Resumo

SANTANA, Ivone Lima et al. Thermal behavior of direct resin composites: glass transition temperature and initial degradation analyses. Rev. odonto ciênc. (Online) [online]. 2011, vol.26, n.1, pp. 50-55. ISSN 1980-6523.

PURPOSE: The association of direct resin composites with simple thermal treatments may improve the mechanical properties of these materials. However, the ideal temperature for heat application depends on the thermal behavior of each material, such as glass transition (T_g) and initial degradation temperatures. To propose a heat treatment methodology, this study evaluated the thermal behavior of five commercial direct resin composites using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). METHODS: Photo-irradiation was achieved in cylindrical specimens (3×2 mm) using a photo-activator source (600 mW/cm² for 40 s). Thermal analyses were performed by DSC and TGA using a temperature range from 25 ºC to 900 ºC. RESULTS: T_g values obtained by DSC were 130.6 ºC for FillMagic, 129 ºC for Glacier, 143.5 ºC for Te-Econom, 147.5 ºC for Prisma APH and 143.7 ºC for Natural Look. A moderate weight loss began at around 270 ºC for all materials, which represented the initial degradation temperature. Conclusion: Regarding the heat treatment itself, it was concluded that the effective temperature for heat treatment is material dependent.

Palavras-chave : Dental composite; thermal treatment; DSC; TGA.