2008 Volume 7 Issue 1 Pages 19-23
Purpose: The brush-on technique has frequently been used when dentures are repaired with autopolymerized acrylic resins. This study evaluated the fluidity and hardening time of autopolymerized acrylic resin applied using this technique.
Methods: Five autopolymerized acrylic resins were tested: Unifast II (GC, Japan), Unifast Trad (GC), Provinice (Shofu, Japan), Metafast (SunMedical, Japan), and Miky (Nissin, Japan). Using both the brush-on and the conventional (L/P: 0.5 ml/g) mixing techniques, all slurry resins were applied on the platform of a rheometer (Seiki, Japan). Fluidity was measured until hardening occurred at room temperature (23±1°C, humidity: 40-50%). To measure the hardening time, the five resins were also poured into silicone tubes (8 mm internal diam., 5 mm long) using the brush-on and the conventional techniques. A thermocouple was placed in the center of each tube to measure the temperature. Hardening time was assessed as the time when the temperature reached the maximum. The data (n=5) were analyzed by ANOVA/Tukey’s test (α=0.05).
Results: Similar fluidity was found for the brush-on and conventional mixing techniques although the onset of hardening was different. Excluding Provinice, there were significant differences in hardening time between both techniques (P<0.05). The hardening time of Metafast was the significantly longest among the resins tested (P<0.05).
Conclusion: The hardening time for the brush-on technique was shorter than for the conventional mixing technique. Because there were great differences in the hardening time of the autopolymerized acrylic resins tested, attention should be paid to handling time during denture repair.
