Dentin Cutting Efficacy Using a High-speed Bur, Ultrasound and Laser

Objectives: Compare a novel diamond bur with a conventional one and Er:YAG laser to perform cavity preparations. The introduction of adhesive dentistry reduces the need for extensive restorations. The clinician's responsibility is to conserve sound tissue whenever possible. Methods: Twelve human molars, submitted and approved by the Ethical Experimental Committee at the University of São Paulo, were prepared and used for this study. In the first group the teeth were embedded in resin and sliced. The abrasion of the surface was performed on each disc by a high-speed instrument and ultrasound on the same sample. In the second group, the cavity preparation was initially performed with a high-speed diamond bur. After the cavity was prepared, the teeth were longitudinally sectioned with a diamond disc. A 2.94 µm Er:YAG laser (Kavo Key, Kavo, Germany), at 400mJ/pulse and 4Hz of frequency was applied on the tooth surface during 30 seconds in a sweeping motion. The samples were analyzed by Scanning Electron Microscopy (SEM). Results: The abrasion surface with conventional diamond bur showed structure removal with different intensity of grooves, evident presence of smear layer and occluded dentinal tubules. The abraded surface with CVD bur was not chipped away but suggested a removal process in layers. The Er:YAG laser irradiated surface showed rough aspect with opened tubules and absence of smear layer. Conclusions: The results of this study suggest that high-speed diamond bur; ultrasound and Er:YAG laser were able to perform the cavity preparation. However CVD bur presented a higher surface quality.