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

• Autor(a) principal: Osternack,Fernando Henrique Ruppel
• Data de Publicação: 2009
• Outros Autores: Caldas,Danilo Biazzetto de Menezes, Rached,Rodrigo Nunes, Vieira,Sérgio, Platt,Jeffrey A., Almeida,Janaina Bertoncelo de
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Dental Journal
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-64402009000100007
• topic: resin composite; refrigeration; Knoop hardness

This in vitro study evaluated the Knoop hardness of the composite resins Charisma® (C) and Durafill 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 COI and C15I (p<0.05). The D groups showed no significant differences (p>0.05) on the bottom surfaces for any tested polymerization condition. After 7 days of storage, the Knoop hardness decreased significantly (p<0.05) for groups C7d and D7d except for C07d, which was not different from COI 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.