Antibacterial Efficacy of Silver Nanoparticles Impregnated Calcium Hydroxide: An in Vitro Study

 

 

Zudia Riaz1                     BDS
Muhammad Raza2         BDS, FCPS, MPH
Amjad Hanif 3                BDS, MSc
Beenish Haider4            BDS
Sadia Akram5                BDS
Shamayem Safdar6      BDS, M.Phil

 

 

OBJECTIVE: To compare the in-vitro antibacterial effectiveness in terms of enterococcus faecalis elimination of conventional
unmodified calcium hydroxide paste with an experimental calcium hydroxide impregnated with 1% silver nanoparticles.
METHODOLOGY: This in vitro study was conducted during the period July 2019 - January 2020 at Materials Research
Laboratory, Centralized Resource Laboratory (University of Peshawar) and Pathology Laboratory (Peshawar Medical College).
Sixty human premolar teeth having single root with mature apices were obtained. These were distributed into two groups
randomly (n=30); experimental group for testing the antibacterial efficacy of calcium hydroxide impregnated with 0.1% by
weight silver nanoparticles and the other was used as a control group for testing the antibacterial efficacy of unmodified calcium
hydroxide. Dentine specimens (size 4 x 4x 1mm) were prepared from the teeth using slow speed cutting saw machine. Smear
layer was removed with EDTA. Specimens were autoclaved to sterilize them. Then each specimen was contaminated with
enterococcus faecalis and incubated anaerobically for 24 hours at 37?C. After the application of medicaments, the zone of
inhibition was measured and number of viable bacteria were determined using SEM. Statistical significance was calculated
using t-test. p<0.05 was taken as significant.
RESULTS: After the application of medicament, the zone of inhibition was greater (9.63mm) in experimental group when
compared to control group (4mm) (p<0.001). Number of viable bacteria before application of medicament were 239 and 208
while after application of medicament reduced to 90 and 54 in control and experimental groups respectively (p<0.001).
CONCLUSION: The addition of silver nanoparticles to calcium hydroxide significantly enhanced its potential to eliminate
biofilm of enterococcus faecalis on dentin specimens.
KEYWORDS: Silver nanoparticles, Calcium hydroxide, Root canal infections, Root canal medicament.
HOW TO CITE: Riaz Z, Raza M, Hanif A, Haider B, Akram S, Safdar S. Antibacterial efficacy of silver nanoparticles
impregnated calcium hydroxide: An in vitro study. J Pak Dent Assoc 2022;31(1):1-4.
DOI: https://doi.org/10.25301/JPDA.311.1
Received: 05 April 2021, Accepted: 08 September 2021

 INTRODUCTION
T
he success of endodontic treatment depends on several factors in which the reduction or elimination of infections is one of the most important aspect. In teeth with apical periodontitis, microorganisms can persist after the endodontic treatment and remain harbored in the dentinal tubules.1 The mechanical preparation used during endodontic treatments alone do not completely eliminate the infection and inflammatory processes in the periapical tissues. Thus, the application of an intra canal medicine helps in eradication of microbes that exists even after preparation of the canal, therefore creating an atmosphere for repair of periapical tissue.2
Enterococcus faecalis is anaerobic gram-positive cocci accountable for majority of endodontic treatment failures.3 It has the ability to withstand adverse environmental conditions.4 It can invade into the tubules inside dentine and has the ability to form biofilm.5 To eliminate such microorganisms, antimicrobial intra canal medicament is
recommended.6 Among the intra canal medicaments, calcium hydroxide is most frequently used because of its wide
antimicrobial spectrum.
Calcium hydroxide Ca(OH)2 is commonly employed as an intra canal medicament. It releases hydroxyl ions which
causes high alkalinity. Nevertheless, the ability of calcium hydroxide in elimination of bacteria from the root canal has been questioned. Antibacterial ability of calcium hydroxide in aqueous environment is linked to the discharge of hydroxyl ions. It can cause damage to the cytoplasmic membrane, bacterial DNA as well as can cause protein denaturation.7 However, calcium hydroxide is not as much effective when used for canal disinfection having established enterococcus faecalis biofilm.8
Recently, numerous studies have introduced silver nanoparticles as an antimicrobial agent.9 Silver nanoparticles have antimicrobial activity and are biocompatible10, silver ions can cause damage to the bacterial cell wall. These are
productive against many microorganisms including E. faecalis.11 Nanoparticles have /polyanionic polycationic properties with a high surface area and positive charge density, which increases their antibacterial activity.12 The
particle size was also related to antimicrobial activity; the smaller particles give more bactericidal effects compared to larger particles.13
Calcium hydroxide do not always eradicate enterococcus faecalis biofilm from root canals.14 Hence, it is essential to
introduce advanced endodontic intracanal medicament approaches that are successful in eradicating biofilm bacteria
inside the root canals. Therefore, the aim of this was to determine the antibacterial efficacy of calcium hydroxide
cement containing silver nanoparticles

METHODOLOGY

The research protocol and the publication of results were approved by the institutional review board (Prime/IRB-2019- 313). The experimental work was performed at the Department of Dental Materials, Peshawar Dental College,
Pathology Laboratory of Peshawar Medical College and Material Research and Centralized Research Laboratory of
Peshawar University.
Total of sixty test specimens were prepared. Thirty specimens (n=30) were made to test the antibacterial ability of commercially available calcium hydroxide paste (Calcipex,Nishika Japan) while the remaining thirty specimens were used to test the antibacterial activity of calcium hydroxide paste containing 1% by weight of silver nanoparticles (Alfa aeser, Germany). Experimental silver nanoparticles impregnated calcium hydroxide was prepared by mixing 1 mg of silver nanoparticles with 1 gm of calcium hydroxide. Sixty human premolars having single root and mature apices were obtained to prepare dentine specimens.
Teeth were cleaned from gross debris by using ultra sonic scaler and then stored in normal saline. After cutting off crown and apical portion, teeth were sectioned vertically along midsagittal plane into equal halves. The cementum
from root surface was removed by using diamond bur. Dentin sections were made having dimensions of 4 x 4x 1mm (width x length x height). Smear layer from the specimens was removed by placing it in EDTA solution for four minutes. All the specimens were washed with sterile water for one minute and placed in autoclave (Hirayama, Japan) for 15mins at 121°C. Brain heart infusion was used to incubate the specimens at 37°C for 24 hrs.
Enterococcus faecalis used in this study was obtained from pathology laboratory of Lady Reading Hospital, Peshawar Pakistan. The bacteria were plated on BHI broth containing 1.5% (wt /vol) agar and incubated anaerobically at 37°C for 24 hrs to obtain colonies. Gram staining was performed and the grown colonies of bacteria were placed in sterile BHI broth at 37°C. Sterilized specimens of dentin were placed in test tubes having E.faecalis for bacterial inoculation on dentine specimen. Fresh BHI broth was exchanged every second day to eliminate dead cells and to confirm viability of bacteria. The specimens were removed from tubes after incubation and rinsed with sterile phosphate buffered saline to remove the culture medium and non adherend bacteria. The zone of inhibition of E.Faecalis was measured and number of viable bacteria were observed under SEM.
One pellet (0.01g) each of the control and experimental groups were placed on infected dentine specimens on a
sensitivity discs. Then anaerobic incubation of these specimens was conducted at 37°C for 14 days in a 100% humid environment. Then each specimen was washed with saline to eliminate the tested medicament. Citric acid (0.5%)
was used to neutralize the treated specimens treated with calcium hydroxide. Then the specimens were examined for
zone of inhibition and number of viable bacteria was determined by using SEM.
Data analysis was performed using the statistical package for social sciences (SPSS) version 22. Mean values and
standard deviations of the number of viable bacteria on dentine specimens were computed. Student’s t test was used
for estimating the significance of the differences of the mean values. p < 0.05 was used for statistical significant.

