Optical properties and surface roughness of prepolymerized poly(methyl methacrylate) denture base materials

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Prosthodontics

Background:

• Limited data exists on the color stability, translucency, and surface roughness of novel computer-assisted design/computer-assisted manufacturing (CAD-CAM) prepolymerized poly(methyl methacrylate) (PMMA) denture base materials.
• Understanding these properties is crucial for evaluating the clinical performance and longevity of CAD-CAM PMMA restorations.

Purpose of the Study:

• To assess the color stability, relative translucency, and surface roughness of conventional and various prepolymerized CAD-CAM PMMA denture base materials.
• To investigate the effects of simulated coffee thermocycling (CTC) on these properties.

Main Methods:

• Six disk-shaped specimens of three CAD-CAM PMMA brands and one conventional PMMA were prepared and polished.
• Specimens underwent 5000 cycles of coffee thermocycling.
• Surface roughness (Ra) and color stability (CIEDE2000) were measured before and after CTC using a contact profilometer and spectroradiometer, respectively. Relative translucency parameter (RTP) was also calculated.

Main Results:

• Coffee thermocycling (CTC) did not significantly alter the color of any tested PMMA materials.
• A significant interaction between material type and CTC was observed for relative translucency (P=.011).
• CTC increased surface roughness (P=.031) for all materials, but values remained below the 0.2 μm plaque accumulation threshold.

Conclusions:

• All tested PMMA denture base materials exhibited clinically imperceptible color changes after 5000 CTC.
• One CAD-CAM material demonstrated significantly lower relative translucency compared to others, both before and after CTC.
• The surface roughness of all evaluated denture base materials remained below the threshold for plaque accumulation.