Influence of water sorption on mechanical properties of injection-molded thermoplastic denture base resins

Abstract

Objective. This study investigated the influence of water sorption on certain mechanical properties of injection-molded thermoplastic denture base resins. Materials and methods. Six thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate) and a polymethylmethacrylate (PMMA) conventional heat-polymerized denture-based polymer, selected as a control, were tested. Specimens of each denture base material were fabricated according to ISO 1567 specifications and were either dry or water-immersed for 30 days (n = 10). The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the denture base materials were calculated. Results. Water sorption significantly decreased the ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of one of the polyamides and the PMMAs. It also significantly increased the ultimate flexural strength of the polycarbonate. Conclusion. The mechanical properties of some injection-molded thermoplastic denture base resins changed after water sorption.

Key Words::

• injection-molded thermoplastic denture base resin
• polyamide
• polyethylene terephthalate copolymer
• polycarbonate
• water sorption

Acknowledgments

This study is part of the BioCity Turku Biomaterials Research Program (www.biomaterials.utu.fi).

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.