The Comparative Studing Of Three Ceramic Inlays' Marginal Fitness

Fitness express the size of between the restoration margin and the tooth cavity . It reflects how fitting and how close the restoration margin to the tooth..It is a mportant indicator to material performance,and it is one of the important indicator to judge the restoration clinic effictiveness. At the same time, It is the key factor of the all ceramic restoration quality and life.When we choose the restoration material,we may think about the fitness of the material besides the strength, tenacity, biological consistent and et al.Objective:To compare the marginal fitness between teeth and inlays made from three diferent ceramic materials,and then to select the best restoration material in clinic.Methods:To select whole adult molar which was extracted recently. Preparaed the tooth cavity with inlay ofⅠtype base on the conventional principle . The occlusal convergence angle is 6o,bottom is flat ,and cliff is straight.There is no inclined plane at the margin.There should be round and dull angle at the bottom point angle.The cavity must be 2.0-3.0 mm depth for the material intensity.Use silicone rubber impression material to duplicate cast 30 of superhard plaster die. Divide them into 3 group in random,fracture inlay with three ceramic materials:polymer ceramic,die-casting ceramic and CAD-CAM ceramic.Stick the inlay to die with glass ionomer cement,fit with hand,and then put the die under the tester with static pressure of 3.5 kg for 10 minutes,clear the more cement,still 24 hours.Coating with selfcuring acrylic resin,making square of 2.0cm×2.0cm×2.0cm ,excide the test piece with hard tissue section machine follow the middle line from the medial to the distal.Polishing the test with sand paper and buff wheel,clean with 95% alcohol,and dry with hot wind. Measure sample with metallography microscope(Shanghai, precisionl0μm) ,enlarge 100 times.Select 5 point of every sample, point A express the fitness of the bottom of inlay,point B,C express the fitness of the middle of inlay,point D,E express the fitness of the upper of inlay. Measure every point for 3 times ,fetch the mean.The mean of the five point express the whole fitness of inlay.Use the statistical software of SPSS10.0 to analyse the each adherence thickness of the three ceramic inlay and the relationship of them.Results:The mean thickness of three ceramic: polymer ceramic is 75.0±12.0μm, heat-pressed ceramic is 78.0±13.0μm, CAD-CAM ceramic is 124.0±35.0μm.P<0.001,there is significant difference between the three ceramic inlay. Comparing with each other: Comparing polymer ceramic with heat-pressed ceramic, there is no significant difference;Comparing polymer ceramic with CAD-CAM ceramic, there is significant difference; Comparing heat-pressed ceramic with CAD-CAM ceramic, there is significant difference.Conclusions: Three material ceramic inlays have the diffetent margin fitness for the material capability and the different fracture technique.There are different between the margin fitness of the three ceramic inlay,but they can be accepted in clinic. Polymer ceramic and die-casting ceramic have good fitness comparatively,and they can be used inlay restoration very well in clinic.To know the fitness through the study,we can choice the more fit restoration material based on the require and the condition of patient in clinic.