulcers and its risk factors. The knowledge score of 4 out of 6 was considered
as adequate knowledge. SPSS version 25 was used to analyze data.
RESULTS: Of 150 participants, the mean age was reported as 22.94±1.65 years (range: 21-25 years). In those 150 participants
46 were males (30.7%) and 104 were females (69.3%). Overall mean score of knowledge was 4.35±1.29. Wherein 73% had
adequate knowledge regarding oral ulceration and its risk factors. The dental students had significantly higher proportion of
adequate knowledge regarding oral ulceration than medical students [p=0.024].
CONCLUSION: Overall students had good knowledge of oral ulceration and its risk factors, wherein knowledge of dental
students was better than medical students.
KEYWORDS: Oral ulcers; Recurrent Aphthous stomatitis; awareness, oral ulceration, risk factors, eating habits
HOW TO CITE: Azfar M, Qureshi S, Iqbal SN, Rizwan S, Khan I, Baig A, Abid K. Awareness regarding oral aphthous ulcers
and its risk factors among BDS and MBBS students-A cross-sectional survey. J Pak Dent Assoc 2021;30(3):215-218.
DOI: https://doi.org/10.25301/JPDA.303.215
Received: 25 November 2020, Accepted: 25 May 2021

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Mansoor Khan                              BDS, FCPS, CHPE

Alia Ahmed                                   FCPS, MHPE

Muhammad Qasim Javed            FCPS, MSc

OBJECTIVE: To assess the perception of buccal corridor width on smile esthetics by Orthodontic residents, General dentists
and Laypersons
METHODOLOGY: A smile photograph was taken of an adult female. The image was modified to obtain five different buccal
corridor widths and were assessed by different evaluators grouped into general dentist, orthodontic resident and laypersons who
rated the attractiveness of each smile by means of a visual analog scale (VAS). Sample size was 97 participants to rate the
picture. Non-probability purposive sampling was done The data was analyzed and mean and SD were calculated for the scores
of rating. ANOVA and Tukey's post hoc test was applied to compare the different ratings of buccal corridors in three groups.
The data of this cross sectional study was collected from general population belonging to different communities, general dentists
and orthodontic residents of different dental colleges of Karachi, Pakistan from August 2019 to March 2020.
RESULTS: There were 97 participants who responded to the images. Highest scores were obtained for Image 1 having buccal
corridor width ratio of 16% followed by image no. 3 having buccal corridor width ratio of 10% and lowest scores were obtained
for Image no. 6 having least buccal corridor widths ratio that is 34% followed by image no 5 having 26% buccal corridor widths.
Among the groups of participants, the highest scores were given by laypersons for all images. Significant differences were
observed between evaluation of groups of Orthodontic resident and layperson in most images.
CONCLUSION: There was a remarkable influence of buccal corridor width on smile esthetics, with the 16% ratio group being
rated as the most attractive by all three groups.
KEYWORDS: Buccal corridors, Smile, esthetics, Attractiveness
HOW TO CITE: Siddiqui H, Rizwan S, Faisal SS, Hussain SS. EFfect of buccal corridors width on smile quality and esthetics.
J Pak Dent Assoc 2021;30(3):204-208.
DOI: https://doi.org/10.25301/JPDA.303.204
Received: 13 November 2020, Accepted: 27 April 2021

INTRODUCTION
   The main reason that is reported for the unfavorable outcome of an endodontic treatment is the microbial
leakage to the periapical area. The leakage of microorganisms is the consequence of suboptimal instrumentation, inadequate cleaning, insufficient length and density of root canal obturation.1 Additionally, missed and untreated root canals have been highlighted as the contributory factors towards the development of periapical lesions.2 Therefore, in order to achieve a successful outcome for the endodontic procedures a thorough knowledge of the root
canal system is required for adequate cleaning, shaping and obturation.
Considering the tooth morphology, one of the most variant and challenging tooth to treat is the maxillary second
molar. A few studies have investigated the morphological variations in the roots and the root canal systems of the
maxillary second molars.3,4,5,6 Pecora et al examined 200 maxillary second molar teeth and found that 58% of the
teeth exhibited three canals, while four canals were found in 42 % of the teeth. The fourth canal was mainly found in
the mesiobuccal root of these teeth.3 However, two distinct canals have also been reported in distobuccal and palatal roots.4,5,6 Libfeld and Rotstein reported that 90.6% of the second maxillary molars had three roots with three or four canals, whereas 6% of the teeth were two-rooted, 3% had a single root, and 0.4% had four roots.7
Moreover, some case reports have also been published with rare findings with respect to the number of canals and
roots in the maxillary second molars. Tank documented a case of maxillary second molar having two palatal roots
with two distinct canals and foramina at the apical level.8 Fava et al reported the presence of one canal and one root
in both second maxillary molars of the patient9 , while Alani reported four roots in the second maxillary molars of the patient bilaterally.10 Baratto-Filho et al. carried out an in vitro study of two maxillary second molars with four canals and two different palatal roots.11 Barbizam et al. reported a similar study of a second maxillary molar with four canals in four distinct roots.12 Benenati presented a clinical case of a second maxillary molar with two palatal roots and a groove located at the palatal side of the tooth.13
Considering, aforementioned variations in the root canal morphology of Maxillary second molar teeth. It is important that detailed visual and radiographic examination should be carried out while performing the endodontic procedure. The utilization of magnification devices like dental operating microscopes and magnifying loupes with proper lighting can significantly improve the location of canals in the clinical settings.14,15,16 The variations of the root canal systems are thought to be related to ethnicity and genetic makeup.17 There are several clinical studies on the maxillary second molars across the world, whereas, the data on the maxillary second molars is limited in Pakistan. The present study describes the use of dental loupes along with dental head light and other clinical aids like transillumination, champagne bubble test and use of 10% India ink for locating the canals in the maxillary second molars.18 The results of the study will help the Pakistani dentists in clinical decision making with regards to pretreatment and peri-treatment planning as well as in diagnosis of endodontic retreatment cases of permanent maxillary second molars. Therefore, the objective of this study was to assess the variations in the root canal configuration of maxillary second permanent molars in the Pakistani subpopulation by using different clinical aides in vivo.

