Exploring the optical behavior and relative translucency parameter of CAD-CAM resin-based composites, polymer-infiltrated ceramic network, and feldspar porcelain

Objectives: To evaluate and compare the optical properties and relative translucency parameter of CAD-CAM restorative materials.

Methods: Four CAD-CAM materials were evaluated: Lava Ultimate (LU), Grandio Blocs (GB), VITA Enamic (VE), and VITA Mark II (VM). Disk-shaped samples in shade A2-HT were prepared (n = 10) and polished to 1.00 ± 0.01 mm of thickness. Scattering (S), absorption (K), albedo (a) coefficient, transmittance (T%), light reflectivity (RI), infinite optical thickness (X_∞), and radiative transfer coefficients (μ_a, and μ'_S) were calculated using Kubelka-Munk method and Thennadil's semi-empirical approach. Root Mean Square Error (RMSE) and Goodness of Fit (GFC) were used as performance optical behavior. Translucency differences were evaluated using the relative translucency parameter (RTP₀₀) and 50:50 % translucency perceptibility and acceptability thresholds (TPT₀₀ and TAT₀₀).

Results: The spectral distribution of S, K, T%, RI, and X_∞ was wavelength-dependent. GFC and RMSE values indicated good spectral behavior matches and good comparative spectral values for RI in LU-GB, LU-VE, and GB-VE, and for K in VE-VM. VM displayed the highest scattering values across the wavelengths, while VE and VM showed lower absorption at shorter wavelengths. LU and GB had the highest transmittance. The X_∞ values indicated that all 1.0 mm thick materials could be influenced by the background. No good spectral match and no good comparative spectral values were found between CAD-CAM materials and anterior bovine maxillary specimens. VM had the lowest RTP₀₀ values with perceptible and unacceptable differences compared to CAD-CAM materials evaluated.

Significance: Understanding the optical behavior of different CAD-CAM materials was essential for guiding clinicians in material selection and optimizing their clinical performance. The findings confirm that the different compositions and microstructure impact the optical properties and translucency of CAD-CAM restorative materials.