Evaluation of the Color Stability, Stainability, and Surface Roughness of Permanent Composite-Based Milled and 3D Printed CAD/CAM Restorative Materials after Thermocycling

Abstract

With the developments in digital dentistry in recent years, subtractive and additive manufacturing and materials have emerged for the production of dental restoration. Novel permanent composite-based restorative materials are also among these materials. Because of their variety and increased use by clinicians, it is also important to know the properties, such as surface roughness and color stability, that are necessary for the longevity of these new materials. This study aimed to investigate the color stability, stainability, and surface roughness (Ra) of additively and subtractively manufactured permanent composite-based restorative materials and compare them with a feldspathic glass ceramic. Two different subtractively manufactured composite-based blocks (Cerasmart 270, Vita Enamic), two different additively manufactured permanent composite-based resins (Crowntec and Permanent Crown Resin), and one feldspathic glass ceramic (Vita Mark II) as a control were compared. A total of 150 specimens were prepared (10 per material for surface roughness and 20 per material for color stability and stainability). The Ra values and the color parameters were measured before and after thermocycling. The specimens of the staining test were then divided into two subgroups and stored for 7 days in distilled water (control) or coffee. The color parameters were remeasured after the storage period. The color differences (∆E00) were evaluated for each measuring range, and these values are interpreted in terms of clinical perceptibility (ΔE00 ≤ 1.30) and clinical acceptability (ΔE00 ≤ 2.25) thresholds. All data were statistically analyzed (α = 0.05). While Vita Enamic exhibited the highest mean Ra, Crowntec showed the lowest mean Ra after thermocycling. Crowntec had the highest mean ΔE00 both after thermocycling and storage in solutions. While Vita Mark II displayed the lowest mean ΔE00 after thermocycling. Cerasmart 270 showed the lowest stainability in coffee. All tested materials showed acceptable surface roughness after thermocycling that was equal to or below the plaque accumulation threshold of 0.2 µm. However, the mean ΔE00 of tested materials were lower than clinical acceptability thresholds, except for Crowntec in all measuring ranges and Vita Enamic immersed in coffee.