Prevalence of Different Gingival Biotypes

Tissue biotype is one of the critical factors that determine the result of prosthodontic treatment. Initial gingival thickness predicts the outcome of any implant procedures or any restorative treatments. It has been documented that patients with thin gingival biotype were more likely to experience gingival recession following implant and restorative procedures. [2] The thicker biotype prevents mucosal recession, hides the restorative margins and camouflages the titanium implant shadows. It also preserves biological seal around implants, thus reducing the crestal bone resorption. Thick biotypes include flat soft tissue and bony architecture, denser and more fibrotic soft tissue with large amount of attached masticatory mucosa, it is more resistant to any acute trauma and respond to disease by pocket formation and infra bony defect. The gingival thickness affects the treatment outcome possibly because of the difference in the amount of blood supply to the underlying bone and susceptibility to resorption. [8],[12],[15] Thin gingival biotype is related with a thin band of the keratinized tissue and scalloped gingival contour which suggest thin bony architecture and is more sensitive to any inflammation or trauma.[8],[13],[14]

The ability of the gingival tissue to cover any underlying material is essential for attaining aesthetic results, especially in cases of implant, restorative dentistry, where subgingival metal restorations are mainly used. In this study, the metal periodontal probe was used in the sulcus to evaluate gingival tissue thickness because it is a reliable, objective, economical and minimally invasive method since periodontal probing procedures are routinely performed during any aesthetic, restorative, and implant treatments.[2],[16]

In the present study gingival biotype presented a significant difference between male and female subjects. These results are in accordance with studies conducted by Muller et al., [18] who stated 1/3rd of the sample to be females with a thinner biotype and Vandana et al, studied on 32 individuals showed thicker gingiva in males reporting a generalized thinner masticatory mucosa for females. [26] R. G. Shiva manjunath et al stated that 44.7% of females have thin gingival biotype and 76.9% of males have thick biotype. Gingival biotype in females varies with age unlike in males. [19] De Rouck et al., in his study also stated a significant difference between male and female subjects. He concluded that 84% of all measured central incisors of male participants showed thick biotype compared to females participants.[4] According to a survey conducted by Bhat et al., the thicker biotype is more prevalent in male population whereas the female population consists of thin and scalloped biotype.[24]

Present study showed significant correlation of biotype with crown height, sulcus depth, width of attached gingiva, papilla height. It is in accordance with studies conducted by Anand et al who stated shallower sulcus depth is expected in teeth with thin biotype, [25] Malhotra et al where significant correlation exists between crown heights, width of attached gingiva, papilla height. [1] Whereas study conducted by Zweers et al, showed narrow zone of attached gingiva in teeth with thick biotype and wide zone of attached gingiva in teeth with thin biotype.[27 ]

In present study no correlation exists between crown width and biotype which is in accordance with study conducted by Cook et al but study conducted by Olsson et al showed significant correlation between biotype and crown width. [28]

Regarding the correlation between gingival biotype and tooth form in maxillary and mandibular teeth, no significant correlation exists between biotype and tooth form in maxillary and mandibular posterior teeth, mandibular anterior teeth whereas highly significant correlation exists between biotype and tooth form in maxillary anterior teeth, suggesting either difficulty in classifying biotype in mandible or difference in biotype exists between maxilla and mandible as well as between anterior and posterior teeth in same patient. In present study the average of each tooth was calculated from the data collected showed no correlation of biotype between anterior and posterior teeth form. The present study results showed maxillary anterior as more relevant teeth for identifying gingival biotype than maxillary posteriors and mandibular teeth. To date all gingival classifications used maxillary anterior teeth as reference for identifying the gingival biotype for both the dental arches. [22]