| Objective: Dental caries is a kind of chronic progressive disease that hard tissue of tooth are damaged principally by bacteria and other many factors.It is still one of the most frequently encountered disease affecting humans.Dental caries developed slowly,so often overlooked.When the pain symptoms,cavities has growed into moderate caries,deep caries,pulpitis and even affect the whole body health.Therefore,the primary problem is the prevention and treatment of early caries.The pit fissure caries is a kind of caries that occur in enamel or dentin superficial layer round pits and fissures on the occlusal surface,which has high morbidity young permanent teeth.The prevention and treatment of pit fissure caries timely is the key to prevent caries disease.With the development of caries disease treatment technology,the treatment of fissure caries has developed from the traditional extension for prevention with silver amalgam filling to preventive resin restoration technology now.A large number of studies have found that the preventive resin restoration was considered as the most appropriate restoration skill for prevention of pit and fissure caries.With the development of dental material,As the new materials for PRR,the flowable composite and flowable compomer also gradually replace the traditional filling method that composite resin combination of pit and fissure sealing.The methods of prepared hole have enriched with the development of minimally invasive technology,among them,the air-abrasion played an important role.Air-abrasion cuts by striking against the tissue of tooth with high kinetic energy,through a beam of high-speed aluminum oxide particles.It can maximize the preservation of teeth and coincide with minimally invasive technology.The experiment contained in this study compares the different preparations with air-abrasion and traditional handpiece method and analysesthe microleakage and gaps under scanning electron microscope between fillings and teeth after filled by 3MTM ESPETM Filtek TM Z350XT and constic.The purpose is to assess whether the air-abrasion can improve the effect of clinical application with the treatment with flowable composite in preventive resin restoration.Methods:The 100 extracted premolars and molars were collected from The Department of oral maxillofacial surgery Dental Hospital of Hebei Medical University.The standard of teeth are:(1)pit and fissure caries which could stuck probes;(2)deep pits and fissures where were the tendency of caries;(3)early-stage caries in fissures,that is,enamel is chalk white or nontransparent;(4)teeth without any other caries or fillings;(5)teeth without dental fluorosis,enamel hypoplasia,tetracycline pigmentation teeth.All teeth were divided into Group A,B,C,Dand E,20 teeth in each group.Select 10 teeth from each group randomly for microleakage test and others are used for outsight of scanning electron microscope.Clean and preserve the teeth in the0.5% chloramine at 4℃.A Traditional handpiece+composite resin+pit and fissure sealingB Traditional handpiece+acid etching+resin adhesive+3M Z350C Traditional handpiece+consticD Air-abrasion+acid etching+resin adhesive+3M Z350E Air-abrasion+constic1 Group A as control group;Group B、C、D、E as experiment groups.For group A、B and C,the cavity was produced along the fissure of teeth by using high speed silicon carbide burs and half ball type slow speed drill,the breadth is about 0.5mm and the depth is about 1 to 1.5mm.For group D and E,the cavity was produced by Kavo RONDOflex plus360 air-abrasion system with the aluminum oxide particles of 50μm diameter.Nozzle perpendicular to the tooth surface and keep 1mm distance with tooth surface.Along the pit fissure caries in vitro teeth loss in shuttle back and forth over and over again,remove the caries,prepare the cavity.After the completion of the caries,the teeth ofgroup A managed by acid etching and resin adhesive before composite resin filling,then smear fissure Sealant on the surface;the teeth of group B 、 D managed by acid etching and resin adhesive before 3M Z350 filling;the teeth of group C、E filled with constic.2 Compound artificial saliva,the filled teeth were immersed in artificial saliva at constant temperature of 37℃ for 30 day.3 Thennocycling test:put the extracted teeth into the test tube,and then stayed in 5℃ cold water for 30 s,in 55℃ warm water for 30 s in a cycle and repeated 500 times.4 10 teeth were pick out from each group randomly for microleakage test and the rest of teeth were measured gaps between fillings and teeth tissue by SEM.5 Recorded and graded microleakage result on each tooth and measured gaps at the edge of the 0.2mm from the cavity between fillings and teeth then analyzed statistically.Result:1 Microleakage level from high to low in turn for group A,C,E,B and D.Group D was the lowest,which showed statistical difference to other groups(P<0.05).Group B、E were better than group C、A,which have statistical difference(P<0.05).There was no statistic difference among group B and E(P>0.05),and same to group C and A(P>0.05).2 Through SEM observation,Gaps between filling body and tooth tissue were group A > C >E> B > D.The gap of group D was smaller than other groups,had statistic difference(P<0.05).The gap of Group B and E were bigger than group D,show statistical difference to group C(P<0.05);There was no statistic difference among group B and E(P>0.05).The gap of group A was the biggest and show statistical difference to group C(P<0.05).Conclusion:1 The microleakage of air-abrasion combined with acid etching、resin adhesive and 3M Z350(group D)was the lowest,the gaps was the smallest,which showed statistical difference to other groups.2 It cloud fill best which prepared by air-abrasion with total etching adhesive system and filled by Filtek TM Z350 XT flowable resin.3 Air-abrasion can produce a kind of similar to the acid corrosion on the surface of the teeth,but its not as good as the total etching adhesive system.4 No matter traditional handpiece or air-abrasion technology,filled with flowable resin for PRR,the effect is better than the traditional method that composite resin filling in combination with the pit and fissure sealing. |
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