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Effect of thermal treatment on flexural strength of bis-acrylic resin
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Resumo(s)
Objective: The aim of the present study was to evaluate the effect of post-polymerization heat treatment on the flexural strength (FS) of two bis-acrylic resins. Materials and Methods: Two commercially available autopolymerized bis-acrylic resins were tested: Structur 3 (S3), (VOCO GmbH, Cuxhaven, Germany) and Protemp 4 (P4), (3M ESPE, Minnesota, USA). A stainless-steel mold was used to fabricate the specimens with a dimension of 25x2x2 mm according to ISO 4049:2000 standards. A total of 50 specimens were fabricated using each material (N=100). After fabrication, specimens were randomly allocated to 10 experimental groups (n=10) and immediately subjected to the respective post-polymerization heat treatment used: no treatment, nt; conventional hairdryer 2200 W at a distance of 20 cm at a temperature of 60°C for 1 minute, hd1; microwave at 750 W for 1 minute, mw1; water bath at 60ºC for 1 minute, wb1; water bath at 60ºC for 5 minutes, wb5. Specimens were stored in a dry environment at room temperature (20±2ºC) until testing. Three-point bending test was performed at 30 minutes after initiating the mixing process. Additionally, a positive control group was made for each material in which the specimens were not submitted to any type of post-polymerization heat treatment and were tested at 24 hours after the beginning of the mix (S3-nt-24 and P4-nt-24). Data was submitted to ANOVA (α = 0,05). Results: All post-polymerization treatments significantly (P<0.001) increased the FS compared to the untreated group measured at 30 minutes for the two resins. The S3-wb5 group had statistically similar values (P> 0.05) to S3-nt-24. P4-hd1, P4-mw1 and P4-wb5 did not show significant differences (P >0.05) compared to P4-nt-24. Conclusion: Post-polymerization heat treatments increased FS of the two resins tested. It is possible to obtain FS values at 30 minutes similar to those obtained at 24 hours with specific treatments.
Descrição
Tese de mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2018
Palavras-chave
Saúde oral Resinas compostas Polimerização Teses de mestrado - 2018