The odontogenic keratocyst (OKC) well-known for its aggressiveness and high recurrence rate, comprises approximately 11% of all jaw cysts. Due to its aggressive behavior it was placed into category of tumour in 2005 by the World Health Organization (WHO). Objectives: The purpose of this study was to determine the Ki-67 expression in Odontogenic Keratocysts to predict its proliferative potential. Study Design: Descriptive study. Setting: Department of Morbid Anatomy and Histopathology, UHS. Periods: June 2014- June 2018. Material & Methods: This is a descriptive study comprising of 39 cases of odontogenic cysts. These surgically removed samples were processed at University of Health Sciences (UHS) laboratory. Routine staining with Hematoxylin & Eosin stain along with immunohistochemistry (IHC) with Ki-67 antibody was performed. Immunohisto chemical scoring was done on the basis of percentage of the nuclear staining of Ki-67. Data was entered into SPSS 22 and descriptive statistics were measured in the form of percentage and frequency. Quantitative variables such as age of patient, size of the cyst, and Ki-67 score were also measured. P value <0.05 was taken as significant. Results: The mean age of the patients was 25.08 ±14.5 years. Significant association was observed between histological variables with odontogenic keratocyst such as parakeratinized epithelial lining (p = 0.00), epithelial hyperplasia both typical and atypical (p = 0.02) and focal spongiosis (p = 0.04). Foci having epithelial atypia demonstrated stronger staining intensity compared to adjacent normal epithelium. However, no significant association was observed between the histological variables and Ki-67 expression. Conclusion: OKC expressed low Ki-67 expression in most of the cases, however, foci of strong expression were also observed in few cases.

Background: Biological behaviour of Odontogenic Keratocyst (OKC) is aggressiveness than others Odontogenic Cysts (OCs) like Dentigerous Cyst (DCs) and Periapical Cyst/Residual Cysts (RCs). The aim of the study was to determine clinicopathological features and expression of Ki-67 in Odontogenic Cysts of the oral cavity. Methodology: This cross-sectional study was conducted at de’Montmorency College of Dentistry (DCD from Feb, 2020 to Feb, 2022 after approval from Institutional Review Board (IRB) of DCD. A total 78 cases of OCs were collected from hospitals which are affiliated with the DCD. Routine lab process for Hematoxylin & Eosin and Immunohistochemistry was performed. Data entry and statistical analysis was carried out in SPSS 21. A Chi- square test was applied to observe the association between cyst and Ki-67. P value < 0.05 was taken as statistically significant.     Results: Among total 78 cases the mean age was 25.08 ±14.5 years with an age range of 6-70 years. Most OCs (64.1%) were reported in males than females (35.89%). Most OCs were reported in mandible (56.4%. Ki-67 expression in OKC was high 7.7%, low in 76.9% and negative in 15.4%). Most of the DCs and RCs expressed low expression of Ki-67 (84.6% and 76.9% respectively).   Conclusion: Most of the odontogenic cysts expressed low expression of Ki-67 while few cases of OKC and DC expressed high expression. Keywords: Dentigerous Cyst, Odontogenic Keratocyst, Immunohistochemistry, Ki-67, Odontogenic Cysts, Periapical Cyst, Radicular Cyst.