Zirconia restorations are widely used in dentistry due to their high esthetic expectations and physical durability. However, zirconia’s opaque white color can compromise esthetics. Therefore, zirconia is often veneered with porcelain, but fractures may occur in the veneer layer. Monolithic zirconia restorations, which do not require porcelain veneering and offer higher translucency, have been developed to address this issue. Zirconia exists in three main crystal phases: monoclinic, tetragonal, and cubic. Metal oxides such as yttrium are added to stabilize the tetragonal phase at room temperature. 3Y-TZP contains 3 mol% yttrium and provides high mechanical strength but has poor optical properties. Recently, 4Y-PSZ and 5Y-PSZ ceramics, which offer better optical properties but lower mechanical strength, have been introduced. This review examines the factors affecting the color change in monolithic zirconia ceramics. These factors are categorized into six main groups: cement type and color, restoration thickness, substrate color, sintering, aging, and zirconia type. Cement type and color are crucial in determining the final shade, especially in thin restorations. Increased restoration thickness reduces the influence of the substrate color while the sintering temperature and process improve optical properties. These findings emphasize the importance of material selection and application processes in ensuring esthetic harmony in zirconia restorations. This review aims to bridge gaps in the literature by providing valuable insights that guide clinicians in selecting and applying zirconia materials to meet both esthetic and functional requirements in restorative dentistry.

The color stability of dental ceramics in the oral cavity is influenced by multiple factors, including the patient’s dietary habits and oral hygiene practices, which can affect the optical and surface properties of resin-containing dental restorative materials. The purpose of this study was to evaluate the effects of surface finishing procedures and simulated tooth-brushing on the surface roughness, surface gloss, and color stability of resin matrix ceramics before and after coffee immersion. Forty specimens were prepared from a resin matrix ceramic and divided into four experimental groups according to surface finishing procedures, coffee immersion, and simulated tooth-brushing. The surface roughness, surface gloss, and color stability of the tested material were measured, and the data were statistically analyzed at a significance level of p < 0.05. The surface finishing procedures, measurement times, and application sequences affected surface roughness, surface gloss, and color stability. The most significant color differences occurred after coffee immersion; however, tooth-brushing had a more significant effect on the surface roughness and surface gloss. Coffee caused perceivable and clinically unacceptable color differences in the resin matrix ceramics. Tooth-brushing had a positive impact on the tested parameters. This study presents a novel approach by integrating both chemical (coffee immersion) and mechanical (tooth-brushing simulation) degradation processes to assess their combined and isolated effects on a resin matrix ceramic material. The findings provide clinically relevant insights into how finishing procedures and oral hygiene may influence the long-term esthetic performance of such restorative materials.

Marginal adaptation is defined as the morphological compatibility between the restoration and preparation margins. Understanding the factors that influence marginal adaptation and implementing effective evaluation methods are critical for enhancing the success of crown restorations. Marginal discrepancies can lead to increased plaque accumulation due to microleakage, cement dissolution, pulpal inflammation, secondary caries, and periodontal inflammation. To reduce the incidence of these conditions, marginal gaps should be minimized. Various methods are available for measuring the marginal and internal adaptation of restorations. This study aims to address the factors affecting marginal adaptation and provide information on the methods used to evaluate the marginal fit between tooth structure and restorative materials.