Mechanical and physical properties of resin-cements polymerized with different methods

Methods: A total of 480 disc-shaped samples (1 mm height and 5 mm diameter) were prepared from different dual-polymerizing resin cements (Duolink, Nexus, Bifix-QM, Panavia F, RelyX Unicem). Photoactivation was performed by using quartz tungsten halogen (high-power and soft-up modes), light emitting diode (standard and exponential modes) and plasma arc (normal and ramp-curing modes) through ceramic discs. Then the samples (n = 8/per group) were stored dry in dark at 37°C for 24 h. For sorption and solubility tests; the samples were stored in a desiccator at 37ºC and weighted to a constant mass. The samples were weighed both before and after being immersed in deionized water for different periods of time (24 h and 7 days) and being desiccated. The diametral tensile strength of the samples were tested in a universal testing machine with a crosshead speed of 0.5 mm/min. Data were statistically analyzed using nonparametric Kruskal Wallis and Mann-Whitney U tests.

Results: Statistical analysis revealed that resin cement and light polymerizing unit had significant effects on diametral tensile strength, water solubility and sorption (p < 0.05). However, no significant differences were obtained with different modes of light polymerizing units (p > 0.05).

Conclusion: Polymerization of resin cements with different light polymerizing units may result in various polymer structures, and consequently different mechanical and physical properties.