[Evaluation of root canal isthmus debridement efficacy of Er:YAG laser in combination with sodium hypochlorite].

ABSTRACT

PURPOSE: To histologically evaluate the efficacy of sodium hypochlorite (NaClO) in combination with ErYAG (erbium-doped yttrium aluminium garnet) laser in dissolving necrotic tissue and cleaning root canals as well as canal isthmuses. METHODS: After scanned by cone-beam CT (CBCT), 50 well-prepared premolars with root canal isthmuses were selected and randomly assigned into 5 groups. They were subsequently subjected to different regimens as followed group A-irrigated with 1% NaClO for 1 minute, group B- irradiated by ErYAG laser at 0.5 W combined with 1% NaClO irrigation for 1 minute, group C- irradiated by ErYAG laser at 1.0 W combined with 1% NaClO irrigation for 1 minute, group D- irradiated by ErYAG laser at 2.0 W combined with 1% NaClO irrigation for 1 minute,group E- negative control. After histological preparation and staining, the cross-sections were evaluated for percentage of tissue removal from root canals and isthmuses. The cleanliness values were calculated using SPSS 13.0 software package. RESULTS: The mean percentage of root canals in group A, B, C and D was 95.24%, 96.53%、97.63% and 98.22%, respectively, and the mean percentage of isthmuses was 16.50%, 51.48%, 52.56% and 53.83%, respectively. The mean percentage of root canal and isthmus cleanliness values were significantly higher in group B, C and D (P<0.05) than that in group A. There was no significant differences of root canal and isthmus cleanliness among group B, C and D. CONCLUSIONS: ErYAG laser combined with 1% NaClO irrigation may be used effectively in root canal and root canal isthmus cleanliness as a new method.