Gingival Biotype and Width of Attached Gingiva - A Prevalence Study
INTRODUCTION
The thickness of the gingiva in the labiopalatal and buccopalatal dimension is termed as gingival biotype which is a genetically determined feature. 1,2 A healthy periodontium possesses variable phenotypic look varying from person to person. In a study, existence of two key variants of gingival tissue structure have been suggested which include Scalloped and thin gingiva and flat and thick gingiva. 3 In another similar study, the authors categorized the gingiva into "thick - flat" with broad zone of keratinized tissue and thick bony architecture and "thin - scalloped" biotypeswith thin bands of keratinized tissue and thin bony architecture. 4 A gingival tissue thickness 2 mm or more is described as thick tissue and a tissue thickness less than 1.5 mm is considered as thin gingival tissue. 5 In one study, three periodontal tissue types have been proposed which include flat, scalloped and pronounced scalloped gingiva, measuring from the bone height interproximally to the height at the midfacial area, 2.1 mm, 2.8 mm, and 4.1 mm respectively. 6 For the sake of simplicity and all practical purposes, gingival tissue can be divided as thick biotype with 85 % prevalence and thin biotype with 15% prevalence. 2,7,8
Prevalence of thick and thin biotype varies according to the gender and race. A study reported in India concluded that thick biotype was 56.75% versus thin biotype 43.25% in their population. 9 Similar study performed in Turkey showed that thick biotype was 70.2% versus thin biotype 29.8% in their population. 10 A study within Chinese population reported thick biotype to be more significant than thin biotype. 11
Clinical identification and classification of gingival tissue aids in appropriate treatment planning and prediction of the future outcome. Thickness of gingival tissue determination, therefore, has gained enormous significance in periodontal therapy from a treatment standpoint. In the dental literature, multiple studies reveal a wide range of clinically distinct form and appearance of gingival tissues. 12 The thick tissue is the most prevalent type of gingival tissue which has thick bony architecture underneath. The thick gingiva is a dense and fibrotic tissue having wider gingival attachment, rendering them resistant to recession. 5,8 The thin gingival tissue, on the contrary, is delicate and thin having scalloped soft tissue and thin bone manifested by dehiscence and fenestrations in the bone. The thin type of tissue is more vulnerable to inflammation, bleeding and ultimate recession. 13 Inflammation of the periodontium causes enhanced pocket formation in thick tissues and recession in thin tissues. 14
Numerous techniques have been proposed for the assessment of tissue thickness. They incorporate invasive and non-invasive techniques such as direct measurement by probe transparency (TRAN) method, ultrasonic devices and cone-beam computed tomography (CBCT). 8,12,15 Though CBCT is one of the advanced diagnostic tool that assists in providing precise measurements of bone thickness as well as soft tissue thickness15,16 as compared to direct measurement17 but TRAN method is an effective and easier strategy to differentiate between thick and thin gingival biotype and has been used in the data collection of this study. Various studies among human populations16 and animals18 have been conducted which concluded that gingival thickness alters in relation to dental arch, gender and age which must have bearing on the outcome of the rehabilitative treatment provided to them. Dental clinicians practicing in various countries have the prior knowledge about the biotype of the population they work with as studies of prevalence of gingival biotype have been performed and well documented. Dental practitioners working with Pakistani population lack this facility as to the best of our knowledge, no study exists which addresses this issue. This study, therefore, was planned to evaluate the prevalence of thick and thin gingival tissue and width of attached gingivae in a subset of the Pakistani population. The authors are unaware of any study that demonstrates such data in this part of the world.
To assess the prevalence of thick and thin gingival tissue and width of attached gingivae in the Pakistani population.
METHODOLOGY
In this cross-sectional study, 400 patients between 20 and 60 years of age were randomly selected from the outpatient department of Periodontology and Implantology of Dental Hospital attached to a community-based university in Karachi from February 2021 to January 2022. All the subjects were briefed verbally about the purpose the study and obligated to sign an informed consent before initiation of a clinically semi-invasive procedure.
The study was approved by the institutional Ethical Review Board (BDC/ERB/2021/001) and all procedures were followed in accordance with Helsinki declaration. The screening of the subjects was done according to Basic periodontal screening.19
The subjects included in this study were native Pakistanis ranging from all the major ethnic groups found in the locality. Non-indigenous populations were excluded from this study henceforth. The participants also possessed disease free periodontium (with BPE scoring of 0) and were termed as "healthy" individuals. Patients above 70 years of age were deemed unfit for testing.
