Periodontitis Phenotypes and Treatment Outcomes Following Combined Periodontal and Orthodontic Therapy: A Cohort Study

Background and Objectives: Periodontitis is a heterogeneous condition, and patients may respond differently to combined periodontal and orthodontic treatment. This study aims to identify latent phenotypes of periodontitis and to evaluate their associations with recurrence and bone regeneration after combined periodontal–orthodontic treatment. Methods: This single-centre observational cohort study included patients with periodontitis who completed combined periodontal and orthodontic treatment in 2023 and were followed for approximately two years, with re-evaluations conducted between January and July 2025. Latent class analysis was used to identify periodontitis phenotypes based on baseline periodontal characteristics. Outcomes included recurrence of periodontitis and bone regeneration. Associations between phenotypes and outcomes were examined using logistic regression models adjusted for age, sex, smoking status, and diabetes. Subgroup analyses were conducted by sex and age. Results: Four distinct periodontitis phenotypes were identified: an inflammatory type, a high inflammation and structural damage type, a moderate and stable type, and a mild or minimal damage type. Compared with the mild or minimal damage phenotype, the high inflammation and structural damage phenotype was associated with a significantly higher risk of recurrence (OR 6.67, 95% CI 2.60– 18.48). For bone regeneration, both the high inflammation and structural damage phenotype, and the moderate and stable phenotype showed a significantly lower likelihood of bone regeneration (OR 0.96, 95% CI 0.93– 0.99, and OR 0.24, 95% CI 0.11– 0.53, respectively). Subgroup analyses indicated that the association between the high inflammation and structural damage phenotype and recurrence was stronger among females and patients aged ≥ 40 years. Conclusion: Periodontitis phenotypes differ in their risks of recurrence and bone regeneration following combined periodontal and orthodontic treatment. Baseline structural damage plays a key role in limiting regenerative potential, while severe structural damage combined with high inflammation substantially increases the risk of recurrence. Keywords: periodontitis, orthodontic treatment, bone regeneration, recurrence, latent class analysis