Effect of ultrasonic chemical cleaning solutions on different dental interim restoration material properties. Part I: Physical properties of color stability and surface roughness.

STATEMENT OF PROBLEM: Cleaning dental interim crowns between treatment visits using chemical agents may affect color stability and surface roughness. Studies investigating the reaction of different interim materials with different cleaning solutions are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of ultrasonic chemical cleaning solutions on the color stability and surface roughness of conventionally and computer-aided design and computer-aided manufacturing (CAD-CAM) fabricated dental interim materials. MATERIAL AND METHODS: A total of 192 interim restoration specimens were fabricated using the following materials and fabrication methods: conventional chemically activated polymethyl methacrylate (PMMA) n=48, bis-acrylic composite n=48, milled PMMA n=48, and 3-dimensional (3D) printed resin n=48. Each group was treated with 4 solutions (water n=12, general purpose cleaner n=12, calculus and stain cleaner n=12, and cement remover cleaner n=12). Each specimen was immersed in the assigned solution for 5 cycles of 10 minutes using an ultrasonic water bath. Color measurements and surface roughness were obtained for each specimen at baseline, after 2 cycles, and after 5 cycles using a spectrophotometer and optical profiler, respectively. A repeated measures linear mixed model analysis was performed to detect differences in color changes and surface roughness between different interim materials and different solutions after 2 and 5 cycles of ultrasonic cleaning (α=.05). RESULTS: Significant differences in color stability and surface roughness were observed across materials and cleaning solutions after 2 and 5 cycles of ultrasonic cleaning (P<.005). Printed resin specimens in general purpose cleaner and milled specimens in cement remover groups showed the most color instability after 2 and 5 cycles of cleaning, respectively. Surface roughness increased significantly in conventional PMMA bis-acryl resin groups that were soaked in cement remover. Cleaning printed resin in water led to smoother surfaces. CONCLUSIONS: Ultrasonic chemical cleaning solutions affect the physical properties of interim materials. Material-solution compatibility should be considered to avoid compromising restoration quality.