Objective: Polyamide, commonly referred to as flexible resin, has been introduced into dentures since 1950 as an alternative to polymethyl methacrylate (PMMA) resins for the fabrication of prosthetic bases. Several studies have been conducted to compare the different properties of these two materials. However, most of these studies were laboratory “in vitro” studies. The aim of this work was to compare the properties and clinical behaviour of flexible resin prosthetic bases with those of conventional resin “in vivo”, once placed into the mouth, through a systematic review of the literature.
Material and methods: The search was performed on MEDLINE via the PubMed consultation interface, using the following Boolean equation: ((“Flexible denture” [Mesh]) OR (“Polyamide denture” [Mesh])) AND (“Acrylic denture” [Mesh]). This search was supplemented by a manual search on “Google Scholars”.
Results: Based on previously established inclusion and non-inclusion criteria, 23 clinical studies involving a total of 713 patients were selected (10 randomised control trials, 7 non-randomised controlled clinical trials and 6 cross-sectional studies). In 15 of the 23 included studies, the flexible prosthesis showed an advantage over the conventional prosthesis in almost all parameters evaluated and for the different types of edentulism.
Conclusion: Polyamide prostheses are therefore an excellent alternative to conventional methyl methacrylate prostheses as they provide more comfort, aesthetics and overall patient satisfaction. Nevertheless, based on the mechanical properties of polyamide, the indication of this material for large partial or total edentulism is still limited.