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Biomedical subjects

J M ten Cate

Publications and source records attributed to J M ten Cate.

At least 19 recordsLinked to original sources
PubMed2003

[110th volume of the Dutch Journal of Dentistry 1. Aspects of the pathogenesis, etiology and prevention of dental caries placed against the concepts of the 1950].

This paper discusses three articles on cariology from the 1950's in view of the current consensus of the pathogenesis, aetiology and prevention of dental caries. While 50 years ago the battle between researchers favouring the chemo parasitary versus those in support of the proteolytic theory of caries was at its peak, bacteria and acids formed in plaque have since been generally accepted as the cause of dental caries. Attention has shifted to the inhibiting role of fluoride in the initiation and progression of tooth decay, and the possible, additive action of antimicrobial therapy. As tooth decay is now a disease less common and progressing more slowly, there is scope for a more directed intervention and a preventive rather than a restorative therapeutic approach. In spite of the successes obtained a sizeable proportion of the population still suffers from dental caries and care should be taken not to diminish the attention for tooth decay both in the general dental practice and in dental research.

Dental Caries↗
PubMed2002

Effect of perfusion with water on demineralization of human dentin in vitro.

Dentinal fluid rarely features in caries studies of dentin. The mutual effects of in vitro perfusion and dentin demineralization were investigated. The correlation between the remaining dentin thickness and demineralization was also analyzed. Buccal cervical dentin windows in human tooth segments were demineralized either with or without perfusion with water at 3.14 kPa. Transverse microradiography revealed that dentin perfusion reduced the amount of mineral loss from the lesions by 22 vol%; the reduction in lesion depth was 8%. Perfusion rate, which was measured throughout the demineralization process by means of a fluid transport model, did not change significantly. Lesions formed closer to the pulp exhibited increased mineral loss and lesion depth. In conclusion, dentinal fluid flow offers some protection against demineralization. For a better approximation of clinical reality, therefore, in vitro studies on dentinal caries should consider the effect of dentinal fluid flow.

Analysis of Variance↗
PubMed2002

The effects of the solubility of artificial fissures on plaque pH.

Dissolution of the fissure walls may buffer acids formed in plaque and thus prevent the penetration of acids into the fissure. To test this, five volunteers wore dentin, enamel, and polyacrylate specimens with narrow grooves for 7 days to accumulate plaque. Temporal (pre- and post-glucose) and spatial (0-0.7 mm) pH profiles were recorded in the grooves in a flow-through reactor with pH microsensors. Mineral loss was assessed by transverse microradiography. We observed that resting pH did not differ among substrata. The median pH 1 hr post-glucose at the bottoms of dentin, enamel, and polyacrylate grooves was 6.7, 6.2, and 5.7, respectively (p < 0.01). On subject level, lesions formed in dentin correlated with pH changes in polyacrylate, where no buffering of acids due to mineral dissolution occurred. We conclude that fluoride-deficient tissue at the bottom of a fissure is at increased risk for caries, if acids are not buffered near the entrance to the fissure.

Acids↗
PubMed2001

What dental diseases are we facing in the new millennium: some aspects of the research agenda.

The next decades will show a shift in the attention given to diseases of the dental hard tissues. Clinical evidence on how to prevent dental caries is now available. More emphasis should be given to optimising the rational use of schemes of prevention. Caries still shows epidemic patterns in many countries while in some developed countries a high prevalence of the disease is limited to a small group. Increased attention is needed for new manifestations of pathology such as dental erosion, and for caries in special high-risk groups. New methods of presenting caries prevalence and incidence data should be implemented to ensure that the diseases of the dental hard tissues continue to have an important place on the political and research agendas.

Adolescent↗
PubMed2001

Remineralization of caries lesions extending into dentin.

Remineralization is one aspect of the overall process of tooth decay. However, it is primarily studied in shallow lesions. The aim of this study was to explore whether caries lesions in enamel and extending into the dentin can be remineralized. A single-section model was developed for the longitudinal and non-destructive monitoring of changes in enamel and dentin. Lesions at least 200 microm into dentin were formed in undersaturated acetate buffers. Next, the lesions were divided into groups (three treatment and one control) and remineralized. The treatments were: weekly immersion in 1,000 ppm fluoride, single treatment with methanehydroxybisphosphonate, and a constant level of 1 ppm fluoride. De- and remineralization was assessed by transverse microradiography. Remineralization was observed in enamel, but also in dentin, indicating that, deep into dentin, the pores become supersaturated to apatite formation. Treatments affected remineralization only in the outer part of enamel. Both findings are explained by a relatively fast diffusion of mineral ions, with precipitation being rate-limiting. The results suggest that dentin remineralization, underneath enamel, can be achieved and could possibly be used in clinical treatment strategies.