Furthermore, subjects who smoked or were mouth breathers were also excluded from this study. Patients with removable dental devices like removable partial dentures, or removable post orthodontic treatment retainers, or missing any of the upper or lower front teeth were deemed inadequate for participation in the research. Also, patients who possessed Miller's Class III or Class IV recession, or had histories of systemic disorders and antibiotic usage over the previous 4 months period, fell under the exclusion criteria. Individuals who required drugs which can perpetually induce gingival hyperplasia, females who were in various stages of pregnancy, or individuals who received scaling and polishing within the previous 6 months and subjects with a history of surgical periodontal treatment within the past 12 months were also excluded from the study.
Facial gingiva was anesthetized with a Lidocaine spray (LOX 10%) to determine the gingival biotype (GB) and width of the attached gingiva (WAG). All the measurements for gingival biotype and WAG were performed on maxillary and mandibular anterior teeth at the mid-buccal area of the tooth using a UNC-15 periodontal probe (HuFreidy®, USA).7,20
The GB was evaluated by the TRAN technique which incorporates delicate inclusion of a periodontal probe into the gingival sulcus at the center point of the buccal surface of every maxillary and mandibular front tooth. To estimate the width of attached gingiva, pocket depth was subtracted from the total width of attached gingiva which is found from gingival margins to mucogingival junction. Assessment bias was controlled by allowing a single person to perform estimations multiple times for every region and recorded readings were chosen as the last estimations.
SPSS software was used for statistical analysis. The results are primarily expressed in frequency and percentages, whereas chi square test was employed to check for the associations. The p-value <0.05 was considered as statistically significant.
RESULTS
Out of the 400 participants who took part in the study, the mean age was 34.0 ± 0.6, with the minimum being 20 years and the maximum being 70 years. Approximately 13% (51 subjects) of the tested individuals were 20 years old. 56.3% (225) were males and 43.8% (175) were females. 57% of the participants possessed thick gingival tissues and 43% possessed a thinner type of gingivae. The overall width of the gingiva was 4.4 ± 0.8.
Overall, the biotype in the maxillary arch for the tested population was predominantly thick in age groups below 40, with the 20 - 30-year-old category showing the greatest difference between the thick and thin types. From the age of 40, the maxillary gingival biotype started to gradually lean towards the thinner side, eventually almost evening out at 61-70 years of age. The total number of thick and thin gingival biotypes reported in the maxillary arch in this study were 228 and 172 respectively, as shown in Figure 1.1. The chi square showed a significant association between the age and maxillary gingival biotype as the p-value was less than 0.05.
Furthermore, the average biotype in the mandibular arch showed similar findings except that at ages 31-40, thicker biotype presented more frequently in the study (Figure 1.2). The total number of thick and thin gingival
Figure 1.1: Occurrence of thick and thin gingival biotype in the maxilla versus age
Figure 1.2: Frequency of thick and thin gingival biotype in the mandible versus age
biotypes reported in the mandibular arch were 227 and 173 respectively. The p-value was found to be <0.001, which shows significant association between the age and mandibular gingival biotype.
The maxillary width of keratinized gingiva showed variable results in different age groups. Individuals belonging to 20- 30 years of age displayed primarily 5mm wide gingiva, whereas people from 31-50 years of age predominantly had 4mm wide gingiva. Sample population from 51-60 years of age showed mixed results, ranging from 2-4mm wide majorly. Lastly, individuals from 61-70 years of age had either as low as 2mm or as high as 6mm wide gingiva chiefly (Figure. 1.3). The p value presented a statistically significant association between the two variables.
