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PubMed1978

Influence of the pulpal route on uptake of 45Ca in enamel and dentin of developing rat molars.

45Ca uptake in developing enamel and dentin was studied by autoradiography. The findings indicate that the pulpal route does not supply significant amounts of calcium to the rapidly mineralizing enamel. Disruption of the odontoblastic layer did not seem to result in altered penetration of calcium into the dentin in a manner similar to that described for disruption of the matrix secreting cell layer of enamel and of bone.

Animals↗
PubMed1979

A non-destructive optical method to study de- and remineralization of enamel.

The absorption and scattering of light in dental enamel or in a carious lesion have been studied quantitatively by using thin slabs. The method thus required destructive preparation techniques. In this paper we describe how the scattering by a bulk sample can be used to obtain semi-quantitative information.

Animals↗
PubMed1979

Human dentition and experimental animals.

A review of the recent literature concerning enamel maturation patterns following cessation of protein matrix secretion confirms that developing rodent enamel exhibits an overall mineral distribution different from that of developing enamel in man, monkey, dog, and swine. This seems to be a result of structural differences of the enamel as the pattern of crystal growth appears similar in these species. Whether the differences in enamel structure are reflected in significant differences in cellular events leading to enamel formation and mineralization remain unknown, as detailed radioautographic and ultrastructural studies almost always have dealt with rodent teeth. It is therefore concluded that such studies should be initiated in experimental animals having an enamel formation and mineralization pattern strictly comparable to that of man. Some requirements for such an experimental animal are suggested.

Ameloblasts↗
PubMed1979

Enamel protein chemistry--past, present and future.

Past progress in the chemistry of enamel proteins is reviewed and the current state of knowledge assessed. The matrix of young enamel is a complex system in which some 20 distinct components with molecular weights in the region of 3,000 to 16,000 are in dynamic equilibrium with much larger aggregates. During maturation, most of these components are selectively lost, more or less completely, from the enamel. 'Amelogenin' components rich in proline and histidine are removed first and 'tuft protein', characterized by high serine and glycine, is often partially retained in mature enamel. Some components have been isolated in a state approaching purity and a measure of agreement has been reached between laboratories concerning their characteristics. Partial amino acid sequences are known for two components, which contain phosphoserine. Though the mechanisms of mineralization and protein removal are not known, various possibilities are discussed. The essential unsolved problem is the nature of the overall protein system.

Amelogenesis↗
PubMed1979

Enamel apatite nucleation and crystal growth.

The course of enamel remineralization in aqueous solution is markedly dependent upon factors such as ionic medium supersaturation, pH, ionic strength, and the relative concentration of mineralizing surface. Although numerous attempts have been made to determine the mechanism of both the spontaneous and seeded precipitation reactions, it is only recently, through the use of a constant solution composition technique, that quantitative information can be obtained concerning the intermediate calcium phosphate phases which are formed during mineralization. Studies of surface phases in the presence of potential anti-calculus and anti-caries agents are facilitated using this approach.

Apatites↗
PubMed1979

Patterns of enamel maturation.

Investigations of the maturation pattern of rat incisor enamel by quantitative electron microscopy and electron-probe microanalysis indicate that mineralization of rat enamel can be regarded, as in humans, as a regular and progressive process pattern of enamel matrix formation. The species variations that have been proposed in the pattern of enamel mineralization can be related to differences in both the rate of formation of the enamel matrix and in the total thickness of the enamel produced. Neither the microradiographic appearance of developing enamel, nor the solubility and staining characteristics of the organic matrix accurately reflects the mineral concentration gradients established during the mineralization process as indicated from electron microprobe analysis.

Ameloblasts↗
PubMed1979

Demineralization and remineralization of dental enamel.

Experimentation in vitro using organic acid buffers as demineralizing media shows that caries-like lesions can be obtained which are very similar in morphology and developmental stages to early lesions formed naturally under oral conditions. The use of these chemical systems and of mechanistic models advanced to explain the unique histological features of incipient caries have yielded a good understanding of the processes involved in caries formation. The study of natural and induced factors influencing the demineralization process has been greatly facilitated by the use of bacteriological systems in which demineralization is produced by direct colonization of cariogenic microorganisms on the surfaces of extracted teeth. Comparison of results obtained with these latter systems and with chemical systems has allowed us, for example, to elucidate the mechanism by which acquired salivary pellicles and fluoride topical solutions decrease the rate of enamel demineralization. The pellicle retards transport of matter across the enamel surface, whereas the fluoride topical solutions decrease the cariogenicity of the colonizing bacteria.

