There is a lot of information on remineralization in the dental literature and within the industry, but I didn’t really feel like I understood the process well enough. Obviously our best data comes from fluoride research, but I wondered what potential role other forms of calcium phosphate might play, and what happens in the mouth, how does nature address the issue? At the request of Doug Young, I spent a couple of years digging into remineralization chemistry, and what research existed. I actually ended up starting back-studying crystalline physics and dynamics. Enamel, it turns out, behaves like all other crystal in nature, it remineralizes by a process described as oriented attachment, with the building block being a 20 nm crystallite of carbonated HA.
One surprising find in the literature is that a 20 nanometer size of carbonated hydroxyapatite is the most thermodynamically stable form of HA. As the pH decreases below 5.5 it demineralizes and as the pH continues to decrease, at 20 nm size the HA particles actually increases it’s acid resistance, an unexpected outcome. The enamel system is beautifully designed, and no small wonder that the basic building block of enamel is a 20 nm particle of HA. That led to the research project with John and Yada. Graeme added his expert SEM images and I’m very pleased with our combined effort in this paper. I hope that it makes the process better understood. We still have much to learn, but a lot of research is currently being done with nano-particle HA, which tends to mimic nature.
Kim Kutsch DMD
Reconsidering Remineralization Strategies to Include Nanoparticle Hydroxyapatite
V. Kim Kutsch, DMD; John C. Kois, DMD, MSD; Yada Chaiyabutr, DDS, DSc, MSD; and Graeme Milicich, BDS
Compendium of Continuing Education in Dentistry
Dental caries is a transmissible biofilm-mediated disease of the teeth that is defined by prolonged periods of low pH resulting in net mineral loss from the teeth. Hydroxyapatite, fluorapatite, and the carbonated forms of calcium phosphate form the main mineral content of dental hard tissues: enamel, dentin, and cementum. Active dental caries results when the biofilm pH on the tooth surface drops below the dissolution threshold for hydroxyapatite and fluorapatite. The clinical evidence of this net mineral loss is porosity, whitespot lesions, caries lesions, and/or cavitation. The potential to reverse this mineral loss through remineralization has been well documented, although previous remineralization strategies for dental hard tissues have focused on the use of fluorides and forms of calcium phosphate. This in-vitro study documented the deposition of nanoparticle hydroxyapatite on demineralized enamel surfaces after treatment with an experimental remineralization gel. This finding supports consideration of an additional approach to remineralization that includes pH neutralization strategies and nanoparticle hydroxyapatite crystals.
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