Efeito do laser Nd:YAG na penetração de um cimento biocerâmico nas superfícies dentinárias do canal radicular: uma análise por microscopia confocal

Abstract

Nd:YAG laser is widely used in endodontics for decontamination of root canals. Its use may modify the mineral dentin composition and cause morphological changes on it. However, the effects that irradiation with Nd:YAG laser can cause when used to decontaminate the root canal prior to obturation with a bioceramic sealer are not well known. This study aimed to study the influence of Nd:YAG laser irradiation on penetration, morphological alteration and dentin composition when previously used in the obturation of root canals with a bioceramic sealer. Forty freshly extracted human mandibular premolars were prepared with Reciproc® and irrigated with 17% ethylenediaminetetraacetic acid (EDTA). They were randomly divided into 4 groups: G1-obturated with control sealer (AH Plus®); G2- filled with bioceramic sealer (Endosequence BC Sealer®); G3- Nd:YAG laser + sealer control and G4- Nd:YAG laser + bioceramic sealer. The samples were cross-sectioned 3 mm and 5 mm from the apex and analyzed using confocal microscopy. The penetration of the sealer in the dentin tubules and penetration of the sealer in the perimeter of the walls of the root canal were evaluated. Another twelve samples were analyzed by scanning electron microscopy (SEM) to evaluate morphological changes and dispersive energy X-ray spectroscopy (EDX) to evaluate mineral alterations. Two-way ANOVA with post hoc Bonferroni was used. Bioceramic sealer presented higher penetration at depths of 3 and 5 mm, regardless of laser use (p <0.05). There was no difference between sealers at 3 mm (p <0.05) for the perimeter of penetrated sealer, regardless of the use of the laser. At 5 mm, the bioceramic sealer and the laser showed a greater penetration perimeter (p <0.05). Regarding the morphological alterations, there were differences for all groups irradiated with laser (p <0.05) and there were no change in the basic mineral composition of any group studied after laser irradiation. It was concluded that the Nd:YAG laser did not cause sufficient morphological alterations to cause dentin permeability decrease and alteration in the basic mineral composition of dentin of the root canals before filling with the bioceramic sealer.