Position of lower wisdom teeth and their relation to the alveolar nerve in orthodontic patients treated with and without extraction of premolars: a longitudinal study

摘要

Objectives The present longitudinal study aimed to compare changes in the lower third molar position and nerve involvement in orthodontically treated patients with and without premolar extractions. Materials and methods The sample consisted of pretreatment and posttreatment panoramic radiographs of 349 orthodontically treated patients subdivided into a non-extraction group (n=263) and an extraction group (n=86). Patients did not present dental agenesis in the lower jaw. The mandibular third molar position was assessed by classifying the teeth according to Pell and Gregory, Winter, and two new classifications. The relation between third molars and the mandibular canal was assessed based on Whaites' classification. The development of third molars was evaluated based on Demirjian's classification. Data were analyzed using frequency analysis, Mann-Whitney U test, Fisher's exact test, and chi-square testing.