Color Stability, Surface Roughness, and Water Absorption of Different CAD/CAM Denture Tooth Materials.

Abstract

Introduction: The design and fabrication of dental prostheses, especially dentures, have been transformed by digital dentistry innovations and advanced technology. However, lifestyle habits of drinking stainable beverages as well as denture care and maintenance continue to impact the color stability and surface roughness of denture base and tooth resin materials. Despite improvements in denture tooth resin materials, discoloration remains a challenge, especially in long-term interim restorations and removable prostheses. This would lead to decreased esthetic properties, increased maintenance, costs, and consequently patient dissatisfaction. Limited data about this in the literature. Therefore, further investigation into the effects of thermocycling, staining liquids, and cleaning on denture tooth resin materials is necessary to improve long-term performance and clinical outcomes. Objective: The aim of this in vitro study was to assess the effects of thermocycling, staining agents, and denture cleaning tablets on the color stability and surface roughness of various CAD/CAM denture tooth resin materials, compared to conventional polymethyl methacrylate (PMMA). Materials & Methods: A total of 600 discs (5 mm thick and 10 mm in diameter) were fabricated from five different resin materials: a conventional resin (Jet), two types of milled resin materials (Ivotion Dent and Candulor “TCR-Mono”), and two types of 3D printed materials (Flexcera “Smile Ultra Smile Plus, and Straumann “Tooth X”); 120 discs for each material. The specimens were ground and polished using a Buehler Automet 250, to get the final thickness 4 ± 0.2 mm. Each material group will be further divided into three subgroups (200 discs per subgroup, 40 discs of each material,): 1. Staining; 2. Thermocycling (TC), followed by staining; 3. Staining, followed by a tablet cleaning process was performed per material. Staining liquids used: deionized water, orange juice, coffee, and red wine. Color stability was assessed by measuring the color difference (ΔE00) before and after staining and again after cleaning for subgroup 1 and 3, and after TC and staining for subgroup 2, using a color spectroradiometer. Surface roughness (Ra) was also assessed before and after each testing by noncontact profilometry using the Dragonfly Confocal Microscope. ΔE00 values were calculated to quantify color changes. Statistical analysis was performed using one-way ANOVA and Tukey post-hoc tests (α=0.05) for the color study. Results: The significant difference in ΔE00 and Ra was detected among different materials and under different treatment. The cleaning effectively processes reduced ΔE00. No significant difference was found in water absorption for each material before and after TC. Conclusions: The material type and staining type appear to have at least individual effects on the color stability and surface roughness of polymer resin teeth materials.