## 4 Discussion  
This systematic review and meta-analysis investigated the impact of fabrication techniques on the fit accuracy of removable partial dentures (RPDs), specifically comparing digital methods, such as CAD/CAM, SLM, and DMLS, with conventional lost-wax casting techniques. The results revealed a weighted mean difference (WMD) of 26.29 \(\upmu\)m, in favor of digital techniques. Still, this difference does not necessarily reflect a superior fit, rather more consistent outcomes across the studies. While digital methods showed a smaller mean gap size (140 \(\upmu\)m) compared to conventional methods (164 \(\upmu\)m), this slight improvement should be interpreted with caution due to the moderate heterogeneity (I\({}^{2}\) = 21%) observed across the included studies. The overall findings suggest that digital techniques might offer marginal improvements in terms of fit accuracy, but they are not as substantial as some previous studies have claimed. The smaller mean gap size observed with digital methods could be attributed to the higher precision and standardization of digital workflows, which minimize the potential for human error during fabrication. CAD/CAM systems, for instance, eliminate several manual steps that are inherent to conventional methods, such as wax-ups and casting, where the operator's skills and material inconsistencies can introduce variability [41]. Digital scanning and milling techniques are more precise and repeatable, which likely explains the slightly better results for digital RPDs [42]. However, it is crucial to note that different digital methods were not compared against each other in this meta-analysis. As such, this study cannot support any claims about the superiority of one method, such as SLM or DMLS, over another. The results were pooled to compare digital versus conventional methods overall, without further stratification by specific digital techniques. This limits the ability to draw conclusions about which digital approach might offer the best fit accuracy. Additionally, while digital methods offer several theoretical advantages, such as reducing the porosity and improving the mechanical properties of RPDs through additive manufacturing techniques like SLM and DMLS, these benefits were not directly measured in this study. The focus here was solely on fit accuracy and, thus, any broader claims about the mechanical performance or clinical longevity of digitally fabricated RPDs are outside the scope of this analysis [30]. For example, studies, like the study by [PERSON] et al. (2019), highlighted the potential of SLM to reduce internal defects due to its layer-by-layer construction, but this aspect was not the focus of the present analysis, which strictly examined the gap size as a measure of fit accuracy [31]. The exclusion of studies that focused on material properties, like PEEK or POM, was necessary to maintain the focus on fit accuracy, rather than delving into material performance. While materials like PEEK are gaining attention due to their biocompatibility and aesthetic advantages, this study did not include material properties as a factor in the comparison. Previous discussions about PEEK's advantages regarding patient comfort and lower thermal conductivity are relevant for future research, but were not evaluated in this meta-analysis, as the focus was specific to dimensional fit accuracy. The moderate heterogeneity observed (I\({}^{2}\) = 21%) suggests that factors, such as the study design, measurement techniques, and digital workflows, varied between the included studies. For instance, some studies used visual inspection or polyvinyl siloxane (PVS) thickness measurements to assess the fit. In contrast, others employed more advanced 3D scanning technologies, like GOM Inspect or Geomagic Control software, which provide a higher level of precision and reproducibility. This variation in measurement techniques likely contributed to the heterogeneity in the results.