Subgingival microbiologic effects of one-time irradiation by CO2 laser: a pilot study.

BACKGROUND: Third-generation carbon dioxide (3-CO(2)) lasers have handpieces that accommodate a periodontal insert that permits irradiation directly into the periodontal pocket/sulcus. The purpose of this pilot study was to evaluate, by scanning electron microscopy (SEM), the surface effects of 3-CO(2) laser treatment on the root surfaces and soft tissues and to investigate the effects of 3-CO(2) laser on periodontal pathogenic bacteria compared to negative controls. METHODS: Five patients with chronic periodontitis and treatment planned for a maxillary immediate denture were included in the study. Periodontal pockets with a mean probing depth of 5.5 +/- 0.8 mm were irradiated one time by CO(2) laser (wavelength of 10,600 nm) at a power of 2.2 W, 50 Hz, an 80-millisecond pulse length, and an exposure rate of 1 mm per 5 seconds. DNA analysis of eight periodontal bacteria was performed on samples collected from laser-treated and control sites prior to and immediately following treatment and was compared between groups. In addition, block biopsies, including soft tissue, were harvested for SEM examination. RESULTS: SEM examination of test group specimens showed heat damage on the soft tissues in three of 17 specimens (17.6%). In addition, 11.7% (two of 17) of the 3-CO(2)-treated teeth exhibited localized slight damage to root surfaces. Microbiologic results of the control sites indicated that 90.6% of the bacterial counts remained the same, 6% increased, and 3% decreased. In the test group, 71.25% of the bacterial count analyses for the eight different periodontal microbes remained the same, 12.50% increased, and 16.25% decreased. CONCLUSION: A one-time use of the 3-CO(2) laser in periodontal pockets did not sterilize or substantially reduce subgingival bacterial populations compared to negative controls.