The clinical study was a single-blind, randomised intervention study to measure surface changes of polished and unpolished enamel in situ following an orange juice acid challenge. Ethical approval for the study was granted by the Stanmore Health Research Authority REC ref 15/LO/0417, and the study was conducted per the guidelines for Good Clinical Practice. The study investigated a total 6 erosion regimes divided in 3 different erosion times plus ex vivo immersion in orange juice drink versus in vivo rinsing of the same orange juice drink.