The Effects of Different Colors and Light Sources on the Bond Strength of Cerec Feldspathic Blocks Bonded to Light-Cured Resin Cement

Objectives: To evaluate the bonding with resin cement of different colored prefabricated feldspathic ceramic blocks used in the computer aided design and computer aided manufacturing (CAD-CAM) technique when different light sources were used beneath the ceramics.

Materials and Methods: Specimens of 2 mm thickness were prepared in nine different colors. All the groups were bonded to composite resin blocks using a light-cured resin cement beneath plasma arc (PAC, 2400 mW/cm²), light emitting diode (LED, 1600–1800 mW/cm²) and quartz tungsten halogen (QTH, 800–1200 mW/cm²) light sources. Following the cementation, all the specimens were kept in distilled water for 24 hours in closed cups before the shear test was performed. The data were analysed by means of a two-way analysis of variance (ANOVA) and the Tukey HSD test (p < 0.05).

Results: The highest light power was observed in the PAC groups, while the lowest light power was observed in the QTH groups, and the difference was found to be statistically significant (p<0.05). The highest bond strengths were obtained in the S2M and S2T color groups without the discrimination of the light source, and no statistically significant difference was found between these groups. The lowest bond strength was obtained in the S4O color group.

Conclusions: This in vitro study found that the bond strength of feldspathic ceramic restorations is directly related to the utilised light source and, further, that the bond strength decreases as the ceramic color becomes darker.