Acids↗
PubMed1979

Modification by salivary pellicles of in vitro enamel remineralization.

The effectiveness of inorganic calcifying solutions to remineralize enamel with subsurface demineralization decreased with saliva pre-treatments conducive to the formation of enamel pellicles. Greater reductions in remineralization rates occurred with longer pellicle formation times. It is suggested that enamel pellicles may act to control surface deposition and favor subsurface precipitation.

Calcium Phosphates↗
PubMed1980

In vivo remineralization using a sustained topical fluoride delivery system.

The efficacy of a new remineralization system was determined in vivo by maintaining a low concentration of approximately 1 ppm fluoride for 48 hrs against a demineralized human tooth. Human subjects were selected who wore removable partial dentures containing two or more of the demineralized teeth with film system. The findings indicate levels of fluoride uptake to 500 ppm at 50 micron depths in experimental sites.

Delayed-Action Preparations↗
PubMed1980

Effects of fluoride in remineralized human surface enamel on dissolution resistance.

Remineralized surfaces of human tooth enamel were dissolved at constant rates in 10 mM acetic acid at pH 4.0, and in 10 mM EDTA at pH 7.4 in a system that prevented redistribution of dissolved F-. Surfaces remineralized 25 hours in 0.4 mM NaF (8 ppm F-) dissolved slower in acid or in EDTA than those remineralized in the absence of F-. The F- in three-hour remineralized surfaces had no effect on rates of mineral dissolution. Resistance to EDTA, as well as acid of 25-hour remineralized surfaces, indicates the occurrence of a maturation process, which may involve F- exchange for OH- ions in newly formed crystals. The results indicated that F- may slow caries by its action on remineralization if given sufficient time for this maturation.

Acetates↗
PubMed1981

The mineralization of enamel surfaces. A constant composition kinetics study.

The in vitro remineralization of acid-etched enamel surfaces offers an attractive model for simulating carious lesion recalcification and the repair of teeth in the oral environment. In the present work the influence of the extent of etching with hydrochloric and phosphoric acids has been examined. The kinetics of growth of hydroxyapatite as an exclusive phase on the pretreated enamel surfaces has been studied by means of a constant solution composition procedure. This method enables studies to be made at low constant supersaturations so that the stoichiometry of the precipitating phase may be defined. The very small rates of mineralization with HAP were determined with a precision hitherto unattainable. In addition, the influence of fluoride ion in enhancing the remineralization of damaged enamel has been investigated.

Animals↗
PubMed1981

The kinetics of mineralization of human dentin in vitro.

The prospect of restoration of damaged dental tissues has recently attracted great interest. An understanding of the remineralization of human dentin in vitro was attempted by using super-saturated calcium phosphate solutions at sustained supersaturation by means of a constant solution composition method. The direct growth of HAP from solutions of low supersaturation on powdered whole human dentin was confirmed. Moreover, it was found that the kinetics were similar to those of the seeded growth at synthetic HAP. A high apparent activation energy pointed to a surface-controlled mechanism.

Calcium Phosphates↗
PubMed1982

The remineralization of fluoride-treated bovine enamel surfaces.

Various etching methods are examined with respect to their ability to induce the surface nucleation and growth of fluorapatite from solutions of low, sustained supersaturation with respect to hydroxyapatite and fluorapatite. The constant composition kinetics method enables the rates of remineralization to be precisely determined, and the possibility of the direct growth of fluorapatite on calcium fluoride crystals in calcium phosphate solutions of low supersaturation has also been examined.

Acid Etching, Dental↗
PubMed1982

The pattern of mineralization of traumatically-induced developmental defects of sheep enamel assessed by microhardness and microradiography.

An earlier study showed that some of the variation in appearance of defects of enamel in sheep incisor teeth induced by trauma during tooth development was related to the phase of activity of the ameloblasts at the time of injury. In the present study, sixteen selected defects were examined by microhardness and microradiography. It was found that in some of the fully formed teeth, the defects had retained the pattern of mineralization present at the time of trauma, i.e., mineralization had ceased. In other teeth, further mineralization of the defects occurred after trauma, resulting in well-mineralized enamel, although sometimes of incomplete thickness. It was concluded that the trauma, depending on its severity, leads to either permanent or temporary dysfunction of the ameloblasts, which also influences the appearance of the resulting lesions.

Ameloblasts↗