Does local antimicrobial therapy improve outcomes in residual periodontal pockets?

Yes, local antimicrobial therapy does provide statistically significant, though modest, improvements in residual periodontal pockets during supportive care.

In patients with residual pockets during supportive periodontal care, adjunctive locally delivered antimicrobials achieve small additional probing pocket depth (PPD) reductions and clinical attachment level (CAL) gains over a follow-up of up to 6 months ^[1]. The chlorhexidine chip and tetracycline fibre showed the most consistent benefit, with PPD reductions of approximately 0.65 mm and 0.64 mm respectively over controls, while other agents did not reach statistical significance compared to scaling and root planing alone ^[1]. Across the broader periodontitis population, meta-analyses confirm statistically significant PPD reductions (weighted mean difference around 0.37 mm) and CAL gains at 6-9 months with adjunctive local antimicrobials, without relevant adverse effects ^[2]. In persistent or recurrent localised deep sites specifically, sustained-delivery devices may offer an additional benefit of roughly 0.4 mm in pocket depth reduction and 0.3 mm in CAL gain ^[3].

Antimicrobial photodynamic therapy (aPDT) as an adjunct to scaling and root planing also showed significant improvements in PPD reduction (MD 0.69 mm) and CAL gain (MD 0.60 mm) for residual pockets in maintenance patients, though this benefit was not significant in smokers ^[4]. In contrast, a systematic review of non-antimicrobial adjunctive therapies during supportive care found only non-significant benefits from PDT, with insufficient evidence for other physical adjuncts ^[5].

Clinically, these gains are statistically significant but numerically modest, and the decision to use adjunctive local agents should weigh this limited benefit alongside considerations of antibiotic stewardship ^[3].