Effect of Er:YAG Laser Irradiation on Dentin Permeability

Lasers have been one of the most hopeful developments that have the potential for dramatically altering the conventional treatment. Although researches in the use of Er:YAG laser for tooth preparation has used microtensile bond strength test as an indicator of potential success, dentin permeability might provide valuable data regarding the way adhesive systems interact with laser irradiated dentin. Objectives: This pilot study evaluated the effect of Er:YAG laser (Kavo Key Laser 3) irradiation with different parameters on dentin permeability. Methods: Nine 5mm-thick dentin disks were etched with 37% phosphoric acid for 15 sec (n=3). After that, specimens had their permeability measured three times for three minutes with a one-minute interval to assess the maximum fluid flow rate (FFR). Then, disks were treated with three different laser irradiation parameters (120mJ/4Hz, 180mJ/4Hz and 200mJ/6Hz) and FFR was evaluated once again. Data were collected and expressed as the percentage reduction on the FFR. One-way ANOVA and Tukey Test analyzed the data at a confidence level of 5%. Results: Means (Standard deviations) observed were: 120mJ/4Hz - 48.33%(7.87)a, 180mJ/4Hz - 99.87%(0.11)b and 200mJ/6Hz - 58.60%(9.89)a. Statistical analysis showed that permeability reduction was significantly higher when dentin was irradiated with 180mJ/4Hz. The other parameters, 120mJ/4Hz and 200mJ/6Hz, showed similar results. Conclusion: Results suggest that Er:YAG laser irradiation on dentin changed its permeability and some parameters of laser irradiation might promote a greater reduction on dentin permeability than others. (Support: #05/60697-9 and #05/56533-0).