Octacalcium phosphate and apatite overgrowths: A crystallographic and kinetic study

Nelson, Douglas C.; Salimi, Hesam; Nancollas, G.H.

doi:10.1016/0021-9797(86)90350-4

Cited by 27 publications

(12 citation statements)

References 23 publications

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“…This morphology is ascribed to the initial formation of OCP Nelson et al, 1986;Terpstra and Bennema, 1987;lijima and Moriwaki, 1991 , and (2) the growth reaction on the side prism planes is characterized by the advancement of growth steps corresponding to one or a few unit-cell thicknesses (Aoba and Moreno, 1984). These discrete morphological features support the theoretical view that different growth mechanisms may act simultaneously on discrete crystal surfaces of a salt (Heughebaert and Nancollas, 1984).…”

Section: Driving Force For Precipitation Of Calcium Phosphatessupporting

confidence: 56%

“…The techniques that have made particular contributions include various types of spectroscopies, e.g., Fourier-transform infrared (FTIR) (Rey et al, 1989(Rey et al, , 1991Pleshko et al, 1991) and FTRaman (Sauer et al, 1994), extended x-ray absorption fine structure (EXAFS) (Harries et al, 1987), magic angle spinning-nuclear magnetic resonance (MAS-NMR) (Yesinowski and Eckert, 1987;White et al, 1988White et al, , 1994Wu et al, 1994). High-resolution electron microscopy (Nelson and McLean, 1984;Nelson et al, 1986;Bres et al, 1989;Cuisinier et al, 1990;lijima et al, 1992a,b;Miake et al, 1993) has allowed us to view the details of lattice structures, including a variety of defects.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Fluoride On Apatite Structure and Growth

Aoba

1997

Critical Reviews in Oral Biology & Medicine

186

120

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Fluoride participates in many aspects of calcium phosphate formation in vivo and has enormous effects on the process and on the nature and properties of formed mineral. The most well-documented effect of fluoride is that this ion substitutes for a column hydroxyl in the apatite structure, giving rise to a reduction of crystal volume and a concomitant increase in structural stability. In the process of enamel mineralization during amelogenesis (a unique model for the cell-mediated formation of well-crystallized carbonatoapatite), free fluoride ions in the fluid phase are supposed to accelerate the hydrolysis of acidic precursor(s) and increase the driving force for the growth of apatitic mineral. Once fluoride is incorporated into the enamel mineral, the ion likely affects the subsequent mineralization process by reducing the solubility of the mineral and thereby modulating the ionic composition in the fluid surrounding the mineral, and enhancing the matrix protein-mineral interaction. But excess fluoride leads to anomalous enamel formation by retarding tissue maturation. It is worth noting that enameloid/enamel minerals found in vertebrate teeth have a wide range of CO3 and fluoride substitutions. In the evolutionary process from elasmobranch through teleost enameloid to mammalian enamel, the biosystems appear to develop regulatory functions for limiting the fluoridation of the formed mineral, but this development is accompanied by an increase of carbonate substitution or defects in the mineral. In research on the cariostatic effect of fluoride, considerable emphasis is placed on the roles of free fluoride ions (i.e., preventing the dissolution and accelerating the kinetics of remineralization) in the oral fluid bathing tooth mineral. Fluoride also has been used for the treatment of osteoporosis, but much still remains to be learned about maximizing the benefit and minimizing the risk of fluoride when used as a public health measure.

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Section: Driving Force For Precipitation Of Calcium Phosphatessupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

The Effect of Fluoride On Apatite Structure and Growth

Aoba

1997

Critical Reviews in Oral Biology & Medicine

186

120

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“…The results of a high-resolution transmission electron microscopic method demonstrated the overgrowth of OCP on apatite prepared using the CC method with either OCP or dental enamel seed material (Nelson et al, 1986). In some cases it was possible to image the OCP-apatite interface using the high-resolution TEM at -2.5 A resolution.…”

Section: Growth Of Calcium Phosphatesmentioning

confidence: 98%

Mineral phases of calcium phosphate

et al. 1989

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Many studies of calcium phosphate precipitation have been made using relaxation techniques in which the concentrations of the lattice ions are allowed to decrease as equilibrium is approached. Since the nature of the phases that form depend markedly on the solution composition, this decrease can lead to concomitant phase transformations during the crystallization experiments. The results of the present constant composition (CC) studies show that defect apatites may be formed under conditions of sustained supersaturation with a non-stoichiometric coefficient dependent on the pH of the growth medium. An important factor in analyzing these experiments is the initial surface modification and ion-exchange processes involving H+ and Ca2+ ions after inoculation of the supersaturated solutions. Thereafter, active growth sites may be eliminated as the crystals undergo lattice perfection. Transformation of dicalcium phosphate dihydrate to octacalcium phosphate, involving dissolution and subsequent nucleation and growth of the new phase, is also influenced by surface roughening of the initial phase. Typical inhibitors that reduce the rate of growth of seed crystals in supersaturated solutions may actually induce the nucleation of calcium phosphate phases when immobilized on inert surfaces. This may be a factor in the modulation of crystal growth in many biological systems.

