OBJECTIVES:The objective of this study was to evaluate the in vivo effects of a 2.6% edathamil gel (Livionex® Dental Gel) on surface microhardness and microstructure in 180 pre-eroded enamel chips. METHODS:This was a double-blind, randomized study. Two enamel chips each were cut from 90 healthy sterilized extracted teeth. One chip from each pair underwent microhardness testing and scanning electron microscopy (SEM) to establish baselines. The remaining 90 samples were demineralized, and then mounted onto intra-oral retainers worn by nine subjects, with five chips mounted on each retainer for each of the two study arms. In one two-week study arm subjects brushed with the control toothpaste; in the other they used the test gel. Study arms were separated by a two-week washout. Sequence of toothpaste use was randomized. At the end of each study arm, samples underwent microhardness measurements (Knoop) and SEM visualization. RESULTS:After intraoral wear, enamel chips recovered fully from demineralization, with no significant difference in microhardness between the two treatments (p > 0.05). In SEM images, enamel surfaces at study's end also appeared comparable in the two groups. CONCLUSIONS:Pre-eroded enamel chips remineralized intra-orally to a similar level after using a control or a test toothpaste containing 2.6% edathamil.