Background: This pilot study was part of a larger study which compared the effect of subgingival air-polishing using trehalose powder with sonic scaling on clinical parameters during supportive periodontal therapy. Within this microbiological part of the investigation subgingival samples were taken from 10 participants to analyze the survival of different bacterial species after the two different treatments as a proof of principle. Methods: In 10 participants two non-adjacent, single-root teeth requiring treatment (PD =5 mm with bleeding on probing (BOP) or > 5 mm) were selected following a split-mouth design and were treated either with a sonic scaler or air-polishing device and trehalose powder. For persistent pockets (PD =4 mm and BOP or > 4 mm), treatment was repeated after 3 months. Subgingival biofilm samples were taken at baseline (BL), subsequently and three and six months after treatment. After determination of the bacterial counts (TBL), isolated bacteria were identified by MALDI-TOF-MS. If unsuccessful, PCR and 16S rDNA sequencing were performed. Results: In both treatment groups, TBL decreased immediately after treatment remaining at a lower level. This confirms the findings of the larger study regarding clinical parameters showing a comparable effect on PD, BOP and CAL. Immediately after treatment, the diversity of detected species decreased significantly more than in the sonic group (p = 0.03). After 3 months, the proportion of Gram-positive anaerobic rods was lower in the airpolishing group (powder/ sonic 7%/ 25.9%, p = 0.025). Also, there was a greater reduction of Gram-negative aerobic rods for this group at this time (air-polishing/ sonic − 0.91 /-0.23 Log10 cfu/ ml, p = 0.020). Conclusion: Within the limitations of this study air-polishing and sonic treatment seem to have a comparable effect on the subgingival oral biofilm during supportive periodontal treatment. Trial registration: The study was registered in an international trial register (German Clinical Trial Register number DRKS 00006296) on 10th of June 2015. HTML&TRIAL_ID = DRKS00006296.

Background Air‐polishing appears to be a promising procedure for subgingival biofilm removal in periodontal treatment. The aim of this study was to compare trehalose powder for subgingival air‐polishing with sonic debridement in residual periodontal pockets during maintenance therapy. Methods In this blinded, randomized, controlled clinical trial conducted over 6 months with a split‐mouth design, single‐rooted teeth in 44 participants with residual pocket depths of 5 mm and bleeding or >5 mm with and without bleeding were included in this study. Subgingival debridement was carried out using either trehalose powder with an air‐polishing device (test) or a sonic device (control). The reduction in the probing depths after 3 and 6 months was defined as the primary endpoint. A visual analog scale was used to evaluate the discomfort of both procedures. Results Both procedures showed statistically significant intragroup reductions in probing depths (test baseline [BL] 5.52 ± 0.93, 6 months 3.66 ± 0.81, control BL 5.55 ± 0.9, 6 months 3.68 ± 0.86, P < 0.001), clinical attachment level (test BL 6.93 ± 1.5, 6 months 5.3 ± 1.52, control BL 7.27 ± 1.8, 6 months 5.84 ± 1.71, P < 0.001), and bleeding on probing (test BL 86%, 6 months 41%, control BL 89%, 6 months 34%, P < 0.001) after 6 months with no significant intergroup differences (P > 0.05, respectively). The visual analog scale showed a significantly lower incidence of discomfort for air‐polishing compared with sonic scaling (test 2.33 ± 2.14, control 4.91 ± 2.65, P < 0.001). Conclusions Subgingival air‐polishing with trehalose powder showed comparable clinical outcomes to sonic scaling. Sonic scaling evoked more discomfort compared with air‐polishing.