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Biomedical subjects

J Arends

Publications and source records attributed to J Arends.

At least 199 records · Page 11Linked to original sources
PubMed1985

Protein loss of bovine dental enamel during in-vitro subsurface demineralization.

A chemical system based on the dialysis principle was used to study protein loss of dental enamel during demineralization with an acetic-acid buffer solution containing calcium and phosphate, in which the fluoride-ion activity was kept constant. This resulted in a subsurface lesion, with a depth of about 130 microns. After demineralization, protein material was isolated from the demineralization solution. u.v. Spectra of the protein showed strong absorbance between 240 and 300 nm. Amino-acid composition showed high glycine, glutamic acid, proline, serine and aspartic acid contents. After 10 days demineralization, the total protein loss was 3 micrograms cm-2; the mineral loss was 16 mg cm-2. Compared with the total enamel-protein content (0.06-0.09 wt per cent) protein loss (0.018 per cent of total lost material) was not proportional to the mineral loss, when a subsurface lesion was formed.

Amino Acids↗
PubMed1985

Quantified marginal leakage of composites in vitro.

In this in vitro study the marginal leakage of three composite systems--Sevriton, Consize and Isocap--has been quantified as a function of time. The method used (v.d. Veen et al., 1984) consists of the determination of the amount of nitrogen gas passing through restoration margins at 2 atm. The results show that the marginal leakage of all composites decreased strongly with time and became negligible after about 1 month. If we rank the three systems investigated according to their marginal leakage we have Consize greater than Isocap greater than Sevriton. The data suggest that water uptake and subsequent expansion of the polymers account for the leakage decrease.

Acid Etching, Dental↗
PubMed1985

Fluorine levels in in vitro remineralized enamel after treatment with 1000 ppm F as NaF, MFP or mixed solutions.

By means of secondary ion mass spectrometry (SIMS) an investigation has been made of the F uptake and the transport of fluorine-carrying ions in artificially carious human enamel after in vitro remineralization. The fluoridation was effected from solutions of pure Na2FPO3 (MFP), pure NaF, or mixtures of MFP and NaF, always with a total F content of 1000 atom-ppm. The recorded in depth profiles of F concentration show that, after 14 days of remineralization, 1) neither the acquired F levels nor the F distributions are greatly dependent on whether fluoridation is from NaF, MFP or mixtures, 2) the F distribution shape is not strongly influenced by a 3-month storage followed by remineralization, 3) the penetration of F beyond the lesion is generally deeper from NaF than from MFP, and 4) the effect of long storage on penetration depth is mainly noticeable for MFP-treated specimens.

Adult↗
PubMed1985

Adhesion of Streptococcus sanguis CH3 to polymers with different surface free energies.

The adhesion of the oral bacterium Streptococcus sanguis CH3 to various polymeric surfaces with surface free energies (gamma s) ranging from 22 to 141 erg cm-2 was investigated. Suspensions containing nine different bacterial concentrations (2.5 X 10(7) to 2.5 X 10(9) cells per ml) were used. After adhesion for 1 h at 21 degrees C and a standardized rinsing procedure, the number of attached bacteria per square centimeter (nb) was determined by scanning electron microscopy. The highest number of bacteria was consistently found on polytetrafluorethylene (gamma s = 22 erg cm-2), and the lowest number was found on glass (gamma s = 141 erg cm-2) at all bacterial concentrations tested. The overall negative correlation between nb and gamma s was weak. However, the slope of the line showing this decrease, calculated from an assumed linear relationship between nb and gamma s, appeared to depend strongly on the bacterial concentration and increased with increasing numbers of bacteria in the suspension. Analysis of the data for each separate polymer showed that the numbers of attached cells on polyvinyl chloride and polypropylene were higher but that those on polycarbonate were lower than would be expected on basis of a linear relationship between nb and gamma s. Desorption experiments were performed by first allowing the bacteria to attach to substrata for 1 h, after which the substrata and attached bacteria were removed to bacterial suspensions containing 10-fold lower bacterial concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adhesiveness↗
PubMed1985

Influence of repeated APF applications on long-term remineralization of initial lesions in bovine enamel.

