Search PubMed⌕ Search

Biomedical subjects

J Arends

Publications and source records attributed to J Arends.

At least 91 records · Page 5Linked to original sources
PubMed1992

Sulcus temperature distributions in the absence and presence of oral hygiene.

In this study we investigated the possibility of using sulcus temperature measurements as an early indicator for the beginning of gingival inflammation. Sulcus temperature distributions over the arches appeared to obey a quadratic polynomial. With a test group of 10 volunteers, all dental students, small changes in temperature were measured after subjects refrained from all oral hygiene: A slight but significant tendency for the frontal temperature to increase after 14 days of no oral hygiene was, however, present. The quality of a quadratic polynomial fit of the temperature distributions over the arches decreased significantly, already after 3 d of non-oral hygiene. This indicates that the coefficient of quadratic correlation for the temperature distributions over the arches is a measure for the oral hygiene of patients and for changes in the physiology of gingival tissues. Furthermore, as its decrease was concurrent with an increase in plaque and gingival indices, it might serve as an early indicator for the beginning of gingival inflammation. However, further development work is needed in order to make this approach useful as a clinical tool.

Adult↗
PubMed1992

Rate and mechanism of enamel demineralization in situ.

In this paper, data are presented on the in situ demineralization of human enamel as a function of the demineralization period. To quantify the mineral loss parameters versus time, it is important to obtain information on the kinetics, and thus on the mechanism of dental caries. The results show that for in situ enamel demineralization, the lesion depth as well as the mineral loss parameter both vary linearly with the demineralization time. This is in contrast to in vitro lesion formation where the third power, or the square power of the lesion depth is linearly related to the demineralization time. In in situ demineralization, the rate-determining step of the demineralization process is the inhibitor-controlled dissolution process at the enamel crystallite surfaces, while the inhibitor content (F-, proteins etc.) in the lesion originating from the plaque, saliva and enamel is high. Furthermore, the study indicates that in in situ demineralization, interprismatic mineral loss is very important.

Dental Enamel↗
PubMed1992

Effect of glutardialdehyde on secondary caries in situ.

In this paper the results are presented on the effect glutardialdehyde (GDA) on the in situ demineralization of human enamel and dentine around an artificial gap of 200 microns width. In this model secondary enamel and dentine caries is simulated in situ; the mineral loss was quantified. The results show that a 2-min application of a 2% acidic GDA solution reduces dentine demineralization substantially, but does not influence enamel demineralization. Microradiography showed a reduction of mineral loss values around the gap in dentine by about 30%. The beneficial effect of GDA on dentine is presumably a combined result of collagen fixation, the reduced diffusion of calcium and phosphate ions out of the dentine lesion, and antibacterial action. The results indicate that GDA might play a role in the future reduction or prevention of secondary dentine caries.

Adult↗
PubMed1992

Secondary caries in situ around fluoride-releasing light-curing composites: a quantitative model investigation on four materials with a fluoride content between 0 and 26 vol%.

In the literature, secondary caries around composite restorations is reported often. Fluoridated composites are therefore interesting materials because they might reduce or inhibit secondary caries. In this article an in situ model investigation is presented in which the effect of F-releasing composites on enamel demineralisation around an artificial gap of 200 microns width was quantified after 1 month. The fluoride content of the composites varied between 0 and 26 vol%. The beneficial effect of the fluoride released was larger in the gap than at the outer enamel surface. In the gap, all fluoridated composites reduced the enamel demineralisation statistically significantly with respect to the non-fluoridated control. Microradiography showed a reduction of lesion depth values of 27-45%, and a reduction of mineral loss values of 25-56%. At the outer enamel surface next to the artificial gap, a beneficial fluoridation effect was measurable only near the most fluoridated composite. The results indicate that fluoridated composites may play a role in the future prevention of secondary caries.

Acrylic Resins↗
PubMed1992

Effects of fluoride and methanehydroxydiphosphate on enamel and on dentine demineralization.

The aim of this article was to investigate the effects of methanehydroxydiphosphonate (MHDP) and fluoride (F) separately and combined, on the demineralization process in enamel and in dentine under constant composition conditions. The demineralization was carried out in solutions containing 3 mM calcium, 3 mM phosphate, pH = 5.0, and either 6 microM MHDP, 12 microM F or 6 microM MHDP and 12 microM F. After demineralization periods (t) between 24 and 140 h, the lesion depth l and the mineral loss delta Z were measured by transverse microradiography of the enamel and dentine specimens. The amount of mineral lost during demineralization averaged over the lesion depth, R = delta Z/l, was calculated. R approximately 17 vol% for both enamel and dentine, both delta Z and l being greater for dentine than for enamel by approximately the same factor. The results show that under the same conditions dentine is attacked much more strongly than enamel. The lesion progress with time is quite different for the two tissues: in enamel the lesion depth progresses als l3 = alpha t + beta, in dentine as l2 = alpha't + beta'. The slopes alpha and alpha' decrease in the order MHDP > F > MHDP+F. In enamel the combined inhibitor effect is only slightly larger than the effect of F alone; in dentine the inhibiting effects of F and MHDP are approximately additive. The inhibitor interactions can be described by the Langmuir adsorption theory.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1992

Demineralization and remineralization evaluation techniques.

