Aim: To evaluate the clinical efficacy of (i) a single session of “full‐mouth ultrasonic debridement” (Fm‐UD) as an initial periodontal treatment approach and (ii) re‐instrumentation of periodontal pockets not properly responding to initial subgingival instrumentation.

Methods: Forty‐one patients, having on the average 35 periodontal sites with probing pocket depth (PPD) 5 mm, were randomly assigned to two different treatment protocols following stratification for smoking : a single session of full‐mouth subgingival instrumentation using a piezoceramic ultrasonic device (EMS PiezonMaster 400, A+PerioSlim tips) with water coolant (Fm‐UD) or quadrant scaling/root planing (Q‐SRP) with hand instruments . At 3 months, all sites with remaining PPD5 mm were subjected to repeated debridement with either the ultrasonic device or hand instruments. Plaque, PPD, relative attachment level (RAL) and bleeding following pocket probing (BoP) were assessed at baseline, 3 and 6 months. Primary efficacy variables were percentage of “closed pockets” (PPD4 mm), and changes in BoP, PPD and RAL.

Results: The percentage of “closed pockets” was 58% at 3 months for the Fm‐UD approach and 66% for the Q‐SRP approach (p>0.05). Both treatment groups showed a mean reduction in PPD of 1.8 mm, while the mean RAL gain amounted to 1.3 mm for Fm‐UD and 1.2 mm for Q‐SRP (p>0.05). The re‐treatment at 3 months resulted in a further mean PPD reduction of 0.4 mm and RAL gain of 0.3 mm at 6 months, independent of the use of ultrasonic or hand instruments. The efficiency of the initial treatment phase (time used for instrumentation/number of pockets closed) was significantly higher for the Fm‐UD than the Q‐SRP approach: 3.3 versus 8.8 min. per closed pocket (p<0.01). The efficiency of the re‐treatment session at 3 months was 11.5 min. for ultrasonic and 12.6 min. for hand instrumentation (p>0.05).

Conclusion: The results demonstrated that a single session of Fm‐UD is a justified initial treatment approach that offers tangible benefits for the chronic periodontitis patient.