Color Stability Determination of CAD/CAM Milled and 3D Printed Acrylic Resins for Denture Bases: A Narrative Review

Abstract

The aim of this paper is to review the available literature on the different methods for color stability determination of CAD/CAM milled and 3D printed resins for denture bases. The methodology included applying a search strategy, defining inclusion and exclusion criteria and selecting studies to summarize the results. Searches of PubMed, Scopus, and Embase databases were performed independently by three reviewers to gather the literature published between 1998 and 2022. A total of 186 titles were obtained from the electronic database, and the application of exclusion criteria resulted in the identification of 66 articles pertaining to the different methods for color stability determination of CAD/CAM acrylic resins for denture bases. Color change in dental materials is clinically very important for the dental operator, as it determines the clinical serviceability of the material. Discoloration of the denture bases can be evaluated with various instruments and methods. Dental resins may undergo color changes over time due to intrinsic and/or extrinsic factors. The extrinsic factors are considered the more frequent causes of color changes. According to a number of studies, CAD/CAM fabricated acrylics have achieved better color stability than the conventional PMMA (polymethyl methacrylate) resins.

The Toothbrushing Effects on Surface Properties and Color Stability of CAD/CAM and Pressable Ceramic Fixed Restorations—An In Vitro Study

“…These findings coincide with Yuan et al, who found no significant color changes between CAD/CAM lithium disilicate ceramics after simulated toothbrushing [19]. Additionally, Garza et al found that no significant difference was detected for shade change over time, irrespective of the technique for the lithium disilicate fabrication [53].…”

“…The current study aimed to assess the impact of toothbrushing simulation on different CAD/CAM and pressable lithium disilicate ceramics in terms of surface roughness, microhardness, and color change. Based on our findings, the Emax CAD, Emax Press, and LiSi Press groups showed a decrease in the surface roughness (Ra) after an equivalent of 1 year of toothbrushing; however, the decrease was insignificant, which may be explained by their excellent physicomechanical stability [19,30]. Additionally, no significant difference in Ra values was observed among the groups after mechanical toothbrushing (p value = 0.842).…”

“…The protocol of toothbrushing was performed by subjecting the specimens to an electric toothbrushing simulation unit (model ZM-3.8, SD Mechatronik, Feldkirchen-Westerham, Germany) for 10,000 cycles, which is equivalent to 1 year of clinical toothbrushing simulation [14,19]. Brush type (Oral-B PRO 1000, Leicester, UK) and Colgate toothpaste slurry solution (250 g with 1 L of distilled water) were replaced after 5000 cycles [14].…”

Colour Stability of 3D-Printed and Prefabricated Denture Teeth after Immersion in Different Colouring Agents—An In Vitro Study

“…According to the research by Koksal and Dikbas, Brewer et al, lighter shades of teeth experience greater discolouration than darker shades [ 40 , 41 ]. Thus, the A2 shade of denture teeth was chosen for our study because it is one of the lightest shades available for the denture teeth brands [ 42 , 43 , 44 ].…”

Color Stability of Zinc Oxide Poly(methyl methacrylate) Nanocomposite—A New Biomaterial for Denture Bases

“…The range of factors influencing possible discoloration related to individual food preferences requires the conclusion that such indicators would be difficult to define; we consider this to be one of the limitations of the study. From our searches in the available literature, similar studies on color changes differed significantly in terms of the staining period and ranged from 7 to 180 days [41][42][43][44]. In our study, we wanted to show the trend between the duration of the coloring agent and the actual color change of ZnO NP-PMMA.…”