Progression of Furcation Involvement: A Multi-Center Cohort Study of Incidence, Timing, and Risk Factors

To analyze the rate, timeline, and risk factors for furcation involvement (FI) progression using a large, multi-center electronic health record database.

This retrospective cohort study analyzed 3924 patients with periodontitis and at least 1 year of follow-up from the BigMouth Dental Data Repository. Furcation progression (increase in the maximum recorded furcation grade for a given tooth during the follow-up period) was assessed at both the patient and tooth level. Time-to-event analysis at the patient level was performed using Kaplan-Meier curves and a multivariate Cox Proportional Hazards model to identify predictive factors. At the tooth level, the primary analysis was a multilevel Cox model, with a Fine-Gray competing risks model performed as a secondary analysis to assess the impact of tooth loss.

Over a mean follow-up of 4.7 years, 57.1% of patients experienced furcation progression, with a median time to the first event of 3.6 years. A Cox proportional hazards model identified smoking as the factor most strongly correlated with progression, increasing the risk by 51% (Hazard Ratio [HR]: 1.51), followed by high blood pressure (HR: 1.25) and diabetes (HR: 1.24). At the tooth level, the initial furcation grade showed the strongest association with progression, increasing the hazard by 3.05 times for each unit increase.

Furcation involvement is a progressive event for a majority of patients diagnosed with periodontitis. The risk of progression is correlated with a combination of systemic factors and the patient's overall periodontal status, but the factor most strongly correlated with a tooth's future deterioration is its own initial furcation grade.