[Dynamic reversibility of tooth mobility and its key prognostic factors in periodontitis: a retrospective study]

Objective: To investigate the longitudinal patterns of tooth mobility and identify prognostic factors for mobile teeth in patients with periodontitis, providing an evidence-based basis for retaining natural teeth in clinical practice. Methods: A retrospective analysis was conducted on the clinical data of 44 patients with periodontitis (including 524 mobile teeth) treated at the Department of Periodontology, School and Hospital of Stomatology, Shandong University from January 2021 to October 2025. Clinical indices and radiographic data were collected following initial periodontal therapy and during the maintenance phase. Linear mixed-effects models were employed to process repeated measurement data to analyze the trends in mobility changes and associated factors. Receiver operating characteristic curves were utilized to analyze the predictive performance and optimal cutoff values of key indicators. Results: Teeth of Grade Ⅰ and Ⅱ mobility showed significant improvement at 3 months, with the improvement rates of 60.1% (185/308) and 73.9% (116/157), respectively. Improvement for Grade Ⅲ mobility was slower, reaching a peak of approximately 61.0% (36/59) after 1 year. Multivariate analysis indicated that higher residual bone-to-root ratio (β=-0.353 3, P=0.006), periodontal splinting (β=-0.233 6, P=0.002), and female gender (β=-0.177 2, P<0.001) were the primary independent protective factors promoting mobility improvement. The optimal cutoff value for the residual bone-to-root ratio in predicting mobile tooth survival was 0.24 (area under the curve=0.81). Conclusions: Tooth mobility exhibits significant dynamic reversibility following standardized periodontal treatment. Grade Ⅲ mobility should not be considered an absolute indication for extraction. Particularly in cases where the residual alveolar bone covers more than one-quarter of the root length, it is recommended to consider periodontal splinting and maintain a follow-up period of at least one year, so as to formulate more precise strategies for retaining mobile teeth and preserve natural teeth to the greatest extent possible.