Purpose: This light microscopic histological analysis was undertaken to evaluate the effect of cavity preparation with Er:YAG laser on pulp and was compared to cavity preparation with conventional burs in high-speed handpieces. Materials and Methods: Cavities were prepared in 20 premolars using a conventional bur in a high-speed handpiece (group I) and with Er:YAG laser in another 20 premolars (group II). Ten premolars were used as control (no cavity preparation, group III). All the teeth from groups I, II and III were extracted. The teeth were then sectioned into 4- to 5-micron-thick sections. After preparing the tissue sections, staining was performed using eosin and hematoxylin stains. All the sections were observed under light microscopy at 4X to 40X magnification to examine the morphology of the normal odontoblasts and variations, if any. Statistical analysis was done on number of samples with different scores. The pulp responses were categorized into two scores: 1: normal responses; 2: moderate inflammatory responses. Results: The Er:YAG group showed that 18 treated teeth responded normally and 2 teeth showed a moderate response. The bur-treated teeth resulted in normal responses in 8 teeth and moderate responses in 12 teeth. The statistical analysis showed that response between groups I and II was not significantly different, but group II (Er:YAG laser) showed a better response compared to group I (bur-treated). Conclusion: Light microscopy revealed less histological change in the pulp when Er:YAG laser was used to prepare teeth compared to teeth prepared with conventional burs in a high-speed handpiece. The laser preparation showed histological findings similar to those of non-manipulated or control teeth.
Keywords: tooth preparation, high-speed handpieces, Er:YAG lasers