Color stability and degree of conversion of a novel dibenzoyl germanium derivative containing photo-polymerized resin luting cement

Aim: To compare the color stability and degree of conversion (DC) of a resin cement containing a dibenzoyl germanium derivative photo-initiator (Variolink Esthetic) to resin cements containing conventional luting agents. Materials and Method: Spectrophotometry and Fourier transform infrared spectroscopy (FTIR) were used to compare the color stability and DC, respectively, of Variolink Esthetic compared to Calibra, Variolink-N, and NX3 resin cements. Ten specimens (1 x 2 mm(2)) of each resin cement were photo-polymerized and then subjected to color stability assessments. In addition, 30 samples of each of the four resin cements were prepared and then immersed in three staining solutions (tea, coffee, and distilled water) for two weeks. Changes in color for the immersed versus non-immersed specimens (control specimens) were determined by comparing Delta L(lightness),Delta a, and Delta b(color components), and an overall Delta E(color difference) obtained from spectrophotometry assays. One-way analysis of variance and a multiple comparison test (Tukey's test) were used to analyze color stability and DC data. NX3 and Variolink Esthetic resin cements exhibited significantly lower values compared to the dual cured resin cements (Variolink-N and Calibra). Results: The highest DC values were observed among the photo-polymerized samples of Variolink Esthetic (87.18 +/- 2.90%), while the lowest DC values were observed among the Variolink-N samples (44.55 +/- 4.33%). Conclusion: The resin cement, Variolink Esthetic, containing a novel dibenzoyl germanium derivative photo-initiator exhibited superior color stability (p< 0.05) and a higher DC than other resin cements containing conventional luting agents in an in vitro setting.