Effects of non‐surgical periodontal therapy on intrabony periodontal defects at different re‐evaluation time points: A systematic review of randomized controlled trials and clinical recommendations

Objective The aim of this systematic review and meta‐analysis was to evaluate the longitudinal temporal pattern of periodontal probing depth (PPD) reduction in intrabony periodontal defects following non‐surgical periodontal therapy (NSPT), both as a monotherapy and with adjunctive locally delivered pharmacological agents. Materials and Methods A comprehensive electronic search was performed in PubMed/MEDLINE and Embase databases to identify randomized controlled trials (RCTs). Eligible studies included adult patients with vertical defects treated with NSPT and reporting defect‐level PPD values at predefined follow‐up intervals (3, 6, 9, or 12 months). Pairwise temporal comparisons were conducted within treatment arms (6 vs. 3, 9 vs. 6, and 12 vs. 6 months) using standardized mean differences (SMD) in a random‐effects model. Risk of bias was assessed with the Cochrane RoB 2 tool and certainty of evidence with GRADE. Results Eight RCTs met the inclusion criteria. Significant PPD reduction occurred between 3 and 6 months (SMD = −1.07; 95% CI −1.70 to −0.45, p < 0.001). Further significant improvements were detected between 6 and 9 months (SMD = −1.35; 95% CI −2.08 to −0.63) and sustained at 12 months compared to 6 months (SMD = −1.70; 95% CI −2.73 to −0.66). High heterogeneity was observed (I 2 = 83–89%). Temporal PPD reduction across consecutive follow‐up intervals was considered the primary outcome. Subgroup analyses suggested similar trends for both NSPT alone and adjunctive therapies. Conclusions Clinical healing of intrabony defects after NSPT is a dynamic process extending up to 12 months, far beyond the traditional 3‐months mark. Initial re‐evaluation at 3 months primarily assesses inflammation control, whereas a 6–12 months window more accurately reflects definitive outcomes. Clinical Relevance Clinicians should exercise caution when scheduling surgical intervention for vertical defects. Delaying definitive decisions beyond 3 months for sites showing progressive improvement may avoid unnecessary surgical procedures and promote patient‐centered outcomes through continued non‐surgical maturation.