Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MICRORADIOGRAPHY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources
PubMed1990

Mineral loss during etching of enamel lesions.

This study was aimed at determining the amount of mineral removed from incipient enamel lesions during acid etching. The rationale being that fissures which are scheduled for sealing will often have undetected demineralized regions. Lesions were formed in bovine enamel specimens using either an acidified gelatine gel or a lactate buffer containing methane hydroxy diphosphonate. Different parts of each lesion were acid-etched either for a 1- or for a 2-min period in 36% H3PO4 or served as control. Mineral content profiles were recorded on thin sections using computerized microradiography to determine the mineral loss resulting from acid etching. The results show that during etching a layer at the outer surface is removed completely. The thickness of this layer was greater for lesions when compared with sound enamel and depended on the lesion characteristics (porosity and fluoride content). The amount of mineral removed from the deeper layers of the lesion was very small; and in the innermost part of the lesions the mineral profiles of the control and acid-etched areas coincide. These observations indicate that the effect of etching is essentially restricted to a thin outer layer, irrespective of the porosity of the underlying tissue. Although the thickness of the etched-off layer was different between the two types of lesions, these findings were made for both types studied. In practical terms this implies that etching of enamel lesions does not cause an excessive mineral loss throughout the lesion.

Acid Etching, Dental↗
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 an antimicrobial-containing varnish on root demineralisation in situ.

The effect of an antimicrobial-containing varnish on root demineralisation was investigated. The in situ demineralisation effect on the varnish, with or without the active ingredients chlorhexidine and thymol, was measured by means of microradiography in comparison with no application after a 2-week period in vivo. Furthermore, the effect of one or two applications was investigated by the 10 participants who carried sound intact roots in an appliance for four consecutive 2-week periods. In each period, different roots were mounted in the buccal flanges of a lower prosthesis, the experiment being of a randomized cross-over design. The results show that: (1) A single varnish treatment with active ingredients reduced lesion depth and mineral loss by about 77 and 82%, respectively. (2) The control varnish had no effect, and it can be concluded that antimicrobial-releasing varnishes are promising materials for root caries prevention.

Administration, Topical↗
PubMed1990

Mineral density and mineral loss after demineralization at various locations in human root dentine. A longitudinal microradiographic study.

From intact roots of human cuspids 83 dentine specimens were cut. The specimens with known location and thickness were embedded in a holder of polymethyl methacrylate and microradiographic images were made. From the longitudinal microradiography (LMR) measurements the average mineral density (kg/m3) of the sound human dentine specimens was calculated. All specimens were subsequently demineralized using a constant composition method in a solution containing 3 mM CaCl2.2H2O, 3 mM KH2PO4, 50 mM CH3COOH and 0.2 ppm fluoride as NaF at pH = 5 for 24 h. After demineralization the LMR measurements were repeated to calculate the amount of mineral lost. The data show that there is no correlation between: (1) the location of a dentine specimen in the root and the mineral density of sound human dentine, (2) the location of a dentine specimen in the root and the degree of demineralization after 24 h and (3) the mineral density of sound human dentine and the demineralization degree. This information is useful for future in vitro and in vivo studies on human roots.

Analysis of Variance↗
PubMed1990

A model study for quantification of approximal caries with a fluorescent dye.

The fluorescence intensity of the dye Fluorol 7GA in in vitro caries lesions was measured through a strip of plastic either 2 or 1.5 mm in thickness. The light scattering in the plastic strips was comparable with light scattering in sound enamel. This method was chosen as a model for fluorescent dye measurement at approximal sites, where the fibreoptic probe cannot be placed directly on the lesion, so that measurements have to be made through a thin layer of sound enamel. It appeared that the fluorescent dye can be measured through a layer of scattering material and that a linear correlation exists between fluorescence intensity and calcium loss as measured by longitudinal microradiography. The correlation coefficient for the 2-mm plastic strip was r = 0.76. With the 1.5-mm plastic strip the fluorescence intensity recordings were about twice as high, and the correlation coefficient was r = 0.81. From these measurements a proposal for an application procedure emerged for the use in a clinical situation. Also the transmission of light at 550 and 650 nm, at which wavelengths the fluorescent dye does not absorb, through plastic strips of varying thickness was measured. It is shown that by measurement of transmission of a non-adsorbing wavelength, the fluorescence intensity measured through a layer of scattering material can be corrected for this layer.

Animals↗
PubMed1991

Evaluation of the effects of a pyrophosphate-fluoride anticalculus dentifrice on remineralization and fluoride uptake in situ.

