Ricardo Huver de Jesus; Kalenna Soriano Lage; Valéria Chiabai Dalboni; Ornella Luisa Delboni; Jefferson David Melo de Matos; Leonardo Jiro Nomura Nakano; Laura Patricia Nadal Ortiz; John Eversong Lucena de Vasconcelos; Marco Antonio Bottino & Lucas Campagnaro Maciel

*Summary*

To evaluate Knoop microhardness and diametral compression strength at different polymerization times. A total of 80 cylindrical samples with Filtek resin™ One Bulk Fill were made to perform the in vitro study, using half of total samples (n=40) for each test and divided equally between groups (n=10). All samples were made according to ISO 4049 using 2 mm thickness Teflon matrix and a central orifice with 4 mm diameter. Four different times of light-curing in Standard mode suggested by the light-unit manufacturer were selected, therefore, group 1 samples (G1) were light-cured for 5 seconds; group 2 (G2) for 10 seconds; group 3 (G3) for 15 seconds, and group 4 (G4) for 20 seconds. A radiant display, which means a power in mW/cm2 by time in seconds was expressed in Joules (J). The samples were stored in a dark container with distilled water at a temperature of 37°C for 48 hours before testing. One-way analysis of variance (ANOVA) with T-Test (LSD) of multiple comparisons of the mean values of Knoop hardness and diametral compression strength was performed, with significance index α=0.05. Regarding the Knoop microhardness test, G1 (35.73 ± 6.2) presented the lowest values, followed by G2, while G3 and G4 did not present statistical differences between them. For the diametral compression test, G1 (1387.76 ± 190.51) obtained the lowest value when compared to the other groups. G2, G3, and G4 did not present significant statistical differences. The different polymerization times influenced the Knoop microhardness and the diametral compression strength of Bulk Fill resin.

**KEY WORDS:** composite resins; hardness; stress, mechanical; physical properties.

*How to cite this article*

DE JESUS, R. H.; LAGE, K. S.; DALBONI, V. C.; DELBONI, O. L.; MATOS, J. D. M.; NAKANO, L. J. N.; ORTIZ, L. P. N.; VASCONCELOS, L, J. E.; BOTTINO, M. A. & MACIEL, L. C. Microhardness and diametral compression strength of single fill composite. Int. J. Odontostomat., 15(1):293-299, 2021.