Flexural strength and surface roughness of four composite resins

Abstract

This study compared the flexural strength and the surface roughness of four composite resins (MF- Master FillTM; CT- ConceptTM, FM- Fill MagicTM and Filtek Z250TM), testing the null hypothesis that these materials have similar properties. Twenty specimens of each material were obtained according to the manufacturer’s instructions and the ISO 4049. Ten specimens (stick shaped - 24x2x2 mm3) were submitted to the three-point bending test (s) and ten specimens (disc shaped – 7 mm x 2 mm) were submitted to a surface roughness evaluation, and the mean roughness (Ra) was recorded. The stick specimens were loaded to fracture in a universal testing machine (EMIC 2000TM) with crosshead speed of 1 mm/min. The Ra was evaluated using a profilometer (Surfcoder SE 1200TM). Data were statistically analyzed, using ANOVA and Turkey test. The mean and standard deviations values of s (MPa) and Ra (μm) were respectively: Z250 – 119,9 ± 14,9 and 0,138 ± 0,042; MF – 80,4 ± 13,7 and 0,296 ± 0,096; CT – 80,3 ± 9,4 and 0,212 ± 0,043; FM – 97,3 ± 19,3 and 0,229 ± 0,057. Z250 showed the greatest mean s of all groups (p < 0.05), which were not statistically different between each other. In relation to Ra, Z250 also showed the best results, follo wed by CT and FM, that didn not show differences between them, and MF that showed the greatest mean Ra value. The micro-hybrid composite Z250 produced mean s and Ra values statistically better than the other materials tested. Key words: Composite resin. Flexural strength. Surface roughness.