Abstract:Objective:The purpose of this study was to evaluate the effects of Er,Cr:YSGG laser irradiation at different energy outputs on periodontal-diseased root surfaces, so as to determine the feasibility and effectiveness of Er,Cr:YSGG laser in the treatment of periodontal diseases.Methods:12 human teeth IIIo-loosened because of periodontal diseases were extracted and divided randomly into 3 groups with 4 teeth in each group. The 3 groups were irradiated at energy settings of 1.5 W, 2.0 W and 2.5 W respectively before scanning electron microscopy (SEM) was used to observe the root surfaces and the longitudinal profiles in each group. Results:Lower magnifications revealed no distinct difference between the root surfaces in each group. All specimens showed clean surfaces and equal roughness with no notable craters observed. Under higher magnifications, the 1.5 W group showed more smooth surfaces. There were no signs of craters, melting or carbonization, and no exposed dentinal tubules were observed.Conclusions:Er,Cr:YSGG laser could effectively remove the smear layers and infected cementum on periodontal-diseased root surfaces without causing negative changes like melting and carbonization. Compared to the other 2 groups, the 1.5 W group produced better results.