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

Fernando Henrique Ruppel Osternack, Danilo Biazzetto de Menezes Caldas, Rodrigo Nunes Rached, Sérgio Vieira, Jeffrey A. Platt, Janaina Bertoncelo de Almeida

Research output: Contribution to journalArticle

5 Scopus citations


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 - 2009


  • Knoop hardness
  • Refrigeration
  • Resin composite

ASJC Scopus subject areas

  • Dentistry(all)

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