It was the aim of the current in vitro study to test the erosion-preventive potential of an experimental surface sealant (K-0184) and currently marketed self-etch adhesive systems under abrasive conditions. Ninety-six dentine specimens were randomly allocated to eight groups (n = 12): (1) positive control (no treatment), (2) K-0184, (3) Shield Force Plus, (4) Xeno Select, (5) Scotchbond Universal, (6) Adhese Universal, (7) OptiBond All-In-One, and (8) Clearfil SE Bond. Before and after sealing, dentine specimens were measured profilometrically to determine the layer thickness of the protective agents. During 12 days, the specimens were demineralized daily for 5 min using hydrochloric acid (pH = 3) and abraded by applying 600 brushing strokes (F = 2.5 N). Calcium content in the hydrochloric acid was determined using atomic absorption spectroscopy. Calcium concentration was consistently highest in the positive control group (p < 0.05 compared to all other groups). The lowest cumulated Ca release was measured for K-0184; it differed significantly (p < 0.05) from that determined in groups 4, 6, and 7. K-0184 also had the highest layer thickness (p < 0.05 compared to all other groups). It was concluded that the experimental surface sealant K-0184 and the adhesive systems Xeno Select, Scotchbond Universal, Adhese Universal, and Clearfil SE Bond prevent dentine erosion under the current abrasive conditions with a total of 7,200 brush strokes.