RESULTS

Mean and standard deviation of zone of bacterial colonies, zone of inhibition of bacterial colonies and number of viable bacteria in both control and experimental groups before and after application of medicament are given in Table 1. Zone of bacterial colonies before application of medicament shows that both groups (control and experimental) contain similar number of colonies with mean value of 20 mm. After the application of medicament, the zone of inhibition of bacterial colonies was more in experimental group (9.63±2.09) than control group (4±2.86) showing statistically significant difference (p<0.001). Number of viable bacteria before application of medicament were 239± 60.3 and 208.03±65.22 while after application of medicament reduced to 90±37.96 and 54.13±23.3 in control and experimental groups respectively (p< 0.001) (Table 1).

DISCUSSION

The current study was conducted to compare the in vitro antibacterial effectiveness of two root canal medicaments
in terms of elimination of bacterial colonies and reduction in the number of viable E. faecalis during a test period of
two weeks. The null hypothesis was rejected since experimental calcium hydroxide having 1% silver nanoparticles statistically significantly reduced the E. faecalis number as compared to the plain calcium hydroxide. In this study E. faecalis was used for the evaluation of antibacterial efficacy of root canal medicaments, as it has a key role in the aetiology of constant root canal infections. E. faecalis is responsible for high rate of root canal failures because these bacteria can stay alive in adverse environment.15 In our study, permanent teeth were used to replicate the real
clinical situation to the possible extent.
Samiei et al reported better efficacy of calcium hydroxide containing silver nanoparticles when compared to
conventional calcium hydroxide in the treatment of root canal infections.16 Balto et al (2020) treated dentine specimens with Ca(OH) 2 containing 0.02% AgNPs. The results of their study showed that the mixture of Ca(OH) 2 and AgNPs exhibited marked antibacterial activity against 3-week-old E. faecalis biofilms. It has been observed that silver has a high affinity for negatively charged molecules within bacterial cells, disables critical functions of bacteria and consequently prevents bacterial proliferation and formation of biofilm.17 The inhibitory effect of the mixture of Ca(OH) 2 and AgNPs on E. faecalis biofilms in our study is similar to that reported in numerous studies regardless of the variation in the assessment approach.16,17
Contrary to our findings, Yousefshahi et al reported statistically insignificant results when E. faecalis was treated
with 1% AgNPs impregnated calcium hydroxide for 24 hours as compared to conventional calcium hydroxide.18 The
difference in the results of the two studies might be due to variation in shape and size of the silver nanoparticles.
Javidi et al reported that after one week of incubation, the number of colony forming units of E. faecalis were
considerably less in specimens treated with calcium hydroxide containing silver nanoparticles as compared to unmodified calcium hydroxide paste (p<0.001.19 Similarly, Afkhami et al reported that the efficacy of calcium hydroxide containing silver nanoparticles against E. faecalis was better than unmodified calcium hydroxide paste when incubated for one week and one month.20 The findings of both the studies are in agreement with the findings of our study.
One of the limitations of this study was that only one concentration of AgNPs in combination with calcium hydroxide and one time period of two weeks was assessed and hence the maximum concentration of AgNPs which
could be added to calcium hydroxide and the minimum time period showing the maximum efficacy was not ascertained.
Although E. faecalis is the commonest bacterial strain present in most patients of persistent intra-radicular infections, but it also needs to understand that the infected root canal system typically has more than one species of bacteria. So the intra canal medicaments showing efficacy against E. faecalis in in-vitro research may not be essentially work well in poly-microbial infection in vivo studies of endodontic origin. However, our investigation may serve as a baseline for further research in this area that could assess the influence of silver nanoparticles and its various combinations on other endodontic pathologies.

CONCLUSION

Within the limitations of this study, it could be concluded that calcium hydroxide containing silver nanoparticles might be more effective in elimination of bacteria from root canal system than conventional unmodified calcium hydroxide. Further studies are required to explore its efficacy in in-vivo along with possible cytotoxicity and other adverse effects like tooth discolouration etc.

CONFLICT OF INTEREST

None declared

REFERENCES

1. De Paz LE. Aetiology of persistent endodontic infections in rootfilled teeth. In Apical Periodontitis in Root-Filled Teeth 2018 (pp. 21- 32). Springer, Cham.
https://doi.org/10.1007/978-3-319-57250-5_3

2. Farhadian N, Godiny M, Moradi S, Azandaryani AH, Shahlaei M. Chitosan/gelatin as a new nano-carrier system for calcium hydroxide delivery in endodontic applications: Development, characterization and process optimization. Materials Science and Engineering: C. 2018;92:540- 6.
https://doi.org/10.1016/j.msec.2018.07.002

3. Siddiqui SH, Awan KH, Javed F. Bactericidal efficacy of photodynamic therapy against Enterococcus faecalis in infected root canals: a systematic literature review. Photodiagnosis and photodynamic therapy. 2013;10:632- 43.
https://doi.org/10.1016/j.pdpdt.2013.07.006

4. Zhang C, Du J, Peng Z. Correlation between Enterococcus faecalis and persistent intraradicular infection compared with primary intraradicular infection: a systematic review. J Endodontics. 2015;41:1207-13.
https://doi.org/10.1016/j.joen.2015.04.008

5. Du T, Wang Z, Shen Y, Ma J, Cao Y, Haapasalo M. Effect of longterm exposure to endodontic disinfecting solutions on young and old Enterococcus faecalis biofilms in dentin canals. J Endod. 2014;40:509- 14.
https://doi.org/10.1016/j.joen.2013.11.026

6. Ahmed S, Ahmed A, Sikander M. Comparison of postoperative pain frequency after single visit and multiple visits root canal treatment with rotary instruments on non-vital teeth. Pak Oral Dent J. 2017;37.

