Clinical Evaluation of The Handling Properties of Photo-activated Composite Resin Pastes

The purpose of this investigation was to examine the relationship between measured values (rheological properties) of composite pastes, such as viscosity coefficient, peeling rate and external force (objective measurements), and a favorable property of such pastes discriminated by touch by dentists (subjective measurements). The rheological properties were examined using a balance beam plastometer. The subjective measurements were performed by eighteen young dentists and repeated four times. The subjective measurements related to four characteristics;hardness of paste (A), retention of shape (B), self-bonding properties (C) and release properties from an instrument for filling (D). There was a significant correlation between the log of the external force (log F) and the log of the peeling rate (logν) in all materials (r=0.950~0.997). A moderate correlation in all materials, except Degufill ultra, Heliomolar, Litefil IIA and Silux plus was also found between the log of the coefficient of viscosity (logη) and logν (r=0.870~0.995). The coefficient of correlation obtained from regression lines between the ratios of favorable properties (log PA, log PB and log PD) in the subjective test and log F or logηshowed a good approximation with a quadratic equation.