Abstract
Amorphous Calcium Phosphate (ACP) is an essential mineral phase formed in mineralized tissues and the first commercial product as artificial hydroxyapatite. ACP is unique among all forms of calcium phosphates in that it lacks long-range, periodic atomic scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at 25 degree 2 theta, and no other different features compared with well-crystallized hydroxyapatite. Under electron microscopy, its morphological form is shown as small spheroidal particles in the scale of tenths nanometer. In aqueous media, ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystalline. It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo. Moreover, it can increase alkaline phosphatase activities of mesoblasts, enhance cell proliferation and promote cell adhesion. The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration. ACP may also be a potential remineralizing agent in dental applications. Recently developed ACP-filled bioactive composites are believed to be effective anti-demineralizing/remineralizing agents for the preservation and repair of tooth structures. This review provides an overview of the development, structure, chemical composition, morphological characterization, phase transformation and biomedical application of ACP in dentistry.
Highlights
Amorphous Calcium Phosphate (ACP) is an essential mineral phase formed in mineralized tissues and the first commercial product as artificial hydroxyapatite
This review provides an overview of the development, structure, composition and morphology characterization, phase transformation and biomedical application of ACP in dentistry
It was suggested that synthetic ACP particles, which appear as 300- 1000 Å spheres in the electron microscope, consist of a random assembly of ion clusters 9.5 Å in diameter, dimensions consistent with the chemical composition of Ca9(PO4)6 [5]
Summary
ACP is usually formed as a metastable phase when calcium and phosphate ions in aqueous solution react to precipitate. A variety of proteins and ions can increase the stability of ACP. ACP becomes increasingly significant in orthopedics and dentistry because of their excellent biocompatibility and mechanical properties. It is believed that ACP will be used even more extensively in the future due to due to the fast development of tissue engineering techniques and applied material science. Author details 1Stomatological Hospital, Nanjing University Medical School, 30 Zhongyang Road, Nanjing 210008, China. Competing interests The authors declare that they have no competing interests Received: 25 March 2011 Accepted: 8 July 2011 Published: 8 July 2011
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