COMPARISON BETWEEN ER-YAG LASER AND CONVENTIONAL TECHNIQUE FOR ROOT CARIES TREATMENT IN-VITRO

Effective ablation of dental hard tissues by means of the erbium-doped :yttrium-aluminum garnet (Er:YAG) laser has been reported recently, an d its application to caries removal and cavity preparation has been ex pected. However, few studies have investigated the capability of the E r:YAG laser to treat caries. In the present study, the effectiveness o f caries removal by using an Er:YAG laser in vitro was compared with t hat of conventional mechanical treatment. Thirty-one extracted human t eeth with root caries were used. Half of the caries in each tooth was treated with the Er:YAG laser, and the other was removed with a conven tional bur or was left untreated as a control. Laser treatment was per formed by means of a combination of contact and non-contact irradiatio n modes with cooling water spray, with a new fiber delivery and contac t probe system. Conventional bur treatment was conducted by means of a low-speed micromotor. Measurements of the time required for caries re moval, histopathological observations of decalcified serial sections, scanning electron microscope (SEM) observations, and hardness measurem ents of the treated cavity-floor dentin were performed for each treatm ent. Due to the careful irradiation technique, a longer treatment time was required for the complete removal of carious dentin by the Er:YAG laser. However, the Er:YAG laser ablated carious dentin effectively w ith minimal thermal damage to the surrounding intact dentin, and remov ed infected and softened carious dentin to the same degree as the bur treatment. Ln addition, a lower degree of vibration was noted with the Er:YAG laser treatment. The SEM examination revealed characteristic m icro-irregularities of the lased dentin surface. Our results show that the Er:YAG laser system is promising as a new technical modality for caries treatment.