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J Arends

Publications and source records attributed to J Arends.

At least 55 records · Page 3Linked to original sources
PubMed1996

A micro-Raman spectroscopic study of hydrazine-treated human dental calculus.

Hydrazine has been used to remove organic components and to isolate the mineral(s) from human calculus. Micro-Raman measurements were performed on the mineral phase. After the hydrazine-treatment, not only a large reduction in fluorescence but also an increase in Raman signal was observed. The treatment was essential in minimizing thermally-induced chemical changes which could otherwise occur to the original calculus mineral due to the intense laser light. The Raman spectral features of the mineral were nearly all identical among the Raman spectra obtained at many randomly-selected sites by the micro-Raman microbe with a lateral resolution of approximately 1 micron, and were consistent with those of impure hydroxyapatite containing CO3(2-) and HPO4(2-). The spectra contained typical hydroxyapatite bands including PO4(3-)bands of the v1, v2, v3 and v4 modes and one OH- stretch band. Other minor bands due to the CO3(2-) v1 and v3 modes and bands possibly due to the HPO4(2-) v1, v2 and v4 modes were observable by the technique despite the hydrazine-treatment that could in principle remove the HPO4 and CO3 ions from the mineral. In comparison with pure synthetic hydroxyapatite, the intensity of the OH- stretch band relative to that of the PO4(3-) v1 band was approximately 70% weaker, and the bandwidth of the phosphate v1 band was 200% broader, reflecting various crystal imperfections presumably present in the calculus mineral.

Adult↗
PubMed1995

Alpha-fetoprotein and acetylcholinesterase activity in first- and early second-trimester amniotic fluid.

Normal ranges of amniotic fluid alpha-fetoprotein (AFP) and acetylcholinesterase activity (AChE) are described for gestational weeks 11-14 using rocket gel immunoelectrophoresis for AFP quantitation and a monoclonal antibody (4F19) enzyme antigen immunoassay for AChE activity measurement. The normal ranges were established by the examination of 281 amniotic fluid samples from 281 normal pregnancies. AFP was found to increase from a median level of 14.0 MIU/l at 11 weeks to a maximum at 13 weeks (median = 18.0 MIU/l) (P < 0.05), thereafter falling (not significant). No AChE test result exceeded 4.8 nkat/l. In addition, AFP and AChE values for three cases of fetal malformation, identified by the biochemical analyses of amniotic fluid, are given. These cases included two fetuses with a neural tube defect and one fetus with an abdominal wall defect. Amniocentesis was performed at 10, 11, and 14 weeks, respectively. The AFP and AChE values were all high.

Abdominal Muscles↗
PubMed1995

Comparison of serine and hippurate as precursor equivalents during infusion of [15N]glycine for measurement of fractional synthetic rates of apolipoprotein B of very-low-density lipoprotein.

Enrichment in hippurate has been measured to indicate precursor enrichment during glycine tracer infusion studies to estimate fractional synthetic rates of individual hepatic export proteins. However, hippurate tends to overestimate precursor enrichment. Since glycine is rapidly converted to serine by liver cells, we compared tracer enrichment in hippurate and serine with that of glycine incorporated into apolipoprotein (apo) B-100. Ten healthy control subjects were studied in the postabsorptive state during an 8-hour primed-constant infusion of [15N]glycine (10 mumol.kg-1.h-1). Apo B of very-low-density lipoprotein (VLDL) was isolated by standard ultracentrifugation and isopropanol precipitation. Glycine and serine were isolated from plasma and hydrolyzed apo B, hippurate was isolated from plasma, and [15N]enrichment was determined by gas chromatography-mass spectrometry. Enrichment in serine and glycine isolated from apo B was identical at all time points, and their enrichment in apo B increased asymptotically, approaching an apparent plateau (mean +/- SD: 91% +/- 10% of calculated plateau at 8 hours) that was taken to represent hepatic protein precursor enrichment. Enrichment in both plasma serine and hippurate followed a biphasic pattern and continued to increase until the end of the study, raising the possibility that precursor enrichment had not reached a steady state during the study. The apo B plateau was lower (factor 0.76 +/- 0.27) than the final enrichment in hippurate and higher (factor 1.38 +/- 0.36) than that in plasma serine; however, predictions of protein precursor enrichment based on either metabolite were flawed by a large coefficient of variation (35% v 26%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

The effects of a sodium hypochlorite treatment on demineralized root dentin.

