Differential Response to Non‐Surgical Periodontal Therapy Between Intrabony and Suprabony Defects: A Retrospective Analysis

Aim: To assess the clinical response to Non-Surgical Periodontal Therapy (NSPT) between suprabony and intrabony defects. Materials and Methods: Totally 200 NSPT patients' records from the King's College London—Oral, Dental and Craniofacial Biobank were included. Periapical radiographs of sites with Periodontal Probing Depth (PPD) > 4 mm were assessed. Changes in periodontal measurements between baseline and three-month re-evaluation were examined and compared across suprabony and intrabony sites. Multilevel analysis was carried out to assess the relative contribution of site-, tooth-, patient- and treatment-related factors on the clinical outcomes. Results: Although intrabony defects showed higher PPD reduction after NSPT compared with suprabony defects, this was a function of initial deeper PPD. In fact, suprabony defects outperformed intrabony defects for ‘pocket closure’ at every initial PPD threshold and overall were 2.60 times more likely to achieve ‘pocket closure’. Defect morphology was one of several factors affecting treatment outcomes. The relative contribution to ‘pocket closure’ was 64.9% for site-, 26.1% for patient-, 9.0% for tooth- and 1% for treatment-related factors. Conclusion: Bone defect morphology influences clinical outcome of NSPT, with suprabony defects being twice as likely to achieve pocket closure and resulting in 0.6 mm more PPD reduction compared with intrabony defects.