The Effect of Aging by Storage on the Flexural Strength of Self-cured and Dual-cured Bis-acryl Resins used as Provisional Restoration Materials in Fixed Prosthodontics

Abstract

Background. Provisional restorative materials require good mechanical properties, such as sufficient flexural strength, to remain functional within the oral cavity. Developments in provisional materials have resulted in the production of bis-acryl resins with varying curing methods. However, their performance in a moist environment remains uncertain.

Objective. This in-vitro study aimed to assess the effect of aging by storage on the flexural strength of self-cured and dual-cured bis-acryl resin materials. 

Methods. Self-cured (Protemp 4) and dual-cured (Care C&B) bis-acryl resins were used in this study. A total of 40 bar-shaped specimens were fabricated and stored in distilled water at 37 ± 1°C. The control group was stored for 1 day (24 hours) while the treatment group was stored for 7 days prior to testing. Flexural strength was determined through a Three-Point Bending Test using a universal testing machine. Paired t-test was used to compare the mean flexural strengths of the bis-acryl resins after 1 day and after 7 days of storage. Independent T-test was used to compare the mean flexural strengths of the self-cured and the dual-cured bis-acryl resin materials within the same storage period.

Results. The results showed that after 7 days of aging by storage in distilled water at 37 ± 1°C, both self-cured and dual-cured bis-acryl resin materials exhibited a statistically significant decline in mean flexural strength (p <0.05). Within the same storage period, the difference in mean flexural strengths of the two materials was not statistically significant (p >0.05).

Conclusion. Within the limitations of the study, it was found that aging by storage significantly decreased the mean flexural strength of the self-cured (Protemp 4) and dual-cured (Care C&B) bis-acryl resin materials. Future studies simulating actual intraoral conditions are recommended.