The Effect Of Temperature On Themicroleakage Of Composite Resins In Vitro

Objective:In recent years,Composite resin with its beautiful performance,high plasticity,low solubility,has been liked by clinical workers.As a result,composite resin has gradually become one of the most commonly used dental filling materials.However,polymerization shrinkage of composite resin can lead to microleakge,which has been widely recognized in the industry.Microleakage can cause loosing and falling off of filling body,postoperative sensitivity and secondary caries,eventually leading to repair failure.In order to reduce the microleakage caused by polymerization shrinkage of composite resin,two kinds of composite resin are chosen in this expriment.Effects of different pretreatment temperature on edge microleakage after tooth defect treatment will be explored,in order to find a optimum temperature to effectively reduce microleakage after resin filling and provide theoretical basis and guide for future clinical operation and researches.Methods:80 freshly extracted molarswere were collected and stored in-20 ?for a short period of time,and the neck was prepared with V type cavities.According to the different composite resin material,by using the random number meethod 80 specimens can be divided into two groups,each group of 40.The first set of 3M Z350 general-purpose resin,a second group of P60 resin.According to the temperature of the composite resin,each group will be divided into A,B,C,D four groups.A1.Precooling Z350 resin to 0? filling the cavity and light B1.Filling the cavity and light with Z350 resin at room temperature Cl.Preheating Z350 resin to 45? filling the cavity and light Dl.Preheating Z350 resin to 55? filling the cavity and light A2..Precooling P60 resin to 0? filling the cavity and light B2.Filling the cavity and light with P60 resin at room temperature C2.Preheating P60 resin to 45? filling the cavity and light D2.Preheating P60 resin to 55?filling the cavity and lightAfter 500 times of cold and hot water circulation test,we use magenta dyeing for 24 hours and keeping the temperature constant at 37?.The teeth along the long axis of the longitudinal slice,slice thickness is about 0.9mm,we use stereo microscope to observe the magenta dye penetration.Results:1.There was no significant difference between the 45 and composite resin in the repair of microleakage between the holes(P>0.05),but there was significant difference between the other temperatures(P?0.05).2.At the same temperature,there was no significant difference between Z350 group and P60 group(P>0.05).Conclusions:1.The temperature has an influence on the microleakage of composite resin.Preheating group minimally,followed by precooling group,composite resin restoration nest at room temperature,which the micro leakage of the hole is the largest.2.The use of preheating and precooling resin filling can reduce the microleakage of class V cavity.3.There was no difference between the Z350 resin and P60 resin in the repair of microleakage.