7. Silva LA, Dermody TS. Chikungunya virus: epidemiology, replication, disease mechanisms, and prospective intervention strategies. J Clin Investigation. 2017;127:737-49.
https://doi.org/10.1172/JCI84417

8. Ghabraei S, Bolhari B, Sabbagh MM, Afshar MS. Comparison of antimicrobial effects of triple antibiotic paste and calcium hydroxide mixed with 2% chlorhexidine as intracanal medicaments against Enterococcus faecalis biofilm. J Dentistry (Tehran, Iran). 2018;15:151.

9. Cheng L, Zhang K, Melo MA, Weir MD, Zhou X, Xu HH. Antibiofilm dentin primer with quaternary ammonium and silver nanoparticles. J dental Research. 2012;91:598-604.
https://doi.org/10.1177/0022034512444128

10. Motshekga SC, Ray SS, Onyango MS, Momba MN. Microwaveassisted synthesis, characterization and antibacterial activity of Ag/ZnO nanoparticles supported bentonite clay. J hazardous materials. 2013;262:439-46.
https://doi.org/10.1016/j.jhazmat.2013.08.074

11. Afkhami F, Pourhashemi SJ, Sadegh M, Salehi Y, Fard MJ. Antibiofilm efficacy of silver nanoparticles as a vehicle for calcium hydroxide medicament against Enterococcus faecalis. J Dent. 2015;43:1573-9.
https://doi.org/10.1016/j.jdent.2015.08.012

12. Du T, Wang Z, Shen Y, Ma J, Cao Y, Haapasalo M. Effect of longterm exposure to endodontic disinfecting solutions on young and old Enterococcus faecalis biofilms in dentin canals. J Endod. 2014;40:509- 14.
https://doi.org/10.1016/j.joen.2013.11.026

13. Zapór L. Effects of silver nanoparticles of different sizes on cytotoxicity and oxygen metabolism disorders in both reproductive and respiratory system cells. Archives of Environmental Protection. 201642:32-47.
https://doi.org/10.1515/aep-2016-0038

14. Wang Z, Shen Y, Ma J, Haapasalo M. The effect of detergents on the antibacterial activity of disinfecting solutions in dentin. J Endod. 2012;38:948-53.
https://doi.org/10.1016/j.joen.2012.03.007

15. Stuart CH, Schwartz SA, Beeson TJ, Owatz CB. Enterococcus faecalis: its role in root canal treatment failure and current concepts in retreatment. J Endod. 2006;32:93-8.
https://doi.org/10.1016/j.joen.2005.10.049

16. Samiei M, Farjami A, Dizaj SM, Lotfipour F. Nanoparticles for antimicrobial purposes in Endodontics: A systematic review of in vitro studies. Materials Science and Engineering: C. 2016;58:1269-78.
https://doi.org/10.1016/j.msec.2015.08.070

17. Balto H, Bukhary S, Al-Omran O, BaHammam A, Al-Mutairi B. Combined Effect of a Mixture of Silver Nanoparticles and Calcium Hydroxide against Enterococcus faecalis Biofilm. J Endod. 2020;46:1689- 94.
https://doi.org/10.1016/j.joen.2020.07.001

18. Yousefshahi H, Aminsobhani M, Shokri M, Shahbazi R. Anti-bacterial properties of calcium hydroxide in combination with silver, copper, zinc oxide or magnesium oxide. European J translational myology. 2018;28.
https://doi.org/10.4081/ejtm.2018.7545

19. Javidi M, Afkhami F, Zarei M, Ghazvini K, Rajabi O. Efficacy of a combined nanoparticulate/calcium hydroxide root canal medication on elimination of E nterococcus faecalis. Australian Endodontic Journal. 2014;40:61-5.
https://doi.org/10.1111/aej.12028

20. Afkhami F, Pourhashemi SJ, Sadegh M, Salehi Y, Fard MJ. Antibiofilm efficacy of silver nanoparticles as a vehicle for calcium hydroxide medicament against Enterococcus faecalis. Journal of Dentistry. 2015;43:1573-9.
https://doi.org/10.1016/j.jdent.2015.08.012

Evaluation of Tooth Wear and its Causative Risk Factors Amongst Patients Attending Dental Hospital of Karachi

 

 

Ayesha Zafar                              BDS
Samira Adnan                            BDS, FCPS, MHPE
Naseer Ahmed                           BDS, FCPS
Maria Shakoor Abbasi              BDS, FCPS
Muhammad Adeel Ahmed        BDS, FCPS, MFDS RCSEd
Rizwan Jouhar                          BDS, FCPS
Saqib Hameed                           BDS, FCPS

 

OBJECTIVE: To assess the perception of patients visiting a dental OPD in Karachi regarding cross infection control measures
that should be taken in dental practice.
METHODOLOGY: A cross-sectional study was conducted at the OPD of Altamash Institute of Dental Medicine from January
to August 2020. A total of 546 patients aged 20-75 years of either gender coming for routine dental check-ups were included
in the study using non-probability convenience sampling. A well-structured and validated questionnaire was used to assess the
knowledge, attitude and practices of patients regarding cross infection measures that should be present in dental practices.
SPSS-25 was used to analyse the data. Descriptive statistics was used to calculate frequency and percentage of qualitative
(gender, socioeconomic and education status, knowledge attitude and practice levels of patients) and quantitative variables
(age groups). Chi-square test was used to detect the relation of patient's knowledge levels with potential factors like the age
groups, gender, socioeconomic and education status. The p-value of (< 0.05) was considered as significant.
RESULTS: Out of the total participants, 79.1% had good knowledge about cross infection control measures in dental practice.
Majority of the patients (84.6%) agreed that dentists should wear gloves during treatment, though majority were of the opinion
that a dentist can treat several patients with the same set of gloves. About 4.9% of the patients said that they ask the dentist to
wear face mask and gloves while treating them, and only 3.3% said that they ask the dentist about sterilization of instruments.
The knowledge level of patients showed variation with their education status but not with respect to socioeconomic status, age
and gender.
CONCLUSION: Although overall the patients visiting dental clinics had good perception and showed positive attitudes towards
cross infection control, the dental health practitioners need to disseminate basic technical information about the infection-control
practices required for safe dental practice to dental patients and the community at large.
KEYWORDS: cross infection, knowledge, dentist, dental patients, perception
HOW TO CITE: Zafar A, Adnan S, Ahmed N, Abbasi MS, Ahmed MA, Jouhar R, Hameed S . Evaluation of cross infection
control in dentistry; A patients’ perception study. J Pak Dent Assoc 2021;30(4):249-254.
DOI: https://doi.org/10.25301/JPDA.304.249
Received: 01 January 2021, Accepted: 15 June 2021