Enamel slabs and thin sections with artificially formed caries lesions were placed in the removable dentures of 15 subjects who brushed them three times daily for 2 weeks with a 1.3% pyrophosphate/1,100 ppm F/1.5% Gantrez dentifrice, a 1,100-ppm F dentifrice without pyrophosphate or Gantrez, or a placebo dentifrice in a double-blind, crossover study. Analysis of the thin sections by quantitative microradiography showed that the pyrophosphate/F dentifrice remineralized the lesions 15.9% (p less than 0.05) and the fluoride dentifrice 11.2%, whereas the placebo produced 4.4% demineralization. Fluoride uptake by the enamel slabs was similar for both fluoride dentifrices and significantly greater from the placebo dentifrice (p less than 0.05). The findings suggest that the anticaries mechanisms of fluoride include not only the prevention of demineralization, but also the promotion of remineralization.

Adult↗
PubMed1991

Effects of phosphoprotein moieties on the remineralization of human root caries.

The noncollagenous proteins, especially phosphoprotein, have been shown to modulate biomineralization. The objective of this study was to investigate the remineralization potential of human tooth root organic matrices which did or did not contain soluble non-collagenous proteins including phosphoprotein. Human tooth roots were completely demineralized using conditions that either removed or did not remove soluble phosphoprotein and were then subjected to remineralization conditions. Removal of soluble phosphoprotein resulted in remineralization while no remineralization occurred in tooth roots that still contained soluble phosphoprotein. Transmission electron microscopy and microradiography demonstrated that demineralized cementum did not remineralize under any of the conditions used in this study. Collagenase digestion of demineralized and salt-reextracted tooth root organic matrices revealed that a nonsoluble phosphoprotein was present in the matrices. Amino acid analysis and SDS-PAGE showed that this nonsoluble phosphoprotein was similar in composition to the soluble phosphoprotein. This work suggests that the removal of soluble, noncollagenous proteins, especially phosphoprotein from root caries lesions, may enhance their remineralization potential.

Amino Acids↗
PubMed1991

Optical quantification of approximal caries in vitro.

A fluorescent dye was applied to extracted premolars with either early artificial lesions or natural white-spot lesions. The teeth were placed in an approximal geometry, and with a specially designed fibre-optic probe the fluorescence of the dye was measured in the lesions. The same fibre-optic probe was used to measure the transmission of light at a wavelength where the dye does not absorb. This transmission of light was used to correct the fluorescence for attenuation by the intermediate layer of sound enamel situated between the probe and the lesion. Both signals varied with time because of the necessary addition of ethanol during the measurement. The mineral loss from the lesions was measured with wavelength independent microradiography (WIM) for the artificial lesions, and the optical caries monitor (OCM) for the natural white-spot lesions. The correlation coefficient between corrected fluorescence and mineral loss was r = 0.86. The results indicate that measurement of dye uptake may be a very sensitive method to diagnose early approximal caries lesions and may enable quantification of these lesions.

Bicuspid↗
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

Increased resistance to artificial caries-like lesions in dentin treated with CO2 laser.

The crowns of 60 permanent human molars were sectioned transversally. The exposed dentin surface was divided into different parts: a first part was kept as control, a second part was immediately varnished, and a third part was irradiated with a CO2 laser using the same irradiation conditions as those applied for caries removal (10 impulses of the same energy; 0.2 s/impulse; energy density/impulse 280-715 J/cm2. After irradiation, a small portion of this area was varnished. The teeth were immersed for 4 weeks in a cariogenic gel (pH = 4.5) at 36 degrees C. Twenty teeth were studied by scanning electron microscopy, and longitudinal sections of the other teeth were prepared for microradiography and microdensitometry measurements. The lased dentin surface appeared smooth for energy densities lower than 425 J/cm2. Longitudinally fractured samples revealed a layer of dentin devoid of tubular structure (20-70 microns thick, depending on the energy density used), whereas below the sealed layer, the dentinal tubules retained their normal aspect. Although the sealed layer showed no demineralization when exposed to acid, demineralization of the underlying dentin occurred, but to a much lesser extent than in the unlased dentin.

Carbon Dioxide↗
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

Combined effects of laser irradiation and chemical inhibitors on the dissolution of dental enamel.

