This paper describes novel and innovative amorphous calcium magnesium fluoride phosphate (ACMFP) core-shell microparticles that may be applied in preventive dentistry for the prevention of caries and the treatment of dentin hypersensitivity. The particles can be synthesized with varied fluoride content, up to approximately 6 wt%, without any observable differences in morphology or crystallinity. Fluoride release from the particles is correlated to the fluoride content, and the particles are readily converted to fluoride-substituted hydroxyapatite or fluorapatite in a simulated saliva solution. The remineralization and dentin tubule occlusion potential of the particles was evaluated in vitro on acid-etched dentin specimens, and treatment with the ACMFP particles resulted in complete tubule occlusion and the formation of a dense mineralization layer. The acid resistance of the mineralization layer was improved compared to treatment with analogous particles without fluoride inclusion. A cross-sectional evaluation of dentin specimens after treatment revealed the formation of high aspect ratio fluorapatite crystals and poorly crystalline hydroxyapatite, respectively. The particles of the current study provide a single source vehicle of readily available calcium, phosphate, and fluoride ions for the potential remineralization of carious lesions as well as exposed dentin tubules for the reduction of hypersensitivity.