Effects of Er,Cr : YSGG laser irradiation in human enamel and dentin: Ablation and morphological studies

Objective: This investigation was performed to determine quantitatively the ranges of ablation and to evaluate the morphological changes in human enam el and dentin irradiated by Er,Cr:YSGG laser with or without water spray. S ummary Background Data: Recently, Er,Cr:YSGG laser has been introduced in d ental clinics to remove carious dental hard tissues in anticipation of repl acing the high-speed dental drill, Methods: A total of 40 extracted human t eeth were used in this study, An Er,Cr:YSGG laser was used to ablate human dental hard tissues with the output powers of 3 to 6 W, Ablation extent wit h or without water spray at different output powers was measured, and the m orphological changes on enamel and dentin were also investigated by stereos copy and scanning electron microscopy (SEM), Results: The irradiation with water spray significantly (p < 0.001) increased the ablation depths compare d to those irradiated without water mist, Morphological findings by SEM ind icated that when irradiated without water spray, carbonization with brown o r dark color was recognized in enamel or dentin, respectively, In addition, cavities with a molten lava-like appearance were produced and an irregular structure with many microholes was observed in dentin, Conclusions: These results suggest that during the Er,Cr:YSGG laser irradiation, water spray d irected at the ablation sites increases the ablation depths and water plays an important role as an initiator of the ablation of dental hard tissues.