A Pilot Study to Predict Lifetime of Resin-Based Materials for Denture: Presentation of an In Vitro Thermally-Accelerated Ageing Method.

Purpose: The aim of this article was to present a method for predicting dental materials lifetime, using in vitro thermally accelerated ageing. The technique was tested to compare the behavior of 3 resin base materials for denture.

Materials and methods: Bar-shaped samples of the poly(methyl methacrylate) PMMA based-resin Probase Hot (Probase), CAD/CAM disc Ivobase CAD (IvoCAD) and high-impact resin IvoCAP were aged in artificial saliva for 15, 30, 45, 60, 90, 120 and 180 days at 55°C, 75°C and 90°C. Flexural strength and surface roughness of the 3 resins for each ageing duration and temperature were measured for 3 samples (n=189). Using the time-temperature equivalence principle and the Arrhenius model, a master curve was constructed, the activation energy of the simulated ageing process was calculated and the lifetime of each material was estimated, based on degradation of flexural strength value over time.

Results: The mean initial flexural strength was 87.98 ± 7.37, 79.35 ± 10.01 and 97.31 ± 4.97 MPa for IvoCAD, IvoCAP and Probase, respectively. Activation energies of the ageing in artificial saliva were measured at 81.9, 82.6 and 66.2 kJ/mol, respectively, and average lifetimes at 37°C were estimated at 19.5, 14.4 and 9.2 years.

Conclusion: In this first approach to estimating the in vitro lifetime in artificial saliva of resin-based materials for dentures, the three materials met the expected criteria, validating the estimation method. Therefore, thermally-accelerated ageing and the Arrhenius model could be an interesting tool to add to routine tests used to validate new polymer materials and manufacturing processes.