Methods:Sixty heat cured acrylic resin specimens were prepared according to ISO1567 and divided into six groups ; positive control (group 1), negative control (group 2) and four experimental groups. Group 2 and all experimental groups were cut in the middle and beveled 45 degree. Group 2 was not treated. Groups 3 and 4 were treated with methyl methacrylate (liquid part of Unifast trad®) for 5 and 180 seconds respectively. Groups 5 and 6 were treated with methyl acetate and methyl formate respectively for 15 seconds. Then repaired with auto-polymerized acrylic resin. A three-point loading test was performed by using Universal testing machine (Instron Corp, USA). One-way ANOVA and post hoc Tukey's analysis at p< 0.05 were used for statistical comparison. Failure analysis was also recorded as adhesive or cohesive failure for each specimen.
Results:The flexural strength of Groups 1 and 3 to 6 were significantly greater than that of the Group 2 (p<0.05) and the flexural strength of Groups 5 and 6 were significantly greater than that of the Group 3 (p<0.05). All fractured specimens in Groups 5 and 6 showed only cohesive failure.
Conclusions:From this study, treating surface with methyl acetate and methyl formate showed high flexural strength and used less time when repairing denture base resin.