This paper compares the experimental techniques utilized to assess the de- or remineralization of enamel or dentin in intra-oral studies. In in situ studies, it is important for one to know how much mineral has been lost or gained, and where the loss or gain occurred. The main emphasis in this paper is on techniques suitable for direct or indirect mineral quantification. The measuring techniques considered are microradiography, iodine absorptiometry, various microhardness tests, polarized light, light-scattering, iodide permeability, and wet chemical analysis. The various techniques are compared concerning suitability for the determination of mineral content in vol% (or wt%), mineral changes in vol% micron (or kg.m-2), and mineral distributions. Furthermore, sample preparation, the importance of protein penetration, nominal mineral loss range, the estimated mineral loss threshold, and the applicability to dentin are compared and considered. It is concluded that, although more than ten techniques are available for the measurement of changes after de- or remineralization in situ, transverse microradiography is the most practical technique for the direct and quantitative measurement of mineral content, mineral changes, and mineral distributions. Cross-sectional microhardness testing and light-scattering are also practical indirect techniques for quantitative mineral loss (or gain) determination in intra-oral studies.

Dental Enamel↗
PubMed1992

Antimicrobial effect of a dental varnish, in vitro.

The effects of a polymer based antimicrobial releasing varnish Cervitec were investigated against different gram-positive and gram-negative bacterial strains as well as a yeast using the agar diffusion inhibitory test (ADT-test in vitro). As positive controls a 1% chlorhexidine gel and 1% aqueous solution of thymol and a placebo polymer varnish without active agents were employed. The test experimental varnish containing 1% chlorhexidine and 1% thymol showed antimicrobial activity against all gram-positive and gram-negative microorganisms tested including one Candida strain. The positive controls were similar in effect compared to the test varnish. No antimicrobial effect was observed with the placebo varnish without active ingredients. Toothpicks and dental floss treated with the test varnish showed an antimicrobial effect against S. mutans even after storing in room temperature up to 12 months. The results from this study support earlier laboratory studies that chlorhexidine and thymol diffuse out of the experimental varnish and that the varnish is active against various of oral pathogens. The possibility to use toothpicks or dental floss impregnated with the varnish with the aim to become chemotherapeutically active against periodontal diseases as well as against dental caries, is promising and should be tested in vivo.

Actinomyces viscosus↗
PubMed1992

The effect of an experimental mouthrinse on enamel lesion remineralization in vitro.

This paper describes the effect of a 2 ppm fluoride containing, slightly acidic mouthrinse (pH = 6) on the remineralization of enamel lesions in vitro. The rinse was applied twice daily for 2 min, on about 85 microns in depth artificial lesions. Artificial enamel lesions were formed at pH = 5 in a 6% CMC gel. The lesions were subsequently remineralized in vitro in a neutral remineralizing solution (1.5 mM Ca and 0.9 mM phosphate) with or without the application of the rinse. After 3 weeks the samples were evaluated by means of quantitative microradiography. The results showed that a statistically significant reduction in lesion depth occurred of 48 and 29% with or without rinse application, with respect to the original lesion depth. The effect of the rinse compared with no rinse decreased the lesion depth by 40%. The data indicate that application of a slightly acidic rinse with 2 ppm fluoride applied twice a day, stimulates the remineralization at the lesion front and does not lead to blocking of enamel pores observed after acidic, high level F applications (APF).

Animals↗
PubMed1992

Adsorption of dentine proteins onto spheroidal calcium phosphate in a neutral and in an acidic environment.

The adsorption of four different dentine protein fractions onto hydroxyapatite (HAP) was investigated in a nearly neutral (pH 6.7) and in an acidic environment (pH 5.0). The soluble dentine proteins were isolated according to their extractability in successively: 4M guanidine-HCl (GuHCl), 0.5M acetic acid pH 3 (after extraction with GuHCl), and 0.01M EDTA pH 7.4 and 0.1M EDTA pH 7.4 (after complete demineralization with acetic acid). The amounts isolated were 1.2, 3.3, 6.1 and 3.7 mg protein per gram dentine, respectively. The GuHCl extractable proteins exhibited the lowest affinity and the acetic acid extractable proteins the highest affinity for HAP. Acetic acid extractable proteins, were significantly less adsorbed than the other protein fractions at pH 5.0. The maximum adsorbed amount of these proteins increased with decreasing pH which indicated that all the soluble dentine proteins, except perhaps those that one GuHCl-extractable have to be considered as potential demineralization inhibitors.

