Biomedical subjects

F C Driessens

Publications and source records attributed to F C Driessens.

At least 19 recordsLinked to original sources

PubMed1992

Acid-susceptibility of lesions in bovine enamel after remineralization in the presence of fluoride and/or carbonate.

After de- and subsequent remineralization at 0.03 and 1.0 ppm fluoride and either 0, 1, 10, 20 or 25 mM carbonate, artificial lesions in bovine enamel were demineralized again. The amount of secondary demineralization was determined after 15, 30 and 70 h of demineralization by means of quantitative microradiography. The results showed that fluoride incorporated during the remineralization period retards lesion formation during secondary demineralization. Carbonate incorporated during the remineralization period enhances secondary demineralization. An interaction between both ions was observed.

Animals↗

PubMed1992

Influence of fluoride and pH on in vitro remineralization of bovine enamel.

Subsurface lesions in bovine enamel slices were remineralized. The remineralization solutions contained either 0.03, 0.3, or 1.0 ppm fluoride at either pH 5.5 or 6.8. The amount of remineralization was determined after periods of up to 610 h, using quantitative microradiography. The results showed that after 126 h of remineralization in the presence of 0.03 ppm fluoride significantly (p less than 0.05) more remineralization occurred at pH 6.8 than at pH 5.5. At 0.3 and 1.0 ppm fluoride no significant differences between pH 5.5 and pH 6.8 were observed. An interaction between fluoride and pH was observed. The observed differences in the rates of remineralization are explained by the formation and subsequent transformation of the precursors octacalcium phosphate (pH 6.8) and brushite (pH 5.5) into (fluor)apatites.

Animals↗

PubMed1992

The influence of various amphiphilic phosphates on in vitro caries lesion formation in human dental enamel.

Some newly designed surface-active phosphates were investigated with respect to their capacity to inhibit caries lesion formation in vitro. On the labial or buccal surfaces of sound human third molars, windows were prepared for investigation. One half of each window was treated with the test compound at pH values of 7.5, 5.5, or 3.5. The other half served as a control. Both halves were demineralized and the generated caries lesions in both parts were compared by means of quantitative microradiography. Mono-, bis- and trisphosphates differed only marginally in their effect on the demineralization. The compounds diminished the demineralization down to 30% of that of untreated enamel. Per molecule at least one long alkyl chain (more than 12 C atoms) was required for achieving decreased demineralization, indicating the importance of a low surface tension. The results suggest that some of the tested compounds have promising properties for their use as anticaries agents, especially when applied in combination with fluoride.

Dental Caries↗

PubMed1991

In vitro remineralization of caries lesions treated with surface-active phosphates.

Intact human enamel was demineralized in vitro to obtain artificial caries lesions. Part of the lesions was then treated with different surface-active compounds and remineralized with a remineralizing solution. The other part of the lesions was de- and remineralized in the same way, but was not treated with a surface-active compound. The results indicate that none of the surface-active compounds do affect the remineralization of the caries lesions. Possible applications of the tested compounds in combination with fluoride, for the prevention of dental caries, are discussed.

Dental Caries↗

PubMed1991

Effect of 2-O-stearoyl glycerol-1,3-bisphosphate on in vitro demineralization of dental root surfaces.

The effect of 2-O-stearoyl glycerol-1,3-bisphosphate (Glydip) on caries lesion formation in root surfaces of sound human third molars was investigated in vitro. For this purpose parts of the root surfaces were treated with Glydip. Adjacent parts of the surfaces were not treated and served as control. Lesions were obtained by demineralization with an acetate buffer of pH 5.0. It was found that Glydip had no inhibiting effect on the rate of lesion formation. Additionally, pretreatments were performed with lauryl sulphate, a chloroform-methanol mixture, an aqueous solution of sodium hypochlorite, and collagenase prior to the treatment with Glydip to enhance the accessibility of the tissue for Glydip. None of these pretreatments or combinations of them revealed an inhibiting effect of Glydip on the rate of caries lesion formation. This result is in contrast to the effect of Glydip on the demineralization of enamel.

Acid Etching, Dental↗

PubMed1991

The distribution of magnesium in developing rat incisor dentin.

