Evaluation of Enamel Acid Resistance and Whitening Effect of the CAP System

This study aimed to compare the effectiveness of a novel professional tooth-strengthening system and a conventional caries-prevention method that involved the use of high fluoride concentrations, to determine whether the system has a whitening effect. Bovine tooth-enamel samples were treated with fluoride gel (conventional APF method) or a mixture of citric acid gel, calcium phosphate (α-TCP), and fluoride gel, referred to as the CAP system; these treatments were performed to generate an acid-resistant layer on the enamel surface. For the evaluation of the acid resistance, a cyclic experiment, involving a 1-h remineralization and a 24-h acid treatment, was conducted thrice after the treatments. The height profiles were observed using a 3D-measuring laser microscope and the hardness was evaluated by Vickers hardness test. The morphological changes in the surface and cross-section of the enamel were observed by scanning electron microscopy. To evaluate the whitening effect, the enamel was ground until the color of the underlying dentin was recognizable; the CAP system was applied once, and the color change was measured using a color difference meter. As a result, it was confirmed that an acid-resistant layer was formed on the tooth surfaces treated with the CAP system, and a whitening effect was obtained.