The effects of a 10% NaOCl treatment for 2 min on demineralized human root dentin were investigated by means of: microradiography (MR), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and secondary ion mass spectroscopy (SIMS). MR measurements revealed that NaOCl caused a tissue contraction not related to water loss but to removal of organic substance(s), resulting in reductions of the lesion depth and mineral loss values by 15% and 42%, respectively. CLSM observations on wet dentin showed that the dentinal tubules underneath the surface are clearly observable and not deformed substantially by the NaOCl, except near the outermost surface. This indicates the importance of wet as well as of dried (high vacuum) observations. SEM micrographs (high vacuum) showed definite changes in the outer dentin surface structure; 85% of the originally open dentinal tubules were closed after NaOCl treatment. No marked changes were observed in the dentin ultrastructure inside lesions, as shown by SEM on fractured surfaces. SIMS data, pertaining to samples in high vacuum, showed a remarkable increase of chlorine (Cl) content in the entire lesion due to the NaOCl, indicating deep penetration of the original OC1 ions. The results suggest that the 2-min treatment of demineralized dentin by NaOCl solutions removes and/or changes part of the dentin matrix in nearly the whole lesion. As a consequence the mineral is somewhat redistributed, the outermost surface of a few mu m is changed, but the main dentin structure and element composition are still intact. These findings indicate that NaOCl treatments are of interest in remineralization and hyper-remineralization studies of dentin.

Adolescent↗
PubMed1995

Effect of air-drying on demineralized and on sound coronal human dentine: a study on density and on lesion shrinkage.

Recently, several papers investigated the linear dimensional changes in dentine after air-drying. This paper pertains to weight changes, volume changes, and density changes caused by air-drying of sound and demineralized intact dentine. The densities of sound and artificially demineralized human coronal dentine were measured in the wet state and after various drying periods of up to 24 h. The volume was assessed either by means of a pyknometer (wet samples) or by means of dimension measurements. The air-drying experiments were done using a Mettler thermobalance at room temperature. The density of wet sound coronal dentine was found to be 2.24 +/- 0.12 g.cm-3; the value of wet demineralized dentine was about 1.6 g.cm-3. The data show that previously published density values of powdered sound dentine may have been influenced by powdering effects, air-drying, and air inclusion. In whole demineralized air-dried dentine, air inclusion can be very severe: up to 30% by volume. The results show furthermore that in demineralized dentine we have two drying stages: during the first one (up to about 10 min of air-drying), the lesions shrink about 23%, while a main part of the water in the lesion evaporates, and air is incorporated into the tissue; during the second stage (drying longer than 10 min), the lesions hardly shrink anymore, but water is evaporated mainly from underlying sound dentine, followed by air incorporation.

Air↗
PubMed1995

The diameter of dentinal tubules in human coronal dentine after demineralization and air drying. A combined light microscopy and SEM study.

The diameter of dentinal tubules after demineralization and/or air drying has been quantified using light microscopy and scanning electron microscopy (SEM). The tubule diameter was assessed at a distance of about 1.5 mm (range 1.0-2.0 mm) from the pulp. Tubule diameter was measured in the wet state, after 10-min and 12-hour air drying as well as after critical point drying (CO2) by SEM. The results show that drying effects on tubule diameter are small in sound tissue, but are sizeable in demineralized dentine. Comparing light microscopic (wet) and SEM observations show that the differences in tubule diameter are small for sound but substantial for demineralized dentine. An important result is that in the wet state the diameters of the tubules (being 1.3 +/- 0.2 microns in sound dentine) are 2.5 +/- 0.3, 2.2 +/- 0.3 and 1.7 +/- 0.2 microns after 1, 2 and 3 weeks of demineralization, respectively. The decreased tubule diameter with increasing demineralization may be important for permeability and transport phenomena in dentine caries and presumably in hypersensitivity.

Adolescent↗
PubMed1995

Formation of phosphate-containing calcium fluoride at the expense of enamel, hydroxyapatite and fluorapatite.