Previous studies have shown that rat incisor dentin contains a considerable amount of magnesium that is distributed heterogeneously. The cementum-related dentin, especially its incisal portion, is richest in magnesium. It was the purpose of the present study to investigate the changes that occur in the magnesium content during dentin maturation. Cross-sections were prepared from rat incisors at the apical, middle, and incisal levels. By means of an electron microprobe, tracings were made of the Ca-, Mg-, and P- signal frequencies. Comparison of corresponding dentin layers within and between the cross-sections showed that the Mg/P molar ratio was always higher in the cementum-related dentin (CRD) than in the enamel-related dentin (ERD) and increased from the apex toward the incisal edge. Especially in the incisal cross-section, an increase in Mg/P was found from the older (peripheral) toward the younger (central) dentin layers. As the Mg/P ratio varied from 0.07 to 0.33, the Ca/P ratio was found to fluctuate from 1.48 to 1.15. The two ratios appeared to be highly correlated (r = -0.97; p less than 0.001), suggesting that Mg replaces Ca and is bound to phosphate.

Animals↗

PubMed1991

Influence of fluoride and carbonate on in vitro remineralization of bovine enamel.

The influence of fluoride, carbonate, and fluoride in combination with carbonate on the in vitro remineralization of bovine enamel was investigated with the use of a sandwich technique. After demineralization, enamel slices were subjected for 610 h to remineralizing solutions with 0.03 or 1.0 ppm fluoride. At each fluoride level, either 0, 1, 10, 20, or 25 mmol/L carbonate was tested. After 0, 22, 62, 126, 192, 329, and 610 h of remineralization, contact microradiographs were made by Cu K alpha-radiation. At 0.03 ppm fluoride, carbonate had an inhibiting influence on remineralization. At 1.0 ppm fluoride, the inhibiting influence of carbonate changed into a stimulation of remineralizatization at 20 and 25 mmol/L carbonate. At 0, 1, and 10 mmol/L carbonate, fluoride had an inhibiting influence on remineralization. The differences in remineralization between the groups were explained by events concerning crystal growth, i.e., different types of minerals might have precipitated with differences in precipitation rates, and retardation of a precipitation step might have occurred under the various remineralization conditions. There was a mutual influence of fluoride and carbonate on the remineralization process. We conclude that the composition of the remineralizing solution with respect to fluoride and carbonate concentrations is important for the remineralization process.

Animals↗

PubMed1991

Acid-susceptibility of lesions in bovine enamel after remineralization at different pH values and in the presence of different fluoride concentrations.

Artificial caries lesions were created in sound bovine enamel slices demineralized at pH 5.0. The lesions were then remineralized at either pH 5.5 or pH 6.8 in solutions containing either 1.5, 15, or 50 mumol/L fluoride. The remineralized slices were then demineralized at pH 5.0 for investigation of acid-susceptibility by means of quantitative microradiography. The results indicated that fluoride, incorporated during the preceding remineralization, had a retarding effect on the demineralization after remineralization, and that for the lowest concentration of fluoride in the remineralizing solution, the inhibitory influence of fluoride depended on the pH of the remineralization solutions used.

Acids↗

PubMed1991

The effect of 2-O-stearoyl-glycerol 1,3-bisphosphate on the demineralization of dental enamel in vitro.

Parts of the buccal and lingual enamel surfaces of sound human third molars were treated with a test compound, and the non-treated parts served as control. After the treatment both parts were demineralized, and the artificial caries lesions were analyzed by means of quantitative microradiography. Treatment during only 1 minute with an aqueous solution of 1.5 mmol/l of the surface active compound 2-O-stearoyl-glycerol 1,3-bisphosphate (Glydip) resulted in a decrease in the rate of enamel demineralization by about 60%. When Glydip was dissolved in a toothpaste/water slurry it inhibited the demineralization by about 30%. When the enamel was covered by a salivary pellicle prior to the application of the slurry, the inhibition of the demineralization disappeared. However, when Glydip was applied in an aqueous solution, the presence of a salivary pellicle did not interfere with the decreasing effect of Glydip on the demineralization. It is concluded that Glydip has promising properties for its use as an anti-caries agent, in combination with fluoride.

Dental Caries↗

PubMed1990

Zinc deficiency-induced changes in the lipid composition and ultrastructure of rat incisor teeth.

The lipids and ultrastructure of the forming, maturing and erupted parts of incisors were compared in rats fed a zinc-deficient diet for 28 days, pair-fed rats and control rats. The lipid levels in the forming portions of zinc-deficient incisors were 30-50% below control levels and were associated with longer Tomes' processes in the secretory ameloblasts, porosities in the forming enamel and fewer malachite green-aldehyde-phospholipid aggregates in the predentine. No marked structural changes were seen in the erupted portions of the teeth, although variations in lipid composition were detected both in the maturing and erupted parts. No differences were found between teeth from the 3 groups of animals for Na, Mg, Cl, Ca and P signals with the electron microprobe.