METHODOLOGY
    The current cross-sectional analytical study was conducted from April to October 2018 at the Operative Dentistry Department of the Dental College of Riphah International University, Islamabad, Pakistan after obtaining the ethical apptoval from the institute (Ref. No. IIDC/1RC/2017/01/07). The sample size was calculated by using WHO calculator. Sample size was found to be 95 with confidence level of 95%, relative precision of 0.10 and estimated population proportion of 58%.3 Nonprobability purposive sampling technique was used. The
patients between the age of 18 and 50 years with adequate mouth opening who reported at the operative dentistry department for the endodontic treatment of maxillary second molars with irreversible pulpitis or pulp necrosis were included in the study after obtaining their consent. Patients who refused to participate in the study, presented with nonrestorable Maxillary second molars or had limited mouth opening were excluded from the study.
The patients were administered local anesthesia by infiltration technique in the buccal sulcus adjacent to the upper second molar which was to be treated followed by the rubber dam application. A standard access cavity was made using the no 4 round bur (Dentsply/Maillefer, USA) and non-end cutting tapering fissure carbide bur (EndoZ bur,
Dentsply/Maillefer, USA). After deroofing the chamber completely and straightening the walls appropriately, bleeding was controlled using sodium hypochlorite wash (PD,Switzerland) and by excavating the coronal portion of
the pulp with a spoon excavator (excavator 123/124, Dentsply Ash instruments, UK). After the hemostasis was achieved the chamber floor was examined with the help of 2.5x magnifying loupes (Gallilean loupes, Keeler, UK). The identified orifices of mesiobuccal, distobuccal and palatal canals were negotiated with size 15 k files (SybronEndo, USA) .The presence of additional canals were then ruled out by using transillumination (TransCure, Kinetic Instruments Inc, USA), champagne bubble test and by staining the floor with 10 % India ink (Pelikan,Germany).18 The additional canals thus found were then negotiated with size 10k files (SybronEndo,USA) and a radiograph was taken after placing the files in all the located canals in order to confirm the presence or absence of these canals. The findings were then recorded on a proforma stating the age and gender of the patients along with all the other information collected during the procedure.
Data analysis was done using SPSS version 23. Mean and standard deviation were described for the demographic
characteristics of the participants (age and gender). Frequencies and percentages of the number of canals in second maxillary molars were also calculated. In order to control the effect modifiers the patients were stratified according to age and gender. Chi-square test was applied to see the effect of age and gender on presence of three canals.
P-value of less than 0.05 was taken as significant. The following null hypotheses were tested: (i) Age have no effect on presence of three canals (ii) Gender has no effect on presence of three canals (iii) In male patients, age has no effect on presence of three canals (iv) In female patients, age has no effect on presence of three canals.

RESULTS
    Total ninety five subjects with 55(57.9%) females and 40(42.1 %) males participated in this study. The female to
male ratio was 1.37:1. The age of the participants was between 18 years and 50 years. Overall, 37(38.9%) patients
were in age group 1(18-30 years), 28(29.4%) patients were in age group 2(31-40 years) and 30 (31.5%) were in age
group 3(41-50 years). Out of the 95 teeth included in the study 6(6.3%) teeth had a single canal, 7(7.4%) teeth had two canals, 58(61.1%) teeth had three canals and 24(25.3%) teeth had four canals (Table 1).
In group 1(18-30 years), total 3 canals were found in 17 patients. In group 2 (31-40 Years) 19 patients were having 3 canals. In group 3 (41-50), 22 patients were found having 3 canals. The results showed that the chances of having 3

canals got significantly higher with the increasing age (p-value=0.049) (Table 2).
Gender-wise evaluation of teeth showed that 3 canals were found in 29 males out of 40 and 29 females out of 55. The difference was found to be statistically insignificant (p-value=0.051) (Table 3).
Data was further analyzed for the presence of 3 canals in male and female patients within different age groups.
Significant difference was noted in the presence of 3 canals in both male and female patients (Table 4 and Table 5).

