Multilevel Analysis of Non-surgical Periodontal Treatment of Patients with Generalised Aggressive Periodontitis.

To investigate various factors affecting the clinical outcome of nonsurgical periodontal treatment and evaluate the treatment effects of adjunctive amoxicillin and metronidazole (AMX + MET) in patients with generalised aggressive periodontitis (GAgP). Forty-two patients with GAgP were recruited and randomly assigned to three groups: scaling and root planing (SRP) only, AMX + MET after SRP, and AMX + MET during SRP. The patients were assessed every 2 months post-therapy. Periodontal clinical and subgingival microbiological parameters were analysed at baseline and 6 months post-therapy. The impacts of different covariates on pocket probing depth (PD) reduction were evaluated. A multilevel analysis revealed that 58% of the variability in PD reduction was attributed to site-level parameters, 27.3% to patient-level parameters and 18.7% to tooth-level parameters. Greater PD reduction can be expected at initially deeper PD sites and sites with intrabony defects, and in patients with adjunctive use of AMX + MET. Persistent Tannerella forsythia infection and tooth mobility after treatment were negatively associated with PD reduction. The clinical outcomes of nonsurgical periodontal treatment were mainly influenced by site-level parameters, and adjunctive use of AMX + MET can lead to better clinical results in patients with GAgP in a short time.