Compressive strength and the effect of duration after photo-activation among dual-cure bulk fill composite core materials

Objectives: to assess compressive strength and effect of duration after photoactivation on the compressive strength of different dual cure bulk fill composites. methods: seventy-two disc shaped (4x10mm) specimens were prepared from three dual cure bulk fill materials,zirconcore (zc) (n=24),multiccore flow (mc) (n=24) and luxacore dual (lc) (n=24). half of the specimens in each material were tested for failure loads after one hour [mc1 (n=12),lc1 (n=12) & zc1 (n=12)] and the other half in 7 days [mc7 (n=12),lc7 (n=12),zc7 (n=12)] from photo-polymerization using the universal testing machine at a cross-head speed of 0.5 cm/minutes. compressive strength was calculated using the formula ucs=4f/πd2. compressive strengths among different groups were compared using analysis of variance (anova) and tukey’s multiple comparisons test. results: maximum and minimum compressive strengths were observed in zc7 (344.14±19.22) and lc1 (202.80±15.52) groups. specimens in lc1 [202.80 (15.52)] showed significantly lower compressive strength as compared to mc1 [287.06 (15.03)] (p<0.01) and zc1 [276.82 (11.51)] (p<0.01). zc7 [344.14 (19.22)] specimens showed significantly higher (p<0.01) compressive strengths compared to lc7 [324.56 (19.47)] and mc7 [315.26 (12.36)]. compressive strengths among all three materials were significantly higher (p<0.01) at 7 days as compared to one hour. conclusions: bulk fill material with zr nano-hybrid filler (zc) showed high compressive strength compared to mc and lc. increasing the post photo-activation duration (from one hour to 7 days) significantly improves the compressive strengths of dual cure bulk fill material. © 2016,professional medical publications. all rights reserved.