## 4 Discussion
In a study investigating the effect of polishing and glazing on surface roughness for two distinct hybrid ceramics and a lithium disilicate glass ceramic (EC), the polished surfaces demonstrated lower and clinically acceptable surface roughness values compared to the glazed surfaces across all materials [63]. Numerous studies have shown that mechanical polishing significantly reduces the surface roughness of zirconia, and that the application of polishing results in acceptable intraoral roughness values [64; 65; 66]. Similar to the previously mentioned studies, our researchfound that mechanical polishing led to lower surface roughness values than glazing for all lithium disilicate ceramic materials. Furthermore, the average roughness values of all polished ceramics were within the acceptable threshold for intraoral applications (critical value: 0.2 \(\upmu\)m), with the following results: CT--0.09 \(\upmu\)m, LS Block--0.08 \(\upmu\)m, EC--0.08 \(\upmu\)m, and KAT--0.12 \(\upmu\)m. As a result, the study concluded that mechanical polishing can be a viable alternative to glazing. Zirconia, with its homogeneous polycrystalline structure and high hardness, presents challenges for conventional polishing systems as they may not achieve a satisfactory polishing effect [67; 68; 69]. Numerous studies have shown that zirconia-specific polishing systems outperform universal polishing systems when used on zirconia restorations. These specialized polishing sets are equipped with abrasives, such as diamonds, SiC, and Al\({}_{2}\)O\({}_{3}\), that are highly effective in dealing with the elevated hardness of zirconia [70; 71; 72; 73]. According to [PERSON] et al., the variations in ceramic microstructures make it highly challenging to determine the best polishing technique for each ceramic [23]. A study by [PERSON] et al. confirmed that different materials require different polishing techniques [74]. In our study, the mechanical polishing and glazing groups exhibited comparable average surface roughness values for the monolithic zirconia ceramic samples. This finding aligns with previous research by several investigators, who also reported similar surface roughness values for both polishing and glazing of monolithic zirconia materials [75; 76]. Nonetheless, the outcomes for our lithium disilicate samples were distinct from those obtained for the zirconia samples. These disparities could potentially be ascribed to the different polishing sets utilized or variations in the microstructure of the materials, as indicated in the previously mentioned research [69; 70]. Several studies in the literature have examined the effectiveness of mechanical polishing versus glazing after ceramic surfaces have been adjusted with a diamond bur. One study [34] reported that monolithic zirconia specimens, when repolished or overglazed after grinding, exhibited comparable surface roughness values within clinically acceptable limits, supporting the use of chairside mechanical polishing as a viable method to restore smoothness after adjustments [34]. Similarly, research on a newer generation of translucent zirconia [77] found no significant difference in surface roughness between specimens that underwent mechanical polishing and those that were glazed following diamond-bur grinding [77]. Another study [78] comparing monolithic zirconia and feldspathic ceramics demonstrated that samples polished after grinding showed roughness values similar to their glazed counterparts [78]. In a separate investigation on lithium disilicate ceramics (IPS e.max Press) [79], immediate mechanical polishing after glaze removal with a fine-gri diamond bur produced surface roughness levels comparable to those achieved through glazing [79]. [PERSON] et al. [80] also reported that, for both zirconia and lithium disilicate ceramics, mechanical polishing and glazing following grinding yielded similar roughness values, while the ground-only group exhibited the highest roughness 80].