Acrylic resins for denture base show higher polymerization shrinkage causing unsatisfactory mechanical properties that can interfere on the mechanical behavior of the prosthetic rehabilitation. The aim of this study will be to evaluate the effect of the thio-urethane oligomers addition in commercial acrylic resin for denture base in relation to following properties: linear dimensional change, gloss, hardness, surface roughness, impact strength, and flexural strength. The additive thio-urethane oligomer has capacity of modular the polymerization reaction through the chain transference, and this fact leads to decrease the polymerization stress. This effect was demonstrated in multifunction methacrylates, and the study hypothesis is that the effect will be more significant on monofunctional methacrylates as those used in complete denture bases. For that, the samples will be made with the experimental material polymerized in water hot bath (74ºC for 9 h) for evaluation of the following physical-chemical properties: linear dimensional change (distance between reference points) gloss (Gloss unit), hardeness (Knoop), surface roughness (Ra-µm), impact strength (Charpy), and flexural strength (three point bending test). The tests will be performed after samples storage in water at 37 ºC for 24 h. The comparison with acrylic resin commercially available can also be considered. Obtained data in the different tests related to samples of commercial and experimental resins will be submitted to pertinent statistical analysis and the means compared by the Tukey's test at significant level of 95%.
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