Prevalence of Agenesis of Mandibular Third Molars in A Tertiary Healthcare Centre of Nepal

INTRODUCTION: Racial variation, genetic inheritance and various other factors can affect the jaw size and ultimately the tooth size and number. Studies for agenesis of mandibular third molars have been carried out in various populations but the data relating to these are not evident from most of the parts of Nepal. Hence, the objective of the present study is to determine the prevalence of agenesis of mandibular third molars among the population of patients visiting the Department of Oral Medicine and Radiology of B. P. Koirala Institute of Health Sciences. METHODS: This descriptive cross-sectional study was conducted at Department of Oral Medicine And Radiology, College of Dental Surgery, B. P. Koirala Institute of Health Sciences from September 2015 to September 2016 after taking ethical approval from Institutional Review Committee. Two hundred and eighty four patients (568 sites of third molar bilaterally), visiting the Department of Oral Medicine and Radiology were studied with Panoramic Radiograph to assess for agenesis of mandibular third molars bilaterally. Data was entered in Microsoft Excel sheet and transferred to Statistical Package for the Social Sciences version 11.5. RESULTS: Out of 284 participants, 568 sites of mandibular third molars were evaluated and agenesis was seen among 163 (28.7%) participants at the confidence interval of 95% (28.643 to 28.757). Total numbers of patient with single missing mandibular third molar were 35 (6.2%). Twenty one had agenesis only on the right side and 14 had agenesis only on the left. The total number of patients with agenesis of both the mandibular third molars was 64 (22.5%). CONCLUSIONS: Agenesis was highly prevalent in this study group. The likelihood of third molar being absent on one side, when there was concurrent missing third molar on the other side of mandible was also high.