A clinical and microbiological comparison of the effects of water and 0.02% chlorhexidine as coolants during ultrasonic scaling and root planing.

The maxillary teeth of 10 patients with moderately advanced chronic periodontitis were treated in a split-mouth design study. The baseline examination included plaque and bleeding scores, probing depths and probing attachment levels. 2 sites in each quadrant were selected for dark-field microscopic analysis. Each quadrant was randomly assigned to test or control and instrumented with an ultrasonic scaler using either 0.02% chlorhexidine or water as the coolant. Measurements were repeated 2, 6 and 10 weeks later, together with additional plaque sampling. Ultrasonic instrumentation with either chlorhexidine or water was equally effective in reducing bleeding scores and improving probing attachment levels. 42% of chlorhexidine- and 38.7% of water-treated sites showed gains of 1 mm or more in clinical attachment. Mean reductions in probing depth were similar (0.9 mm chlorhexidine, and 0.8 mm water). At the final examination, the chlorhexidine-treated quadrants had significantly more sites with probing depths in the 1-3 mm category and less in the greater than 3 mm category than the control quadrants (P less than 0.05). Both treatments reduced the microscopic counts of motiles and spirochaetes, resulting in a subgingival microbiota consistent with periodontal health. The results indicate that chlorhexidine has a slight adjunctive effect in the reduction of pocket depth when used as a coolant during ultrasonic root planing for the treatment of chronic periodontitis.