A priority research area in minimal intervention dentistry is the characterization of the early stages of dental erosion. The aim of this in vitro study was to assess the effect of short, repetitive erosive challenges to human enamel over 2 min at pH 1.5 and 3.0 under conditions simulating gastric regurgitation.Enamel surfaces were subjected to erosive challenges at pH 1.5 (Group 1, n=10) and pH 3.0 (Group 2, n=9) for periods of 30s (stage 1), 60s (stage 2) and 120 s (stage 3). Quantitative changes were assessed longitudinally by measuring the 3D average surface roughness (Sa) values using 3D confocal microscopy. Qualitative micrographic assessment of surface changes was also conducted by using environmental scanning electron microscopy.Linear mixed model analysis showed significant effects of the pH values (p<0.001) and the stages (p<0.001) on the observed Sa values. Post hoc tests showed significant increases in the Sa values between baseline and other stages in both groups (p<0.01). The mean Sa values also increased significantly from stage 1 to stage 2 in Group 1 (p<0.05). Micrographic analysis displayed severely etched enamel rods in Group 1, but only subtle changes in Group 2.The complexity of the enamel surface is influenced by both acid concentration (pH value) and duration of acid exposure during early stages of erosion. Erosion occurring under conditions simulating GORD can be detected in its initial stages, opening up the possibilities of early diagnosis and management of this condition.Erosive tooth wear occurs progressively and insidiously, often creating complex treatment challenges. This emphasizes the need for early diagnosis and management in accordance with minimal intervention philosophy. Our findings provide a foundation for further research that could lead to the development of highly-sensitive clinical diagnostic tools and preventive strategies.