Influence of Chemical Aging on Antagonist Enamel Wear, Restorative Material Wear, and Surface Roughness of Zirconia and BioHPP: An In Vitro Study

Abstract Background The clinical performance of restorative materials depends on their resistance to wear and degradation within the oral environment. Zirconia ceramics are widely used because of their favorable mechanical properties and biocompatibility; however, concerns remain regarding their wear behavior against opposing enamel. BioHPP, a high-performance polyetheretherketone-based polymer, has emerged as a potential alternative restorative material, although evidence regarding its wear behavior following chemical aging remains limited. Objective To evaluate the effect of different aging media on antagonist enamel wear, restorative material wear, and surface roughness of translucent zirconia (TZ), opaque zirconia (OZ), and BioHPP. Materials and Methods Thirty-six disc specimens (n = 12 per material) were fabricated from TZ, OZ, and BioHPP and allocated to three aging conditions: distilled water, artificial saliva, and acidulated phosphate buffer (n = 4 per subgroup). Following 7 days of immersion and thermal aging at 55°C, wear testing was performed using a pin-on-disc tribometer under a 25 N load for 4,800 cycles. Pre- and post-test weights of enamel antagonists and restorative discs were recorded. Surface characteristics were evaluated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed using repeated-measures analysis of variance and post hoc testing at a significance level of 0.05. Results A significant reduction in antagonist enamel weight was observed following wear testing (p = 0.021), confirming measurable enamel wear. However, no significant differences in antagonist enamel wear were detected among restorative materials or aging conditions (p > 0.05). Restorative disc wear differed significantly among experimental groups (p < 0.001), with greater wear observed in specimens exposed to acidic conditions. AFM and SEM analyses demonstrated increased surface roughness and morphological alterations following acidic aging, particularly in translucent zirconia and BioHPP. Conclusions Under the short-term experimental conditions of this study, restorative material type and aging medium did not significantly influence antagonist enamel wear. However, chemical aging affected restorative material wear and surface characteristics, with acidic conditions promoting greater material degradation. Further long-term studies using clinically relevant aging protocols are required to validate these findings.