Impact of refrigeration on the surface hardness of hybrid and microfilled composite resins.
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 degrees C); refrigerated at 4 +/- 1 degrees C and immediately photo-activated after removal from the refrigerator (0); and, refrigerated at 4 +/- 1 degrees 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 (alpha=0.05). On the top surface, C(AI) was statistically similar to C(15I) and D(AI) to D(15I) (p>0.05). On the bottom surface, C(AI) presented higher hardness values when compared to COI and C(15I) (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 C(7d) and D(7d) except for C(07d), which was not different from C(OI) at either surface (p>0.05). D(07d) showed higher Knoop hardness (p<0.05) values on the top surface when compared to the other groups.
Osternack
Fernando Henrique Ruppel
FH
Department of Restorative Dentistry, Pontifical Catholic University of Paraná, Curitiba 80215-901, PR, Brazil.
Caldas
Danilo Biazzetto de Menezes
DB
Rached
Rodrigo Nunes
RN
Vieira
Sérgio
S
Platt
Jeffrey A
JA
Almeida
Janaina Bertoncelo de
JB
D003188:Composite Resins / Q000737:chemistry*; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D012034:Refrigeration
C084111:Charisma composite resin; D003188:Composite Resins; C039734:Durafill