Impact of refrigeration on the surface hardness of hybrid and microfilled composite resins

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This in vitro study evaluated the Knoop hardness of the composite resins Charisma® (C) and Durafll VS® (D) polymerized in 3 different conditions: at room temperature (A) (23 ± 1°C); refrigerated at 4 ± 1°C and immediately photo-activated after removal from the refrigerator (0); and, refrigerated at 4 ± 1°C and photo-activated after a bench time of 15 min at room temperature (15). One hundred and twenty specimens (4 mm diameter and 2 mm depth) were made using a stainless steel mold and following manufacturer's instructions. All specimens were tested immediately after polymerization (I) and after 7 days of water storage in the dark at room temperature (7d). The data were subjected to ANOVA and post-hoc Tukey's test (a=0.05). On the top surface, CAI was statistically similar to C15I and DAI to D15I (p>0.05). On the bottom surface, CAI presented higher hardness values when compared to C0I and C15I (p<0.05). The D groups showed no signifcant differences (p>0.05) on the bottom surfaces for any tested polymerization condition. After 7 days of storage, the Knoop hardness decreased signifcantly (p<0.05) for groups C7d and D7d except for C07d, which was not different from C0I at either surface (p>0.05). D07d showed higher Knoop hardness (p<0.05) values on the top surface when compared to the other groups.

Original languageEnglish (US)
Pages (from-to)42-47
Number of pages6
JournalBrazilian dental journal
Issue number1
StatePublished - Dec 1 2009

Cite this

Osternack, F. H. R., Caldas, D. B. D. M., Rached, R. N., Vieira, S., Platt, J. A., & de Almeida, J. B. (2009). Impact of refrigeration on the surface hardness of hybrid and microfilled composite resins. Brazilian dental journal, 20(1), 42-47.