Correlation between third molar impaction and mandibular anterior segment crowding

Abstract

Background: Anterior crowding represents a discrepancy between mesiodistal tooth widths and available alveolar space. The role of third molar eruption in the development of lower incisor crowding remains controversial. Aim: To evaluate the correlation between mandibular third molar impaction and lower anterior segment crowding. Methods: A retrospective study was conducted at the Orthodontic Unit, Lagos University Teaching Hospital, over four years (Jan 2019 to Dec 2022). Patients aged 18 years and above with erupted permanent teeth and complete clinical records were recruited. Panoramic radiographs and study casts were assessed for third molar impaction status and tooth-bone ratio. Data were analyzed using SPSS version 23, employing descriptive (frequency and percentages) and inferential (Chi-square) analysis with significance set at p < 0.05. Results: Of 794 panoramic radiographs assessed, 181 adult patients (122 females, 59 males) met inclusion criteria. Lower incisor crowding was present in 72 patients (39.8%), while 74 (40.1%) had unilateral or bilateral third molar impaction. A significant association was found between third molar impaction and crowding (p = 0.032), with over 50% of patients with impaction showing crowding. However, the association between impaction symmetry and crowding severity was not statistically significant (p = 0.066). Conclusion: A significant correlation exists between third molar impaction and anterior segment crowding. Patients with impacted third molars are more likely to have mandibular anterior crowding.