Background. In the field of pediatric dentistry, preventing microleakage of glass ionomer cement (GIC) is important for clinical success. The abrasion and roughness of the surface of the restorative material that results from brushing can cause microleakage. The application of surface protection is intended to prevent this situation. Objectives. The aim of the study was to evaluate the levels of microleakage following toothbrushing after the application of GICs with or without surface protection. Material and methods. Cavities formed on the buccal surfaces of 180 extracted primary teeth were restored with resin-modified glass ionomer cement (RMGIC), and the teeth were divided into 3 groups according to the surface protection application, with an equal number of samples in each group (n = 60). The thermal cycle was applied to all samples. Subsequently, the groups were divided into 5 subgroups (n =12/group) according to the brushing simulation (no brushing, and 1, 3, 6, and 12 months of brushing). The samples were stored in 2% methylene blue for 24 hand sectioned in the buccolingual direction. The presence of microleakage was determined with the use of a stereomicroscope. The data was statistically analyzed. Results. No statistically significant differences were observed between the main groups at all brushing times (p > 0.05). However, higher microleakage results were obtained in the group without surface protection. When the groups were evaluated according to the duration of brushing, no statistically significant differences were identified (p > 0.05), but higher microleakage results were obtained in the samples that underwent brushing for 12 months. Conclusions. Although statistically significant results were not obtained in terms of microleakage regarding surface protection application and brushing, it should be noted that coating restorations with surface protectants may contribute to a smoother surface and marginal integrity, and may be beneficial in reducing microleakage.