Analysis of Variance↗
PubMed2001

Conofocal microscopy study of undisturbed and chlorhexidine-treated dental biofilm.

Culturing of dispersed plaque samples and vitality staining of plaque smears are the most commonly used methods for evaluating the effects of antimicrobials on dental plaque. The visualization of the antimicrobial action on oral biofilm present on the substrate surface (in situ) would add valuable information to the existing knowledge about the treatment effects. This study aimed at combining the advantage of confocal laser scanning microscopy (CLSM) to visualize plaque non-destructively with a vitality staining technique to assess the immediate bactericidal effect of chlorhexidine (CHX) on biofilm. Three 200-microm-wide grooves were cut into bovine dentin discs for plaque accumulation. The discs were worn by six subjects for 6, 24, and 48 hrs, then broken into halves, one of which received a one-minute extraoral 0.2% CHX treatment, while the other served as control. Both halves were stained for vital fluorescence measurements and visualized by CLSM. Plaque vitality (in %) was quantified by image analysis in three plaque layers-outer, middle, and inner. The CHX effect was significant in six-hour samples (p < 0.001) and only in the outer layer of the 48-hour plaque (p < 0.001), demonstrating a resistant nature of dental biofilm to a single CHX treatment. With the present approach, we have shown that it is possible to visualize and quantitate the antimicrobial treatment effect on biofilm still present on the substrate on which it was grown.

Adult↗
PubMed2000

Effects of fluoride- and chlorhexidine-containing varnishes on plaque composition and on demineralization of dentinal grooves in situ.

The aim of the study was to compare the effects of Cervitec, containing 1% chlorhexidine (CHX) and 1% thymol, Fluor Protector, containing 0.1% fluoride, their 1:1 mixture, and a placebo varnish on the percentage of mutans streptococci and lactobacilli in plaque and on the underlying dentin demineralization, as assessed by microradiography. Bovine dentine discs, fitted with three parallel grooves, received one of the varnish treatments into the first groove and on the adjacent part of the dentin surface. Volunteers (n = 23) wore the discs fixed to their partial dentures for four consecutive 3 wk periods. Microbiological analysis of plaque accumulated in the grooves showed no difference between groups. Fluoride varnishes (Fluor Protector and mixed varnish) had a significantly larger inhibitory effect on mineral loss in the treated groove than Cervitec or placebo. All treatment varnishes had more pronounced effect in panelists (n = 14) with higher degree of demineralization (mineral loss in placebo group > or = 1,200 vol% x microm). In these panelists, CHX-containing varnishes showed an inhibitory effect on demineralization in all grooves, also in the two non-varnished grooves. As fluoride varnishes had the largest localized effect on demineralization, and CHX varnishes were showing a peripheral effect, a combined treatment could be the preferred method to obtain an optimal caries preventive effect in caries-prone individuals.

Aged↗
PubMed2000

Biological mercury measurements before and after administration of a chelator (DMPS) and subjective symptoms allegedly due to amalgam.

The aim of the study was to explore multivariately the relationship between subjective symptoms allegedly due to amalgam and mercury measurements before and after administration of a chelator. Of 120 participants, the mercury concentrations in urine (U-Hg) and plasma (P-Hg) before and after a chelating agent or placebo were determined as were the numbers of fillings and symptoms allegedly due to subjective symptoms. The dental status was charted. Blood was analysed on 13 parameters. The analysis revealed neither the parameters in blood nor the subjective symptoms to be associated with a dimension dominated by 'mercury indicators'. The final analysis was therefore performed with 'number of subjective symptoms' and enabled to distinguish two subsamples. One subsample was characterised by > 2 subjective "symptoms", highest scores for U-Hg, P-Hg and filled surfaces, and chewing gum for > 1 h a day. The other subsample comprised the subjects with few filled surfaces and low U-Hg and P-Hg, but was not characterised by "no subjective symptoms". The chelator was considered neither to invalidate nor to improve these findings and was concluded not to be helpful in diagnosing "symptoms". The chelator caused side effects in 42% of the subjects and the placebo in 27%. A relationship between amalgam fillings and subjective symptoms could not be shown. Therefore, the mere fact of knowing to have amalgam fillings was assumed to be the reason why subjective symptoms were attributed to amalgam and side effects were ascribed to the treatment.

Adult↗
PubMed2000

Effect of acid-etching on remineralization of enamel white spot lesions.