INTRODUCTION
Tooth wear is a term defined as the loss of dental hard tissue in a damaged tooth if there is no existing dental caries or trauma.1 Tooth wear can be sub-classifies as attrition, erosion, abrasion and abfraction.2 Attrition is a mechanical type of wear, which results due to the grinding of teeth. Abrasion is also mechanical wear caused by oral hygiene measures and biting habits. Erosion is chemical wear that results from the ingestion of acidic foods /drinks/ gastroesophageal reflux.3-5 Abfraction is a non carious tooth loss which is characterized by v shaped notch
or wedge shaped at the cervical area of tooth.
inically and experimentally in combination.6 It might be unnoticeable in its initial developmental stage but it may affect aesthetics and appearance in some patients especially if anterior teeth are involved.7,8 Excessive tooth wear leads to hypersensitivity and exposed dentin.9
The prevalence of tooth wear varies with wide-ranging values reported due to different study populations, methodologies, recording indices used.10 These studies reported that the prevalence of tooth wear varies from one population to another. It was reported 38.6% in Pakistani
population11, 64% in Norway12,13 75% in Sweden14 and 95% in Saudi Arabia.7
There are many techniques to measure tooth wear both in vitro and in vivo. Techniques to quantify tooth wear in vitro are profilometry, microradiography, scanning electron microscopy, atom force microscopy, nano- and microhardness test, iodide permeability test.15,16 To measure tooth wear in vivo, many indices are used like the Eccles index of dental erosion, Smith and Knight index, and Erosion index by
Lussi.17 Some of these indices measure tooth wear on every surface of each tooth, some measures selected sites and specific surfaces.17 Smith and Knight19 introduced tooth wear index (TWI) which is capable of measuring all four visible surfaces (buccal, cervical, lingual, and occlusalincisal) of all teeth present. Except for a few studies, not much work has been done in Pakistan on this topic. Toufique H et al 201719 in a study reported that only 10% of the patients had tooth wear whereas in the present study 92.4% of them had tooth wear. Therefore, the present cross-sectional study was done to Evaluate Tooth wear and its causative risk factors amongst Patients Attending the Dental Hospital
of Karachi

METHODOLOGY
The current study was a cross-sectional study conducted on adult patients recruited from the Out-Patient Department of Oral Diagnosis from May 2018 – December 2018. Patients were examined for the presence of tooth surface loss by using the Tooth Wear Index (TWI). The Ethical Review Board (ERB ) DC/ERB/2018/010), Baqai Dental College, gave ethical approval to proceed with this study. Patients with the complaint of tooth surface loss aged 18-45 years were included in the study.A consecutive sampling technique was used and 250 adult patients were selected for the study. Open Epi version 3.01software was used to calculate the sample size. Keeping a 20% prevalence rate with a 95% confidence interval with a 5% error, n=250 sample size was calculated based on the prevalence tooth wear reported by
Daly et al.20
Oral and Dental examinations were performed using the dental chair with a sterile mouth mirror and dental probe after signing a written consent by the patient. The chief examiner examined the patients while the dental chair assistant recorded the readings. A structured questionnaire prepared by those skilled in the restorative subject was used, which included etiological aspects of parafunctional habits, oral
hygiene measures, eating habits, and clinical history. Tooth wear was assessed by using Smith and Knight Tooth Wear Index (TWI index).18 The surfaces were designated as cervical surface (C), buccal surface (B), the lingual surface (L) or palatal surface (P) Incisal surface (I) or, occlusal surface (O). Patients who reported having symptoms of sensitivity were further assessed by a blast of air from the air-water syringe for 3 sec at a distance of 1cm from the tooth surface. Any uncomfortable feeling aroused by the blast was recorded on the clinical form according to different tooth surfaces.21 Data was entered and analyzed for Descriptive analysis (frequency and percentages). A Chi-square test was performed to assess the association between gender and its etiological factors by using IBM SPSS version 20.

RESULTS
The subject populations of 250 adult patients were assessed for tooth surface loss by using the Tooth wear index. According to Smith and Knight TWI, 201018 reported that 7.6% scored 0, 11.6% scored 1, 24.4% scored 2, 25.2% scored 3 and 31.2% scored 4. Out of which 178 were male (71.2%) and 72 (28.8%) were females aged 18 to 48 years old. Table 1 showed the Demographic profile.
In table 2,association of gender with etiological factors is mentioned which shows insignificant association that is 42 (23.6%) males and 17 (23.6%) females reported sensitivity, followed by 20 (11.2) males and 9 (12.5%)females with poor previous tooth aesthetics. (p = 0.535), 33 (18.5%) of males and 19 (26.4%) females reported a history of scaling. (p = 0.110). A significant association was seen when 89
(50%) of males and 24 (33.3%) of women had a history of pan/ betel nut chewing, (p<0.001). No significant association was reported regarding toothbrush technique and 121 (68%) men and 52 (72.2%) women used horizontal brush technique (p = 0.136)
Regarding tooth wear and dentin sensitivity, it was found that dentinal sensitivity increased with the age group. This
difference was not found to be statistically significant. (p=0.10) Table 3.
It was found that tooth wear increased with age group. For the age group, 18-28, 29-39 and 40-50 scores 2 and 4,

