Defect morphology dictates success: suprabony lesions outperform intrabony defects in non-surgical periodontal therapy: a 3-month prospective observational study

This study aimed to compare the clinical response of suprabony and intrabony defects to non-surgical periodontal therapy (NSPT) and evaluate the influence of defect morphology on treatment outcomes. A prospective observational study with a 3-month follow-up was conducted on 413 patients who underwent NSPT at a tertiary hospital. Periapical radiographs and clinical parameters, including probing pocket depth (PPD), bleeding on probing (BoP), and clinical attachment level (CAL), were assessed at baseline and 3-month follow-up. Defects were classified as suprabony or intrabony based on radiographic morphology. Multilevel modeling was used to analyze the contributions of site-, tooth-, patient-, and treatment-related factors to clinical outcomes, with pocket closure (PPD ≤ 4 mm without BoP) as the primary endpoint. Intrabony defects exhibited greater absolute PPD reduction (0.9 ± 2.4 mm) compared to suprabony defects (0.7 ± 1.8 mm), a difference attributable to their deeper baseline PPD (6.1 ± 2.4 mm vs. 4.2 ± 2.0 mm). Multilevel modeling, after adjusting for baseline severity, demonstrated that defect morphology was the strongest predictor of therapeutic success. Suprabony defects achieved a greater adjusted PPD reduction and CAL gain (by 0.6 mm each) compared to intrabony defects. Suprabony defects demonstrated superior pocket closure rates and were 2.4 times more likely to achieve closure than intrabony defects. Site-related factors accounted for 64.9% of outcome variability, followed by patient- (26.1%), tooth- (9.0%), and treatment-related factors (1%). Multilevel analysis confirmed defect morphology as the strongest predictor of success, with suprabony defects showing 0.6 mm greater PPD reduction and CAL gain. Defect morphology significantly influences NSPT outcomes, with suprabony defects exhibiting higher pocket closure rates and better clinical improvements than intrabony defects. These findings highlight the need for morphology-adapted treatment strategies in periodontal therapy. However, the interpretation of these results should be cautious due to the relatively short 3-month follow-up period, which may not fully reflect long-term treatment stability and periodontal remodeling.