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“…In addition, calcium phosphate compounds are involved in wastewater treatment processes, in agriculture as fertilizers, and in industrial water systems as hard deposits on heat exchanger surfaces. During the precipitation process at ambient temperature, the following calcium phosphate phases have been shown to be formed depending upon the level of supersaturation, pH, and ionic medium: dicalcium phosphate dihydrate (CaHP04.2H20, DCPD), octacalcium phosphate (Ca8H2(P04)6-5H20, OCP), tricalcium phosphate (Ca3(P04)2, TCP), hydroxyapatite (Ca5(P04)30H, HAP), and amorphous calcium phosphate, ACP (6)(7)(8)(9). Results of previous studies have shown that the kinetically favored precursor phases such as ACP, DCPD, OCP, and TCP are formed prior to the formation of the thermodynamically stable HAP phase.…”

Section: Introductionmentioning

confidence: 99%

Constant composition study of crystal growth of dicalcium phosphate dihydrate. The influence of polyphosphates, phosphonates, and phytate

Amjad¹

1988

Can. J. Chem.

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The influence of inhibitors of varying functional groups on the crystal growth of calcium phosphate dihydrate (CaHP04.2H20, DCPD) on DCPD seed crystals at pH 6.00,37"C, has been studied using the constant composition technique. The inhibitors studied include: (a) polyphosphate (sodium pyrophosphate, sodium hexametaphosphate, SHMP), (b) phosphonates (nitrilotris(methy1ene phosphonic acid), NTMP; I-hydroxyethylidene-1,l-diphosphonic acid, HEDP; ethylenediaminetetra (methylene phosphonic acid), ETMP; hexamethylenediaminetetra(methy1ene phosphonic acid), HMDP); and (c) myoinositol hexaphosphoric acid (phytic acid). The effect of these inhibitors on the growth kinetics have been studied at several inhibitor concentrations. The retarding effect of these inhibitors is discussed in relation to calcium-inhibitor complex formation on the DCPD seed crystals and the structural features of the inhibitor molecules. The fit of the Langmuir adsorption to experimental data supports a mechanism of inhibition through molecular adsorption of the inhibitor ions on the surface of growing crystals. Based upon the kinetic data, the overall order of inhibitors effectiveness is ETMP > HMDP > phytic acid > hexametaphosphate > HEDP > pyrophosphate ZAHID AMJAD. Can. J. Chem. 66, 2181 (1988. OpCrant a un pH de 6,0, i une tempkrature de 37°C et utilisant la technique de la composition constante, on a CtudiC l'influence des inhibiteurs portant divers groupements fonctionnels sur la croissance cristaux de phosphate de calcium dihydrate (CaHP04.2H20, DCPD) sur des cristaux de DCPD ensemences. Les inhibiteurs examinks comportent; (a) des polyphosphates (pyrophosphate de sodium, hexamCtaphosphate de sodium, HMPS), (b) des phosphonates (nitrilotris(acide methylkne phosphonique), NTMP; acide hydroxy-1 tthylidkne diphosphonique-1,1, HEDP; Cthyl&nediaminetCtra(acide mCthylkne phosphonique), HMDP; et (c) l'acide hexaphosphorique du myoinositol (acide phytique). On a CtudiC l'effet de ces inhibiteurs sur la cinCtique de la croissance i plusieurs concentrations d'inhibiteurs. On discute de l'effet retardant de ces inhibiteurs en

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Octacalcium phosphate and apatite overgrowths: A crystallographic and kinetic study

Cited by 27 publications

References 23 publications

The Effect of Fluoride On Apatite Structure and Growth

The Effect of Fluoride On Apatite Structure and Growth

Mineral phases of calcium phosphate

Constant composition study of crystal growth of dicalcium phosphate dihydrate. The influence of polyphosphates, phosphonates, and phytate

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