Acids↗
PubMed1991

[Alcohol-induced hypoglycemia in type I diabetic patients].

The hypoglycemic effect of alcohol, probably caused by inhibition of gluconeogenesis in the liver, is well known. However, accurate data on the effect of usual amounts of alcohol on the blood sugar in type 1 diabetics are not available. We therefore investigated the effect of an evening dose of alcohol on the blood sugar in 23 male type 1 diabetics (age 32.8 [20 to 64] years, duration of diabetes 11.5 [0.5 to 38] years, Broca index 0.98 [0.83 to 1.34] HbAlc 8.4 [5.8 to 12.2]%). On one day, the diabetics were given 0.56 g ethanol per kg body weight to drink in the evening, corresponding to about one liter of diabetic beer, on another day, the same volume of mineral water. In addition, eleven of the 23 patients received half the amount of alcohol on a third evening. Between 7 and 11 o'clock in the morning after alcohol consumption, blood glucose levels were significantly lower. The number of hypoglycemic episodes in the morning of the day following alcohol administration was appreciably greater. Usual amounts of alcohol consumed after the evening meal thus increase the risk of hypoglycemia the following morning. Diabetics should be instructed accordingly.

Adult↗
PubMed1991

[Delayed absorption of carbohydrates in the therapy of Type II diabetes: comparison between dietary (Muesli) and pharmacological (Alpha-glucosidase inhibition) modification].

Slowly resorbable carbohydrates are preferred in the dietetic therapy of patients with type 2 diabetes. In this study we compared the efficacy of a "müsli" with the alpha-glucosidase inhibitor miglitol in delaying the resorption of carbohydrates. 24 patients with NIDDM took, in randomized order, four different breakfasts with equal amounts of carbohydrate: a standard breakfast with bread and marmelade, a müsli, and both breakfasts with 100 mg miglitol. We calculated the maximal blood glucose concentration, the postprandial difference, the time of the maximum and the area under the curve (AUC). The postprandial blood glucose increase after the müsli breakfast was significantly lower compared with the standard breakfast (maximal blood glucose 12.3 vs. 13.9 mmol/l, postprandial difference 3.6 vs. 5.1 mml/l, AUC 360 vs, 468 mmol/l x min). The blood glucose increase after the standard breakfast with miglitol was even lower (maximum 11.6 mmol/l, postprandial difference 2.9 mmol/l, AUC 241 mmol/l x min). Miglitol also lowered the blood glucose values after the müsli breakfast. This study shows that the alpha-glucosidase inhibitor miglitol in a dose of 100 mg is more effective in lowering the postprandial blood glucose increase than a müsli. In cases of non-acceptance of a modern diet with slowly resorbable carbohydrates, alpha-glucosidase inhibitors may be a therapeutic alternative.

1-Deoxynojirimycin↗
PubMed1991

An in vivo study on the merits of two glass ionomers for the cementation of orthodontic bands.

The purpose of this study was to investigate the cariostatic effect of two glass ionomer cements on in vivo demineralization of partly uncovered enamel beneath orthodontic bands. A 4-week clinical trial was conducted on a group of five patients with nine pairs of premolars to be extracted for orthodontic purposes. Specially designed orthodontic bands were cemented with either Ketac-Cem (K-C) or Aqua-Cem (A-C). A local cariogenic milieu was created between the buccal surface of the premolars and the inner surface of the bands to secure plaque accumulation. The mineral content of the teeth was quantified by microradiography. The data were compared with data from a previous study of patients in the same age group with bands that had been cemented with a non-F cement. After comparison with the non-F group, the lesion depth (ld) was reduced by 63% for K-C and by 55% for A-C. This reduction was statistically significant at the 2.5% level (t test). The total mineral loss in teeth cemented with glass ionomer cements (delta Z) was reduced, in comparison with the loss in teeth cemented with non-F cement, by 49% with K-C and by 27% with A-C. The differences were statistically significant only for the K-C group (t test, p less than 0.025). There were no significant differences between the two glass ionomer cements with respect to either lesion depth or total mineral loss values (paired t test; p greater than 0.05). This investigation shows that fluoride released from glass ionomer cements contributes substantially to demineralization "reduction." However, these cements do not provide complete caries protection in sites where access is difficult.

Acrylic Resins↗
PubMed1991

Effect of fluoride mouthrinsing on caries lesion development in shark enamel: an in situ caries model study.