During the caries process complex reactions involving calcium, phosphate, hydrogen and fluoride ions as main species take place. In this study the precipitation and dissolution reactions occurring in suspensions of enamel, hydroxyapatite (HAP) and fluorapatite (FAP) on addition of fluoride were investigated under well-defined conditions. pH and pF were monitored; calcium and phosphate concentrations were measured at selected times; the solid phases were examined by infra-red, X-ray diffraction and transmission electron microscopy. Precipitation of phosphate-containing calcium fluoride crystals, CaF2(P), can cause severe reduction in the calcium ion concentration and release of hydrogen ions from the precipitated phosphate. These reactions result in considerable dissolution of enamel, HAP and even of FAP. More of the added mineral dissolves with 50 mmol/l fluoride than with 10 mmol/l fluoride, mainly due to the greater reduction in calcium ion concentration. This work shows that phosphate-containing calcium fluoride is most likely an important compound to be considered in the caries process.

Animals↗
PubMed1995

The influence of air-drying on hyper-remineralization of demineralized dentine: a study on bulk as well as on thin wet section of bovine dentine.

The influence of air-drying on the remineralization of demineralized bovine dentine was examined in wet bulk samples, in dried bulk samples as well as in wet thin sections. Bulk samples of bovine dentine were first demineralized in an acidic gel (pH = 5) at 37 degrees C for 3 weeks. After 24-hour pre-treatment of either air-drying or immersion in water, the bulk samples were remineralized in a solution containing 1.5 mM Ca, 0.9 mM phosphate and 10 ppm F (pH = 7) at 37 degrees C for 2, 4 or 8 days. Separately thin sections prepared from demineralized bulk dentine were immersed in water for 24 h and were also exposed to the remineralization solution for 2, 4 or 8 days. The results show that air-drying of the bulk samples increased remineralization of dentine considerably; the microradiographic parameters (ld, delta Z and la) show that the degree of remineralization ranks: thin wet sections > bulk dried > bulk wet. Especially, the remineralization inside lesions was greatly enhanced in thin sections and dried samples. It is presumed that the increased remineralization in dried samples is caused by a 'sponge effect', in which the remineralization fluid is sucked up in a dried shrunken lesion, resulting in fast and deep penetration of remineralization solution and/or presumably increased nucleation.

Air↗
PubMed1995

Effect of post-brushing water rinsing on caries-like lesions at approximal and buccal sites.

The aim was to study the effect of two different water rinsing procedures after toothbrushing with an NaF-containing dentifrice on the degree of de- or remineralization of enamel and dentine at approximal and buccal sites. Seven adults, wearing complete dentures, participated in two experimental periods (A and B) in a randomised order. During period A, they brushed with the dentifrice for 2 min, followed by 1-min active mouthrinse with the toothpaste-foam combined with 10 ml of water. No more water was used after the slurry had been spat out. During period B, the brushing was followed by 3 thorough rinsings of approximately 15 ml water each. These two procedures were carried out twice daily, i.e. in the morning (after breakfast) and in the evening (just before bedtime), during 3 months. Demineralized enamel and dentine samples were mounted at two locations--approximally and buccally--in the first molar region of the upper prostheses. Quantitative microradiography (TMR) was used to assess the lesion depth (ld) and the mineral loss (delta Z). The results showed that the approximally located samples continued to lose mineral during both periods A and B. However, the ld and delta Z values for enamel (p < 0.01) and dentine (p < 0.05) increased less during A than B. The buccally located enamel and dentine samples remineralized during the experiment, but no statistically significant differences were found for the ld and delta Z values of either enamel or dentine between periods A and B.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Screening of newborn infants for cystic fibrosis. A combined analysis of immunoreactive trypsin and delta F508 mutation--a screening without false positive results].

A total of 1081 blood screening cards taken from newborn babies, were anonymously selected for cystic fibrosis (CF) screening by quantitation of immunoreactive trypsin (IRT, Delfia) and by delta F508 mutational analyses using polymerase chain reaction followed by a time resolved fluorescence hybridization assay (Delfia). The IRT values showed a log normal distribution and were significantly higher in girls than boys and in 28 carriers compared with 1052 normals. In 12 newborns, corresponding to 1.02%, an IRT concentration greater than 70 micrograms/l was found. One of these was a delta F508 homozygote with an IRT concentration of 380 micrograms/l. delta F508 mutational analyses showed 1052 normals, 28 heterozygotes, and one homozygote, i.e., a carrier frequency of this mutation for delta F508 of 1:39. In future newborn CF-screening programmes we therefore recommend Delfia IRT followed by Delfia delta F508 analyses for IRT values greater than 70 micrograms/l.

