## 4 Discussion
The influence of exposure time on surface roughness has been documented in the literature, where prolonged exposure to abrasive powders has been shown to increase the risk of surface degradation [6]. This study adds to that body of evidence, demonstrating that careful management of polishing time is crucial, particularly when using sodium bicarbonate. Clinicians should be aware of the potential trade-offs between cleaning efficacy and surface preservation, especially in scenarios where extended polishing might be necessary, such as in cases of heavy plaque accumulation or staining. The difference in response between 3M Filtek(tm) Supreme XTE composite resin and Fuji(tm) IX glass ionomer cement is also noteworthy. The composite resin generally exhibits lower roughness values compared with Fuji(tm) IX when subjected to the same polishing conditions. This difference could be attributed to the intrinsic material properties, such as the hardness and filler content, which affect how each material interacts with the abrasive particles [24]. The higher variability in roughness observed in Fuji X samples, particularly with sodium bicarbonate, suggests that this material may be more susceptible to surface alterations, potentially compromising its clinical performance over time. Fuji(tm) IX, as a glass ionomer cement, is known for its fluoride release and biocompatibility, which makes it a material of choice in many clinical situations, particularly in pediatric dentistry and in patients with high caries risk [25]. However, its relatively softer surface compared with composite resins means that it may not be as resilient to mechanical polishing, especially with more abrasive agents like sodium bicarbonate. The findings of this study suggest that, while Fuji IX offers distinct clinical advantages, its surface characteristics must be carefully managed, particularly during maintenance procedures. These findings have important clinical implications. In the context of restorative dentistry, selecting the appropriate polishing powder is crucial for optimizing the surface finish of the restoration. While sodium bicarbonate remains a popular choice due to its effectiveness in plaque removal, its use should be carefully considered, especially on materials like Fuji(tm) IX that are more prone to surface roughening. Erythrhitol and glycine, offering a gentler alternative, may be better suited for maintaining smooth surfaces, particularly in esthetically demanding areas or when working with materials sensitive to abrasion [26]. Moreover, this study highlights the need for further research to explore the long-term effects of these polishing agents on the mechanical properties of restorative materials. Understanding how surface roughness evolves over time, especially under functional loading, will be critical for developing guidelines that ensure both the esthetic and functional longevity of restorations [27]. Future studies should also consider evaluating the impact of these polishing agents on newer restorative materials and their potential role in the prevention of secondary caries and other complications. The potential for future research extends beyond just the mechanical properties. There is also a need to investigate the biological implications of surface roughness changes, particularly concerning bacterial adhesion and biofilm formation. Rougher surfaces are more prone to biofilm accumulation, which can increase the risk of secondary caries and periodontal disease. Thus, the choice of polishing agent should not only focus on mechanical outcomes but also consider the biological environment in which the restoration will function. In conclusion, the choice of air-polishing powder and the control of exposure time are key factors in managing the surface roughness of 3M Filtek(tm) Supreme XTE composite resins and Fuji(tm) X glass ionomer cements. Sodium bicarbonate, while effective in cleaning, poses a risk of increasing surface roughness, particularly with extended exposure.