Radiographic identification of symptomless mandibular third molars without clinical pericoronitis.

Objectives: The aim was to identify radiographic characteristics of mandibular third molars in young adults without symptoms or clinical signs of pericoronal infection.

Materials and methods: An existing cross-sectional material, including records from clinical oral examination and panoramic radiographs (PANs) of university students, was submitted to retrospective analysis. The outcome variable was a symptomless and clinically pericoronitis-free mandibular third molar. Predictor variables for the third molar were clinical eruption level, pathological signs in the follicle, marginal bone level, radiographic depth in bone, inclination, stage of root development, and available space for eruption. Statistics included χ² and Mann-Whitney U tests.

Results: Analysis included 345 mandibular third molars in 189 participants (20% men, 80% women; mean age 20.7 years; SD ± 0.6). Symptomless and clinically pericoronitis-free mandibular third molars were characterized as follows: clinically unerupted in 78% of teeth, associated with reduced marginal bone level in 70%, located deeper in the bone in 87%, mesially inclined in 73%, and stage of root development incomplete in 68% (p ≤ 0.001 for all).

Conclusions: Radiographic characteristics of symptomless mandibular third molars without clinical pericoronitis in young adults can be assessed from a PAN with 68-87% certainty.

Clinical relevance: These findings may prove useful when trying to exclude non-pathological mandibular third molars from diseased teeth.