The Effect Of Different Microwave Polymerizations On Accuracy And Physical Properties Of Denture Base Resin

Objective: The aim of this study is to evaluate the effect of microwave polymerizations of different power and curing time on accuracy and physical properties of denture base resin.Methods:①Fourty-five wax patterns of maxilla edentulous yaws were made by 402U standard maxilla edentulous yaws model and standard maxilla complete denture's impression were randomly divided into nine groups, which groups contains five wax patterns;after flasking,losting wax and filling denture base resin, wax patterns were subjected to polymerization by water-bath heat polymerization (group 0) and microwave polymerizations(group 1-8) of different power(500W,800W) and curing time (6min,8min,10mim,12min). All the denture bases and standard models were cut off at the distal surface of second maxilla molar to measure the gaps at A, B, C, D, E,between maxilla complete denture's tissue surface and standard models by digital microscope.②Fourty-five wax patterns (60.0mm×10.0mm×2.5mm)which were made by the same size metal mold were randomly divided into nine groups, which respectively contained five specimens. after flasking,losting wax and filling denture base resin, resin specimens were subjected to polymerization by water-bath heat polymerization (group 0) and microwave polymerizations(group 1-8) of different power(500W,800W) and curing time (6min,8min,10min,12min). Wax patterns was tested in universal test machine to evaluate Flexural strength and Flexural modulus;③Fourty-five wax patterns (60.0mm×10.0mm×2.5mm)which were made by the same size metal mold were randomly divided into nine groups, which respectively contained five specimens. after flasking,losting wax and filling denture base resin, resin specimens were subjected to polymerization by water-bath heat polymerization (group 0) and microwave polymerizations(group 1-8) of different power(500W,800W) and curing time (6min,8min,10min,12min). Wax patterns were tested by roughness tester to measure the surface roughness (Ra).Results:①The five gaps between maxilla complete denture's tissue surface and standard models of different groups are of no statistical differences (P>0.05).②there are statistically differences among Flexural modulus of different groups (P<0.05), while among microwave heating groups, there are no statistically difference(P>0.05), among microwave heating groups and water bath group there are statistically difference(P <0.05).③No statistically differences are found among the Ra means of different groups (P>0.05)Conclusions:Microwave polymerizations when power setting at 500-700W, time setting at 6-12min can well meet the clinical application needs,and the changes of power and time have no significant effect on the mechanical properties of denture base resin.