1：Experimental Design and Method Selection:

The study evaluated the total loss of irradiance (TL) through four CAD/CAM indirect restorative materials at different thicknesses (0.5, 1.0, 1.5, and 2.0 mm) using a plasma-arc dental light-curing unit. Spectral irradiance was measured for blue (425–490 nm) and violet (350–425 nm) wavelengths. Statistical analysis included two-way ANOVA and post-hoc Tukey test.

2：5, 0, 5, and 0 mm) using a plasma-arc dental light-curing unit. Spectral irradiance was measured for blue (425–490 nm) and violet (350–425 nm) wavelengths. Statistical analysis included two-way ANOVA and post-hoc Tukey test. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Specimens (15 mm diameter) were fabricated from each material (n=5 per thickness). Materials included resin/ceramic hybrid (Lava Ultimate), feldspathic ceramic (VitaBlocs Mark II), and two zirconia ceramics (Katana and Lava Zirconia).

3：List of Experimental Equipment and Materials:

Equipment included a plasma-arc light-curing unit (Arc Light-II), spectroradiometer (USB2000), integrating sphere (CTSM-LSM-60-SF), software (Spectra Suite v5.1), diamond disc for sectioning, digital micrometer, thermopile (PM-10 and Fieldmate), laser beam profiler (LBA-FW v4.89), and scanning electron microscope (JEOL JSM-5600LV). Materials included the restorative materials and abrasive papers (SiC, 600, 1200, 2000 grits).

4：1), diamond disc for sectioning, digital micrometer, thermopile (PM-10 and Fieldmate), laser beam profiler (LBA-FW v89), and scanning electron microscope (JEOL JSM-5600LV). Materials included the restorative materials and abrasive papers (SiC, 600, 1200, 2000 grits). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Specimens were sectioned, ground to specified thicknesses, and measured. The light-curing unit was characterized for power and spectral output. Specimens were placed between the light source and integrating sphere, and irradiance was measured at 5 seconds into exposure. Control measurements were taken without specimens.

5：Data Analysis Methods:

Data was analyzed using two-way ANOVA and post-hoc Tukey test (α=0.05). Absorbance and absorbance coefficients were calculated for specific wavelengths (400 nm, 450 nm, 500 nm).