## 4 Discussion
### Factors Influencing Microleakage  
Coating agents have a role in the prevention of microleakage; G-Coat Plus was studied in some studies with primary [39; 40; 41] and permanent teeth [27]. [PERSON] and [PERSON] [39], in their study, concluded that conventional GIC (Fuji IX) with nano-coating (G-Coat Plus) has microleakage values equal to RMGIC (Fuji II LC) without coating. These outcomes are consistent with the results of the study conducted by [PERSON] et al. [41], who found that conventional GIC and RMGIC without G-Coat Plus coating showed more microleakage when compared to conventional GIC and RMGIC with G-Coat Plus. These findings were also confirmed in the study by [PERSON] et al. [40]. Thus, using nano-coating with all types of GICs is preferred to minimize microleakage.  
The different preparation techniques in the cavity may be another factor influencing the microleakage score results. In studies using laser cavity preparation [48; 49; 50], the researchers found that RMGICs performed better than conventional GICs in conditioned cavities treated with Er:YAG laser. Scanning electron microscopy (SEM) was applied to visualize the effect of the conditioner on the lasered tooth structure. Photographs demonstrated that the edges of the cavities obtained by Er:YAG laser irradiation were irregular, wrinkled, and free of a smear layer. Based on the authors' opinions, this irregularity in cavity outlines and crater-like character free of the smear layer can improve the adhesion mechanism of GICs as it is favorable for micromechanical retention. Furthermore, conditioning is recommended to obtain a smoother surface with partial occlusion of dental tubules, which may improve contact between the GIC and the tooth. [PERSON] et al. also described that the chemomechanical removal of caries with Cariosolv in Class I cavities in young primary teeth did not affect the microleakage results in the GIC materials Fuji IX and Ketac N100. Furthermore, Cariosolv helps preserve dental tissue, although the clinical time is longer than when high-speed excavation is used [46].  
There is weak evidence about the margin-sealing ability of GICs subjected to erosive challenges, and only one study [42] evaluated the behavior of GICs after subjecting them to Coca-Cola and orange juice. The results showed that they have a negative effect on the marginal sealing in both conventional and RMGIC materials. However, in vitro tests performed with composite materials have demonstrated that other variables can have a significant influence on long-term durability, such as depth of cure [70], curing type [71], and interface contamination [72]. Therefore, future studies on the influence of these factors on GICs are needed to expand our knowledge of these materials.  
The results of many studies indicate that the gingival margins show more leakage than the occlusal margins. This behavior could be attributed to the fact that adhesion to enamel is stronger than dentin due to differences in morphologic, histologic, and compositional characteristics between the two because dentin has high organic and water content, low surface energy, and the presence of a smear layer [27; 44; 48; 49].  
In short, there are many factors that can affect the microfiltration of the materials, derived from the characteristics of the substrate, the conditioning of the fabrics, and the characteristics and handling of the material itself.