Does the bonded cross-sectional surface area affect the microtensile bond strength of resin cement to glass-ceramic?
OBJECTIVE
The aim of this study was to evaluate the effect of the bonded cross-sectional area on the bond strength of a resin cement to a glass ceramic. The hypothesis tested was that the decreased bonded surface area results in increased bond strength.


METHODS
Twelve glass-ceramic blocks (6x6 x4 mm) (Vita VM7) were conditioned with 10% hydrofluoric acid for 1 min, washed and rinsed thoroughly and silanized. The resin cement was applied on the treated-surface and the cement-ceramic sets were sectioned to produce specimens with the bonded areas of about 0.7x0.7 mm (0.5 mm(2)-Gr1), 1x1 mm (1 mm(2)-Gr2), 1.4x1.4 mm (2 mm(2)-Gr3), which were submitted to the microtensile test.


RESULTS
The results were affected significantly by bonded surface area (P<0.0001) with the highest mean value (MPa) obtained from Gr1 (26.3+/-8.2a), followed by Gr2 (20.8+/-6.5b) and Gr3 (16.1+/-5.7c) (ANOVA and Tukey's test, alpha=0.05). A negative correlation was found between the bonded surface area and the bond strength results (r=-0.5234; P<0.0001) (Pearson correlation test). Pre-test failures were more common when the bonded surface area was 0.5 mm(2).


CONCLUSIONS
With the increased bonded surface area, the mean microtensile bond strength of the resin cement to the feldspathic ceramic decreased.
Valandro
L F
LF
Division of Prosthodontics, Department of Restorative Dentistry, Federal University of Santa Maria, School of Dentistry, Santa Maria, Brazil. lfvalandro@hotmail.com
Ozcan
M
M
Amaral
R
R
Passos
S P
SP
Bottino
M A
MA
D002516:Ceramics; D003764:Dental Materials; D008422:Materials Testing; D019279:Resin Cements; D013499:Surface Properties; D013718:Tensile Strength
D003764:Dental Materials; D019279:Resin Cements; C023506:Glass ceramics