Gülce Alp1, William M Johnston2, Burak Yilmaz3. 1. Former Visiting Professor, Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, Ohio; Assistant Professor, Department of Prosthodontics, Okan University Faculty of Dentistry, Istanbul, Turkey. Electronic address: gulce165@hotmail.com. 2. Professor Emeritus, Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, Ohio. 3. Associate Professor, Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, Ohio.
Abstract
STATEMENT OF PROBLEM: Studies of the color stability, relative translucency, and surface roughness of newly introduced computer-assisted design and computer-assisted manufacturing (CAD-CAM) prepolymerized poly(methyl methacrylate) (PMMA) denture base materials are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the color stability, relative translucency, and surface roughness of conventional and different prepolymerized CAD-CAM PMMA denture base materials after coffee thermocycling (CTC). MATERIAL AND METHODS: Six disk-shaped specimens (10×2 mm) were prepared from 3 different brands of prepolymerized CAD-CAM PMMA and a conventional heat-polymerized PMMA denture base material (N=24). Specimens were polished conventionally in 2 stages. The specimens were subjected to 5000 coffee thermocycles. The surface roughness (Ra) of each specimen was measured 3 times before and after CTC, using a contact profilometer, and the mean roughness (Ra) values were calculated. The color coordinates of the specimens were determined by using a noncontact spectroradiometer, and color differences and relative translucency parameter (RTP) values were calculated by using CIEDE2000 color difference and RTPCIEDE2000 formulas. ANOVA was used to analyze surface roughness values, CIEDE2000 color differences, and RTP values (α=.05). RESULTS: CTC did not change the color of the tested materials. However, with regard to relative translucency, 2-way ANOVA revealed a significant interaction between the material and CTC (P=.011). Also, although CTC increased the surface roughness of all tested materials (P=.031), Ra values were lower than the plaque accumulation threshold of Ra=0.2 μm. CONCLUSIONS: Mean color changes in all materials were clinically imperceptible after 5000 coffee thermocycles. One tested material had significantly lower relative translucency than other materials before and after CTC. The surface roughness values of all tested denture base materials were below the plaque accumulation threshold.
STATEMENT OF PROBLEM: Studies of the color stability, relative translucency, and surface roughness of newly introduced computer-assisted design and computer-assisted manufacturing (CAD-CAM) prepolymerized poly(methyl methacrylate) (PMMA) denture base materials are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the color stability, relative translucency, and surface roughness of conventional and different prepolymerized CAD-CAM PMMA denture base materials after coffee thermocycling (CTC). MATERIAL AND METHODS: Six disk-shaped specimens (10×2 mm) were prepared from 3 different brands of prepolymerized CAD-CAM PMMA and a conventional heat-polymerized PMMA denture base material (N=24). Specimens were polished conventionally in 2 stages. The specimens were subjected to 5000 coffee thermocycles. The surface roughness (Ra) of each specimen was measured 3 times before and after CTC, using a contact profilometer, and the mean roughness (Ra) values were calculated. The color coordinates of the specimens were determined by using a noncontact spectroradiometer, and color differences and relative translucency parameter (RTP) values were calculated by using CIEDE2000 color difference and RTPCIEDE2000 formulas. ANOVA was used to analyze surface roughness values, CIEDE2000 color differences, and RTP values (α=.05). RESULTS: CTC did not change the color of the tested materials. However, with regard to relative translucency, 2-way ANOVA revealed a significant interaction between the material and CTC (P=.011). Also, although CTC increased the surface roughness of all tested materials (P=.031), Ra values were lower than the plaque accumulation threshold of Ra=0.2 μm. CONCLUSIONS: Mean color changes in all materials were clinically imperceptible after 5000 coffee thermocycles. One tested material had significantly lower relative translucency than other materials before and after CTC. The surface roughness values of all tested denture base materials were below the plaque accumulation threshold.
Authors: Amália Moreno; Daniela Micheline Dos Santos; Clóvis Lamartine de Moraes Melo Neto; André Luiz de Melo Moreno; André Pinheiro de Magalhães Bertoz; Marcelo Coelho Goiato Journal: PLoS One Date: 2020-10-12 Impact factor: 3.240