This in vitro study aimed at investigating whether full remineralization would occur in white spot lesions when the surface porosity was increased by acid-etching. The effect of fluoride was also investigated. Enamel blocks with in vitro produced white spot lesions were used. Group A was exposed to a remineralizing solution only. In group B, the lesions were etched with 35% phosphoric acid for 30 s, then treated as in group A. Group C was treated as group A + daily treatment with a fluoride toothpaste slurry (1,000 ppm) for 5 min. Group D was treated as group B + the daily fluoride treatment of group C. The remineralization was measured weekly with Quantitative Light-induced Fluorescence during the experimental period. After 10 weeks of remineralization, mineral profiles were assessed with transverse microradiography. The enamel fluorescence was partly regained. There were significant differences in the lesion depth, mineral content at the surface layer, and integrated mineral loss between the groups. Addition of fluoride accelerated the remineralization only in the beginning; in later stages the process leveled out and even reached a plateau in all the groups. It was concluded that full remineralization was not achieved by etching, by the addition of fluoride, nor by the combination of both treatments in this in vitro study.

Acid Etching, Dental↗
PubMed2000

The effect of triclosan toothpaste on enamel demineralization in a bacterial demineralization model.

Triclosan has been incorporated into toothpaste to enhance inhibitory effects on bacterial metabolism in dental plaque. Many studies have confirmed these effects by showing a reduction of accumulation of dental plaque, gingivitis and calculus. However, there is no evidence for triclosan having an inhibitory effect on the dental plaque-induced demineralization of the dental hard tissues. Therefore, the effect of 0.3% triclosan added to non-fluoride and fluoride toothpaste was tested in an in vitro model, in which bovine enamel specimens were to be demineralized by acids produced in overlaying Streptococcus mutans suspensions. In a first set of experiments the toothpastes were added to the S. mutans suspensions at 1:100, 1:1000 and 1:10,000 (w/v) dilutions. After 22 h incubation at 37 degrees C the suspensions were removed and assessed for calcium and lactate content, and pH. In this set of experiments, triclosan had no additive protective effect to the non-fluoride or fluoride toothpaste. In a second set of experiments, the enamel specimens were immersed daily for 3 min in 30% (w/v) slurries of the toothpastes before the 22 h incubation with the S. mutans suspensions. Under these conditions, triclosan showed an additional protective effect compared with non-fluoride toothpaste at a low concentration of S. mutans cells (0.07 mg cells dry weight per 600 microL suspension). It is concluded that the enamel surface may act as a reservoir for triclosan, which may protect the enamel surface against a mild acid attack. In combination with fluoride, however, as in toothpaste, triclosan has no additional protective effect against demineralization.

Animals↗
PubMed1999

Protection of dentin by triclosan toothpaste in a bacterial demineralisation model.

The effect of the addition 0.3% triclosan to a non-fluoride and fluoride toothpaste was tested in an in vitro demineralisation model. This model comprised bovine dentin specimens overlaid with acidogenic Streptococcus mutans suspensions in agarose at two different concentrations of cells. Before the experiments, subsurface lesions were made in the dentin specimens in a methylcellulose gel system. In a first set of experiments, the toothpastes were diluted in the S. mutans suspensions at w/v dilutions of 1:100, 1:1,000, and 1:10,000, respectively. After 22 h of incubation at 37 degrees C, the suspensions were removed and assessed for calcium, lactate and pH. In this set of experiments, an additive protective effect of triclosan to the non-fluoride toothpaste was found at the lowest concentration of S. mutans cells and when the toothpaste was relatively undiluted (1:100 w/v). No additive effect was observed to the fluoride toothpaste. In the second set of experiments, the specimens were immersed daily for 3 min in 30% (w/v) slurries of the toothpastes before the 22-h incubations with the S. mutans suspensions. At the lowest concentration of S. mutans cells, triclosan had an additional protective effect to the non-fluoride and fluoride toothpaste. It is concluded that triclosan may contribute to the protection of dentin under a mild acid attack both when it is present in dental plaque and when it has been adsorbed to the dentin.

Adsorption↗
PubMed1999

Effect of high fluoride concentration on bovine dentin demineralization in narrow grooves in vitro.

Previously, a dentin groove model was developed to investigate caries at plaque retention sites, such as marginal gaps, and pits and fissures. The aim of the present study was to investigate the in vitro effect of fluoride on the demineralization of dentin in the depth of the grooves at various distances from a freshly prepared resin-modified glass ionomer cement (RMGIC), which was used as the source of high fluoride release. Three parallel grooves (280 microm wide x 500 microm deep) were cut in the labial surface of 20 bovine coronal dentin discs. In 10 discs, the surface area (approximately 6 mm2) between the first groove and the edge of the disc was covered with RMGIC. The discs were exposed to an acidified methylcellulose gel system for 1 or 2 wk. Changes in mineral content were obtained by transverse microradiographic analysis. The results showed that integrated mineral loss (IML) was reduced up to 60% in the RMGIC groups, although the lesion depth was not significantly influenced by RMGIC. The pattern of demineralization differed between groups: the subsurface lesions in RMGIC groups did not decrease in IML towards the base of the groove to the same degree as in the control groups. It is concluded that high amount of fluoride inhibits loss of mineral, while not affecting the lesion depth. The homogeneity of the lesions with depth in the RMGIC group may be explained by a fluoride-induced inhibition of demineralization at the entrance of the grooves.

