The effect of bond strength after laser application of adhesives applied on the coronal and root canal dentin

Er:YAG laser can be used instead of air-turbine for cavity preparation in dentistry. However, the bond strength achieved after Er:YAG preparation is not as good as that achieved after bur preparation. In this study the effect of Nd:YAG-treatment on the adhesive applied onto Er:YAG prepared coronal dentin was investigated. The bond strength achieved so was compared with that achieved after bur preparation. Also, the effect of Nd:YAG-treatment on adhesive was tested in the root canal post space.In the first part, coronal dentin was prepared either with tungsten carbid bur or Er:YAG laser. Then, adhesive (Scotchbond Multi-Purpose, Adper Single Bond 2, Clearfil SE and Clearfil S3) was applied onto the dentin. In some of the teeth in Er:YAG preparation, the adhesive was heated with Nd:YAG lasing (100mJ, 10Hz). The bond strength as evaluated using the microtensile test. The bur group, as expected, revealed higher bond strength. Nd:YAG-treatment increased the bond strength in all adhesive systems. While bond strength values were stil lower in the Nd:YAG-treated group, but statistically significant difference was not found between the Nd:YAG-treated and bur groups.In the second part, root canal was prepared and obturated. A post space was then prepared using a post dril. The adhesive was applied into the post space and heated with Nd:YAG lasing prior to polimerization in some of the teeth. The bond strength was evaluated using the push-out test. Again, Nd:YAG application was found to increase the bond strength in all adhesive systems.SEM analysis showed that coronal or root canal dentinal tubule penetration was greater when the adhesive was treated with Nd:YAG laser prior polimerization.As conclusion, heating of adhesive using Nd:YAG laser was found to develop the bond strength on coronal and root canal dentin.