## 2 Materials and Methods
It involves two steps: pre-polishing with a #9507U polisher at 7000-10,000 rpm to remove irregularities and smoothen the surface, followed by high-shine polishing with a #9786 polisher at 3000-10,000 rpm. For the OG group, one uniform layer of OPTIGLAZE light-polymerized glazing agent (GC America Inc., Alsip, IL, USA) was applied in a circular motion without air contamination using the micro-brush provided with the kit. The glazing agent was light-polymerized using a hand-held curing unit (light-emitting diode, Bluephase G2, Ivoclar Vivadent, Schaan, Liechtenstein) for 40 s. Finally, the specimens in the MP+PP group were treated similarly to the MP group, followed by additional polishing using a polishing paste (SHOFU Dental GmbH, Ratingen, Germany). The paste was applied on a wet surface with a #9 soft bristle brush (Abbott-Robinson, Keystone Dental Group, Bosworth, UK) at 9000 rpm to prevent excessive heat generation. The specimen distribution and the study process are presented as flowcharts in Figure 1.  
To ensure consistency, all the surface treatment protocols were performed by a single operator ([PERSON]) using a custom-made hand piece holder (Figure 2). After surface treatment, all specimens were washed with running water and air-dried before being measured for surface roughness and gloss. Figure 1: Flowchart for the specimen distribution and study process. Surface roughness (Ra) was measured using a non-invasive 3D optical non-contact profilometer (Bruker, Tucson, AZ, USA) that employs the white light interferometry technique. The height differences on the specimen surfaces were measured using the refractive indices of the white light components [43], which provides a quantitative evaluation of the surface [44]. The roughness was determined using a 5\(\times\) Michelson magnification lens, a Gaussian regression filter, 1 \(\times\) 1 mm\({}^{2}\) field of view, and 1\(\times\) scan speed. The simple vision 64 application software (Bruker, Tucson, AZ, USA) converts the data into accurate high-resolution images while also controlling device movements. Before each group, the system was re-calibrated. Three parallel readings were obtained at the different specimen areas and averaged for each specimen [41]. A representative specimen from each group was observed under a scanning electron microscope (SEM, JSM-6610 LV, JEOL Ltd., Tokyo, Japan) for qualitative analysis of the treated surface. The specimens were gold sputter coated (\(-\)10 nm) in a coating machine (Q150R, Quorum tech, East Sussex, UK). The specimens were then placed on the sample holder of the SEM machine, and the image was processed at a working distance of 10 mm, 20 kV power and \(\times\)100 magnification. A gloss meter (Novo-Curve, Rhopoint Instruments Ltd., East Sussex, UK) was used to measure gloss per ISO 2813 specification [34,42]. A gloss meter is a reflectometer that includes an incandescent light source, a photodetector, and a collimator. The laser beam was focused at a 60\({}^{\circ}\) angle onto the surface of the specimen, and the intensity of the reflected light was measured using a photodetector positioned in the incident beam's specular direction. The reflectometer measures gloss by the proportions of the directed reflected light; as a result, high reflectometer readings indicate high gloss. The gloss measurement is expressed as gloss units (GU). Data were analyzed using IBM SPSS software (v.25; IBM Corp, Armonk, NY, USA). Data were normally distributed, and hence parametric testing was applied. Multivariate  
Figure 2: Customized holder used for surface treatment. analysis of variance (MANOVA) was used to determine the overall significance. A one-way ANOVA was used to test each dependent variable, followed by [PERSON]'s post hoc test for multiple comparisons between the groups (\(\alpha\) = 0.05).