Morphological and ultrastructural comparative analysis of bone tissue after Er:YAG laser and surgical drill osteotomy.

ABSTRACT

OBJECTIVE: The purpose of this study was to analyze morphological, chemical, and crystallographic changes of bone tissue after osteotomy performed with an erbiumyttrium-aluminium-garnet (ErYAG) laser and a low speed pilot drill. MATERIALS AND METHODS: Bone blocks were prepared from porcine ribs, and on each block, two tunnel preparations were performed using the ErYAG laser (pulse energy 1000 mJ, pulse duration 300 µs, pulse repetition rate 20 Hz) or the low-speed surgical pilot drill. The morphological changes of the cortical and the spongious surface of the tunnel preparations were analyzed under the field emission scanning electron microscopy (FE-SEM) at low and high resolution. The distribution and the level of chemical elements in the treated surfaces were evaluated by qualitative and semiquantitative energy dispersive x-ray analysis (SEM-EDX). Diffraction x-ray analysis was used to detect any differences and thermally induced modifications of hydroxyapatite crystals. RESULTS: FE-SEM revealed sharp edges of the ErYAG preparations, with empty intertrabecular spaces and no signs of carbonization. In the drill group, the surface of the preparations was smooth, completely covered with smear layer and microcracks, and with hairy-like irregularities on the edges. SEM-EDX analysis did not reveal any differences in the number of specific chemical elements between the laser and the drill group. There were no thermally induced modifications of hydroxyapatite crystal structure in the bone tissue in either group. CONCLUSIONS: The ErYAG laser ablation did not cause any chemical or crystallographic changes of the bone tissue. Compared with the drill, ErYAG laser created well-defined edges of the preparations, and cortical bone had no smear layer.