The predictive performance of surgical treatment in upper molars with combined bony defect and furcation involvement: a retrospective cohort study

BACKGROUND: To evaluate the impact of combined defects, bony destruction and furcation involvement, on disease resolution after surgery in terms of pocket elimination, absence of inflammation, furcation improvement and predictive performance. METHODS: Combined bony (intrabony (+) or (−)) and furcation defects (FI degree 1 or 2) at maxillary molars in patients diagnosed as periodontitis stage III to IV, being through periodontal surgery and at least 6 months follow-up were retrospectively screened. Cumulative predictability (CR, %), failure of treatment and the change of clinical parameters from baseline at pre-operative visit to the latest maintenance care, including pocket depth (PD), horizontal and vertical furcation involvement (FI) were analyzed. Failure of treatment with low predictability was defined as residual PD > 4 mm with bleeding on probing during maintenance period. RESULTS: Thirty-three patients with fifty-one combined defects were included. Statistical analysis showed significant overall PD reduction and FI improvement (p < 0.001). Combined FI degree 2 with intrabony (+) defects revealed more horizontal furcation improvement compared with FI degree 2 with suprabony defect (p = 0.007). However, type of combined defects was not relevant to CR (p = 0.702) and PD reduction (p = 0.707). Among all parameters, baseline PD with proximal FI degree 2 was indicated to failure of treatment. CONCLUSIONS: Different types of combined defects, deep baseline pocket and proximal FI degree 2 would compromise the predictability of treatment outcomes in upper molars. Nevertheless, the combination of surgical treatment and strict maintenance care could still yield high predictability and survival rate. Trial registration: retrospectively registered. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12903-022-02196-0.