Association between root resorption severity and alveolar bone loss after fixed orthodontic treatment: A tooth-based...

This study aimed to assess whether the severity of orthodontically induced inflammatory root resorption (OIIRR) and alveolar bone loss follows a parallel pattern during orthodontic treatment.

This retrospective study included 62 patients treated with standardized 0.022-in McLaughlin, Bennett, and Trevisi fixed appliances and nonextraction protocols. Patients were divided into 2 groups based on the presence (group 1, n = 31) or absence (group 2, n = 31) of posttreatment root resorption. In both groups, mesial and distal alveolar bone levels were measured on panoramic radiographs before treatment (T₀) and after treatment (T₁) using a ratio-based method, and changes between T₀ and T₁ were calculated to quantify alveolar bone loss. Root resorption severity in both groups was assessed per tooth using the Levander and Malmgren index. Statistical analyses included a linear mixed-effects model, generalized estimating equations, and Spearman correlation (P <0.05).

Alveolar bone loss was significantly greater in group 1 than in group 2 (P <0.001). Significant effects of group, tooth, and region were observed, indicating that bone loss varied across different teeth and sites. No consistent association was found between the severity of root resorption and alveolar bone loss. The severity of root resorption differed significantly by tooth, with higher levels observed in anterior teeth.

Patients with posttreatment OIIRR demonstrated slightly greater alveolar bone loss; however, the difference was small and root resorption severity did not predict the extent of bone loss. These findings suggest that OIIRR and alveolar bone loss should be evaluated as separate treatment outcomes during posttreatment assessment.