DISCUSSION
    The goal of endodontic therapy is to relieve pain and achieve healing of the periapical area. The failure to accomplish aforementioned goal results in the post treatment disease.2 The failure to eradicate the intra-radicular bacteria is the main etiological factor for the post treatment disease. These bacteria may survive within the canal due to a host of reasons including the inability of the disinfectants to reach the bacteria or missed canals during the preparation of access cavity.2 The canals which may go undetected during the access cavity preparation stage are the additional canals that occur in certain type of teeth as normal morphological variations. Apart from a thorough knowledge of the anatomy of the teeth, use of magnification and clinical adjuncts can also greatly increase our ability to identify and negotiate the canals.14,15,16 The present study was designed to make use of clinical aids during access cavity preparation of maxillary second molars in order to identify the variations in the root canal configuration of maxillary second permanent molars. The aids included the magnifying dental loupes, staining of
the pulp chamber floor, use of trans-illumination and the champagne bubble test.
The prevalence of one and four canals in the current research were comparable with the findings of study
conducted by Shafqat et al on the Pakistani population.19 The prevalence of second maxillary molar teeth with one
and two canals was significantly higher in Pakistani population as compared to the Brazilian population (0%).3 Conversely, Pecora and colleagues reported significantly higher percentage of second maxillary molars (42%) with 4 canals in Brazilian cohort.3 The percentages of four canals in Pakistani population were found to be 25.3% in current study and 21.25% as reported by Shafqat et al.19 Accordingly, Peikoff et al noted 22.7% of the maxillary second molars with four canals in the American population while using radiographic method to assess the number of canals.20 Olczak reported 70% maxillary second molars with three canals while 23.2% teeth had four canals in polish population. The frequency of one canal was 1% and two canals was 3.9 % in the same study.21 Interestingly, although observed using CBCT which is a very accurate method for detecting root morphology, the findings of Olczak et al closely match the result of the present study. According to Naseri et al 31% teeth had 3 canals while 4 canals were found in 67.5 % teeth. 1.2 % teeth had 5 canals while none of the teeth had single canal or two canals.22
The variation in the findings might be attributed to the difference in the ethnicities that can affect the morphology of the root canals and the number of root canals.23 Another factor can be the different investigative methods used by the researchers.3,20,24
All the teeth with four canals in the current study had fourth canal in the Mesio-buccal (MB) root. The findings
were in line with several previous researches where fourth canal was found as an additional canal in the MB root of
the maxillary second molar.3,5,7,15,16,20 Pecora et al investigated 200 maxillary second molars by utilizing the clearing technique and found that 42 % of the teeth with four canals had the fourth canal exclusively located in their MB roots.3 Likewise, Peikoff and colleagues, while investigating 520 Maxillary second molars reported that fourth canal was located in the MB root of all the teeth with four canals (22.7%).20
The prevalence of three canals in present study was about 61%. Whereas the study by Shafqat et al on Pakistani
population has reported the prevalence of 50%.19 The authors did not find any further study on second maxillary molars in Pakistani population. The findings of current study were in line with the results reported in American (56.9%) and Brazilian (58%) populations. Cross tabulation of the age and the frequency of different canals showed that the highest number of three canaled molars was present in group 3(41-50 years) that is 22 teeth which is consistent with the trend observed in other in vivo24,25 and in vitro studies.3,26,27 This suggest that with age calcification of the mb 2 canals leads to its obliteration and decreases the number of negotiable canals to 3. The lowest number of three canaled molars was present in the group 1(18- 30 years) that is 17 teeth. The incidence of four canaled molars however, showed a reverse trend. The highest incidence of these teeth was found in group 1(18-30years) that is 18 teeth. The lowest incidence of these teeth was found in group 3(41-50 years), that is only 1 tooth. The findings obtained via correlation between age and number of canals were in line with the findings of the previous studies which suggest that in younger individuals the mb2 canal is not completely calcified and may be negotiable clinically even under 2.5 x magnification.3,20
The comparative findings of various studies also show great discrepancy in the incidence of the second
mesio-buccal canal. The frequency of its occurrence ranges from 18.6% to 93%.28 Apart from this the presence of lesser number of four canaled molars in groups with individuals of older ages may also be due to the difference in the
methodology applied in detecting the number of canals with sensitivity of 2.5x loupes being significantly less than in
vivo methods like examination under dental operating microscope. Several studies have shown that the use of higher magnification methods such as the use of dental operating microscopes significantly improve the ability of the operator to locate and negotiate additional canals such as the MB2 canal.14,15,16 Das et al reported that their ability
to localize the second MB canal increased from 36% to 68% in the subjects with age between 36 and 45 years, when
selective dentine removal using ultrasonic devices was done under the dental operating microscope.29 This demonstrates that in older individuals, even with increased chance of calcification of canals, the use of magnification and appropriate instruments may significantly increase the success of localization and negotiation of MB2 canal.
Several in vitro methods have been used to evaluate root canal morphology and the number of root canals. These
include clearing of tooth and various ink injections into the canal22,30 pulp floor inspection with scanning electron
microscope31 and examination of teeth with the three dimensional (3D) radiographic methods like CBCT and micro CT.32 The 3D radiographic methods have reported a higher incidence of a second mesiobuccal canal as compared
to other methodologies.27,28,32 The 3D reconstruction of the root canal system, as provided by this technique, greatly improves the ability of the operator to locate canals which would otherwise be missed in 2 dimensional radiographic techniques.27 The downside to CBCT is the large radiation dose when used in vivo and lower resolution as compared to the micro CT. This makes micro CT a more attractive tool in finding prevalence of canals. Micro CT is however an in vitro tool only and cannot be employed in vivo to detect the number of canals and root morphology
preoperatively, unlike CBCT.33,24
The limitations of the current study include the limited sample size, single center study and the use Dental loupes
with 2.5x magnification for canal location. Being a single centered study a discreet approach should be employed
while generalizing the findings of the study. The study also did not take into examine the number of roots of maxillary second molars in the studied population. It is recommended that in future multicenter study with a large sample size should be conducted by utilizing the three dimensional radiographic methods. The findings of such study will be applicable to whole Pakistani population.

