The Kois examined crestal bone levels and classified

The term  “gingival biotype” was introduced to describe the thickness of gingiva in a buccolingual dimension (thin or thick).1 Various studies have shown a wide range of clinical difference in form and appearance in tissue biotypes in individuals.2, 3, 4, 5, 6 Different factors contribute to these differences including genetics, tooth morphology, tooth position, age, gender and growth.7 In 1923, Hirschfeld performed an extensive study on human skull in American museum. He assumed that a thin alveolar bone contour was probably covered with a thin gingival form.8 In 1969 Ochsenbein and Ross indicated that gingival biotypes are of two types – they are scalloped and thin or flat and thick. The authors reported that flat gingiva was associated with a square tooth form, while scalloped gingiva was associated with a tapered tooth form.9  In 1977, Weissgold emphasized that the form and function are related and also observed that the gingival tissues in a scalloped periodontium are generally thinner than in a flat periodontium. Therefore the terms thin-scalloped and thick-flat type were introduced.10 In 1986 Claffey and  Shanley defined the thin tissue biotype as a gingival thickness of ?1.5 mm, and the thick tissue biotype was referred to gingiva having a tissue thickness ?2 mm (measurements of 1.6 to 1.9 mm were not accounted for).11 Seibert and Lindhe in 1989 categorized the gingiva into ”thick-flat” and ”thin- scalloped” biotypes.12 In a 1994 article, Kois examined crestal bone levels and classified them as normal {crestal bone level is 3 mm apical to the cementoenamel junction (CEJ)}, high (crestal bone level is <3 mm apical to the CEJ), and low (crestal bone level is >3 mm apical to the CEJ and found in patients with recession). 13 Becker et al. in 1997 proposed three different periodontal biotypes: flat, scalloped and pronounced scalloped gingiva.14 In a study by De-Rouck et al. (2009), the thin gingival biotype associated with slender tooth form occurred in one-third of the study population and was prominent among women, while thick gingival biotype which was associated with square teeth form occurred in two-thirds of the study population and occurred mainly among men.4

Many methods (both invasive and noninvasive) have been utilized to evaluate the thickness of facial gingival and other parts of the masticatory mucosa. These methods include conventional histology on cadaver jaws,8  visual evaluation,12 injection needles, transgingival probing,15, 6 histologic sections,16 cephalometric radiographs,17 probe transparency,18 modified calipers,5 ultrasonic devices,19, 20 and cone beam computed tomographyCBCT.6

The identification of the gingival morphology is considered important because differences in soft and hard tissue architecture have shown to exhibit a significant impact on the final esthetic outcome of restorative therapy, periodontal therapy, root coverage procedures, and implant esthetics.21  Studies have revealed that thin gingival biotype is associated with more problems. In response to inflammation, thin gingival biotype was associated with rapid loss of bone and gingival recession.2, 22 A tendency for the more gingival recession was found with immediate single tooth implant restoration in a population with a thin scalloped biotype.23 The loss of peri-implant structures may result in thin, translucent tissue over the implant, which appears grayish, especially if the facial plate is lost and implant threads are exposed.24

At the best of my knowledge, no study is conducted yet in Nepalese population which assesses the prevalence of gingival biotype. By conducting this research, we would be able to predict the prevalence of the type of gingival biotype in this part of the country. The rationale of study is that the result obtained from this could be baseline data for further researches in gingival biotype. We can aware the patients with thin biotype of gingival recession if he/she developed periodontitis. Further, by understanding the nature of tissue biotypes, we could employ appropriate periodontal management to minimize bone resorption and recession which would provide a more favorable outcome. For example, in the cases where there is thin gingival biotype, we can go for procedures to increase the thickness of gingiva before going to restorative, implant surgery and orthodontic therapy. The present study aimed to determine the prevalence of different gingival biotype in patients visiting the Department of Periodontology and Oral Implantology with simple probe transparency technique.