## 4 Discussion  
The primary aim of this study was to evaluate the impact of various surface finishing and grinding procedures on the surface gloss and roughness of three types of monolithic lithium disilicate ceramics and one monolithic ultra-translucent zirconia ceramic. This investigation is particularly important because ceramic restorations often undergo intraoral adjustments during clinical procedures, which can compromise their surface integrity. Ensuring that these restorations maintain optimal surface properties--such as smoothness and gloss--is essential for achieving aesthetic satisfaction, minimizing plaque accumulation, and prolonging the lifespan of the restoration. However, there remains a lack of consensus in the literature regarding the most effective method to restore or enhance surface quality following such adjustments. This study contributes valuable insights by comparing the performance of mechanical polishing, glazing, and repolishing protocols across different ceramic materials. Based on the study's outcome, glazing and mechanical polishing had a significant effect on the roughness and gloss values of the ceramic materials (\(p<0.050\)), thereby rejecting the first null hypothesis. According to the results from the glazing, grinding, and repolishing groups, the second null hypothesis is partially rejected. After grinding the glaze layer, the mechanical polishing process was significantly able to eliminate the adverse effects of the adjustments. Since mechanical polishing and glazing have varied effects on the smoothness and appearance of dental ceramic surfaces, it was interesting to evaluate in what distinct ways the finishing processes affected surface gloss and roughness [43; 44; 45]. Roughness and gloss assessments allow dental ceramics to be analyzed superficially and compared in terms of surface characteristics after surface finishing. Surface roughness and gloss are two essential components that contribute to a restoration's aesthetic appearance [46; 47]. Despite advancements in CAD-CAM equipment, chairside adjustments--such as grinding, polishing, and glazing--are frequently required during prosthetic rehabilitation to refine the emergence profile and occlusal or proximal relationships of restorations [48]. Occasionally, additional surface modifications may be necessary even after the restoration has been glazed and permanently cemented to address minor interferences. For long-term clinical success, the surfaces of all ceramic restorations must be adequately smoothed [37; 49]. Well-finished surfaces minimize technical and aesthetic complications by enhancing material hardness [50; 51], gloss [46], translucency, and color stability [47; 52]. A smooth surface also significantly improves patient comfort. Studies have shown that surface roughness (Ra) values exceeding the critical threshold of 0.2 um are associated with increased risks of dental caries, plaque accumulation, and periodontal inflammation [53]. As a result, numerous investigations have examined the impact of various finishing and polishing techniques on the surface roughness of dental restorative materials [54; 55; 56]. Multiple studies consistently report that mechanical polishing not only matches but often surpasses glazing [42; 57; 58; 59] in producing smooth ceramic surfaces. [PERSON] and [PERSON], for example, found that manual polishing techniques yielded outcomes comparable to those achieved with glazing [60]. According to [PERSON] et al., using polishing kits and pastes for clinical polishing of ceramics can serve as a secure and efficient substitute for glazing procedures, particularly concerning surface roughness [61]. [PERSON] et al. recommended polishing as an alternative to glazing for IPS e.max Press restorations [62].