CONCLUSION
    In conclusion the chances of having three canals in both male and female got high with the increase in age and there was no significant difference in prevalence between male and female subjects. The study also highlighted the
importance of magnification and other clinical aids in the detection of the canals. Therefore, while preparing the access cavity in the maxillary second molars the pulp floor should be carefully examined under magnification, supplemented with clinical aids, to detect all present canals.

CONFLICT OF INTEREST
 None to declare

REFERENCES

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2. Siqueira JR JF, Rôças IN. Clinical Implications and Microbiology of Bacterial Persistence after Treatment Procedures. J Endodon 2009;34:1291-301.
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7. Libfeld H, Rotstein I. Incidence of four-rooted maxillary second molars: literature review and radiographic survey of 1,200 teeth. J Endod 1989;15:129-31.
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8. Aljabreen TM. Maxillary second molar with two palatal roots: A case report. J Pak Dent Assoc 2005 ;14:49-51.

9. Fava L, Weinfeld I, Fabri F, Pais C. Four second molars with single roots and single canals in the same patient. Int Endod J 2000;33:138-42.
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10. Alani AH. Endodtontic treatment of bilaterally occurring 4-rooted maxillary second molars: case report. J Can Dent Assoc 2003;69: 733-35.

11. Barrato-Filho F, Fariniuk LF, Ferriera EL, Pecora JD, Cruz-Filho AM, Soussa-Neto MD. Clinical and macroscopic study of maxillary molars with two palatal roots. Int Endodontics J 2009;35:796-801.
https://doi.org/10.1046/j.1365-2591.2002.00559.x

12. Barbizam JV, Ribeiro RG, Tanomaru Filho M. Unusual Anatomy of Permanent Maxillary Molars. JEndodontics 2004;30:668-71.
https://doi.org/10.1097/01.DON.0000121618.45515.5A

13. Benenati FW. Maxillary Second Molar with Two Palatal Canals And Palatogingival Groove. Journal of Endodontics 1985;11:308-10
https://doi.org/10.1016/S0099-2399(85)80163-1

14. Schwarze T, Baethge C, Stecher T, Geurtsen W. Identification of second canals in the mesiobuccal root of maxillary first and second molars using magnifying loupes or an operating microscope. Aust Endod J 2002;28:57-60.
https://doi.org/10.1111/j.1747-4477.2002.tb00379.x

15. Buhrley LJ, Barrows MJ, BeGole EA, Wenckus CS. Effect of magnification on locating the MB2 canal in maxillary molars. J Endod 2002;28:324-27.
https://doi.org/10.1097/00004770-200204000-00016

16. Liang RZ, Wu YN, Hu M. Diagnostic test study of dental operating microscope used for locating the second mesiobuccal canal orifice in maxillary first molars.West China J Stomatolog 2007;25:125-8.

17. Song JS, Choi HJ, Jung IY, Jung HS, Kim SO. The prevalence and morphologic classification of distolingual roots in the mandibular molars in a Korean population. J Endod 2010;36:653-7.
https://doi.org/10.1016/j.joen.2009.10.007

18. Hargreaves KM, Berman LH. Cohen’s pathways of the pulp expert consult. Elsevier Health Sciences; 2015.

19. Shafqat A, Munir B, Sajid M. Maxillary Second Molar; Variations in Root Canal Morphology in Maxillary Second Molar in Patients undergoing Root Canal Treatment. Prof Med J. 2018;25:981-86.
https://doi.org/10.29309/TPMJ/18.4570

20. Peikoff MD, Christie WH, Fogel HM. The maxillary second molar: variations in the number of roots and canals. Int Endod J 1996;29:365-69.
https://doi.org/10.1111/j.1365-2591.1996.tb01399.x

21. Olczak, K., Pawlicka, H. The morphology of maxillary first and second molars analyzed by cone-beam computed tomography in a polish population. BMC Med Imaging 17, 68 (2017).
https://doi.org/10.1186/s12880-017-0243-3

22. Naseri M, Ali Mozayeni M, Safi Y, Heidarnia M, Akbarzadeh Baghban A, Norouzi N. Root Canal Morphology of Maxillary Second Molars according to Age and Gender in a Selected Iranian Population: A Cone-Beam Computed Tomography Evaluation. Iran Endod J. 2018;13:373-380.

