Effect of different parameters Er: YAG laser irradiation on the structure of dental hard tissue

Abstract

Objective To investigate the effect of Er:YAG laser irradiation on the structure of dental hard tissue.Methods 2 teeth (8 samples) were randomly selected from 26 teeth enamel group(104 samples) for blank control(group C).The remaining 24 teeth (96 samples) were randomly divided into A group (irradiation 10 s) and B group (20 s irradiation),each group according to power were randomly divided into 1,2,3,4,5,6 W six subgroups,each subgroup had 8 samples.Using a Er:YAG laser at 20 Hz frequency,according to the corresponding packet (with different power and different irradiation time) were irradiated for each sample.Dentin grouped with enamel group.To observe the changes of different energy and the pit diameter and depth.Results The enamel surface pit diameter was compared by different irradiation time and power,different power within the same irradiation time (t =1.89,2.02,2.76,1.98,1.37,1.42,all P ＜ 0 05) ; compared between B group and the A group under the same power (t =1.23,3.23,2.04,1.45,1.42,1.87,all P ＜ 0.05).The enamel surface pit depth was compared by different irradiation time and power,different power within the same irradiation time (t =1.15,3.09,2.32,1.76,1.51,1.59,all P ＜ 0.05) ;compared between B group and the A group under the same power (t =1.15,3.09,2.32,1.76,1.51,1.59,all P ＜0.05).The dentin surface pit diameter was compared by different irradiation time and power,different power within the same irradiation time (t =1.15,3.09,2.32,1.76,1.51,1.59,all P ＜ 0.05) ; compared between B group and the A group under the same power(t =1.15,3.09,2.32,1.76,1.51,1.59,all P ＜ 0.05).The dentin surface pit depth was compared by different irradiation time and power,diffe rent power within the same irradiation time (t =2.12,2.04,1.82,1.43,1.31,1.76,all P ＜ 0.05) ; compared between B group and the A group under the same power(t =2.34,3.13,2.76,1.45,1.34,1.62,all P＜0.05).Conclusion With the increase in the laser energy and the irradiation time,the diameter and depth of enamel pits produced also continuously increase;With the increase in the laser energy and the irradiation time,dentin diameter and depth of the pits produced constantly increased.The different parameters of Er:YAG laser irradiation of dental hard tissues have different effects on the structure. Key words: Er: YAG Laser; Hard tissue of tooth ; Laser parameters ; Interfacial reaction