DISCUSSION
The present study was done to evaluate tooth surface loss in patients attending the Out-Patient Department of Baqai Dental College. In this study, 92.4% of them reported tooth wear and only 31.2% has extended to severe stage of the tooth wear and men reported severe tooth wear than women did.
A study done in the Dutch population reported that tooth surface loss was a common condition amongst the adult population.22 In this present study, 7.6% of participants reported no tooth surface loss and 92.4% of them reported tooth wear however, only 31.2% had reached to severe stage of tooth wear. Toufique H et al. in 201719 reported dissimilar results that only 10% of participants had tooth wear while
90% did not have tooth wear in their study. A study by Van’t Spijker23 reported the frequency of patients with tooth surface loss was increased to 3 % at the age of 20 years, 17% increased at 70 years of age
The present study according to Smith and Knight TWI, 2010 18 reported that 7.6% scored 0, 11.6% scored 1, 24.4% scored 2, 25.2% scored 3 and 31.2% scored 4. R Wirdatul et al24 in a study reported different values, 17.4% surfaces had tooth wear; 80% scored 1, 18% scored 2 and
2% scored 3. Oral habits are repetitive behaviors within the oral range, leading to loss of dental structure, such as eating habits, brushing techniques, bruxism, functional habits, and regurgitation. The effect depends on the nature, manifestation, and duration of the habit. The role of acids in food and beverages can be important in the development of toot wear. Laboratory studies have shown that low acid foods and
beverages cause erosion of enamel and dentin which may lead to dentin sensitivity.25-27
Dentinal hypersensitivity (DH) is a common symptom which affects 8-57% of adult and is associated with the oral hygiene.28 The present study reported an association of tooth wear with dentin hypersensitivity and age groups. Deshpande S29 in a study reported that there is a connection between grades of tooth wear with dentin sensitivity. Ayer A et al30 in a study reported that dentin hypersensitivity is associated with tooth surface loss. Idon P et al31 in a study reported an association of dentin hypersensitivity with tooth surface loss. Kehua Q et al.21 in a study reported that there is an association between dentin hypersensitivity and age groups. Ali K et al.32 find abnormal tightening and bruxism with a significant relationship with tooth surface loss. The present study reported that only 7.6% experienced tooth surface loss due to tightening/ bruxism, while 45.2% experienced tooth surface loss due to chewing pan. As tooth surface loss is multifactorial, therefore the abrasive effect of tooth brushing can cause a tooth surface loss. The present study reported that people using a brush with medium bristles (41.2%) in horizontal technique (69.2) % with medium force (40.4) % tend to have more tooth surface loss which shows a correlation with the study reported by Ahmed et al32 that brushing with moderate type of brush (48.4) % shows relevant tooth surface loss. Another study reported by Mushtaq et al.33 also observed a substantial association between participants using different types of toothbrushes and hard tissue abrasive lesions was reported(p<0.05). The cause of these injuries is important to prevent further injuries and to prevent existing injuries. Enamel reduced by acids (erosion), may be scrubbed away with tooth brushing (abrasion) and damaged away by chewing or tooth grinding.25
Males in the present study were more liable to have tooth surface loss possibly due to majority of males assessed as compared to females and this result was similar to other various studies.7,34,35 The factors which result in more tooth surface loss in males were mainly due to age, biting force, reduced tendency for malocclusion, more muscle mass, decreased occlusal tactile sensitivity.36,37
Generally, patients are more concerned about their esthetics and wish that their age process could be delayed and evidence revealed that tooth wear is related to the aging process.28 The present study reported that tooth wear increase with increasing age. Deshpande S28 and Meshramkar R38 et al. in a study also reported similar results.
Proper steps need to be taken for immediate action, as they are essential to restore the form and function of teeth. Dental wear is a preventive and curable condition. To avoid the problem of getting worse in the future, we must try to fight the problem from its early stages. One of the methods to prevent and cure the condition is to increase awareness among practitioners and to develop general public prevention programs among individuals. The present study has some limitations, which include that it was a single centre study, there were more male participants, and lacks the inclusion of other demographic variables. Evaluation of tooth wear should be added as a component of regular dental checkups amongst patients attending dental hospitals.

CONCLUSIONS
Recognizing the multifactorial nature of the condition is the first step in managing it, as a misunderstanding, it can lead to inadequate management and the ultimate failure of rehabilitation therapy. The present study concluded that tooth surface loss is associated with its etiological factors and was observed more in males when compared to females. However, steps should be taken to increase awareness among people regarding their teeth and the management of several condition .

CONFLICT OF INTEREST
None to declare

ETHICS APPROVAL /DISCLOSURE
The study Titled “A cross-sectional study: Evaluation of Tooth wear and its causative risk factors amongst Patients Attending Dental Hospital of Karachi.” is approved by the Ethical Review Board of Baqai Dental College under the reference # BDC/ERB/2018/010.

AUTHORS CONTRIBUTIONS 
AS contributed in writing and tabulating research paper AW analyzed and interpreted the patients’ data TMS provided overall supervision MH and KA contributed to the collection of patients’ data.

ACKNOWLEDGMENTS
Thanks to the institution for supporting the study.

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2. Lopez-Frias FJ, Castellanos-Cosano L, Martín-González J, LlamasCarreras JM, Segura-Egea JJ. Clinical measurement of tooth wear: tooth wear indices. J Clin Exp Dent 2012; 4: e48-e53
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3. Ganss C. Definition of erosion and links to tooth wear. Monogr Oral Sci. 2006; 20:9-16.
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14. Isaksson H, Birkhed D, Wendt L-K, Alm A, Nilsson M, Koch G. Prevalence of dental erosion and association with lifestyle factors in
Swedish 20-year olds. Acta Odontol Scand.2014; 72:448-57.
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15. Attin T, Wegehaupt FJ. Methods for assessment of dental erosion. Monogr Oral Sci. 2014; 25:123-42.
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17. Margaritis V, Nunn J. Challenges in assessing erosive tooth wear. Monogr Oral Sci. 2014; 25:46-54.
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30. Ayer A. Association between Severity of Tooth Wear and Dentinal Hypersensitivity. J Coll Med Sci-Nepal. 2016; 12:94-8.
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Evaluation of Tooth Wear and its Causative Risk Factors Amongst Patients Attending Dental Hospital of Karachi

Aneeqa Shahab             BDS, MME (scholar)
Aisha Wali                      BDS, MPH, PhD (scholar)
Talha M Siddiqui            BDS, MCPS, MME
Mobeen Hamed              BDS
Kiran Aslam                    BDS

 

