Determinants and therapeutic outcomes of maxillary sinus mucosal thickening in periodontitis: a retrospective cohort study.

AIM: To investigate the clinical effects of periodontal therapy and tooth extraction on patients with periodontitis-associated maxillary sinus mucosal thickening. METHODS: This retrospective study included 120 maxillary sinuses from 73 patients with periodontitis-associated mucosal thickening. Of these, 99 received periodontal therapy and 21 underwent tooth extraction. Cone-beam computed tomography was used to evaluate mucosal thickness before and 3 months after treatment. Analyses were performed both in patients with severe alveolar bone loss and after propensity score matching to balance baseline characteristics between treatment groups. Mixed-effects models were performed to identify factors associated with treatment outcomes, accounting for patient-level clustering. RESULTS: Both periodontal therapy and tooth extraction resulted in a significant reduction in periodontitis-associated maxillary sinus mucosal thickness (mean change: 2.77 ± 3.73 mm and 2.83 ± 3.34 mm, respectively; P < 0.05). In subgroup analysis, periodontal therapy significantly reduced mucosal thickness in patients with ≥ 1/3 alveolar bone resorption (Grade II: 2.63 ± 3.67 mm, Grade III: 3.34 ± 3.84 mm, P < 0.05), whereas no significant change was observed in those with < 1/3 bone resorption (Grade I: 0.01 ± 0.97 mm, P > 0.05). No clear superiority was observed between extraction and periodontal therapy after accounting for baseline disease severity. Pre-treatment mucosal thickness, age and root-to-sinus distance were also independently associated with treatment outcomes. CONCLUSIONS: Periodontal therapy and tooth extraction both mitigate periodontitis-associated maxillary sinus mucosal thickening, with different applicability. CLINICAL RELEVANCE: This study provides clinical evidence for managing periodontitis-associated maxillary sinus mucosal thickening: it confirms treatment can reduce thickening, clarifies indications (periodontal therapy for ≥ 1/3 alveolar bone resorption, extraction for unsalvageable teeth), and identifies prognostic factors to guide efficacy prediction and individualized strategies.