Retrospective analysis of the long-term effect of subgingival air polishing in supportive periodontal therapy.

AIM: Glycine powder air polishing (GPAP) procedure has become popular. Aim of the analysis was to compare the clinical outcomes during supportive periodontal therapy (SPT) of subgingival application of GPAP with those using sole conventional mechanical debridement (SC). MATERIAL AND METHODS: Over a median SPT period of 5.3 years (re-evaluation through last observation), the GPAP cohort (n = 263) received supra- and subgingival biofilm removal with GPAP. Supragingival calculus was removed using curets and sonic scalers here. Patients in the SC cohort (n = 264) were treated with sonic scalers, curets and rubber cup polishing only. Changes in, that is pocket probing depth (PPD) and furcation involvement were assessed retrospectively. A bootstrapping equivalence testing method in line with the principle of the two one-sided tests (TOST) procedure was used to compare clinical outcomes. RESULTS: The GPAP procedure was statistically equivalent to SC regarding the number of sites with stable PPDs (83.3%; IQR 68.8%, 91.0% vs. 84.0%; IQR 77.8%, 90.0%). However, in the GPAP cohort, a trend towards deterioration in furcation status (no equivalence) was noted. CONCLUSIONS: In periodontal maintenance, the use of GPAP instead of mechanical plaque removal does not improve the clinical outcome. It seems to be contraindicated to treat furcation defects with GPAP only.