Observation of Cervical Enamel and Root Dentin of Treated Cavity after Root Caries Removal Using Er: YAG, Laser

Abstract

The purpose of this study was to examine morphological and histopathological changes of the cervical enamel and root dentin of the treated cavity after root caries ablation using an Er: YAG laser. The prepared surfce using the Er: YAG laser was compared with that of conventional mechanical treatment. Ten extracted human teeth with root caries were used. Half of the carious lesion in each tooth was ablated with the Er: YAG laser, and the other was removed with a steel bur mounted on a low-speed micromotor. Er: YAG laser treatment was carefully performed under water spray using a combination of contact and non-contact irradiation modes. SEM and histopathological observations were performed for each treatment. The Er: YAG laser was able to ablate root carious lesion effectively without major thermal damage to the surrounding dental hard tisssues. However, the treated cavity margin tended to be irregular and unclear. Due to the careful irradiation technique, the irregularity of the cavity floor was relatively small and the residual structural change of the lased dentin was generally minimal except for the scarce highly-damaged area. The super ficial layer of the lased dentin showed deep staining with hematoxylin in the histological observation and typical microirregularities in the SEM examination. On the lased enamel, however, large microcraks and microirregularities were noted in the SEM evaluation.In order to perform effective caries removal and cavity preparation using the Er: YAG laser, further studies are required on the irradiation conditions and techniques, and on the conditioning of the lased surface for adhesive restorations. Especially, structural changes and finishing of the marginal enamel of the lased cavity should be investigated more minutely.(J. Jpn. Soc. Laser Dent. 8: 31-37, 1997, Reprint requests to Dr. AOKI)