Resumo

LANCELLOTTI, Ailla Carla et al. Evaluation of activation modes on flexural strength and elastic modulus of a restorative composite testing bars with different shapes. RFO UPF [online]. 2011, vol.16, n.2, pp. 172-176. ISSN 1413-4012.

Introduction and objective: the objective of this study was to evaluate the influence of two photo-activation modes on flexural strength and elastic modulus of a composite resin by using two shapes bars. Materials and methods: ten bars were fabricated according to ISO 4049/2000 specification (25 x 2 x 2 mm) with 20s photo-activation as a control (CO) and twenty experimental bars with 7 x 1 x 2 mm (length x high x width) were fabricated and divided into 2 groups: G1 - 20s with continuous mode photo-activation and G2 - pulse delay irradiation with 2s initial irradiation and 18s second irradiation after a five minutes delay. After 24h of storage in distilled water (37 oC) the flexural strength test was performed in a universal testing machine with a cross head speed of 0.5 mm/min. The flexural strength (MPa) and elastic modulus data (GPa) were calculated by using the software Blue Hill 2 and submitted to one way ANOVA and Tukey's test (5%). Results: CO showed the highest values of flexural strength (158.6 ± 10.6) and modulus (12.20 ± 0.25) compared to G1 (131.65 ± 21.2 and 9.28 ± 3.7) and G2 (131.1 ± 16.9 e 10.1 ± 4.4) that resulted in equivalent values for the two properties. Conclusion: It was possible to conclude that the bar, which was under the ISO's recommendations, showed the highest values of flexural strength and elastic modulus compared to experimental bars shape. The activation modes had no influence on the properties of the experimental bars.

Palavras-chave : Composite resin.; Flexural strength.; Dental materials..