OBJECTIVE: Tooth wear is a term defined as the loss of dental hard tissue in a damaged tooth if there is no existing dental
caries or trauma. Tooth wear rarely exists alone and is observed clinically and experimentally in combination. Excessive tooth
wear leads to hypersensitivity and exposed dentin. Tooth wear can be classified as attrition, erosion, abrasion. The frequency
of normal tooth preservation is greater than ever, thus a better prevalence of tooth wear is experiential in the population.
Therefore, the objective of the present cross-sectional study was to evaluate tooth wear and its causative risk factors amongst
patients attending the Dental Hospital of Karachi.
METHODOLOGY: The current study was a cross-sectional study conducted on adult patients recruited from the Out-Patient
Department of Oral Diagnosis from May 2018 - December 2018. A consecutive sampling method was used and 250 adult
patients aged 18-45 years were included. Tooth wear was assessed by using Smith and Knight Tooth Wear Index (TWI index).Data
was entered and analyzed by using SPSS, frequency, percentages were calculated, and a chi-square test was performed to find
the association between gender and risk factors.
RESULTS: The subject populations of 250 were assessed. Out of which 178 were male (71.2%) and 72 (28.8%) were female
with age ranging between 18 to 48 years old. In this study, 92.4% of them were suffering from tooth wear and only 31.2% have
extended to the severe stage of the tooth surface loss.
CONCLUSION: The present study concluded that there is an association between tooth wear and its risk factors.
KEYWORDS: Tooth Wear; Dental Wear; Tooth Wear Indices; Sensitivity and Specificity; Risk Factors.
HOW TO CITE: Shahab A, Wali A, Siddiqui TM, Hamed M, Aslam K. Evaluation of tooth wear and its causative risk factors
amongst patients attending dental hospital of Karachi. J Pak Dent Assoc 2021;30(4):255-260.
DOI: https://doi.org/10.25301/JPDA.304.255
Received: 06 January 2021, Accepted: 07 August 2021

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Preparation and Assessment of Antimicrobial Property of Resin Based Composites Impregnated with Proanthocyanidin and Titanium Dioxide

 

 

Mumtaz ul Islam                  BDS, M.Phil
Sardar Muhammad             MBBS, DOMS, M.Phil
Fazal Ghani                         BSc, BDS, MSc, CMP, PhD, FDSRCPS (Post Humous)

 

OBJECTIVE: To synthesize three experimental resin based composites (RBCs) out of a commercial preperation (Control)
by impregnating into each a fixed weight (0.01%) of titanium dioxide (TiO2) and three different weight % (0.01, 0.02 and 0.03)
of proanthocyanidin (PA) and to compare antibacterial property, from the zones of inhibition of streptococcus mutans
(S. mutans), of the specimen restorations made in the experimental and control RBCs.
METHODOLOGY: In the first phase, Streptococcus mutans were isolated and identified from the oral cavity of patients and
identified on the basis of morphogenic appearance of colonies and confirmed through catalase test and microscopic examination.
Isolates were then incubated and cultured for sensitivity. Specimens for control and experimental RBCs were made through a
metallic mold having 2mm thickness and 5mm diameter for all the 4 groups. Specimen restorations made in the commercial
as supplied RBC acted as the control (Group A). Specimen restorations in the Group B, C, and D were made in each of the
experimental RBCs modified with 0.01% proanthocyanidin (PA) and 0.01% titanium dioxide (TiO2), 0.02% PA and 0.01% TiO2
and 0.03% PA and 0.01% TiO2. The antimicrobial property of all the specimen restorations in all the groups was evaluated by
Bauer-Kirby (Disc Diffusion) method through the formation of zones of inhibition of S. mutans colonies on blood agar plates.
Data were computed using SPSS version 21 for descriptive statistics and analyzed using one-way ANOVA with p value 0.05
taken as significant.
RESULTS: The range of the zone of inhibition for specimen RBC restorations (N= 12) containing PA and TiO2 was 0.00 for
Group A, 10-12mm for Group B, 12-14mm for Group C and 9-10mm for Group D. The mean inhibition zone for the experimental
restoration specimens was 11±2mm for Group B, 12.7±1mm for Group C and 9.7±1mm for Group D compared to no inhibition
zones (0.00 mm) with the control RBC Group A. The order of the inhibition zones from maximum to minimum was
Group C > Group B > Group D > Group A. The differences between the mean values for the control and the experimental RBC
restoration specimens were significant (p < 0.000). The specimen restorations in the Group D appeared under cured and could
impact on their mechanical properties.
CONCLUSION: Irrespective of the mentioned concentrations, impregnating PA and TiO2 rendered the RBC antimicrobial.
RBC restorations made with the experimental RBC with 0.02% PA and 0.01% TiO2 proved relatively more effective in terms
of antimicrobial effect.
KEY WORDS: dental materials, resin based dental restorations, antibacterial resin based composite, proanthocyanidin, titanium
dioxide.
HOW TO CITE: Islam MU, Muhammad S, Ghani F. Preparation and assessment of antimicrobial property of resin based
composites impregnated with proanthocyanidin and titanium dioxide. J Pak Dent Assoc 2021;30(4):243-248.
DOI: https://doi.org/10.25301/JPDA.304.243
Received: 27 January 2021, Accepted: 17 August 2021


INTRODUCTION
 The involvement of microbes in the process of dental caries is well-established due to the virulence of streptococcus mutans. 1-3 Dental resin based composites (RBCs) suffers polymerization shrinkage, have lower strength and lack antimicrobial property. These have been noted to cause failure of the RBC restoration because of fracture as well as recurrent carries at the tooth-restoration interface. 4 To address these issues, there is an ongoing research focus to produce RBCs with antimicrobial property. Antibacterial agents of bioactive nature, caries preventive additives, polymer antibiotic conjugates and quaternary ammonium salts were added in resins to elicit antimicrobial activity. 4-9
The antioxidant action and free-radical scavenging effect of Proanthocyanidin (PA) have been established when applied to a surfaces.
10 Cariogenic environment causing degradation of dentine has been prevented with PA. 11 The antibacterial action of Titanium Dioxide (TiO2) is through photo catalysis with water to release the hydroxyl radical with subsequent formation of superoxide as an antimicrobial agent. 12
Knowing the fact that there are inconsistencies in the literature regarding the antimicrobial property of RBCs, the search for making them antimicrobial is continue. 13-14 Both PA and TiO2 are naturally occurring and easily available, hence their incorporation into RBC for possible antimicrobial property of the resulting restorations justifies an investigation. When proanthocyanidin was incorporated
in adhesive agent in different concentrations ranging from 1% to 6% the antibacterial activity was same as of the control which is devoid of Proanthocyanidin. 15 Antibacterial activity of TiO2 in concentrations from 0-10% was also evaluated in orthodontic composites which provided better antibacterial activity with concentration of 10%. 16 Therefore, we have designed a comprehensive study that is looking at
the effect of adding PA and TiO2 to RBC in terms of enhancement of antimicrobial and mechanical properties. This report presents the results on the antimicrobial effect of incorporating different concentrations of PA and a fixed quantity of TiO2 in RBC and assessing their antibacterial property of specimen restorations against S. mutans isolated from the oral cavity of subjects.

