Objective: 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).
Methods: 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.
Results: 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.
Conclusion: 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.