Histological examination of experimentally infected root canals after preparation by Er:YAG laser irradiation.

The influence of Er:YAG laser irradiation on periodontal tissues along the root surface and apical region during root canal preparation was histologically evaluated using experimentally infected root canals of rats. Eighty experimentally mesial infected root canals of mandibular first molars in rats were divided into four groups. In three groups, root canals were irradiated using an Er:YAG laser at 2 Hz with 34, 68, or 102 mJ/pulse for 30 s. Non-irradiated canals served as controls. The influence of laser irradiation on periodontal tissues along the root surface and apical area was evaluated histologically under light microscopy at 0 (immediately after), 1, 2, 4, and 8 weeks after irradiation. At all periods, no inflammation or resorption on the root surfaces caused by laser irradiation was observed in any cases in the control or 34 mJ/pulse-irradiated groups. However, mild to severe inflammation with resorption of root surfaces was observed in some cases in the 68- and 102-mJ/pulse-irradiated groups. No significant difference was apparent between control and laser-irradiated groups at the apical area for all experimental periods (p > 0.05). These results suggest that thermal influences on periodontal tissues of experimentally infected root canals during root canal preparation by Er:YAG laser irradiation are minimal if appropriate parameters are selected. Er:YAG laser irradiation is thus a potential therapy for human infected root canals.

Basic study of the use of laser on detection of vertical root fracture.

OBJECTIVE: Many methods are used to detect vertical root fractures, but most are not adequate for identification of incomplete fractures or cracks. The purpose of this study was to evaluate the effects of three detergents on detection of vertical root fractures by DIAGNOdent with methylene blue (MB) solution. METHODS: Vertical incomplete fractures were artificially created on the roots of extracted human teeth, the DIAGNOdent values (D values) recorded in the presence or absence of MB solution, and the effects of detergents on D values examined. The effects of 20% ethanol on enhancing detergent action were also investigated. Statistical analysis was performed using the Mann-Whitney U-test; a value of p<0.01 was considered significant. RESULTS: D values increased significantly when MB solution was used with 0.1% or 1.0% polyoxyethylene (10) octylphenyl ether compared to MB solution only. CONCLUSION: These findings suggest that 0.1% or 1.0% polyoxyethylene (10) octylphenyl ether could be used as an enhancer for detection of vertical root fractures by DIAGNOdent using MB solution.