Effect Of Different Polishing Tools On Mechanical Properties Of IPS E.max CAD Glass-ceramic

ObjectiveThe purpose of the experiment was to compare the mechanical properties of different polishing tools on IPS e.max CAD glass-ceramic by bending strength,hardness and fracture toughness for clinical polishing tool selection.MethodsPreparing seventy?e.max CAD glass-ceramic bending strength specimens which size was?14.0mm*4.0mm*1.2mm,thirty-five?e.max CAD glass-ceramic hardness spe-cimens which size was?15.0mm*10.0mm*4mm,?seventy e.max CAD glass-ceramic fracture toughness specimens which size was?15.0mm*10.0mm*4mm,then the operation surface of the specimens was polished by 220^#?400^#sandpaper,crystallize and adjusting with carborundum yellow standard needle.The experiment was divided into three groups:bending strength Group,Vickers hardness Group and fracture toughness Group,each of the three groups was randomly divided into 7groups:group C?the conditional control group with adjusting?,group G?glazing?,group?SF?Porcelain AdjustmentKit+CeraMaster?,group 3M?3M Sof-Lex Discs?,group EVE?EVE DIAPRO system?,group Tob?TobooM system?,group Ivo?Ivoclar Vivadent OptraFine system?.Specimens were treated with glazing and polishing as required.The bending strength?hardness and fracture toughness of the specimen was measured.Then the surface morphology and fractographic morphology of the specimen were observed by scanning electron microscope?SEM?.ResultsThe bending strength values of each group from high to low were?as?follows:3M₁?302.42MPa±28.78MPa?>G₁?300.74MPa±17.71MPa?>Ivo₁?276.64MPa±39.78MPa?>SF₁?275.84MPa±24.55MPa?>EVE₁?250.29MPa±28.89MPa?>Tob₁?225.83MPa±24.45MPa?>C₁?201.66MPa±19.85MPa?.There was no statistical difference between 3M₁ and G ₁groups,similarly,Ivo₁ and SF₁ groups,but the differences among the other groups were statistically significant.The results of surface morphology and fractographic morphology of SEM are consistent with the results of bending strength statistics.There is no statistical difference between hardness values of the specimens.The fracture toughness values of each group from high to low were?as?follows:3M₃(1.78MPa.m^0.5±0.16MPa.m^0.5)>G₃(1.77MPa.m^0.5±0.16MPa.m^0.5)>Ivo₃(1.54MPa.m^0.5±0.07MPa.m^0.5)>SF₃(1.47MPa.m^0.5±0.11 MPa.m^0.5)>EVE₃(1.28MPa.m^0.5±0.10MPa.m^0.5)>Tob₃(1.26MPa.m^0.5±0.14MPa.m^0.5)>C₃(1.07MPa.m^0.5±0.07MPa.m^0.5).There was no statistical difference between 3M₃ and G₃ groups,similarly,Ivo₃ and SF₃ groups,EVE₃ and Tob₃ groups,but the differences among the other groups were statistically significant.ConclusionsThe effects of five polishing tools on the bending strength and fracture toughness of e.max CAD glass-ceramic were significantly different.The effect of 3M sof-lex system and glazing are the best;the effect of OptraFine system and Shofu system is better;EVE DIAPRO system and Toboo M system is the worst.Polishing and glazing have no effect on the hardness of glass-ceramic.