BACKGROUND

We aimed to comprehensively examine how the anatomic characteristics of asymptomatic third molars (As-M3s) affect distal pathologies of adjacent second molars (Ad-M2s).

MATERIALS AND METHODS

Patients with at least 1 quadrant having intact As-M3s and first and second molars were enrolled. Distal pathologies of Ad-M2s, including caries, pocket depth of 4 mm or more (PD4+), and alveolar bone loss of 3 mm or more (ABL3+), were analysed based on As-M3 status (absent/impacted/nonimpacted). Especially within nonimpacted M3s (N-M3s), the effects of regions (maxillary vs mandibular) and dental intervals (narrow vs wide) on Ad-M2 pathologies were further compared.

RESULTS

A total of 248 patients with their 805 quadrants were finally included in this cross-sectional study. The impacted and nonimpacted As-M3s elevated the risk of any distal pathology (caries, PD4+, or ABL3+) of Ad-M2s vs M3 absence with odds ratios (ORs) of 8.33 and 3.27, respectively. Within N-M3s, mandibular regions increased the odds of PD4+ (OR, 1.96); wide dental intervals increased the odds of ABL3+ (OR, 3.01). However, maxillary regions and narrow dental intervals contributed to more severe bone loss in Ad-M2s with ABL3+.

CONCLUSIONS

The presence of As-M3 is a risk factor for Ad-M2 pathologies irrespective of impaction status. Within N-M3s, Ad-M2 pathologies are significantly influenced by anatomic characteristics such as regions and dental intervals.