Analysis of Variance↗
PubMed1999

Current concepts on the theories of the mechanism of action of fluoride.

The caries-preventive effect of fluoride is mainly attributed to the effects on demineralization/remineralization at the tooth oral fluids interface. Sub ppm levels of fluoride in saliva are effective in shifting the balance from demineralization, leading to caries, to remineralization. This is attributed to the fluoride-enhanced precipitation of calcium phosphates, and the formation of fluorhydroxyapatite in the dental tissues. Low fluoride levels are found in saliva after toothbrushing with fluoride containing dentifrices. Similar concentrations are ineffective in interfering with processes of growth and metabolism of bacteria, and also do not result in a significantly reduced dissolution of tooth mineral as a result of (firmly bound) fluoride incorporation. Comparative studies of fluoride efficacy have shown that higher concentrations in solution are needed in pH-cycling studies of dentine than in enamel to maintain the mineral balance or to induce remineralization. This is attributed to the greater solubility of the dentine and the smaller size of the dentine crystallites compared to enamel. Fluoride slow-release devices, in the form of fluoride-releasing restorative materials, may serve to increase the fluoride levels in saliva and plaque to levels at which caries can be prevented, also in high-risk patients. Research questions for the next millennium and future perspectives for fluoride applications should be found in the retention and slow release of fluoride after various combinations of fluoride treatment, the combination of fluoride and anti-microbial treatment, the individualization of caries prevention, and the combination of preventive schemes with new developments in caries diagnosis.

Cariostatic Agents↗
PubMed1999

In situ fluoride retention in enamel and dentine after the use of an amine fluoride dentifrice and amine fluoride/sodium fluoride mouthrinse.

The aim of this in situ investigation was to study the effect of an amine fluoride/sodium fluoride mouthrinse (total F = 250 ppm) in addition to an amine fluoride dentifrice (F = 1,250 ppm) on the amount of acquired fluoride in enamel and dentine. In the partial prosthesis of 12 participants a combined specimen of slightly demineralized enamel and dentine was placed. During two consecutive experiments, each lasting 3 weeks, the participants used an amine fluoride dentifrice alone or in combination with a fluoride mouthrinse. After the in situ period the specimens were retrieved and both the enamel and the dentine specimens were analysed for the amount of KOH-soluble fluoride and structurally bound fluoride. The results showed a significant increase in both KOH-soluble and structurally bound fluoride in enamel and dentine when a fluoride mouthrinse was used. Whether the rinsing procedure was performed immediately after toothbrushing or with a delay of 2 h did not influence the results. Furthermore it was shown that dentine acquired substantially more fluoride than enamel during the experimental period. The results indicate that a fluoride mouthrinse used in addition to a fluoride dentifrice may have a beneficial effect on the protection of enamel and dentine against caries.

Adsorption↗
PubMed1999

Fluoride mechanisms.

This article discusses fluoride mechanisms in relation to dental caries. The authors specifically address firmly bound versus loosely bound fluoride; different fluoride active ingredients; fluoride and demineralization and remineralization; fluoride slow-release devices and F-releasing dental materials; antimicrobial effects of fluoride; the uptake of fluoride by oral bacteria; inhibition of enolase, protein-intruding ATPase and sugar transport; the various aspects of plaque as it relates to fluoride; and the rational use of fluoride.

Anti-Bacterial Agents↗
PubMed1998

A novel pyrroleninone cross-link from bovine dentine.

The aim was to identify suspect collagen cross-links in dentine, eluting close to known cross-links in ion-exchange HPLC. Bovine tooth roots as source of dentine were powdered, demineralised, reduced, and acid-hydrolysed. Cross-linking amino acids were isolated from the acid hydrolysate by size exclusion, adsorption, and sequential ion exchange chromatography. In addition to dihydroxylysinonorleucine and hydroxylysylpyridinoline, an unknown cross-link was isolated (V-2). The ultraviolet, mass, and nuclear magnetic resonance spectra support the proposed structure of V-2, a trimeric amino acid with a pyrroleninone nucleus.

Amino Acids↗