A method for assessing force/work parameters for stickiness of unset resin-composites

摘要

Objectives. To evaluate the stickiness of unset resin-composites, at different speeds and temperatures, in terms of maximum probe separation-force (F_(max)) and work-of-separation (W_s).Materials and methods. Eight commercial light-cured resin-composites were selected. Each material was placed in a cylindrical mold (if = 7 mm x 5 mm depth) held at 25 C or 37 C. The maximum force (F_(max), N) and work probe separation (W_s, N mm) were measured by using a texture analyzer to register force/displacement. A flat-ended stainless-steel probe (φ = 6 mm) was mechanically lowered onto and into the surface of the unset sample. When a 'trigger' compressive force of 0.05 N was registered, data-acquisition commenced. Descent continued until a compressive force of IN was reached, which was held constant for Is. Then the probe was moved vertically upward at constant speed. This was varied over the range 2, 4, 6 and 8mm/s. The tensile force produced on the probe by the sticky resin-composite was plotted against displacement and the maximum value was identified (F_(max))- W_s was obtained as the integrated area. Data was analyzed by multivariate ANOVA and multiple pair wise comparisons was done by using a Tukey post hoc test to establish homogenous subsets (at p = 0.05). Results. F_(max) and Ws were taken as potential measures of stickiness. They ranged from 0.47 to 3.68 N and from 0.11 to 2.84 N mm, respectively. Multivariate ANOVA showed a strong interaction of withdrawal speed, temperature and materials on both F_(max) and W_s (p < 0.001). Conclusion. F_(max) and W_s are useful parameters for characterizing the handling-stickiness of resin-composite materials, additional to previously reported stickiness-strain or 'peak-height'. The resin-composites investigated could be differentiated, mostly showing increases in F_(max) and W_s stickiness with increased temperature and probe-withdrawal speed.