Influence Research of the Different Expansion Coefficient Plaster Cast Material on Resin Denture Accuracy and Physical Properties
|Keywords||Plaster Accuracy Impact strength Bending strength Surface roughness|
Objective To study the plaster model of the different coefficients of expansion material denture precision and physical performance . Method using high , medium and low three different expansion coefficients of the plaster model material : ① the three kinds of gypsum mastering maxillary full mouth non- the edentulous standard model five and making its the maxillary Thermocoagulation methyl methacrylate denture . Then in the equivalent of the parts cut off Underpinning the standard model , and the maxillary second molars universal digital microscope measuring a total of five parts of the distance between the surface and the standard model of maxillary complete denture base organizations . ② the buried type cartridge mounted to the above three kinds of model material , respectively, each produce 5 50mm × 6mm × 5mm ; 64mm × 10mm × 3.5 mm ; 30mm × 10mm × 6.0 mm , the resin denture base sample , respectively, to measure the impact strength , bending strength, elastic modulus and hardness . ③ then each produced five resin denture base specimen of 30mm × 10mm × 6.0mm , the surface roughness was measured . Results ① plaster model , low coefficient of expansion material maxillary dentures , precision in 280μm ~ 340μm, 198μm ~ 220μm and 50μm ~ 98μm . The difference was highly statistically significant ( P <0.01 ) . ② high impact strength , low coefficient of expansion of the gypsum model material sample was produced , respectively : 5.79 ± 0.90KJ · m -2 sup>, 7.21 ± 0.16KJ · m -2 sup > 8.89 ± 0.58KJ · m -2 sup>; bending strength were : 71.03 ± 2.23MPa , 85.18 ± 5.32MPa and 110.06 ± 4.06MPa ; flexural modulus were : 2797 ± 83MPa ± 2512 , 88MPa and 2088 ± 42MPa; hardness (Rockwell ) were : 16.30 ± 0.35,20.50 ± 0.38,26.80 ± 0.14, the differences were highly statistically significant ( P <0.01 ) . ③ high , low thermal expansion coefficient of the plaster model material resin surface roughness : Ra values ??were 1.64 ± 0.22,1.08 ± 0.13,0.65 ± 0.26 ; Rz values ??were 6.44 ± 1.12,5.18 ± 0.96,3.35 ± 0.95 , the difference was highly statistically significant ( P <0.01 ) . Conclusion ① the resin denture highest accuracy of the low thermal expansion coefficient of the plaster model material . The physical properties of the resin denture ② low coefficient of expansion plaster model materials . ( 3 ) low coefficient of expansion plaster model material resin denture surface roughness value of the minimum .