Dental and skeletal factors potentially influencing second molar mesialization following first permanent molar extraction: A 5-year follow-up study.

OBJECTIVES

To evaluate dental and skeletal factors influencing spontaneous space closure and axial angulation of the second molar (P2M) and second premolar (SP) five years after permanent first molar (P1M) extraction.

MATERIALS AND

METHODS

This retrospective cohort study included 79 patients (mean age 9.5 ± 1.6 years) with unilateral P1M extraction. Panoramic radiographs were analyzed at T1 (pre-extraction) and T2 (5-year follow-up). P2M developmental stages (Demirjian), initial vertical positions, and baseline skeletal parameters (gonial angle, condylar inclination, and antegonial notch angle) were assessed on T1 panoramic radiographs. Angulation changes were compared between the extraction and the non-extraction control sides.

RESULTS

Complete space-closure status did not differ significantly among Demirjian developmental stages (p > 0.05). In the maxilla, P2M angulation changes differed significantly among developmental timing groups (p = 0.018). In the mandible, SP showed significant distal tipping within all developmental groups (p < 0.05), whereas no significant SP angulation change was observed in the maxilla. A significant positive correlation was identified between baseline antegonial notch angle and complete space closure (p = 0.011). Compared with the contralateral non-extraction side, the extraction side showed significant angular differences for both P2M and SP.

CONCLUSIONS

The P2M developmental stage alone appeared insufficient for explaining complete space closure following unilateral P1M extraction. Post-extraction angular changes differed according to jaw and tooth type, and baseline antegonial notch angle showed an exploratory association with complete space closure. These findings suggest that selected panoramic observations may provide supplementary information during case assessment, but should not be interpreted as standalone predictive criteria.

CLINICAL RELEVANCE: In children requiring P1M extraction, P2M developmental stage should not be used as the sole criterion for estimating spontaneous space closure. Expected post-extraction tipping patterns and selected panoramic findings, particularly the antegonial notch angle, may provide supplementary information during case assessment.