Effect of photo-polymerization mode on the degree of conversion of resin cement under different ceramic materials.

Background: This study evaluated the effect of different polymerization modes and duration on the degree of conversion (DC) of resin cement under different types of ceramics.

Methods: Ceramic materials were divided into 3 groups (N.=60): group 1, Cerasmart; group 2, Vita Enamic; and group 3, Vita Mark II. Each group was then divided into three subgroups (N.=20) according to the polymerization mode (A: low-intensity; B: high-intensity; and C: soft-start). Subgroups were then divided into two further groups according to the polymerization time (I: 10 s; and II: 20 s). DC of light-cured resin cement beneath different kinds of ceramics was tested using FTIR spectroscopy. Results were compared to a control group cured without overlying ceramic.

Results: While the type of ceramic and mode of polymerization showed a significant effect on the DC of resin cement, polymerization duration did not. Vita Mark II group showed the highest DC of resin cement followed by Vita Enamic and Cerasmart. High- and low-intensity polymerization modes did not show significant difference, but both showed significantly lower DC when compared to soft start mode.

Conclusions: Type of ceramic and polymerization mode showed a direct effect on the DC of resin cement.