23. Sert S, Bayirli GS. Evaluation of the root canal configurations of the mandibular and maxillary permanent teeth by gender in the Turkish population. J Endod 2004;30:391-98.
https://doi.org/10.1097/00004770-200406000-00004

24. Al Shalabi RM, Omer OE, Glennon J, Jennings M, Claffey NM. Root canal anatomy of maxillary first and second permanent molars. Int Endodontic J 2000;33:405-14.
https://doi.org/10.1046/j.1365-2591.2000.00221.x

25. Nosonowitz DM, Brenner MR. The major canals of the mesiobuccal root of the maxillary 1st and 2nd molars.NYJ Dent 1973;43:12-5

26. Pineda F, Kuttler Y. Mesiodistal and buccolingual roentgenographic investigation of 7,275 root canals. Oral Surgery, Oral Medicine, Oral Pathology 1972;33:101-10.
https://doi.org/10.1016/0030-4220(72)90214-9

27. Pomeranz HH, Fishelberg G. The secondary mesiobuccal canal of maxillary molars. J Am Dent Assoc 1974;88:119-24
https://doi.org/10.14219/jada.archive.1974.0045

28. Ghasemi N, Rahimi S, Shahi S, Samiei M, Frough Reyhani M, Ranjkesh B. A Review on Root Anatomy and Canal Configuration of the Maxillary Second Molars. Iran Endod J 2017;12:1-9.

29. Das S, Warhadpande MM, Redij SA, Jibhkate NG, Sabir H. Frequency of second mesiobuccal canal in permanent maxillary first molars using the operating microscope and selective dentin removal: A clinical study. Contemp Clin Dent 2015;6:74-78.
https://doi.org/10.4103/0976-237X.149296

30. Khan M, Khan RM, Javed MQ, Ahmed A. Root Canal Configuration of the Mesio-buccal Root of Maxillary First Permanent Molars in Local Population. JIIMC 2018; 13: 210-14.

31. Gilles J, Reader A. An SEM investigation of the mesiolingual canal in human maxillary first and second molars. Oral Surg Oral Med Oral Pathol 1990;70:638- 43.
https://doi.org/10.1016/0030-4220(90)90415-O

32. Grande NM, Plotino G, Gambarini G, et al. Present and future in the use of micro-CT scanner 3D analysis for the study of dental and root canal morphology. Ann Ist Super Sanita 2012;48:26-34.

33. Zhang R, Yang H, Yu X, Wang H, Hu T, Dummer PM. Use of CBCT to identify the morphology of maxillary permanent molar teeth in a Chinese subpopulation. International Endodontic J 2011;44:162- 69.
https://doi.org/10.1111/j.1365-2591.2010.01826.x

34. Wolf TG, Paqué F, Woop AC, Willershausen B, Briseño-Marroquín B. Root canal morphology and configuration of 123 maxillary second molars by means of micro-CT. Int J Oral Sci. 2017;9:33-37.
https://doi.org/10.1038/ijos.2016.53

Mansoor Khan                              BDS, FCPS, CHPE

Alia Ahmed                                   FCPS, MHPE

Muhammad Qasim Javed            FCPS, MSc

OBJECTIVE: The aim of the study is to assess the variations in the root canal configuration of maxillary second permanent molars in the Pakistani subpopulation by using different clinical aids in vivo.
METHODOLOGY: The Cross-sectional analytical study was conducted from April to October 2018 at the College of Dentistry, Riphah International University, Pakistan. The root canal configurations of Maxillary second molars were evaluated in 95 adult patients that presented to the Operative Department, after obtaining consent. After access cavity preparation the orifices were identified and cross checked using 2.5x magnification and different clinical tests. Data analysis was done by utilizing SPSS version 23.
RESULTS: Out of the 95 teeth 6(6.3%) teeth had a single canal, 7(7.4%) teeth had two canals, 58(61.1%) teeth had three canals and 24(25.3%) teeth had four canals. Age-wise analysis of the frequency of different canals showed that prevalence of molars with three canals was significantly higher in the subjects with age between 41 and 50 years.
Conclusion: Overall, the study noted four morphological variations in the root canal configuration of Maxillary second molar teeth in Pakistani subpopulation. Hence, while executing the endodontic treatment in the maxillary second molars a thorough assessment of the root canal system should be carried out. The results of the study can guide Pakistani dentists.
KEYWORDS: Permanent Maxillary second molar, Dental Morphology, Endodontics, Pakistan
HOW TO CITE: Khan M, Ahmed A, Javed MQ. Root canal configuration of the maxillary second permanent molars in Pakistani subpopulation. J Pak Dent Assoc 2021;30(3):209-214.
DOI: https://doi.org/10.25301/JPDA.303.209
Received: 29 January 2021, Accepted: 06 April 2021

