Hydroxyapatite deposition

Hydroxyapatite Deposition on Polymers Modified with Silanol Groups... 

Kamitakahara, M., Ohtsuki, C., Morihara, Y., Ogata, S. and Tanihara, M. (2005) Hydroxyapatite deposition on collagen-like polypeptide modified with silanol groups, in Archives of BioCeramics Research (eds F. Watari, T. Akazawa, M. Uo, T. Akasaka), Vol.5, pp. 210-213. 

It was also observed in earlier studies that mitochondria not only accumulate Ca2+ as an alternative to phosphorylation of ADP (Ca2+ uptake uncouples phosphorylation from electron transport), but could also accumulate much larger amounts of Ca2+ if phosphate was also taken up, resulting in precipitation of Ca2+ within the matrix as insoluble hydroxyapatite, visible as electron-dense granules by EM. An unusual feature of these hydroxyapatite deposits is that they fail to become crystalline and remain amorphous even over protracted periods of time. Their presence in mitochondria in a number of disease conditions underlines the role for mitochondria as a sort of safety device, which can enable the cell to survive, if only for a limited period of time, situations of cytoplasmic Ca2+ overload. 

Ostomel TA, Shi QH, Tsung CK, Liang HJ, Stucky GD (2006) Spherical bioactive glass with enhanced rates of hydroxyapatite deposition and hemostatic activity. Small 2 1261-1265. 

Fluoride ion, F", replaces hydroxide in the normal hydroxyapatite deposits in bone. This replacement causes a hardening of the teeth and protects them from decay. Too much fluoride will cause mottling (discoloration). Fluoride is toxic but is tied up preferentially in bone and once released has such a low solubility in water that it is not believed to reach toxic levels. 

Forsgren, J. et al.. Formation and adhesion of biomimetic hydroxyapatite deposited on titanium substrates, Acta Biomater., 3, 980, 2007. 

Biomimetic hydroxyapatite deposition routes were investigated on titanium oxide surfaces (Xia etal., 2011), silicon nitride (Chaves Guedes e Silva etal., 2008), wollastonite (Huang, Jiang and Tan, 2004), canasite (Ca5Na3K3Si12O30(OH,F)4) glass ceramic (Miller etal., 2002) and also pyrolytic carbon and carbon-carbon composite (CCC) ceramics (Hoppe etal., 2013). 

Figure 5.15 Morphological changes of carbonated hydroxyapatite deposited by the thermal substrate technique from a solution containing 0.7 mmol CaCI2 and 0.3 mmol Ca(H2P04)2 with varying amounts of NaHCOj (a and b) as well as collagen I added (c and d). (a) Carbonated HAp with type B substitution (+0.5 mmol NaHCOj, 140 °C, 15 min).

De Sena, A., de Andrade, C., Malta Rossi, A., and de Almeida Soares, G. (2002) Hydroxyapatite deposition by electrophoresis on titanium sheets with different surface finishing. /. Biomed. Mater. Res., 60 (1), 1-7. 

Kuroda, K., Ichino, R., Okido, M., and Tokai, O. (2002a) Effect of ion concentration and pH on hydroxyapatite deposition from aqueous solution onto titanium by the thermal substrate method. Biomed. Mater. Res., 61, 354-359. 

Singh, R.P. and Batra, U. (2013) Effect of cold spraying parameters and their interaction on hydroxyapatite deposition. /. Appl. 

Early studies in experimental models suggested that hydroxyapatite deposition is not detectable until 12-24 h after infarction (Bonte et al. 1974). 

Most of the data available on this topic refer to hydroxyapatite deposited by plasma spraying. Although compounds may form at the metal/hydroxy-apatite interface, particularly in the case of titanium, their existence has not been unequivocally demonstrated. Titanium phosphates and phosphides, as well as calcium titanates, may exist, but they probably form very thin layers. The large surface roughness, caused by grit blasting of the substrate prior to hydroxyapatite deposition, is another factor that renders identification of any interfacial compounds by surface analysis techniques difficult. 

Tretinnikov, O. N., Kato, K., and Ikada, Y. (1994). In vitro hydroxyapatite deposition onto a film surface-grafted with organo phosphate polymer. J. Biomed. Mater. Res. 28 1365-1373. 

Zinc added to bioglasses improve their chemical durability, mechanical properties and endows antimicrobial activity moreover, the release of small concentration of zinc incorporated into an implant material promotes bone formation around the implant and accelerates recovery of the patients, improve adhesion of denture adhesives, etc... Still, it is important to control the Zn releasing rate in order to prevent adverse reactions and to optimize the glass composition to reduce glass degradation without affecting the hydroxyapatite deposition. 

The intra-articular involvement of calcium hydroxyapatite deposition disease—a condition more commonly referred to as calcifying tendinitis because of the involvement of tendons near to their osseous insertion—may produce an acute arthritis (chronic apatite arthropathy) possibly mimicking an infectious condition (see Chapter 6). 

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