Animals↗

PubMed1990

Influence of fluoride on in vitro remineralization of artificial subsurface lesions determined with a sandwich technique.

Remineralization experiments of bovine enamel with subsurface lesions were carried out with the use of a sandwich technique. The remineralizing solutions contained no or 2 ppm fluoride added to the solution. The amount of remineralization was determined after remineralization periods up to 324 by means of quantitative microradiography. After 84 h the group with fluoride showed significantly (p less than 0.05) less remineralization than the nonfluoride group. This inhibition of fluoride on the remineralization may be explained by the inhibiting effect that fluoride at certain concentrations has on the crystal growth of apatites.

Animals↗

PubMed1990

Effect of X-ray irradiation on the permeability of bovine dental enamel.

To estimate permeability properties of bovine dental enamel, complex impedance measurements and radioisotope diffusion experiments were carried out before and after X-ray irradiation (single dose, 72 Gy) of enamel specimens. Neither impedance measurements nor diffusion experiments showed significant changes in permeability.

Animals↗

PubMed1990

Is systemic treatment of osteoporosis and mandibular resorption possible?

It is argued that mandibular resorption can be considered as osteoporotic in nature. This calls for a systemic approach in its treatment. One aspect mostly neglected is the tendency of bone to bind calcium and phosphate ions. A direct measure for this tendency is the difference in pH between the bone extracellular fluid and blood plasma with octocalcium phosphate. Calculation of these degrees of saturation of about 2000 data of blood plasma compositions given in the literature learned that calcitonin injections, estrogen replacement and magnesium supplementation increase the tendency of bone to bind calcium and phosphate ions and, hence, should be used in the therapy of mandibular resorption and of bone resorption in general.

Bone Resorption↗

PubMed1990

Aluminium in tooth pastes and Alzheimer's disease.

Epidemiological studies from Norway and England suggest a relation between the frequency of Alzheimer's disease and the concentration of aluminium in the drinking water. Estimates, made in this study, show that the role of aluminium from tooth pastes may be even more important than that from the drinking water. For that reason we determined in samples of tooth pastes taken from the BENELUX market which brands contained aluminium. This appeared to be the case for about 22% of the brands which according to the manufacturers cover about 60% of the market.

Aluminum↗

PubMed1990

[The use of aluminum-containing toothpaste and its potential risk].

Epidemiological studies from Norway and England suggest that there is a relation between the frequency of Alzheimer's disease and the concentration of aluminum in the drinking water. A recent Dutch study suggests further that the role of aluminum from tooth pastes may be even more important than that from drinking water. For this reason we determined in samples from the Belgian market which tooth pastes contained aluminium oxyhydroxide as abrasive. This happened to be the case in 5 out of 27 brands. It is not know to us which part of the market these tooth pastes represent.

Aluminum Hydroxide↗

PubMed1989

Plasma calcium difference between man and vertebrates.

1. Literature data about the plasma content of total calcium, ionized calcium and inorganic phosphate in healthy animals and man of different age and sex were collected. 2. It was established that under normal conditions ionized calcium is about 45% of total calcium. 3. The degree of saturation of these blood samples with respect to octocalcium phosphate OCP was calculated. 4. In young animals and man the blood plasma has a higher degree of saturation than in adult animals and man. 5. The blood plasma of healthy animals is supersaturated with respect to OCP during their whole life. 6. However, the blood plasma of healthy human adults is slightly undersaturated with respect to OCP.

Age Factors↗

PubMed1989

Effects of surface-active compounds on the demineralization of dental enamel.

Slices of bovine enamel and intact human enamel were treated with (a) a two-step treatment consisting of phytate followed by hexadecyl amine, or (b) 2-O-stearoylglycerol-1,3-diphosphate (Glydip), or (c) phosphatidic acid. The effect of these agents on the rate of caries lesion formation and on the permeability of dental enamel was quantitatively determined. Glydip had the most pronounced effect on lesion formation and showed a strong inhibiting effect on the rate of demineralization, combined with a reduction of the permeability. The results indicate that at least a part of the effect of Glydip on the demineralization was caused by a reduction of the rate of dissolution of the enamel mineral. The reduction in permeability may have had an additional effect.

Amines↗

PubMed1989

The influence of fluoride on in vitro remineralization of bovine enamel.

Remineralization experiments using bovine enamel were carried out with 2 ppm fluoride or no fluoride added to the remineralizing solutions. The group without fluoride showed (quantitative microradiography) significantly more remineralization in the first 50 microns of the lesion than the fluoride group. It is suggested that fluoride may inhibit remineralization.

Animals↗