Shrinkage and Dimensional stability in Self-curing acrylic resin

Objectives: Quick self-curing acrylic resin is used as a fixative in implant restorations. Fixative shrinkage is an important factor affecting the dimensional accuracy of the superstructure. However, there were no optimal materials for fixation, so we developed a new resin. In this study, we evaluated the shrinkage (curing after 30 min) and dimensional stability (after 3 days) of the new resin and commercially available products.

Methods: Four quick self-curing acrylic resins [New resin FIXPEED (FX, GC Corporation), Pattern resin (PR, GC Corporation), Pi-Ku-Plast (PKP, Breadent), and Duralay2 (DL, Reliance Dental)] were evaluated. The mixture (powder/liquid ratio; 2 g/1 mL) was filled to the V-block. Two markers were placed on the mixture at approximately 40-45 mm. The length between the two markers was measured by digital comparator STM5 (Olympus Co., Ltd.). 1.5 min after the commencement of the mixing, the initial length l₀ between the two markers was measured. After 30 min and 3 days, the length was measured again. All data were analyzed by one-way ANOVA and Tukey's test.

Results: Shrinkage after 30 min of FX was equal to PR, earning it recognition as a low-shrinkage resin. Further, FX showed significantly low shrinkage compared with other products [PKP (p < 0.01) and DL (p < 0.05)]. In addition, FX showed no significant differences in shrinkage ratio (after 30 min and 3 days). However, PR showed a significant difference (p < 0.05).

Mean values of shrinkage ratios, including standard deviations, are in the Table below (tests per material; n = 3).

Conclusion: It was concluded that FIXPEED has improved dimensional stability and other properties for fixation in comparison with commercially available products.