Objective: This study aimed to determine the prevalence of third molar impaction and related pathologic conditions in a cohort of patients living in North-eastern Peninsular Malaysia.

Methods: In this retrospective study, 490 orthopantomograms (OPGs) of patients who were referred to the Oral and Maxillofacial Surgery department between January 2010 and December 2019 were assessed. Data including age, gender, ethnicity, frequency of third molar impactions, their angulations and levels of eruption, retromolar space, and associated pathologic conditions were collected. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) version 24.0. The significance level was set to P < 0.05.

Results: A total of 490 patients with a mean age of 28.87 years (range: 20-64) demonstrated 1957 impacted third molars (1022 mandibular + 935 maxillary). Impacted third molars were more likely present in females than males (1:2.20) (p < 0.05); and in Malay-ethnic (44.49%) patients followed by Chinese (34.45%) and Indians (21.02%). Mesioangular was the most common angulation of impaction both in the maxilla (24.68%) and mandible (18.34%). The most common pattern of third molar impaction was IIA (61.67%), and the retromolar space was significantly larger in males (13.6 mm; P < 0.05) than females (11.6 mm). The most frequently occurring pathological condition associated with third molars impaction is dental caries in the second or third molar (15.38%).