Enamel apatite

The 8 C values of the Preclassic humans at Cuello (Table 2.1) average -12.9 0.9%o (n = 28) in collagen, -9.8 1.0 in bone apatite (n = 16), and -8.7 2.3%o in tooth enamel apatite (n = 33) the S N values in collagen average 8.9 1.0%o (n = 23). The discrepancy in the number of specimens is due to the fact that more teeth were available than post-cranial material, while some of the specimens contained insufficient collagen to measure the nitrogen isotope ratios. Additional bone apatite analyses are in progress. 

Eanes, E.D. 1979 Enamel apatite chemistry, structure and properties. Journal of Dental Research Special Issue B 829-836. 

Ultrastructural properties of human enamel apatite. In Lazzari, E., ed.. Handbook of Experimental Aspects of Oral Biochemistry, Florida, CRC Press 159-179. 

Wilson, R.M., Elliott, J.C. and Dowker, S.E.P. (1999) Rietveld refinement of the crystallographic structure of human dental enamel apatites. American Mineralogist, 84, 1406-1414. 

M. lizima and Y. Moriwaki, In vitro study of the formation mechanism of tooth enamel apatite crystals - Effects of organic matrices on crystal growth of octacalcium phosphate(OCP),/.Japan. Assoc. Crystal Growth, 26,1999,175-83 (in Japanese with English abstract)... 

Nancollas GH Enamel apatite nucleation and crystal growth. J Dent Res 1979 58B 861-869. 

Ericsson Y Enamel apatite solubility. Acta Odontol Scand 1949 8(suppl 3) 1—139. 

As mentioned at the beginning of this review, the very large surface area of the crystals in bone makes it very problematical to try to determine the unit cell contents from the chemical composition of the mineral. With the much smaller surface area of the crystals in enamel, it is much more feasible and several formulae have been published (Elliott 1997). As the density of enamel apatite is not known, the absolute contents cannot be determined, so it is usually assumed that the number of ions in the phosphate sites... 

Aoba T, Moriwaki Y, Doi Y, Okazaki M, Takahashi J, Yagi T (1980) Diffuse X-ray scattering from apatite crystals audits relation to amorphous bone mineral. J Osaka Univ Dental School 20 81-90 Aoba T, Yagi T, Okazaki M, Takahashi J, Doi Y, Moriwaki Y (1981) Crystalhnity of enamel apatite an X-ray diffraction study of human and bovine-fetus teeth. J Osaka Univ Dental School 21 87-98 Bacon GE, Bacon PJ, Griffiths RK (1979) Stress distribution in the scapula studied by neutron diffraction. Proc Roy Soc London B204 355-362... 

Elliott JC (1997) Stmcture, crystal chemistry and density of enamel apatites. In Dental enamel (Ciba Foundation Symp 205). Chadwick D, Cardew G (eds) John Wiley Sons, Chichester, UK, p 54-67... 

Teeth are subjected to a continuous demineralization/mineralization process and, therefore, the apatite in enamel is modified in response to the microenvironment around the teeth. Applications of fluoride through toothpaste and drinking water result in the exchange of F for OIT in hydroxylapatite to form the more stable and acid resistant fluorapatite. Also, development of caries lesions is decelerated as dissolution removes carbonate and magnesium from the outer enamel layer, which further stabilizes the enamel apatite (Le Geros 1999). 

A probable example of vectorial crystal aggregation can be found in the biomineralization of calcium phosphate. With the exception of enamel apatite, the vast majority of the microscopic (0.1 /um) crystals of vertebrate apatite are observed to be embedded in an extracellular, largely collagenous, matrix. These crystallites are arranged at a late... 

Commonly, treatments of enamel white spot lesions have either been preventive (noninvasive), with a combination of fluoride-based remineralization [110] and readaptation of the patient s diet, or restorative (invasive), where the lesion is drilled and treated with the polymeric restorative materials and strategies described in sections Polymers in Dental Adhesion and Polymers in restorative composites resins . Recently, monomers that are commonly utilized for adhesive restorative treatments, or combinations thereof, were modified to enable impregnation of white spot lesions with photocrosslinkable materials of low viscosity (Fig. 9.3) [111]. The rational behind this strategy stems from the idea that the infiltrant occludes the lesion porosity and blocks further diffusion pathways for cariogenic acids [111]. Moreover, polymeric resins are much more resistant to acid degradation than enamel apatite is resistant to acidic dissolution, hence further cavitation is prevented after infiltration and photopolymerization (Fig. 9.2). 

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