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Hina Siddiqui                           BDS

Sadia Rizwan                           BDS, FCPS

Sadia Rizwan                           BDS, FCPS

Syed Sheeraz Hussain            BDS, DCPS, MCPS, FCPS

OBJECTIVE: To assess the perception of buccal corridor width on smile esthetics by Orthodontic residents, General dentists
and Laypersons
METHODOLOGY: A smile photograph was taken of an adult female. The image was modified to obtain five different buccal
corridor widths and were assessed by different evaluators grouped into general dentist, orthodontic resident and laypersons who
rated the attractiveness of each smile by means of a visual analog scale (VAS). Sample size was 97 participants to rate the
picture. Non-probability purposive sampling was done The data was analyzed and mean and SD were calculated for the scores
of rating. ANOVA and Tukey's post hoc test was applied to compare the different ratings of buccal corridors in three groups.
The data of this cross sectional study was collected from general population belonging to different communities, general dentists
and orthodontic residents of different dental colleges of Karachi, Pakistan from August 2019 to March 2020.
RESULTS: There were 97 participants who responded to the images. Highest scores were obtained for Image 1 having buccal
corridor width ratio of 16% followed by image no. 3 having buccal corridor width ratio of 10% and lowest scores were obtained
for Image no. 6 having least buccal corridor widths ratio that is 34% followed by image no 5 having 26% buccal corridor widths.
Among the groups of participants, the highest scores were given by laypersons for all images. Significant differences were
observed between evaluation of groups of Orthodontic resident and layperson in most images.
CONCLUSION: There was a remarkable influence of buccal corridor width on smile esthetics, with the 16% ratio group being
rated as the most attractive by all three groups.
KEYWORDS: Buccal corridors, Smile, esthetics, Attractiveness
HOW TO CITE: Siddiqui H, Rizwan S, Faisal SS, Hussain SS. EFfect of buccal corridors width on smile quality and esthetics.
J Pak Dent Assoc 2021;30(3):204-208.
DOI: https://doi.org/10.25301/JPDA.303.204
Received: 13 November 2020, Accepted: 27 April 2021

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Hina Siddiqui                           BDS

Sadia Rizwan                           BDS, FCPS

Sadia Rizwan                           BDS, FCPS

Syed Sheeraz Hussain            BDS, DCPS, MCPS, FCPS

OBJECTIVE: To assess the perception of buccal corridor width on smile esthetics by Orthodontic residents, General dentists
and Laypersons
METHODOLOGY: A smile photograph was taken of an adult female. The image was modified to obtain five different buccal
corridor widths and were assessed by different evaluators grouped into general dentist, orthodontic resident and laypersons who
rated the attractiveness of each smile by means of a visual analog scale (VAS). Sample size was 97 participants to rate the
picture. Non-probability purposive sampling was done The data was analyzed and mean and SD were calculated for the scores
of rating. ANOVA and Tukey's post hoc test was applied to compare the different ratings of buccal corridors in three groups.
The data of this cross sectional study was collected from general population belonging to different communities, general dentists
and orthodontic residents of different dental colleges of Karachi, Pakistan from August 2019 to March 2020.
RESULTS: There were 97 participants who responded to the images. Highest scores were obtained for Image 1 having buccal
corridor width ratio of 16% followed by image no. 3 having buccal corridor width ratio of 10% and lowest scores were obtained
for Image no. 6 having least buccal corridor widths ratio that is 34% followed by image no 5 having 26% buccal corridor widths.
Among the groups of participants, the highest scores were given by laypersons for all images. Significant differences were
observed between evaluation of groups of Orthodontic resident and layperson in most images.
CONCLUSION: There was a remarkable influence of buccal corridor width on smile esthetics, with the 16% ratio group being
rated as the most attractive by all three groups.
KEYWORDS: Buccal corridors, Smile, esthetics, Attractiveness
HOW TO CITE: Siddiqui H, Rizwan S, Faisal SS, Hussain SS. EFfect of buccal corridors width on smile quality and esthetics.
J Pak Dent Assoc 2021;30(3):204-208.
DOI: https://doi.org/10.25301/JPDA.303.204
Received: 13 November 2020, Accepted: 27 April 2021

