Comparison Of Mechanical Properites Of Three Machined Resin Ceramic Composite Materials

Objective:This study was to compare the flexural strength,fracture toughness and hardness of three machinable composite materials to a glass ceramic,in order to provide experimental basis for clinical.Methods:Choose three kinds of resin ceramic composite materials Upcera Hyramic,3M Lava Ultimate,Vita Enamic and a feldspathic glass ceramic Vitablocs MarkII.Bar-shaped specimens（16×4×1mm、16×4×2mm）were prepared for the flexural strength experiment;specimens（17×4×3mm）were prepared for the fracture toughness experiment and specimens of 4mm thickness were prepared for hardness test.Flexural test and fracture toughness experiment were performed with an Universal Testing Machine at a cross-head speed of 0.5mm/min.Hardness test was performed with an micro hardness tester.Scanning electron microscope was to observe the fracture surface of specimens.One-way variance analysis was used to determine the statistical differences of all data with SPSS 17.0 software package.Results:The mean flexural strength results of the tested blocks at 1mm thickness are Hyramic（207.7515±13.12MPa）>Vita Enamic（182.0286±15.18MPa）>Lava Ultimate（145.8469±8.98MPa）>Vitablocs MarkⅡ（103.0542±18.19 MPa）;The mean flexural strength results of the tested blocks at 2 mm thickness are Hyramic（208.1986±25.07MPa）>Lava Ultimate（172.9297±12.73MPa）>VitablocsMarkⅡ（158.6587±15.37MPa）>Vita Enamic（155.3670±13.77 MPa）.The mean fracture toughness results are Vita Enamic(1.6357±0.16MPa.m^1/2)>Lava Ultimate(1.4286±0.11MPa.m^1/2)>Vitablocs MarkII(1.3233±0.10MPa.m^1/2)>Hyramic(1.0614±0.09 MPa.m^1/2).The mean hardness results are VitablocsMarkⅡ（691.28±68.27Hv）>Vita Enamic（240.95±9.21Hv）>Hyramic（121.45±2.42Hv）>Lava Ultimate（111.85±2.88Hv）.Conclusions:According to ISO 6872/2008 standard,three kinds of machinable resin ceramic composites meet the needs of clinical strength.Hyramic showed higher flexural strength at different thickness,it is an ideal material for dental restoration;Vita Enamic has not only higher flexural strength at the thickness of 1mm,but also good toughness,it is suitable for the repairment of patients that have limited occlusal space and great bite force,named occlusal veneer.