Hydroxyapatite enamel repair

In the realm of dentistry, restoration and protection of tooth enamel are of great importance in operative and conservative dentistry. Yamamoto et al. (2013) used PLD to create a freestanding flexible double-layered sheet composed of a 4 pm thin hydroxyapatite (HAp) layer coated with a 0.5 pm thin TCP layer. The adhesive strength between the HAp/TCP sheet and enamel was 5.7 MPa, decidedly higher than that between the monolayered HAp sheet and enamel (1.9 MPa). Electron microscopical observation revealed that the HAp/TCP sheet was largely fused with the enamel. Therefore, the double-layered HAp/TCP sheet can be used as a material to promote the repair of tooth eruption and to maintain healthy dentine. 

Dentin is a bone-like tissue, consisting of collagen fibrils reinforced with carbonated hydroxyapatite particles. It constitutes the body of teeth and is covered by a hard enamel layer. It has long been used by humans as a material in the form of ivory. Given the function of teeth, the design of the dentine structure needs to sustain many years of extreme loads without any repair mechanism similar to bone remodeling. As a consequence, the dentin stmcture is likely to be very well adapted... 

There are a certain number of options to control and reduce dental caries, the biggest problem in tooth care. The use of fluoride salts is one of the most effective methods to prevent or slow down demineralization that causes tooth decay [16,17]. The action of fluoride can be explained by its antimicrobial action, its interaction with enamel to form a fluorinated hydroxyapatite compound (hydroxyfluorapa-tite or fluorapatite Ca5(P04)3F) by substitution of an hydroxyl ion in hydroxyapatite Ca5(P04)3(0H), which is more resistant to add than enamel on its own, and its repairing effect by formation of calcium and phosphate, which ranineralize the tiny lesions in which caries begin. 

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