Effect Of Two Pretreatment Methods On Micro-leakage Of Class V Resin Filing

Objectives:The purpose of this project is to study the influence of preheating temperature(45?,55?)and pre-etching time(3s,10s,15s)on the micro-leakage of composite resin after being filled,and to figure out the two factors' impact on resin filling,and providing a theoretical basis for clinical practice.Methods:This project is aimed at the above controversies to carry out experiments,after the design of V type cavity;in the molar teeth after the resin filling,simulate the changes in the oral cavity after filling the composite resin through cold and hot water circulation,using the dye penetration method(magenta solution)and 0-4 rating standard evaluates the size of the microleakage at the edge of the composite resin.This topic is divided into two parts:Experiment one,compared with the control group,45?,55? as the experimental group,respectively,to study the effects of two preheating temperatures on the microleakage after filling V-shapes.In the second experiment,37%phosphoric acid was used to selectively etch the enamel and its edge 0.5mm to achieve pre-etching.Kuraray SE Bond was used as the control group,and the time gradient of 3s.10s.15s was pretreated with phosphoric acid.The experimental group studied the effect of acid etching pretreatment time on microleakage.Results:Experiment one:Results of this study showed that both preheating can significantly reduce the microleakage after resin filling(P<0.05);however,there was no significant difference in preheating to 45? and 55? group(P>0.05).Experiment two:The results of the study showed that the microleakage of the three pre-etching groups was less than that of the direct filling group(P<0.05);there was no significant difference between the time of the different etching time and the microleakage after the cavity filling.(P>0.05).Conclusions:1.Various pretreatment methods can reduce microleakage after resin filling,but they can not completely eliminate microleakage;2.Preheating can significantly reduce the edge micro-leakage after 3M Z350 resin filling to achieve a better edge closure effect;3.Relative to preheating to 55?,preheating to 45? can maintain good edge closure while retaining better physical properties and bond strength;4.Pre-etching can reduce the edge micro-leakage after the two-step self-etching adhesive filling,and achieve a good enamel edge closure effect;5.Compared to the selective enamel etching of 15 seconds,the enamel acid etching in a shorter time(3s)can also achieve a similar degree of edge closure,and it can also reduce the adverse effect of eroding normal dentin on the repair effect.