METHODOLOGY
Preparation of specimen restorations:
 Group A was the control group in which no additives were added. In each group 4 specimens were prepared from a commercially available RBC, Nexcomp (Meta Biomed Co. Ltd) with 1% TiO2 which was fixed for all the experimental groups. Group B, C, & D all were test groups which have 0.01, 0.02 and 0.03% PA. Sample size was calculated according to the following values the confidence level for this study was considered as 95% while power of the study kept 80 with a response distribution 60% and margin of error kept 5% the calculated sample
size was 3 used in this pilot study.
The research protocol for the study was approved by the Board of Advanced Studies and Research (BASR) of the university (Riphah 25th meeting, dated, October, 18th, 2018) as well it was approved for publication of the research findings by the institutional review board (PRIME/IRB/ 2019-166.) The experimental work was conducted during the period of (01 May to 30 June, 2018) at the Department
of Dental Materials and Microbiology Lab, Department of Pathology, Peshawar Medical and Dental College (Pakistan). The materials used in the study including the experimental RBC are detailed in (Table 1).
Proanthocyanidin (PA) was characterized for purity using Fourier Transform Infrared Spectroscopy (FTIR) in Material Research Laboratory, Physics Department Peshawar University, Pakistan (Figure 1).

Each of the relevant weight % of PA & TiO2 were first assimilated in the resin bonding agent to facilitate easy and thorough mixing and then impregnated into a commercially available light-cure nanohybrid RBC NexcompNanohybrid Resin Composite Nexcomp contains
Bis-GMA, Bis-EMA, UDMA, TEGDMA while Meta P&Bond Adhesive contains bisphenol a Glycerolate dimethacrylate, Urethane
Dimethacrylate, Pyromellitic glyceryl dimethacrylate, 2-Hydroxy ethyl methacrylate, Ethyl alcohol (Table 1). The
 three experimental RBCs were prepared by adding in each a fixed weight % of TiO2 (0.01%) and the various weight % of the PA (0.01%, 0.02% and 0.03%) to the commercially supplied RBC. The as supplied commercial RBC acted as the control RBCs.
The specimen restorations were prepared in each of the three experimental and the control RBC using a stainless steel mold according to ISO specification No. 4049. The mold facilitated the preparation of specimens having 2 mm thickness with 5 mm diameter. Specimen restorations were made by pouring each of the RBC into the mold and cured with a light curing unit (O-Light by DTE, 5 watts, Light Intensity from 1000 to 2300 mw/cm2 ) for 20 seconds from one side. The poured resin was kept pressed under a 1mm

Assessment of antibacterial property of the specimen
restorations
 This was determined by Bauer-Kurby disc diffusion test using S. mutans from the oral cavity of patients who were negative for HbV and HcV infection. Swabs were taken from carious teeth of patients to collect S. mutans. Written consents of patients were obtained and duly signed
by witnesses. The swabs were transferred to Microbiology Department Peshawar Medical & Dental College within
confirmed through catalase negative test and finally confirmed through microscopic evaluation (Figure 3).
Colonies of S. mutans were tested for sensitivity by

DATA ANALYSIS
 Using SPSS Version 21, mean, mode and percentages for the data were computed. Data were also analyzed using one-way ANOVA to see the statistical significance of the within and between the specimen groups differences from the mean values with p value set as 0.05 considered
significant. Post hoc test is not presented due to selfexplanatory results of four groups of this pilot study.

RESULTS
The specimen restorations in the control group did not exhibit any antimicrobial property in-comparison to those in the experimental groups. Similarly, the antimicrobial property was maximum for the restoration specimens in group C. The order of antibacterial effect among the specimens in the various groups was Group C > Group B > Group D > Group A. (Table 2).
The mean size of the inhibition zone was 8.42mm for the specimens in groups B to D out of 13 mm. Maximum sizes of inhibition zones were found in two specimen restorations belonging to group C. None of the control group
DISCUSSION
 For assessing the antimicrobial property of RBC restorative materials, the method of disc diffusion has also been previously used.17 Studies on anti-microbial property of experimental RBCs have used standardized microbial strains species like ATCC3566818 , ATCC 2517519 and a different strain of S. mutans (10449) has been used for assessing the antimicrobial effect of benzalkonium incorporated RBC.20 A concern about these studies is that these have not mimicked the actual mode of action of the antimicrobial agent added to the resin. In this study strains of S. mutans collected from patient’s mouth, making the testing method relatively more relevant because virulence/activity of standard cultures is questioned and reported as of low or no bacterial activity.21
At present, a definite methodology for testing antimicrobial properties of a material is lacking. Therefore, authors preferred the easy and commonly used method for this study.22 The disc diffusion method for establishing the antimicrobial efficacy of PA to S. mutans has also been used in another study.15 Quantitative methods like plate count method, flow cytometry and quantitative polymerase chain reaction for
antimicrobial assessment are available but were not employed in the present study due to their technique sensitivity.23 Results obtained through disc diffusion method are better than other protocols.24 This was employed to verify the results obtained through direct contact test between microbial strains and the restorations and to validate the antibacterial action. Discs prepared for experimental and control RBC specimens had the same dimensions as used by other investigator.25 Furthermore, following the preparation of standardized specimen restorations and the selection of defect free specimens for testing obviated the need for using many specimens.
The incubation procedures employed for S. mutans strains were according to the Bergey’s manual of determinative microbiology.26 Due to vast discrepancy in literature for the growth medium and its yield, blood agar was used as nutrient medium for proliferation of the S. mutans colonies and their killing by the RBC specimen restorations. There is a positive correlation between genotype and phenotype evaluation of bacteria which confirms and validate the phenotypic evaluation of the
bacterium.16 The colonies obtained after incubation were identified in the present study for morphology of the colony followed by confirmation through catalase test and finally through microscopic examination (Figure 2).
The findings of the present study are in accordance with those of a previous study, in which the range of size of zones of inhibition was 9.33mm to 12.67mm for antibacterial activity of resin containing 0.25% concentration of benzalkonium chloride.20 Size of zones of inhibition always will be more than the size of discs if smaller than discs then it will be of no use and considered as no zone of inhibition.
When a drug is placed in a medium where a bacterial culture is present if that drug is of antibacterial potential it produces areas of no growth around that drug specimen these areas are zones of inhibition. The findings of the present study are more encouraging as a comparable yet better antimicrobial effect has been achieved with a small concentration of PA (0.02%). Our finding of the lack of antibacterial property in the specimen restoration made in the control RBC are supported by the finding of another study where no zones of inhibition were also observed in case of specimen restorations in the control RBC.27
In the present study, the RBC specimens in the control group exhibited no antibacterial effect as observed from no zones of inhibitions. In the present study a much lower concentration of TiO2 and PA showed comparable antibacterial activity. In the present study lower concentration of PA (0.01, 0.02 and 0.03%) were used and found effective against S. mutans.
As titanium dioxide is highly opaque material therefore its concentration in the RBC was kept 0.01% so as to avoid the problem of shade change which was confirmed through another pilot study.

