Impact of the presence of partially erupted third molars on the local radiographic bone condition

The decision on retaining or prophylactically removing asymptomatic lower third molars is still discussed in the literature. This study aimed to verify the association between asymptomatic lower third molars and local bone conditions through periapical radiographs. Based on sample size calculations, 288 radiographs were required. Dependent variables were alveolar bone crest status and radiolucency between the distal aspect of the third molar crown and the ascending mandibular ramus. Independent variables were sex, age, Pell and Gregory and Winter’s classification, angulation and distance between second and third molars, third molar side. Advanced ages (OR 1.15; CI 1.08–1.24; p < 0.001) and greater third molar angulations (OR 1.03; CI 1.01–1.04; p < 0.001) significantly increased the chance of radiographic alterations in the bone crest between second and third molars. Radiolucency distal to third molars was solely impacted by patient’s age (OR 1.05; CI 1.01–1.11; p = 0.036). Older patients and lower third molars with greater angulations about adjacent second molar should be evaluated for third molar removal because of the increased chance of alveolar bone crest alterations. Older patients should also be monitored for wider radiolucent pericoronal spaces distal to lower third molars and its consequences.