EVALUATION OF THE EFFECTS OF POST-POLYMERIZATION HEAT TREATMENT ON THE MECHANICAL AND OPTICAL PROPERTIES OF RESTORATIVE COMPOSITES

• DOI: https://doi.org/10.22533/at.ed.159562515015

• Palavras-chave: resin composites; flexural strength; modulus of elasticity; color; contrast ratio; heat treatment.

• Keywords: resin composites; flexural strength; modulus of elasticity; color; contrast ratio; heat treatment.

• Abstract:

  Objective: To evaluate the flexural strength (FR), modulus of elasticity (ME), color difference (∆ E) and Contrast Ratio (CR) of composites subjected to heat treatment (TT) after polymerization and the effect of storage in dyes (distilled water, soda and wine). Methodology: Rectangular specimens 10mm X 2mm X 1mm were made for the analysis of RF and ME and disks of 2mm height X 8mm diameter for the study of∆ E and RC using 2 composites (nano-particulate and hybrid). All CPs (n=76) were subjected to 170ºc heat treatment for 10 or 30 minutes in an oven, except for the TT control groups (n=38). The CIELAB system was used to evaluate∆ E and the reflectance of the sample on a black background (Yb) and the reflectance of the same sample on a white background (Yw) were used to determine the RC of the materials, where RC = Yb/Yw. The three-point bending test was used to analyze RF and ME. The data obtained was submitted to the Shapiro-Wilk, Levene and Tukey tests (α =0.05). Results: The 30-minute TT showed lower∆ E and RC compared to the 10-minute TT and control groups. The wine dye showed greater staining potential compared to water and soda. In the nano-particulated composite both TTs showed higher RF and ME values after the TTs compared to the control group and in the hybrid composite there was no statistical difference between the means observed in the control group and the groups with TTs. Conclusion: TT in 30 minutes proved to be effective for color stability and contrast ratio, as well as improving RF and ME properties in nano-particulated composites.