Use of polyethylene terephthalate as a prosthetic component in the prosthesis on an overdenture implant.

The aim of this study was to evaluate the physical-mechanical and morphological properties of polyethylene terephthalate (PET), for a new application as a prosthetic component for overdentures implant-retained, compared with different polymers. Were prepared 20 specimens for each material: Polyethylene terephthalate (PET), Polyacetal, Polytetrafluoroethylene (PTFE) and Polyethylene, for analysis of roughness and hardness surface, compressive strength and pull out test. For fatigue strength test, a total of 200 capsules (n = 40) were captured in pairs with acrylic resin and subjected to 2900 insertion/removal cycles, simulating 24 months of overdenture use. In this test, a group was added (o-ring Intra-Lock System) as a standard of comparison. The morphological and structural analysis were realized by stereomicroscopy, scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD). All specimens in this study were analyzed before and after thermocycling (5-55 °C, for 10,000 cycles). Two-way ANOVA with repeated measurements and Tukey test were used (α = 0.05). For roughness, difference was observed only between the materials, with lowest averages for Polyacetal and PET (p < 0.001). For the hardness there was no statistically significant difference between the materials (p > 0.001). For compressive strength, Polyacetal, followed by PET (p < 0.001) presented the highest values independent of thermocycling. In the pullout test, PET and polyacetal presented, the highest values (p = 0.033). In the fatigue test, for 24 months analysis, difference was observed before and after thermocycling for O-ring group (p = 0.010) and polyacetal (p = 0.002), PET also presented higher values of resistance in relation to the o-ring (p < 0.001). The thermocycling did not alter the polyethylene surface through SEM images as well as the structure of all the materials analyzed by FTIR and DRX. In this study, the PET presented results compatible with those expected, which suggests its application for making retention capsules for implant-retained overdentures.