Study on Fracture Resistance of Occlusal Veneers Fabricated by Three Different CAD/CAM Ceramic Materials
Objective To explore the fracture resistance of occlusal veneers fabricated by three different CAD/CAM ceramic materials.Methods A right mandibular first molar with normal morphology in vitro was scanned and its digital model was constructed.Then digital preparation of occlusal veneer were processed on the digital models,the thickness of the digital veneers was 1.0 mm,1.5 mm,2.0 mm,2.5mm separately.Then the data was transferred to the carving machine and the processing of the veneers was completed with a sort of resin-based ceramic ignot and two sorts of lithium disilicate glass-ceramic ignot.120 occlusal veneers were fabricated while every sort of ceramic ingot with every thickness is 10.Then the occlusal veneers were bonded to the 3D printed hard resin bodies.After cyclic loading,the vertical loading experiment was conducted to the veneers by electric universal test machine.The fracture resistance strength was recorded and the failure modes were observed.SPSS22.0 was used to analyze the data.Results The results of fracture load showed that the difference of fracture load between the three materials was statistically significant when the thickness was 1.0 mm,1.5 mm and 2.0 mm(P＜0.05),while there was no statistically significant difference between the two glass-ceramics when the thickness was 2.5 mm(P＞0.05).There was significant difference in fracture load between glass ceramics and resin-based ceramics(P＜0.05).The fracture load increases with the increase of the thickness of the two glass-ceramics(P＜0.05).The fracture load of resin-based ceramics increased with the thickness of 1.0 mm,1.5 mm and 2.0 mm(P＜0.05).The fracture modes of the three kinds of occlusal surfaces were cracks,crushing and fracture.Conclusion The fracture resistance of three different CAD/CAM ceramic occlusal veneers can meet the demand of the restoration of posterior tooth occlusal defect,the operation steps of resin-based ceramics are relatively simple.In clinical practice,the thinner veneer should be selected to repair the temporal-mandibular joint,so as to facilitate the adaptation of temporal-mandibular joint.
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