Objective:To explore the effects of different combination of Er∶YAG laser irradiation parameters on the dentinal tu-bule sealing.Methods:160 dentin discs with 2 mm thickness were etched with 0.5 mmol/L EDTA to establish the dentine hyper-sensitivity models.The discs were randomly divided into 16 groups(n=10).The R02 and R14 handpieces were used to deliver Er∶YAG laser to the dentin discs according to the different output power(W),irradiation distance(cm)and irradiation time(s/cm2).Then,the samples of each group were divided into immediate irradiation subgroup and acid etching and wear subgroup(n=5).The dentinal tubules were observed with SEM,and the exposed area,the sealed rate and the occlusion depth of dentinal tubules were e-valuated with ImageE-Pro Plus 6.0 software.Results:The dentinal tubules in the control group opened uniformly with clear perime-ter,they were enlarged and opened after acid etching and tooth brushing.The dentinal tubules shrinked or sealed well with the melt layer after treatment by Er∶YAG laser irradiation with either parameter combination.Especially,uniform and seamless melt layer as well as similar dentin surface morphology before and post the acid etching and tooth brushing were obtained when the dentin discs were exposed to the following Er∶YAG laser irradiation parameter combinations,i.e.(R02,0.5 W,3 cm,20 s/cm2),(R14,0.5 W,3 cm,20 s/cm2)and(R14,0.6 W,3 cm,20 s/cm2).Significantly decreased exposed area and increased seal rate in the dentinal tubules treated in the above 3 laser irradiation parameter combina-tion groups were observed than those in the other groups(P＜0.05).Morphological analysis confirmed that whether the acid etching and tooth brushing were exerted.The occlusion depth of dentin tubule was more than 2.0 μm in the dentinal tubules treated in the above 3 groups.Conclusion:Er∶YAG laser irradiation parameter combinations of R02,0.5 W,3 cm,20 s/cm2,R14,0.5 W,3 cm,20 s/cm2 and R14,0.6 W,3 cm,20 s/cm2 are suitable for the best dentin tubule sealing.

Objective:To explore the effects of different combination of Er∶YAG laser irradiation parameters on the dentinal tu-bule sealing.Methods:160 dentin discs with 2 mm thickness were etched with 0.5 mmol/L EDTA to establish the dentine hyper-sensitivity models.The discs were randomly divided into 16 groups(n=10).The R02 and R14 handpieces were used to deliver Er∶YAG laser to the dentin discs according to the different output power(W),irradiation distance(cm)and irradiation time(s/cm2).Then,the samples of each group were divided into immediate irradiation subgroup and acid etching and wear subgroup(n=5).The dentinal tubules were observed with SEM,and the exposed area,the sealed rate and the occlusion depth of dentinal tubules were e-valuated with ImageE-Pro Plus 6.0 software.Results:The dentinal tubules in the control group opened uniformly with clear perime-ter,they were enlarged and opened after acid etching and tooth brushing.The dentinal tubules shrinked or sealed well with the melt layer after treatment by Er∶YAG laser irradiation with either parameter combination.Especially,uniform and seamless melt layer as well as similar dentin surface morphology before and post the acid etching and tooth brushing were obtained when the dentin discs were exposed to the following Er∶YAG laser irradiation parameter combinations,i.e.(R02,0.5 W,3 cm,20 s/cm2),(R14,0.5 W,3 cm,20 s/cm2)and(R14,0.6 W,3 cm,20 s/cm2).Significantly decreased exposed area and increased seal rate in the dentinal tubules treated in the above 3 laser irradiation parameter combina-tion groups were observed than those in the other groups(P＜0.05).Morphological analysis confirmed that whether the acid etching and tooth brushing were exerted.The occlusion depth of dentin tubule was more than 2.0 μm in the dentinal tubules treated in the above 3 groups.Conclusion:Er∶YAG laser irradiation parameter combinations of R02,0.5 W,3 cm,20 s/cm2,R14,0.5 W,3 cm,20 s/cm2 and R14,0.6 W,3 cm,20 s/cm2 are suitable for the best dentin tubule sealing.

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