Figure 1.3: Width of keratinized gingiva in the maxillary arch versus age
When age was compared with the width of the keratinized gingiva in maxillary arch, the highest average width in the maxillary arch was 5mm. The results showed an inverse relationship of age with the width of the gingiva as the age increased. There was a strong significant association (p-value < 0.001) between age and width of maxillary keratinized gingival tissue (Figure.1.3)
The mandibular width of keratinized gingiva showed quite similar results in different age groups. Figure 1.4 shows that most of the people from any age range had 4mm wide mandibular keratinized gingiva, except for people belonging to 61-70years. This age range predominantly had 3mm wide gingiva. The most wide keratinized gingiva was found to be 7mm which was only seen in individuals from age range of 20-30years. Chi
Figure 1.4: Width of keratinized gingival tissue in lower arch with participants' age
square revealed a highly significant association between the age and mandibular gingival thickness (p-value<0.001). When gender was compared with the tissue type and the width of the keratinized gingival tissue in both the arches, it was found that an insignificant relationship existed between the variables. In the maxilla, out of 225 males and 175 females tested, 228 possessed a thick biotype while only 172 had a thin gingival biotype. In the mandibular arch, similar findings were observed and there seemed to be no significant relationship between gender in comparison to gingival tissue biotype and width of keratinized gingiva. Generally, a thick biotype was observed between the two sexes at any given age on average in both maxillary and mandibular arches. Figure 1.5-1.6 shows gender in comparison with gingival biotype.
Figure 1.5: Gender in comparison with gingival biotype in the maxillary arch
Figure 1.6: Gender in comparison with gingival biotype in the mandibular arch
DISCUSSION
In this study, majority of the Pakistani population examined, possessed thick periodontal biotype. This is in accordance with Olsson and Lindhe who reported that majority of the population (85%) has thick gingival tissue whereas merely 15% possesses thin biotype. 2 1
When age was evaluated against gingival biotype, most of the patients of 20-30 years group had a thick biotype as compared to age groups above 40. This is in alignment with various studies that portray thick biotype to be related to age.22 A recently published study on Pakistani population demonstrate the similar findings.23 In another study, the authors studied gingival thickness in relation to age and their findings revealed that the gingiva in the younger subjects was thicker than in the older participants.33 The logical cause may be age-linked changes in oral epithelium as with ageing, thinning of the epithelium and diminished keratinization occurs. Furthermore, with advancing age, interdental papilla recede which give rise in higher prevalence of thinner tissue type in older ages. According to findings of Warasswapati et al., racial and genetic factors play a impactful on occurrence of biotype.24
Contrarily, Kuriakose et al and Kolliyavar et al. found that the younger age individuals possess significantly thinner oral mucosa than older age group.25,26 Further research into how gingival changes occur with the progression of age need to be carried out as there is limited literature available on this issue.
The upper arch demonstrated a thicker gingival tissue when compared with the lower Jaw in the present study. Issrani et al demonstrated similar results in their research where maxillary arch showed thicker gingival biotype in comparison to mandibular arch .27 Thickness of the gingival tissue was observed greater in younger age group and reduced advancing age. This indicates that a variety of gingival features can be affected by age, sex and the arch area as well.
The gingival tissue thickness was higher in maxilla when contrasted with the mandible, that is, 5mm and 4mm respectively over the distinctive age groups. Its thickness decreases with increase in age. However, this finding is in opposition to the few studies wherein the thickness diminishes due to ageing28 whereas Waraaswapati et al reported that thickness of palatal gingiva increases with the growing age.24 The difference in the outcome in examination can be a result of the inappropriate conveyance of the subjects of selected three age groups and unequal gender proportion inside the groups. The thickness likewise was different for each arch.
Gender did not have a significant predilection on gingival biotype in this study. This finding is in accordance with the study done involving Yemeni population.29 However, when Kolte et al. observed gender against biotype, the younger subjects showed a significantly thicker gingival biotype but lesser width than older individuals. Gingiva was thinner having lesser width in women as compared to men.20 Another study reveals that thicker tissue is more common in male participants as compared to female participant.30 At a point when both genders were compared for the gingival thickness and keratinized gingival width in the maxillary and the mandibular arches, insignificant relationships were found between the groups. In the maxilla, out of the 225 males and 175 females tested, 228 possessed a thick biotype while only 172 had a thin gingival biotype. In the mandibular arch, no critical connection between gender and biotype was portrayed either.
It is recommended that future multicentered studies with larger sample sizes and more diverse populations be conducted to validate the findings of this study.
CONCLUSION
It has been demonstrated that the thick biotype was more prevalent in overall population with maxillary arch having significant findings. However, the thickness of gingivae reduces with increasing age.
CONFLICT OF INTEREST
None to declare
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