Cystic Fibrosis↗
PubMed1994

The effect of titanium tetrafluoride (TiF4) application around orthodontic brackets.

In the present in vivo study, the cariostatic potential of a titanium tetrafluoride (TiF4) solution applied topically around orthodontic brackets was investigated with quantitative microradiography. Also characteristics of the TiF4-treated enamel surface were examined with scanning electron microscopy (SEM). Ten pairs of premolars to be extracted for orthodontic treatment were used in the first part of this study. Brackets were bonded on all teeth with an orthodontic adhesive, and 10 randomly selected premolars served as controls, whereas a similar number were treated with 1% TiF4 around brackets for 60 seconds. After 4 weeks with no topical fluoride supplementation, all teeth were extracted and stored for analysis. Results indicated the 1% TIF4 solution reduced lesion depths and total mineral loss, at the bracket periphery, significantly during the 4-week period. The presence of a surface coating was demonstrated by SEM micrographs. It was concluded that TiF4 may provide a high level performance as a prophylactic agent for orthodontic purposes.

Child↗
PubMed1994

A new simple and rapid dual assay for AFP and free beta hCG in screening for Down syndrome.

We have evaluated a simple and rapid 2-step dual-label assay (DELFIA) for alphafetoprotein (AFP) and free beta subunit of human gonadotropin (hCG beta) in second-trimester screening for Down syndrome. Based on stored serum samples from 1059 normal control pregnancies and 72 cases of Down syndrome, we have found the mean Multiple of Median (MoM) for AFP and free hCG beta to be 0.70 and 2.31, respectively. This is slightly but not significantly better than the values for the separate assay for AFP (0.76 MoM) and for intact hCG (2.11 MoM). However, the dual assay is much simpler than the separate assays and therefore prospective comparison trials should be carried out.

Chorionic Gonadotropin↗
PubMed1994

Effect of a combined chlorhexidine and NaF mouthrinse: an in vivo human caries model study.

Chlorhexidine (CHX) is probably the most widely used and the most potent chemical plaque inhibitory agent, whereas fluoride (F-) is the only truly accepted anticaries agent available at present. As they have discrete mechanisms of action, a combination effect of these agents on human dental caries may exist. The inhibitory effect of CHX on the formation of, and acid production in, plaque may reduce a relatively extreme cariogenic challenge sufficiently for it to be overcome by the local F- concentrations achieved by brushing or rinses. The aim of this study was to evaluate the possible caries inhibitory effect of combining 2.2 mM CHX mouthrinses used twice daily with daily 11.9 mM NaF rinses in an in vivo human caries model using plaque-retaining bands on premolars scheduled for extraction. Nine subjects (a total of 28 teeth) were fitted with the bands for 4 wk. Saliva and plaque samples were collected before and after the study period for bacterial cultures, and the tooth surfaces were analyzed by microradiography after careful tooth extractions. The combination of CHX and F- rinses resulted in enamel mineral loss only slightly higher than that observed in "sound" enamel and clearly less than with F- rinses alone. Both total plaque bacteria and Streptococcus mutans were reduced by CHX rinses, confirming the discrete mechanisms of action.

Adolescent↗
PubMed1994

Closing of dentinal tubules by glutardialdehyde treatment, a scanning electron microscopy study.

