The Effect of Eruption Level and Angulation of Third Molars on Interdental Root Proximity: A Case-Control Study

This study was designed to assess the possible relationship between the level of eruption or impaction status and angulation of third molars (TMs) and the interdental root proximity (RP) in this quadrant, in adults with healthy periodontium and in patients with history of periodontitis. Root proximity was studied in the interdental spaces of 250 patients with periodontitis and 80 subjects with healthy and intact periodontium. Linear measurements were performed in digital radiographs. Root proximity was detected when the distance at the closest proximity level between the roots of adjacent teeth was < 0.8 mm. Eruption level was classified as full or partial, based on occlusal plane. Impaction status was assessed as semi or complete, based on coverage by soft tissues or alveolar bone. The Z-test, X2, Fisher’s exact test and Mann-Whitney test were used for the statistical analysis. In total, 718 TMs and 4,308 interdental spaces were studied in 330 subjects. In subjects with healthy periodontium, the angulation of mandibular TMs statistically significantly influenced the presence of root proximity in the interdental space between first and second molars. In periodontitis subjects, TM angulation statistically significantly affected the presence of root proximity in the interdental space between first and second molars in the maxillary left and mandibular right quadrants as well as in the interdental space between the mandibular right premolars. The eruption level or impaction status of TMs statistically significantly affected the presence of root proximity only between the first and second mandibular right molars both for subjects with healthy periodontium and for periodontitis patients. Within its limits, this study found that the angulation and eruption level or impaction status of third molars seem to be related to root proximity among the adjacent teeth, especially between lower first and second molars, irrespective of the presence or absence of periodontitis.