Study On Biocompatibility And Mechanical Properties Of SiCw/ZTA Composite Ceramic Brackets

ObjectivesAlumina?Al₂O₃?and zirconia?ZrO₂?were used as ceramic raw materials,and different mass ratios of SiCw?0wt%,3wt%,5wt%,7wt%?were added to prepare four kinds of SiCw/ZTA composite ceramic brackets,material as tested material.The biosafety properties of four SiCw/ZTA ceramic materials are determined by MTT colorimetric in vitro cytotoxicity test and acute hemolysis experiment.The fracture toughness,elastic modulus and Vickers hardness of four SiCw/ZTA ceramic materials are tested by universal testing machine and Vickers hardness tester.The brittleness index is calculated to determine the mechanical properties and processability of SiCw/ZTA composite ceramics.Provide experimental basis for clinical applications.Methods1 Four kinds of ceramic growth blocks?size 5 mm×5 mm×10 mm and 3 mm×2 mm×30 mm?are cut and surface-polished,the former for cytotoxicity test and the latter for hemolysis test.They are degreased with 95% ethanol for 10 minutes,sonicated for 20minutes,rinsed several times with deionized water,dried and autoclaved at 121°C and 33MPa for 30 mins.100% concentration extracts and 50% concentration extracts of four ceramic materials are prepared from 10% FBS 1640 medium respectively.The experiment is divided into 10 groups:group A is a 100%extract of ZTA;group B is a 50% extract of ZTA;group C is a 100% extract of 3wt% SiCw/ZTA;group D is a 50% dip of 3wt% SiCw/ZTA Extract;group E is 5wt% SiCw/ZTA 100% extract;group F is 5wt% SiCw/ZTA 50% extract;group G is 7wt% SiCw/ZTA 100% extract;group H is a 50% extract of 7wt% SiCw/ZTA;a negative control group:1640 medium?10% FBS?;a positive control group:0.1% phenol.The above materials are tested for in vitro cytotoxicity according to the evaluation criteria.Mouse fibroblast L929 cells are cultured in the above10 groups of liquid for 24h,48h,72h,and observe the cells,morphology?inverted microscope?,and the absorbance values of each group are determined by the MTT colorimetric method,calculate the RGR,and determine the toxicity level;According to the experimental requirements,the physiological saline extracts of four ceramic materials are prepared to carry out the acute hemolysis experiment of the materials.The experiment is divided into 6 groups:group a is ZTA extract group;group b is 3wt% SiCw/ZTA extract group;group c is 5wt% SiCw/ZTA extract group;group d is 7wt% SiCw/ZTA extract group;negative control group:normal saline;positive control group:distilled water.The absorbance values of the above extract after adding rabbit blood are measured,and the hemolysis rates are calculated to determine whether there is acute hemolysis.2 The four kinds of ceramics are cut into rectangular parallelepipeds or cakes of appropriate size according to the requirements of each experiment.The surfaces are polished to 2000 mesh by sandpaper,cleaned by ultrasonic cleaning machine,and dried by electric blower.Among them,the fracture toughness cut size is 2.5 mm×5.0 mm×30.0 mm,and a gap between a preformed depth of 2 mm and a width of 0.24⁰.26mm are required.The required dimension for the elastic modulus test is 2.0 mm×3.0 mm×20.0 mm.The Vickers hardness test requires a block having a thickness of 3 mm.The fracture toughness and elastic modulus tests require 6 specimens per set of materials.The Vickers hardness test requires 1 specimen per set of materials and 5 tests at different locations.On the universal testing machine,the rupture toughness is measured by the single-edge beam three-point bending?SENB?method on a universal testing machine.The loading speed is 0.05mm/min,the span is 30 mm,and s/w=4,?/w=o.5 are required.K_ICC is the average of the data measured for the six test pieces.The universal testing machine uses a three-point bending strain measurement method to determine the elastic modulus?E?of the material,with a span of 16 mm and a loading speed of 0.05 mm/min.The hardness?HV?is measured on a micro Vickers hardness tester with a load of 5 kg and a dwell time of 10 s.The brittleness index is calculated according to the formula,and the workability reference index is obtained.The fracture surface and crack propagation path are observed under scanning electron microscope?SEM?after the fracture surface of various materials sprayed with gold.Results1 The cells in the A^H experimental groups grow well with no abnormal morphology,and the difference from the negative control group is not significant.After 24H of culture,A to H groups and the negative control group and positive control group have no significant difference,no statistical significance?P>0.05?,after 48 H and 72 H of cultivation,A to H groups and the negative control group have no significant difference,no statistical significance?P>0.05?,but between the positive control group have statistical differences?P<0.05?,and A^H each experimental cell toxicity grading are between 0and 1;hemolysis rates are 0.76%,0.88%,1.39%,3.03%,respectively,all below 5%safety standards.2 As the mass ratio of SiCw increases?0wt%⁵wt%?,the fracture toughness,modulus of elasticity and vickers hardness of the composite ceramics increase and the brittleness index decrease,but as the mass ratio of SiCw increases?5wt%⁷wt%?,Their mechanical parameters decrease and the brittleness index increase.Finally,5wt% SiCw/ZTA mechanical parameters:fracture toughness 7.965 MPa.m^1/2,elastic modulus76.063 GPa,Vickers hardness 14.775 GPa,brittleness index 1.85?m^-1/2,with the lowest brittleness index and good mechanical parameters.Conclusions1 SiCw/ZTA composite ceramic bracket materials are negative in vitro cytotoxicity,negative for acute hemolysis,and have good biosafety.2 When the mass ratio of SiCw added to the SiCw/ZTA composite ceramic bracket is 5%,it has good processability and meets the clinical requirements for the mechanical properties of the material.Figure 9;Table 8;Reference 138...