The properties of dentin are strongly influenced by the so-called smear layer. This layer is always present on the dentin surface after cutting, drilling, sawing, etc. The smear layer can be removed by various chemical treatments, such as those of acid etching or ethylenediaminetetraacetic acid (EDTA). These treatments remove the smear layer and open the tubules. In this paper, the effect on the smear layer of human dentin of treatment with a 2% glutardialdehyde (GDA) solution at pH 3.5 for 2 min and a 0.5-M EDTA solution at pH 7.4 for 4 min was investigated by scanning electron microscope (SEM). The dentin samples were dried by air or critical-point drying before SEM photography was employed. The number of open dentin tubules was quantified on micrographs of EDTA- and GDA+EDTA-treated dentin. The results show that the GDA treatment fixed part of the smear layer and the superficial dentin surface in such a way that at least 50% of the tubules remained closed after EDTA treatment. By closing the dentinal tubules, the GDA-fixed layer might have a positive effect on dentin hypersensitivity, root caries, and bonding of composite to dentin.

Adolescent↗
PubMed1994

Effect of xylitol and sorbitol in chewing-gums on mutans streptococci, plaque pH and mineral loss of enamel.

Seventeen subjects with more than 3 x 10(5) mutans streptococci per millilitre of saliva completed this randomised, cross-over study. Four different chewing-gums, containing: (1) 70% xylitol, (2) 35% xylitol + 35% sorbitol, (3) 17.5% xylitol + 52.5% sorbitol, and (4) 70% sorbitol, were tested. The participants used 12 pieces of each gum per day for 25 days. During the four experimental periods, they wore a removable palatinal plate containing two demineralised enamel samples, and brushed their teeth with a non-fluoridated toothpaste. The results showed that an increased concentration of xylitol in the gum resulted in a lower number of mutans streptococci in both saliva and dental plaque, although the decreases were only significant in the saliva samples (p < 0.01). The pH drop in plaque, measured in vivo after a 1-min mouthrinse with a 10% sorbitol solution, was least pronounced after the 70% xylitol gum and most pronounced after the 70% sorbitol gum period (p < 0.01). No significant differences were found after a mouthrinse with a 10% sucrose solution. All demineralised enamel samples lost mineral during the experimental periods. However, the lesion depth as well as the mineral loss values, assessed microradiographically, did not differ significantly between the four chewing-gums.

Adult↗
PubMed1994

Secondary caries in dentine around composites: a wavelength-independent microradiographical study.

Composite restorations are prone to develop secondary caries if a gap exists between tissue and restoration. The aim of this article was to quantify the effects of a fluoridating and non-F composite on secondary dentine caries in vitro as a function of time. The mineral loss in dentine was assessed in an artificial gap of 200 microns width at the composite/dentine interface; the samples were demineralised in a carboxymethylcellulose gel (pH = 5, 37 degrees C) for 8 weeks. Once a week the mineral content of the samples was determined using non-destructive wavelength-independent microradiography (WIM). After 8 weeks transversal microradiography (TMR) was done on the samples to investigate the mineral distribution of the dentine lesions. The WIM results show that the fluoride-releasing composite decreased the dentine demineralisation statistically significantly with respect of the non-F control by approximately 45%. The mineral loss values are found to be strictly proportional to time; the demineralisation reduction is expected to continue over extended periods of clinical relevance. The TMR results show that the fluoridating composite reduced the mineral loss values significantly with respect to the non-F control by approximately 55%, but had a negligible effect on the lesion depth values. This study indicates that WIM is an accurate and reliable technique to measure in vitro secondary dentine caries next to a composite restoration as a function of time.

Animals↗
PubMed1994

Effect of frequent consumption of starchy food items on enamel and dentin demineralization and on plaque pH in situ.

The aim of this cross-over study was to determine the cariogenic potential of starchy food items as between-meal snacks. This was done by measuring demineralization of human enamel and dentin as well as the pH of dental plaque in situ. Eight volunteers with complete dentures carried two enamel and two dentin specimens, mounted in the molar regions of their mandibular prostheses. There were three test periods, each lasting for 21 days, followed in a randomized order: (1) consumption of starchy food products, 12-15 times a day, in addition to the normal diet (starch period); (2) consumption of sucrose products, 12-15 times a day, in addition to the normal diet (sucrose period); and (3) no addition of test products to the normal diet (control period). Both the starch and the sucrose diets increased the demineralization of enamel and dentin compared with the control period. However, only the sucrose period resulted in significant demineralization of dentin compared with the control period. The plaque pH, followed during 60 min after a one-minute mouthrinse with 10% sucrose, was lower at all time points after both the starch and the sucrose periods compared with the control period.

Aged↗