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At least 73 records · Page 4Linked to original sources

Albumin interaction with caries-like lesions in bovine enamel.

The exposure of bovine enamel to an albumin-containing demineralizing solution results in penetration of protein into the porous enamel. Washing of this albumin-containing enamel results in a complete (low pretreatment albumin concentrations) or partial removal of the albumin (pretreatment concentrations greater than or equal to 200 micrograms/ml-1). Subsequent exposure to increasing salt concentrations of fluoride, phosphate, calcium or chloride shows a partial removal of albumin at fluoride or phosphate concentrations of 75 mM while complete removal occurred at 150-200 mM fluoride or phosphate. Exposure to either calcium or chloride, even at 3 M concentrations, showed a negligible albumin release. It is proposed that protein removed at high fluoride or phosphate concentrations is bound by a strong interaction between protein-carboxyl groups and calcium on the surface of the enamel mineral. The partial removal of albumin released at low fluoride or phosphate concentrations indicates an enamel-albumin interaction by means of Ca-bridging between protein-carboxyl groups and mineral phosphates. Finally, it is suggested that salt-free washing removes albumin that has lost its native form upon binding to the partially dissolved crystallites of the enamel. It is concluded that enamel is mainly protected from demineralization by the inhibitory effects of protein penetrated into the pores, in addition to possible protection by the pellicle on the surface.

Albumins↗

[The effect of calcium glycerophosphate and Remodent on the dental enamel permeability in dogs with fluorosis].

In 14 dogs aged 6 months with severe fluorosis, the authors studied the effects of intake of calcium glycerophosphate and local remodent application on 45Ca enamel incorporation and the depth of its penetration into the dental hard tissues. The treatment led to a substantial decrease in both enamel 45Ca accumulation and the depth of its penetration under severe fluorosis. Combined use of the drugs was more beneficial in terms of enamel 45Ca permeability.

Animals↗

Influence of tooth cryopreservation on human dentin permeability, in vitro.

OBJECTIVES: In order to use cryopreserved teeth in laboratory studies, cryopreservation must not modify the functional properties of teeth, in particular dentin permeability. The purpose of this study was to evaluate the effects of tooth cryopreservation on human dentin permeability. METHODS: Three hundred and sixty freshly extracted human noncarious third molars were used. The teeth were randomly assigned to two groups: 180 teeth were stored in phosphate-buffered saline at 4 degrees C and tested within 4 h of collection; 180 teeth were cryopreserved. Hydraulic conductance was calculated according to the method developed by Pashley (Outhwaite et al., 1976). RESULTS: Cryopreserved teeth presented a hydraulic conductance of 8.97 x 10(-3) +/- 4.21 x 10(-3) microL.cm-2.min-1.cm.H(2)0(-1) slightly higher than the hydraulic conductance of the freshly extracted teeth of 8.03 x 10(-3) +/- 3.87 x 10(-3) microL.cm-2.min-1.cm.H(2)0(-1). No statistically significant difference was found between the two groups. SIGNIFICANCE: Under the conditions of this study, cryopreservation did not modify dentin permeability.

Analysis of Variance↗

Clinical and experimental observations on resinifying therapy.

The principles, indications, and techniques of resinifying therapy and the composition of a resinifying agent are described in this article. The permeability and bacteriostasis of the agent and the volume change of the agent after treatment were observed, and 14C-labeled phenoaldehyde showed that the agent not only filled the main canals and accessory canals but also infiltrated into dentinal tubules with a depth one fourth to one third the total length of the tubules. The antimicrobial activity of the agent after polymerization for 2 to 6 months was determined. Even 9 months after treatment, no change in volume of the agent was found in vivo, and sealing of canals was maintained. Seventy-eight teeth in 69 patients with pulpoperiapical diseases were subjected to resinifying therapy and followed up for 6 to 12 months; the success rate was 82.05%. The histologic study indicated that, of the specimens experimentally treated for 6 to 12 months, 85.7% showed mild or no inflammation while 53.6% showed complete healing or an obvious healing tendency. Furthermore, the mechanisms and advantages of this therapy are discussed.

Animals↗

A theoretical model for the hydraulic conductance of human dentine.

A theoretical model was devised that describes the dependence of the hydraulic conductance of dentine disks on the decrease in dentine tubule radius and dentine tubule density (number per area of cross-section) in the pulp-enamel direction. A parameter that describes the decrease in tubule radius was calculated from experimental results from the literature.

Chemical Phenomena↗

Dentin permeability: determinants of hydraulic conductance.

A technique is described which permits measurements of the ease with which fluid permeates dentin. This value, the hydraulic conductance of dentin, increased as surface area increases and/or as dentin thickness decreases. It increased 32-fold when dentin was acid etched due to removal of surface debris occluding the tubules.

Acid Etching, Dental↗

The relationship among the permeability to iodide, pore volume, and intraoral mineralization of abraded enamel.

The results indicate that Ip measurements are fairly closely related to the pore volume of the enamel to a depth of about 13 micrometer. A previous finding - that intraoral exposure produced substantial mineralization of abraded enamel after one h, and a slower rate of mineralization during the next two h - was confirmed, and it was shown that the rate of mineralization decreased with a decrease in the pore volume of the enamel. The rapid rate of intraoral mineralization represents a powerful mechanism for maintaining a fully mineralized enamel surface. The sensitivity of the Ip method demonstrated in this study, and the finding that Ip measurements relate to the pore volume of the enamel, coupled with previous findings that the increase in Ip produced by mild acid etching of intact enamel is proportional with the amount of dissolved Ca, indicate that the method provides valid measurement of intraoral de- and remineralization.

Acid Etching, Dental↗

[Studies of the permeability of human dentin Part I: Basic studies of constant physiological parameters and experimental variables (author's transl)].

Diffusion processes proceeding in the dentin are of fundamental scientific interest and of major importance to numerous therapeutical measures, with the permeability of dentin playing an essential role. Their exact quantitative determination is possibly in vitro only and depends upon various factors. Relevant investigative results obtained using standardized parameters and the methods employed are subjected to a critical analysis and interpreted with regard to the possibility of using them for specific comparative studies. The results reported in this paper are only indirectly applicable to clinical studies. However, they can considered a useful starting point for further studies.

Adult↗