INTRODUCTION
   A mile is one of the most unique features describing the personality. In humans, it is naturally a manifestation signifying delight, cheerfulness, and enjoyment. An attractive smile increases self-assurance, self-worth and confidence.1 It is the utmost means by which individuals convey their feelings. It is defined as ‘a transformation of face expression encompassing eyes enhancement, uphill bowing of the curls of lips with no sound and reduced alteration of the muscles than in laugh which possibly will precise enjoyment, amusement, care, love, warmth, merriment, sarcasm, or any of many different sentiments.2 Its impact, though, is not linked solely to the individual dental beauty.3 The esthetics remain an imprint in the intellect encouraged by its specific insight; hence, the learning of individual attractiveness has ensued in all beliefs throughout past and beauty employs a personal idea. It is a
noteworthy part of one’s personality and the awareness of the individual and in addition it is imperative in the evaluation that others have of our expression and character.4
There are four key features of aesthetic perception of smile: facial, gingival, micro and macro-aesthetics. Smile Esthetics depends upon teeth as well as soft tissue.5 Smile analysis includes valuation of smile arc, smile line, tooth
and gingival display, presence or absence of buccal corridor widths, facial and dental midlines, proportions of tooth,
gingival heights and shade of tooth.6 One of potential smile feature is buccal corridors.7 However some data on the
perfect size of buccal corridors is available in the literature, maximum of it is stranded in views of clinicians, although the researches that endeavored this issue produced controversial assumptions.8 Numerous researches exhibited that broad smiles with reduced negative spaces are cherished and considered more eye-catching.9 Lately, extremely wide BCs are denoted by many orthodontic consultants as a “negative space,” and must be omitted by expansion of the upper arch. It is predictable in the literature of prosthodontics that one of the configurations of an unnatural denture like smile is the absence of buccal corridors.10 It might not an easy task to recognize the problem with the smile esthetics because of the variations in opinions among orthodontists and laypersons.11 A welcoming and eye catching smile is deliberated as a crucial benchmark by many patients, describing the accomplishment of treatment, even though the attainment of a proportionate smile can be perplexing due to the bias of assessment. It is significant to assess the consequence of the dentition on the smile. A lack of data has prohibited an acceptable considerate of the appealingly proportionate widths of the smile. Consequently, it is essential to generate common guidelines to help clinicians in improving smile esthetics with sufficient treatment objectives fulfillment.12
Visual analog scale appears to be reliable for evaluation of smile esthetics.13 In present practice of dentistry, an
enormous number of patients are demanding a highly aesthetic treatment result.14 Buccal Corridors can be best assessed on the Frontal Smile Photograph which is now an essential component for Orthodontic Diagnosis & Treatment Planning. Presence or absence of buccal corridors has been best evaluated by analyzing Buccal Corridor width. Buccal corridors were defined by Frush and Fisher as the space from the buccal surface of visible posterior teeth and the corners of lips, when the patient is smiling.3
In a study conducted by Bilal R buccal corridors was the 5th most desired feature amid orthodontists.11 In a study
conducted by Zaib F et al. prefer smiles with minimum visible buccal corridors, where male orthodontists rated 20%
pictures as acceptable and female orthodontist judges rated 23% pictures as acceptable.15 Abdullah Alper Öz concluded that both orthodontists and oral surgeons gave ratings of 12% BC width as the most appealing, whereas group of prosthodontic consultants and laypersons accepted a rating of width of buccal corridors being 0% as the most beautifully agreeable.10 Lay perceptions of smile esthetics are imperative to better understand the treatment objectives from perspective of a patient. However, it is clear that laypeople can recognize numerous factors which affect smile esthetics. Perception is defined as a reasoning process involving understanding of a stimulus and recognition of the object generating a sensation.16
This study will help us understand the opinion and perception of laypersons, which often are not given the due
importance in the treatment planning. Also it will help orthodontic residents realize that they should not impose
their own perception of smile and esthetics on their patients. This individual assessment is an effort to validate and expand on earlier studies of smile acceptability and deliver esthetic ideals.

METHODOLOGY
    It was a questionnaire based cross sectional study. This data of this cross sectional study was collected from general population belonging to different communities, general dentists and orthodontic residents of different dental colleges of Karachi, Pakistan. Sample size was 97 participants to rate the picture which is calculated by taking anticipated population proportion (P) as 20% acceptable, margin of error 8% and 95 % Confidence interval. Non-probability purposive sampling was done. Participants, including both males and females of age range 24-34 years were recruited in the study. Three groups of participating evaluators were formed. The first group consisted of 32 Orthodontic residents from different institutes in Karachi, the second group comprised of 32 general dentists practicing in different dental hospitals in Karachi and third group included 33 laypersons. Orthodontic residents having minimum 2 years of experience in the field were selected, General dentist having minimum 2 years of experience and laypersons were graduates in any field other than dentistry. People who do not give consent to participate were excluded.
The data was collected after taking approval from ethical review board in KMDC (Ref. no 025/18) by taking frontal photograph of 1 female individual of age 23 years by using DSLR camera; Canon 700d. Frontal smile view photograph with the head in naturally relaxed position of the subject will be taken and only close up smile image was framed. Original photograph had ratio of buccal corridor width of 16%. The photograph was modified by software of adobe photoshop 7.0 to obtain 5 different buccal corridor width ratios that is; 8%,10%, 22%, 26% and 34%. (Figure no. 1) Informed consent was taken from the photographed female and all the participating evaluators. All images were printed and were given to participants to rate the facial attractiveness from 1 to 10 of each image by using visual analogue scale keeping 1 as least attractive and 10 as most attractive in a predesigned proforma. The current study altered only the buccal corridor ratio for smiles which eliminated the possibility of other confounding aesthetic variables influencing perceptions.
The space perceived between the facial surface of the
teeth in posterior region and the corners of the lips when the patient smiles is known as the buccal corridor. The
measurements are taken from the mesial line angle of maxillary first premolar to the inferior part of the commissure
of the lip.17
The data was statistically analyzed using SPSS 23. Mean and SD were taken for scores given by the participating
evaluators for all the images. Differences between ratings by groups of participants were analyzed by applying
one-way ANOVA and Tukey’s post hoc test taking p-value less than 0.05 as significant.

