Comparison On Fracture Resistance And Marginal Microleakage Of Three Kinds Of Resin Inlays

ObjectiveThe prognosis of teeth after root canal therapy is related to the quality of crown prosthesis.There are different ways to repair the defect of maxillary first premolars after root canal treatment.The first maxillary premolars with type II cavity after root canal therapy were used to investigate the biomechanical properties and their functions,so that can find out the most suitable resin materials for inlay production,and providing evidence for materials option in clinical operation.Methods1.Experiment one:fracture resistance test75 human complete extracted maxillary premolars which have the same measurements were collected and randomly assigned to five groups:control group?RCT group?Filtek ^TMZ350 group?Tetric N-Ceram group?Micerium Hri group.60samples were carried out access cavity preparation but control group,then determining working length.All test teeth were endodontically prepared.Irrigation and drying,followed by root canal filling were completed.The quality of root obturation was evaluated by x-ray.Resin inlays were made in accordance with groups.Adhesive were coated evenly according to the instructions.Then light curing and polishing were operated.The light body of silicone impression material was used to simulate the periodontal ligament.A block of self-curing acrylic resin was used for alveolar bone.A universal loading machine was used for fracture test.All specimens were loaded until fracture,and the maximum breaking loads were recorded in newtons?N?.All date were analyzed using ANOVA variance analysis and LSD test for multiple comparisons by SPSS 24.0.The level of significance was set at 5%.2.Experiment two:microleakage test30 maxillary premolars were randomly divided into three groups:Filtek ^TMZ350group?Tetric N-Ceram group?Micerium Hri group.Three kinds of inlays were fabricated,then inserted into the teeth and polished as mentioned above.All teeth were stained with Rhodamine-B for 24h after experienced 1000 cycles in the cold and hot water.All samples were sliced longitudinally to observe the penetrating depth and graded under confocal laser scanning microscope.The Kruskal–Wallis test and Mann-Whitney U test was ued to compare the microleakage,P value was considered as significance statistically when it is<0.05.Results1.There were no statistical differences about the measures:the length of the crown,the length of the root,the width and the thickness of the crown?P>0.05?.2.Fracture load results showed:The fracture resistance strength of control group?Filtek ^TMZ350 group?Tetric N-Ceram group?Micerium Hri group were higherthan RCT group,with statistical difference?P<0.05?.After pairwise comparison,control group had a better effect than Filtek ^TMZ350 group,Tetric N-Ceram group,Micerium Hri group;Tetric N-Ceram exhibited the lower fracture load comparedwith Filtek ^TMZ350 and Micerium Hri?P<0.05?;Filtek ^TMZ350 and MiceriumHri had no significant difference.3.The percentage of type I fracture ranged from high to low as follows:TetricN-Ceram group 80.0%,Micerium Hri group 66.7%,control group 60.0%,Filtek^TMZ350 group 53.3%,RCT group 20.0%,the differences were remarkable.Therepairable samples in Tetric N-Ceram group and Micerium Hri group were morethan that in group RCT group?P<0.05?,without differences among other groups?P>0.05?.4.The distribution of microleakage grades of the three groups was different?P<0.05?;Tetric N-Ceram was different from Micerium Hri in microleakage scores?P<0.05?.With no statistical significance among others.ConclusionsThe ability of the teeth to resist fracture was significantly reduced after RCT.Filtek ^TMZ350?Tetric N-Ceram and Micerium Hri had enhanced their fracture resistance,so that can meet people's daily chewing.Unfortunately,the overall performance of the complete teeth can not be achieved.Z350 and Micerium Hri resin inlay seem to have higher strength,lower microleakage grade and better effect.Accordingly,they are good inlay materials and recommended to make resin inlays.