Optical behavior and surface roughness analysis of pressable zirconia-reinforced lithium silicate ceramics used as...

Zirconia-reinforced lithium silicate (ZLS) ceramics have been widely used for their mechanical and optical properties, but the effects of thermocycling remain unclear. Vita Ambria, being relatively new, has not been extensively studied in terms of aging, indicating a need for foundational data.

The purpose of this in vitro study was to evaluate how thermocycling affected the surface roughness and optical properties of pressable zirconia-reinforced lithium silicate ceramics (Vita Ambria and Celtra Press).

Thirty-two pressable zirconia-reinforced lithium silicate ceramic Ø10×1-mm disks were divided into 2 groups (Vita Ambria and Celtra Press), each with 16 specimens. These were further subdivided into polished and glazed subgroups based on surface finishing. The specimens underwent 10 000 cycles of thermocycling between 5 °C and 55 °C which simulated approximately 1 year of intraoral aging, with surface roughness (arithmetic average roughness (Ra), arithmetic mean roughness height (Sa) measured by a 3-dimensional laser confocal scanning microscope, and optical properties assessed with a spectrophotometer before and after aging. A 3-way repeated measures ANOVA was performed to evaluate the effects of material type, surface treatment, and thermocycling on each outcome, with Bonferroni corrections applied (α=.05).

Thermocycling significantly increased surface roughness, (Ra): +28% in polished Vita Ambria (P=.007) and reduced translucency (TP: -22.8% in glazed Celtra Press; P=.005). Celtra Press showed consistently lower Ra values after aging. Sa increased notably in polished specimens (Vita Ambria: +25.3%; P=.007). These material-dependent changes emphasize the clinical relevance of surface treatment in long-term esthetic performance.

Thermocycling induced changes in the surface roughness and optical properties of both Vita Ambria and Celtra Press ceramics, influenced by material type and surface treatment. Even though the roughness values were within clinically acceptable limits after aging, the increase observed may still lead to greater plaque accumulation and a diminished esthetic value over time. This highlights the importance of selecting appropriate materials and surface finishing protocols to preserve long-term esthetic outcomes in ceramic restorations.