Effect of staining beverages and thermocycling on VITA 3D-Master shade components of a nanohybrid resin composite: an in vitro longitudinal study

Objective: To evaluate longitudinal changes in the value, chroma, and hue components of the VITA 3D-Master shade system in a nanohybrid resin composite exposed to staining beverages, with and without thermocycling, over a 28-day period. Materials and Methods: Seventy-two disk-shaped specimens (8 mm × 2 mm) of a nanohybrid resin composite (Spectra Smart®, Dentsply Sirona) were allocated to three immersion media: saline solution (control), carbonated cola beverage, and ready-to-drink tea (n = 24 each). Each group was further divided according to thermal-aging condition (with or without thermocycling; n = 12 per subgroup). Thermocycled specimens underwent 1,000 cycles between 5°C and 55°C. Specimens were immersed in their respective solutions for 1 h/day for 28 days and stored in distilled water at 37°C between exposures. Shade was assessed using a VITA Easyshade V spectrophotometer and recorded according to the VITA 3D-Master system at baseline, 7 days, and 28 days; thermocycled specimens were additionally assessed immediately after thermal aging. Value, chroma, and hue were analyzed separately. Categorical transitions relative to baseline were summarized as frequencies and percentages, and exploratory comparisons were performed using Fisher's exact test (α = 0.05). Results: Value and chroma showed minimal longitudinal variation. Chroma remained unchanged in all specimens throughout the study, while only 2/72 specimens (2.8%) exhibited a value transition at 28 days. In contrast, hue transitions occurred in 48/72 specimens (66.7%) at 7 days and 46/72 (63.9%) at 28 days. Among thermocycled specimens, 26/36 (72.2%) exhibited a hue transition immediately after thermal aging. At 28 days, hue transitions were observed in 29/36 thermocycled specimens (80.6%) compared with 17/36 non-thermocycled specimens (47.2%). Hue transitions were also frequent in saline controls, indicating that the observed changes could not be attributed exclusively to exposure to staining beverages. Conclusions: The individual components of the VITA 3D-Master shade system exhibited distinct longitudinal behaviors. Value and chroma remained highly stable, whereas hue showed frequent categorical transitions, particularly among thermocycled specimens. Because only categorical shade codes were available, the magnitude, perceptibility, and clinical acceptability of these transitions could not be determined. Therefore, stability of value and chroma should not be interpreted as overall color stability, and no definitive ranking of the staining potential of the evaluated beverages can be established.