Effects Of Er,Cr:YSGG Laser Combined With Different Irrigating Agents On The Pretreatment Of Post Space Of Isolated Tooth On The Bonding Strength Of Fiber Post

Object: To compare the effect of three dentin pretreatment protocols on the cleaning of post space on the bonding strength of fiber post.Methods: 60 teeth without caries were randomly divided into 6 groups: Group A:distilled water group(n=10);Group B: 1% NaClO + 17% EDTA group(n=10);Group C:1% NaClO + MTAD group(n=10);Group A1: Er,Cr:YSGG laser + distilled water group(n=10);Group B1: Er,Cr:YSGG laser + 1% NaClO + 17% EDTA group(n=10);Group C1: Er,Cr:YSGG laser + 1% NaClO + MTAD group(n=10).Each fiber post was bonded with self etching resin adhesive and double curing resin cement,respectively.The maximum tensile force value of each group of fiber posts was measured.Then the fracture mode of bonding interface was observed by stereomicroscope.Results: The bonding strength of group A,B,C,A1,B1 and C1 were(181.31 ±13.18)MPa,(217.43 ± 8.42)MPa,(245.78 ± 7.00)MPa,(212.18 ± 8.59)MPa,(271.56 ±10.75)MPa and(317.22±31.63)MPa,respectively.Among them,the bonding strength of groups A1,B1,and C1 was greater than that of groups A,B,and C,respectively,and the difference was statistically significant(P<0.05).The bonding strength of groups B and C are all greater than that of group A,and the bonding strength of group C was the greastest and the difference is statistically significant(P<0.05).The bonding strength of groups B1 and C1 are all greater than that of group A1,and the bonding strength of group C1 was the greastest and the difference is statistically significant(P<0.05),and the difference is statistically significant(P<0.05).The main fracture modes of each group were the failure between the root canal dentin wall and the bonding material(52%),other failure modes were: the failure between the fiber pile and the bonding material(27%),and the mixed failure(21%).Conclusion: the Er,Cr:YSGG laser washing method and chemical washing method can both significantly improve the bonding strength of fiber post compared with the method of distilled water washing;Whether Er,Cr:YSGG laser is used,1% NaClO solution combined with MTAD solution is the most effective method to improve the bonding strength of fiber post.Objective: To study the micro morphology of dentin wall of post space after pretreatment with Er,Cr: YSGG laser combined with different irrigating agents.Methods: 66 single isolated teeth with single root without caries were randomly divided into 6 groups according to different preparation methods of post space: group A:distilled water group(n = 11);group B: 1% NaClO + 17% EDTA group(n = 11);group C: 1% NaClO + MTAD group(n = 11);group A1: Er,Cr: YSGG Laser + distilled water group(n = 11);group B1: Er,Cr: YSGG Laser + distilled water group(n = 11),Cr:YSGG Laser + 1% NaClO + 17% EDTA group(n = 11),C1 group: Er,Cr: YSGG Laser+ 1% NaClO + MTAD group(n = 11),One specimen was randomly selected from each group to observe the micro morphology of the dentin wall of post space 3 mm from the tip of the post cavity with scanning electron microscope.Results: In the distilled water group,a large number of debris were found on the dentin surface,and the dentin tubules were completely blocked;in the 1% NaClO + 17%EDTA group,a small amount of debris was seen on the dentin surface,and most of the dentin tubules were open;in the 1% NaClO + MTAD group,a large number of debris were seen on the dentin surface,and some of the dentin tubules were blocked,In the Cr:YSGG Laser + distilled water group,a large number of debris were observed on the dentin surface,and most of the dentin tubules were blocked;in Er,Cr: YSGG Laser +1% NaClO + 17% EDTA group,no obvious debris was found on the dentin surface,and the dentin tubules were open;in Er,Cr: YSGG Laser + 1% NaClO + MTAD group,a small amount of debris was seen on the dentin surface,and some of the dentin tubules were blocked.Conclusion: Er,Cr: YSGG laser pretreatment has a stronger effect on removing the smear layer than conventional irrigation,but it is very limited;1% NaClO solution combined with EDTA solution,1% NaClO solution and MTAD solution can both effectively remove the smear layer compared with distilled water pretreatment,in which1% NaClO solution combined with EDTA solution can more fully expose dentin tubule orifice,which is conducive to the construction of three-dimensional reticular junction,in addition,a better cleaning effect can be obtained.