Shark enamel consists of nearly pure fluorapatite and has been shown to demineralize in an in situ caries model. The present study was conducted to investigate whether additional fluoride supplementation in the form of mouthrinsing would inhibit lesion development in shark enamel. The study slabs of shark enamel were mounted in dental appliances. Six individuals wore the appliances while rinsing daily with a neutral 0.2% NaF solution for 4 wk. The specimens were analyzed by means of quantitative microradiography, and the data compared with a previous study using untreated shark enamel and the same participants. It was found that fluoride rinsing did not measurably inhibit enamel demineralization in 4 wk. Scanning electron microradiographs showed that calcium fluoride-like material was not formed on shark enamel after neutral fluoride treatment, supporting a previous study. The present study indicates, therefore, that formation of a calcium fluoride-like material on the enamel surface may be essential for the cariostatic effect of topical agents.

Adolescent↗
PubMed1991

Demineralization of human dentine compared with enamel in a pH-cycling apparatus with a constant composition during de- and remineralization periods.

A comparison was made between the demineralization of enamel and dentine with and without abraded surfaces. This was done in a pH-cycling experiment for different demineralization/remineralization ratios--in the range from 1:1 to 1:4--and for different fluoride additions (up to 2 ppm) in solution. A new automatic pH-cycling system, in which the de- and remineralization solutions have a constant composition during the de- and remineralization cycles, was used to create mineral loss in human dentine and enamel. Changes in mineral content were monitored by means of longitudinal microradiography. A linear correlation was found between the amount of mineral lost and the total demineralization time for both dentine and enamel. The demineralization rates were comparable for abraded enamel and dentine and for polished enamel and dentine, and this rate was roughly doubled by the removal of the outer surface for both tissues. This showed that the presence of the outer surface is equally important to dentine and enamel. Under the pH-cycling conditions used, a logarithmic relation was found between the addition of fluoride and the decrease in demineralization for both enamel and dentine. The inhibitory effect of fluoride on demineralization was most pronounced on abraded enamel, followed by pumice-polished enamel, abraded dentine and pumice-polished dentine. About 2 ppm fluoride was needed under the conditions used to stop enamel demineralization completely; in the case of dentine, however, this amount of added fluoride did not inhibit demineralization.

Analysis of Variance↗
PubMed1991

Determination of chlorhexidine in saliva and in aqueous solutions.

A new method is presented for the determination of chlorhexidine in centrifuged saliva and in aqueous solutions by means of fluorescence spectroscopy. The method relies on complex formation between chlorhexidine and eosin. The fluorescence value of the chlorhexidine-eosin system decreases with increasing chlorhexidine concentrations. In centrifuged saliva a linear relation was found between the fluorescence at 541 nm and the chlorhexidine content up to about 15 ppm; the reproducibility of the method was found to be better than 1 ppm chlorhexidine. The biological spreading for centrifuged saliva from different participants as well as the spreading due to the period of saliva collection are about 3%. In whole uncentrifuged saliva the fluorescence method has been a detection limit of about 8 ppm chlorhexidine, due to the binding of the compound to salivary constituents. Above 8 ppm chlorhexidine, the biological variation in saliva is such that chlorhexidine determinations by means of fluorescence can be done only with a reproducibility of +/- 10 ppm. Advantages and disadvantages of the ultraviolet spectroscopy method, the radioactive labelling technique, and the fluorescence method for chlorhexidine determinations are discussed.

Centrifugation↗
PubMed1991

The effect of EHDP concentration on enamel demineralization in vitro.

The depth of caries lesions produced in bovine enamel situated in an unstirred 0.1 mol/L lactic acid buffer at pH 4.5 has been studied as a function of time and of concentration of the inhibitor ethane-1-hydroxy-1, 1-diphosphonate, EHDP. At concentrations of EHDP up to 5 mmol/L, the lesion progress decreased with increasing concentration of inhibitor. At higher concentrations, the opposite effect was observed. At low inhibitor concentration (0.1 mmol/L), the lesion depth to the third power varied linearly with time. At intermediate concentrations (0.25-5 mmol/L), the square of the lesion depth varied linearly with time. At high inhibitor concentrations (25-100 mmol/L), the lesion depth varied linearly with time. It was also shown that the rate of dissolution of calcium hydroxyapatite crystals was retarded by low concentrations of EHDP, but accelerated by high concentrations of EHDP. The results are related to a physico-chemical model describing lesion formation.

Animals↗
PubMed1991

Ritanserin, a 5-HT2 receptor blocker, as add-on treatment in narcolepsy.

In a double-blind placebo-controlled trial, ritanserin (a 5-HT2 receptor blocker) 5 mg/day or placebo was added to the usual medication in 28 patients with narcolepsy during 4 wk. The effect was assessed by means of polysomnography, daily and weekly subjective evaluations, and Multiple sleep latency tests (MSLT). During the night ritanserin increased the amount of nonrapid eye movement slow wave sleep and reduced wakefulness after sleep onset. It improved the feeling of being refreshed in the morning after awakening and reduced subjective daytime sleepiness. The drug did not significantly influence sleep latency in the MSLT.

Adolescent↗