LIMITATIONS OF THE STUDY
 An obvious limitation of this study may be the use of few samples and using a method for antimicrobial properties of the test RBCs restorations that does not mimic the real clinical situation in which the restorations are functioning. However, in case of in-vitro studies, using standardized dimension specimens that are defect-free, the use of few specimen restorations is justifiable. On the other side, in
the present study, the specimen RBC restorations have been subjected to relatively harsher bacterial insult than that could be expected in the oral cavity. Despite this, it was encouraging to have seen enhanced antibacterial property in case of experimental RBC restorations containing PA and TiO2.
Incorporation of additives in RBC may produce any effect on the mechanical properties which was not evaluated in current study. This aspect is being currently under investigation for the experimental RBCs used in this study. Another limitation, of this study is the addition of PA and TiO2 to the commercial RBC, which have altered the actual formulation of the commercial RBC. Therefore, it is recommended that this aspect should be kept in mind in future studies by synthesizing the experimental RBC with the mentioned additives.
effect has not been followed up over a larger duration of time and hence the sustained long term antibacterial effect of the RBC restorations cannot be predicted from the present study making observation at one time-point. It is recommended that the specimen restorations be tested repeatedly after simulated usage scenarios to give a clear picture of how much stable and long-lasting would be the observed antibacterial property as documented in this study.

CONCLUSION
 Within limitations of this study, PA and TiO2 imparted antimicrobial properties to the RBC especially PA 0.02% along with TiO2 0.01% which produced larger zones of inhibitions.

CONFLICT OF INTEREST
 None declared.

AUTHORSHIP CONTRIBUTIONS
All authors (MUI, FG, MS) contributed equally to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript; All authors have given final approval and have agreed to be accountable for all the aspects of the research work and its publication. FG had accepted the responsibility as the corresponding author but after his unfortunate death MUI is now corresponding author.

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Preparation and Assessment of Antimicrobial Property of Resin Based Composites Impregnated with Proanthocyanidin and Titanium Dioxide

Mumtaz ul Islam                  BDS, M.Phil
Sardar Muhammad             MBBS, DOMS, M.Phil
Fazal Ghani                         BSc, BDS, MSc, CMP, PhD, FDSRCPS (Post Humous)

 

OBJECTIVE: To synthesize three experimental resin based composites (RBCs) out of a commercial preperation (Control)
by impregnating into each a fixed weight (0.01%) of titanium dioxide (TiO2) and three different weight % (0.01, 0.02 and 0.03)
of proanthocyanidin (PA) and to compare antibacterial property, from the zones of inhibition of streptococcus mutans
(S. mutans), of the specimen restorations made in the experimental and control RBCs.
METHODOLOGY: In the first phase, Streptococcus mutans were isolated and identified from the oral cavity of patients and
identified on the basis of morphogenic appearance of colonies and confirmed through catalase test and microscopic examination.
Isolates were then incubated and cultured for sensitivity. Specimens for control and experimental RBCs were made through a
metallic mold having 2mm thickness and 5mm diameter for all the 4 groups. Specimen restorations made in the commercial
as supplied RBC acted as the control (Group A). Specimen restorations in the Group B, C, and D were made in each of the
experimental RBCs modified with 0.01% proanthocyanidin (PA) and 0.01% titanium dioxide (TiO2), 0.02% PA and 0.01% TiO2
and 0.03% PA and 0.01% TiO2. The antimicrobial property of all the specimen restorations in all the groups was evaluated by
Bauer-Kirby (Disc Diffusion) method through the formation of zones of inhibition of S. mutans colonies on blood agar plates.
Data were computed using SPSS version 21 for descriptive statistics and analyzed using one-way ANOVA with p value 0.05
taken as significant.
RESULTS: The range of the zone of inhibition for specimen RBC restorations (N= 12) containing PA and TiO2 was 0.00 for
Group A, 10-12mm for Group B, 12-14mm for Group C and 9-10mm for Group D. The mean inhibition zone for the experimental
restoration specimens was 11±2mm for Group B, 12.7±1mm for Group C and 9.7±1mm for Group D compared to no inhibition
zones (0.00 mm) with the control RBC Group A. The order of the inhibition zones from maximum to minimum was
Group C > Group B > Group D > Group A. The differences between the mean values for the control and the experimental RBC
restoration specimens were significant (p < 0.000). The specimen restorations in the Group D appeared under cured and could
impact on their mechanical properties.
CONCLUSION: Irrespective of the mentioned concentrations, impregnating PA and TiO2 rendered the RBC antimicrobial.
RBC restorations made with the experimental RBC with 0.02% PA and 0.01% TiO2 proved relatively more effective in terms
of antimicrobial effect.
KEY WORDS: dental materials, resin based dental restorations, antibacterial resin based composite, proanthocyanidin, titanium
dioxide.
HOW TO CITE: Islam MU, Muhammad S, Ghani F. Preparation and assessment of antimicrobial property of resin based
composites impregnated with proanthocyanidin and titanium dioxide. J Pak Dent Assoc 2021;30(4):243-248.
DOI: https://doi.org/10.25301/JPDA.304.243
Received: 27 January 2021, Accepted: 17 August 2021

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Comparison of Repeated Chemical and Microwave Disinfection on Dimensional Accuracy of Gypsum Casts

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


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