Objective       To investigate the effect and mechanism of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on the remineralization of demineralized dentine

and provide reference for the prevention or non-invasive intervention of root caries and dentine hypersensitivity.        Methods       Twenty dentine specimens demineralized with 37% phosphoric acid gel for 30 s were randomly divided in 2 groups with a random digital table. Then the specimens were treated with simulated body fluid (SBF) and CPP-ACP

respectively

for 15 d. The dentine surfaces were subjected to microhardness measurement

micromorphological evaluation and X-ray diffraction analysis. Collagen fiber nickel-titanium meshes were constructed and treated with SBF and CPP-ACP for 1 d. Then

the meshes were subjected to micromorphological observation and selected area diffraction analysis by transmission electron microscopy.        Results       The Vickers hardness values of the dentine surfaces in the CPP-ACP group and SBF group were 47.92±4.25 and 42.72±4.65

respectively

and the microhardness in the CPP-ACP group was significantly higher than that in the SBF group after treatment for 15 d (P0.05). The dentine surface in the CPP-ACP group was more compact than that in the SBF group

and many sediments were generated on the dentine surface and identified mainly as hydroxylapatite (HA). Lots of 50~60 nm fusiform ACP was distributed on the recombinant collagen fibers and the periphery in the CPP-ACP group

and only a few of round ACP was observed in the SBF group by transmission electron microscopy.        Conclusion       CPP-ACP can promote in vitro remineralization of demineralized dentine

and generate HA as main minerals on the dentine surface. So it can be used for the non-operative treatment of root caries and dentin hypersensitivity.