Identification of predictors for bone regeneration at the distal aspect of the second molar after impacted mandibular third-molar extraction.

BACKGROUND

The authors evaluated predictive factors for alveolar bone regeneration at the distal aspect of the second molar after mandibular third-molar extraction.

METHODS

Cone-beam computed tomography (CBCT) data from 146 patients (161 cases) who underwent horizontal or mesioangular impacted mandibular third-molar extractions were analyzed. Preoperative and postoperative scans using CBCT obtained at least 6 months apart were evaluated; the mean (SD) follow-up period was 37.3 (24.6) months. Multiple linear regression analysis was performed to determine predictors of bone regeneration. Multicollinearity was assessed and regression assumptions were verified via residual analysis.

RESULTS

The mean (SD) initial defect depth was 5.42 (2.07) mm, final defect depth was 3.89 (1.75) mm, healing ratio was 27.3% (17.7%), and age of patients was 25.7 (9.0) years (72 male, 74 female). Regression analysis identified initial defect depth, patient age, and distance from ramus to second molar (ramus class) as significant predictors (R2 = 0.713; P < .001); all variance inflation factor values were less than 2.0, indicating no significant multicollinearity. The predictive equation is: Y (final depth) = 0.243 + 0.636 × X₁ (initial depth) + 0.045 × X₂ (age) - 0.676 × X₃ (ramus class). Cases with initial defects greater than 6 mm or from 5 through 6 mm combined with a ramus Class I had a higher likelihood of limited bone recovery (> 4 mm final defect depth).

CONCLUSIONS

These findings emphasize the limited natural recovery of alveolar bone and the importance of initial defect depth, ramus class, and age in predicting outcomes and optimizing postoperative management.

PRACTICAL IMPLICATIONS: Preoperative CBCT assessment of defect depth, ramus proximity, and patient age can help identify patients at risk of having limited bone regeneration.