Purpose <p>To evaluate if covering occlusal cavitated dentine caries lesions with limited extension (no more than one third of the bucco-lingual or disto-mesial width of the occlusal surface) in primary molars with resin-based sealing (RBS)—without previous removal of caries—would result in a lower 3-year rate of success than if all caries was removed and the cavity was filled with a resin-modified glass-ionomer cement (RMGIC), and to assess if the experience of the two treatments differed according to evaluation performed by the children and the dentists.</p> Methods <p>RBS and RMGIC treatments of occlusal cavitated dentine caries lesions with limited extension in primary molars were evaluated as “defective” or “defect-free” after 3, 6, 12, 24, and 36&#xa0;months in a split-mouth-study of 66 children (30girls, 36 boys) aged 4.77 ± 1.27&#xa0;years. The children ranked their own experience (C-Face) for each treatment on a 7-grade face-scale, and the dentists evaluated the child’s experience (D-C-exp), cooperation (D-coop) on a four-grade scale as either ‘very bad’, ‘quite bad’, ‘quite good’, or ‘very good’.</p> Results <p>After three years 71.2% of RBS and 84.8% of RMGIC were defect-free (p = 0.093). D-C-exp was better for RBS (1.27 ± 0.51) than for RMGIC (1.53 ± 0.81) (p = 0.005), while no significant difference regarding C-Face or D-Coop was found between the two methods.</p> Conclusion <p>RBS method for treatment of occlusal cavitated dentine caries lesions with limited extension (no more than one third of the bucco-lingual or disto-mesial width of the occlusal surface) in primary molars did not have a significantly lower rate of success, and was preferred by the patients, as compared to the conventional RMGIC method, according to the dentists’ evaluation of patient experience.</p> <p>ClinicalTrials.gov Identifier: NCT05475145</p>