RESUMO
Introduction: Mandibular third molar impaction is the most common impaction as third molars are last to erupt at the age of 17-25 years. Despite its high prevalence and negative impacts, there is limited study about mandibular third molar impaction. The aim of this study is to find out the prevalence of mandibular third molar impaction among patients visiting the outpatient Dental Department of a tertiary care centre. Methods: A descriptive cross-sectional study was conducted among patients visiting the Outpatient Dental Department of a tertiary care centre from 1 January 2023 to 30 June 2023. Ethical approval was taken from the Institutional Review Committee of the same institute. A total of 414 orthopantomograms were prospectively reviewed for the angulation of impaction, depth and position. The indication for extraction was recorded from patients' cards during the time of extraction. Convenience sampling method was used. The point estimate at a 95% confidence interval was calculated. Results: The prevalence of mandibular third molar impaction was 37.13% (34.29-39.97, 95% Confidence Interval). There was a high prevalence of mesioangular 344 (45.38%) pattern followed by vertical 249 (32.85%) for mandibular third molar impaction, the most commonly involved group was 20-30 years, with female 247 (59.70%) predominance. Bilateral impaction 344 (83.10%) was more prevalent than unilateral. Depth A, 639 (84.3%), ramus relation level I, 602 (79.42%) was the most common level of impaction. Recurrent pericoronitis 160 (38.6%) was the common indication for extraction followed by dental caries 145 (35%). Conclusions: The prevalence of mandibular third molar impaction was lower than other similar studies done in similar settings. Keywords: impacted tooth; pericoronitis; prevalence; third molar.