درمان گام به گام عقرب زدگی در جنوب غرب ایران

Background and objective: denture fracture due to excessive thickness, malocclusion or other traumas during sneezing or washing are disadvantages of acrylic prosthetics and pmma resin. so further methods are needed to increase their transverse strength. although there are many studies on reinforcing and modifying with copolymers, cross–linking or use of metallic or fibric strengtheners to enhance mechanical properties, there are limited studies with paradoxical results. the aim of this study was to compare the transverse strength between reinforcement with polyethylene fiber and two older methods (stainless steel, metallic mesh).subjects and methods: in this study 40 pmma resin samples (65x12x3 mm) were made and categorized in 4 groups : with no reinforcing agent ( control group ); with metal wire (diameter 1.0 mm); with metal mesh (diameter 0.3 mm) and with polyethylene fiber (fibre–braid). these samples were put to 3-point loading test by instron universal testing machine. results: the average transverse strength in control group was 78.37 mpa and for three other groups: metallic wire, mesh and polyethylene fibers, in sequence, were 80.25 mpa , 9 mpa and 78.56 mpa . the results were not statistically significant ( p > 0.05).conclusion: reinforcing the acrylic resin using different techniques do not produce increases in transverse strength in comparison with the conventional acrylic resin with no reinforcement. therefore, none of the tested techniques are recommended.