Initial lesions in bovine enamel were remineralized in vitro for periods lasting from one hour to two weeks; in some cases, remineralization was interrupted daily for a ten-minute APF application. After two weeks, surface coatings appeared on APF-treated specimens; SEM and TEM observations, including selected area and micro-electron diffraction, indicated both a layered structure within these coatings, and the predominance of calcium fluoride single crystals, ranging from 0.1 to 1.0 micrometer in size. Using double (45 Ca and 32 P) labeled remineralizing solutions, we obtained depth profiles of deposited labeled calcium and phosphate; these indicated that repeated APF applications prevented inward penetration of calcium and phosphate and limited the deposition of these ions to an outer surface region corresponding to the surface coating. These phenomena are explained in terms of the composition and apparent reactivity of the coating.

Acidulated Phosphate Fluoride↗
PubMed1985

An in vivo investigation of the fluoride uptake in partially demineralized human enamel from several different dentifrices.

In this study, the total fluoride uptake in partially demineralized enamel from in situ brushing with six dentifrice systems was investigated in vivo among 22 panelists. Five dentifrices with different fluoride systems were compared with a placebo control. Two demineralized enamel discs were placed in proximal positions on specially fabricated dentures worn by each participant. Each treatment involved use of the placebo dentifrice for one week, followed by two weeks of twice-daily use of the test dentifrice. The F- contents of the dentifrices were: A = 1000 ppm F as Na2PO3F + 450 ppm F as NaF; B = 1100 ppm F as NaF; C = 1000 ppm F as Na2PO3F; D = 1000 ppm F as SnF2; E = 1500 ppm F as Na2PO3F; and P = 0 ppm F (placebo). The F- uptakes from A, C, D, and E were not significantly different from each other but were all significantly higher than the placebo. Statistical analysis showed a significantly higher F- level from the NaF-based paste B than that from all other systems. No differences existed between mesial-distal specimens; there was no correlation between F- uptake and age. Significant uptake differences were found between panelists with full and partial prostheses.

Adult↗
PubMed1985

The effect of a jet abrasive instrument (Prophy Jet) on root surfaces.

A Prophy Jet instrument was tested in order to analyze the abrasive effect and surface alterations on human root cementum and dentine. Photomicrographs from scanning electron microscopy (SEM) and a profilometer technique for depth analyses were used for evaluation. The results of the experiments demonstrated that the Prophy Jet technique had an abrasive effect reaching about 25 microns in depth after 30 seconds treatment. The root surface, cementum as well as dentine also became rougher after treatment judging from the SEM micrographs. Clinical advantages and disadvantages by using the Prophy Jet instrument will be discussed. Further studies seems to be justified concerning the jet abrasive technique.

Dental Cementum↗
PubMed1984

The hardness of bovine dentine after glutaraldehyde treatment.

Bovine dentine specimens were treated with glutaraldehyde 2% for periods of 10, 20 min. and 48 h. The differences in Knoop hardness were measured and evaluated. It can be concluded that treatment of bovine dentine with glutaraldehyde gives first a remarkable softening (+/- 15%); afterward the treated dentine is +/- 15% harder than untreated dentine.

Aldehydes↗
PubMed1984

Quantification of marginal leakage of amalgam restorations in vitro.

A method is described to quantify marginal leakage of amalgam restorations in vitro as a function of time. The method consists of the determination of the amount of nitrogen gas passing through the margins of the restoration at 2 atm. pressure in 30 min. The method described needs about sixteen specimen per experiment. The standard error is 20-30% of the mean leakage value and is independent of the type of condensation and the amalgam type. Two amalgams, the non-gamma 2-Dispersalloy and the conventional, Amalcap was compared longitudinally over a period of 4 months. The results showed: (1) The marginal leakage of Dispersalloy decreased strongly with time; the time dependency of Amalcap was less pronounced. (2) That carefully condensed Amalcap showed significantly less marginal leakage than Dispersalloy. (3) Whereas the marginal leakage of Amalcap was dependent on the condensation procedure, the leakage of Dispersalloy did not depend strongly on it.

Animals↗
PubMed1984

Quantitative cement solubility experiments in vivo.

The dissolution and dissolution rate of dental luting cements was measured longitudinally. Cement samples in enamel were placed in a full prosthesis and worn in the mouth for up to 6 months. At given intervals, replicas of the cement surfaces were made and quantified by means of SEM stereographic photographs. With a stereometer the distance between cement surface and original enamel surface can be determined quantitatively. The results show in vivo solubility rates for zinc-phosphate and glass-ionomer cement of about 80 microns week-1 and 2 microns week-1 respectively.

Animals↗