RESULTS
    Table I illustrated the means and standard deviations for the ratings obtained from evaluators for individual
groups., the maximum ratings were attained for Image 1 having buccal corridor width ratio of 16% followed by

Image no 3 having buccal corridor width ratio of 10% and lowest scores are obtained for Image no. 6 having least
buccal corridor widths ratio that is 34% followed by image no 5 having 26% buccal corridor widths. The highest scores are given by laypersons group for all the photographs.
Table II demonstrated the statistically significant differences among the groups of evaluators for the perception
of smile attractiveness, mostly differences are observed between evaluation of groups of Orthodontic resident and
layperson and are significant for Image no. 2,4,5 and 6. In image 5 and 6 where buccal corridor width was markedly
increased orthodontic residents differed significantly in ratings with laypersons.

DISCUSSION
    Orthodontists used to widen the maxilla to relieve crowding, it is noteworthy to know how variations in the display of teeth while smiling affect facial attractiveness. In our study, the image having Buccal Corridor width ratio of 16% appeared to be most attractive among all images and the image having buccal corridor width ratio of 34% were rated to be least attractive followed by image having 26% buccal corridor width ratio which means all three evaluators groups preferred lesser buccal corridor widths. Image having reduced buccal corridor width 8% also received lower ratings by Orthodontic residents and general dentists whereas laypersons did not critically scored image having reduced buccal corridors. This study also showed that orthodontic residents analyzed pictures more critically as compared to laypersons having significant differences in four pictures. Overall scoring was greater by laypersons as compared to other two groups of evaluators.
In a comparable study, smiling pictures of female were used for assessment, Ioi et al. stated that orthodontic specialists and laypersons evaluated a buccal corridor width of 10% and 5%, as the most appealingly attractive. Where as in our study less buccal corridors around 16% are most acceptable and least buccal corridors i.e.; 8% received lower ratings, and smiles with buccal corridor width of 34% received much lower ratings from all three evaluator groups.18
Outcomes of our study are also in favor with findings of Moore et al, he used full face slides and changed the maxillary dentition to 5 widths. The results of their study also showed that wider smiles were preferred, as shown in our study.19 The findings of this study are consistent with that of Parekh et al., he found significantly reduced ratings for smiles having flat smile arcs and increased buccal corridors similar to our study. Our study also showed very low scores for increased buccal corridor space.20 Our study findings also supported results of Martin et al who also concluded that orthodontists and laypeople scored smiles having less buccal corridors as more attractive than those with increased buccal corridors.21 Our findings are also in agreement with those of Kokich et al, who stated that laypersons, dentists and orthodontists have different altitudes of recognition of variations in smile features and that laypersons were the most forgiving.22
However, in a study conducted by Roden-Johnson et al. declared that the extent of buccal corridor width was not an important aspect in the charm of smile. Though, significant dissimilarities were found in the approaches of this study when matched to the present research.10 Their study showed that the occurrence of buccal corridors does not influence smile esthetics. However, there are variations in how dentists, orthodontists, and laypeople scored smiles and in what arch form respective group desires. Ritter et al. examined the significance of different buccal corridor widths, but samples they used were unchanged smile pictures of the subjects10 which can lead to bias in ratings due to other smile features which affect the smile attractiveness. Furthermore, the number of inspectors are also reduced which affect the outcome of study. They found that buccal corridor width did not influence the attractiveness of smile. Contradicting to our study, McNamara et al. showed significant agreement in the decisions between laypersons and orthodontic specialists regarding perception of smile, whereas our findings demonstrated significant differences in four images between orthodontic resident and laypersons.23 A study by Husley proved that smile arc had greater scores and buccal corridors did not have any consequence on smile aesthetics which is contradicting to the present study. The disagreement might be due to different treatment groups taken for evaluation of buccal corridors widths.24 Al Taki et al stated that orthodontists showed great precision in tolerating deviations in the smile
arc and buccal corridors25 which is similar to findings of our study showing more sensitive ratings made by orthodontic residents among all groups of evaluators.

CONCLUSIONS

1. All three groups of evaluators that is orthodontic residents, general dentists and laypersons preferred smiles having 16% buccal corridors width ratio.

2. There is no gender or age group difference in ratings given by evaluator groups.

3. Excessive buccal corridor widths i.e.; 34% and minimum buccal corridors widths i.e.; 8% both are rated to be least acceptable by all three evaluator groups.

4. Orthodontists and general dentists, shared more similarities than differences when evaluating smile
esthetics in the present study.

5. Differences in ratings were observed among Orthodontic resident and layperson groups.

6. The layperson group were more forgiving in scoring smile related to buccal corridor width ratio than Orthodontic residents and general dentists.

CONFLICT OF INTEREST
None to declare

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