[Preliminary study of subgingival microorganism changes after glycine powder air-polishing treatment during periodontal maintenance phase].

To research the variation of subgingival microorganisms after 65 μm glycine powder air-polishing (GPAP) in patients with periodontitis during periodontal maintenance phase and make comparison with conventional method. From Department of Periodontology, Peking University School and Hospital of Stomatology, twenty-one patients at the age of 35-72 (8 males and 13 females) who were systematically healthy were recruited in this study. According to splitting-mouth design, one side of a mouth was randomly assigned to the experiment group (21 patients, 248 teeth, 1 488 sites) with 65 μm GPAP therapy while the opposite side served as the control group (21 patients, 249 teeth, 1 494 sites) with ultrasonic scaling plus polishing paste therapy. The clinical periodontal parameters including probing depth (PD), bleeding index (BI), bleeding on probing (BOP) and plaque index (PLI) were recorded. Using sterile currette, the subgingival plaque samples were collected at the mesio-buccal site of the first or second molars at baseline, 2, 4, 8 and 12 weeks after therapy, respectively. After Congo red staining, the microorganisms were classified into cocci, bacilli and spirochetes and counted respectively. All clinical periodontal parameters have no difference between two groups at baseline and after treatment 12 weeks. In the experiment group and the control group, PD ([2.33±0.90] and [2.37±1.18] mm), BI (0.96±0.70 and 0.98±0.78) and PLI (0.00[1.00] and 0.00[1.00]) of two groups after treatment 12 weeks were better than those at baseline (PD: [2.48±1.17] and [2.46±0.99] mm; BI: 1.07±0.72 and 1.08±0.75; PLI: 0.00 [1.00] and 0.00 [1.00]) (0.05). But BOP(+)% was observably reduced only in the control group after treatment 12 weeks ([17.25±2.21]% vs [25.23±2.83]%) (0.05). The percentages of cocci, bacilli and spirochetes were stable and there were not significant differences between the two groups (>0.05). After 65 μm GPAP therapy, the differences of proportion of subgingival microorganisms are not significant, while the control group has the same trend. The spirochetes remained at a low level, but they rebounded fasterly in the test group than that in the control group. The results indicate that 65 μm glycine powder air-polishing has the similar clinical effects compared with ultrasonic scaling plus polishing paste. However, the clinical indications should be limited to the patients with shallow pockets and without obvious dental calculus.