GC Tooth Mousse, a complex containing amorphous calcium phosphate (ACP) and casein phosphopeptide (CPP), is recommended in dentin hypersensitivity reduction due to its ability to block opened dentinal tubules. It acts synergistically with fluorine in slowing caries progression. Whether CPP-ACP can act synergistically with fluorine in the dentin hypersensitivity treatment is unknown. The aim of this study was to assess the effect of CPP-ACP combined with fluoride varnish in cervical dentin hypersensitivity treatment.