It has previously been shown that the susceptibility of human teeth to acid dissolution can be reduced by the presence of various chemical agents in the dissolution medium or by pretreatment of the teeth with laser irradiation. Now synergism between these two approaches to improving acid resistance has been demonstrated. Extracted human teeth were irradiated with a continuous-wave carbon dioxide laser at a wavelength of 10.6 microns. Energy doses of either 65 or 130 J/cm2 given over periods of 2 or 4 s, respectively, were applied and the teeth subjected to a severe acid challenge (0.1 M acetate buffer, pH 4.5, no calcium or phosphate common ion present) for 24 h. Mineral loss was assessed by measurement of mineral density profiles with quantitative microradiography. Experiments were carried out in the presence or absence of three chemical inhibitors with distinctly different mechanisms of action: ethane-1-hydroxy-1, 1-diphosphonic acid, fluoride, and dodecylamine HCl. Laser irradiation alone was found to lead to increased resistance of the teeth to acid challenge, with the higher energy dose being more effective than the lower dose. Each of the chemical inhibitors was effective on both lased and unlased teeth, with the percent reduction of dissolution greater when the inhibitors were applied to teeth lased with an energy dose of 130 J/cm2 which were already more resistant to acid challenge than were unlased teeth or teeth lased with a dose of 65 J/cm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1992

Effects of chewing gums sweetened with sorbitol or a sorbitol/xylitol mixture on the remineralisation of human enamel lesions in situ.

Intra-oral remineralisation of experimental caries-like lesions in human enamel, as determined by polarised light microscopy and quantitative microradiography, was promoted to a similar extent (% fall in delta Z, 18.6 and 19.0) by chewing a sorbitol or sorbitol/xylitol (3:1)-sweetened gum for 20 min after each of three meals and two sugary snacks daily. The results suggest that reported differences in the properties of the two sweeteners do not affect their ability to enhance remineralisation due to salivary stimulation.

Adult↗
PubMed1993

Fluoride and mineral content in hyper-remineralized coronal bovine dentine in vitro after an acid challenge.

In this paper the acid resistance of hyper-remineralized dentine was quantified by means of fluoride and mineral measurements. Hyper-remineralization was achieved by demineralization of dentine in an acidic gel system (pH 5) for 3 weeks, followed by remineralization in a solution containing 1.5 mM Ca, 0.9 mM phosphate and 10 ppm F at pH 7 and 37 degrees C for 8 days. The samples were subsequently again demineralized in the gel system mentioned for 1, 2 and 3 weeks. Analysis for fluoride was done by means of the microdrill biopsy technique and to obtain information on the fluoride distribution by secondary ion mass spectrometry (SIMS); mineral was assessed by microradiography. The results showed that in hyper-remineralized dentine the original fluoride content was approximately 30,000 ppm F. This value was still in the same order after the acid challenge of 3 weeks at pH 5. These values were substantially higher than the baseline values in sound or in demineralized dentine being about 900 ppm F. The main microradiographic result was that there was no significant mineral change in the hyper-remineralized dentine due to the acid challenges. There was, however, a tendency for mineral redistribution deeper into the dentine lesion leading to lamination phenomena. The SIMS experiments on some of the samples showed a fluoride distribution in agreement with the microdrill fluoride data. Furthermore a fluoride redistribution took place in deeper parts of the lesion due to the acid challenges. The combined fluoride concentration and microradiographical data indicate that fluoride-enriched and highly mineralized hyper-remineralized dentine is more acid resistant than sound or demineralized dentine.

Animals↗
PubMed1993

An in vitro evaluation of fluorescein penetration into natural root surface carious lesions.

In order to develop a method for detection and quantification of initial root surface carious lesions, the use of fluorescein sodium as a fluorescent dye is evaluated. The penetration depth of fluorescein sodium into human roots containing natural carious lesions was measured on approximately 130-microns-thick slices, cut in a direction perpendicular to the pulp. This depth was compared to the lesion depth that was measured on the same slice with transversal microradiography. The results indicate that fluorescein sodium in water penetrates into demineralized layers of root dentine even if a surface layer with a high mineral content is present. The penetration depth is about 1.1 times the microradiographically determined lesion depth.

Dental Caries Activity Tests↗
PubMed1993

Shrinkage of sound and demineralized human coronal dentine slabs.

In this article a method is presented for dentine shrinkage measurements. The relative shrinkage of sound dentine slabs is assessed using a Perthometer with respect to a steel reference. The relative shrinkage of lesions in dentine slabs can be estimated using combined Perthometer/microradiography measurements. The results show that the relative lesion shrinkage of lesions in thick slabs is quite different from the shrinkage of lesions in thin sections used for microradiography. The relative lesion shrinkage is, for periods up to 30 min, linear with the air drying period and increases strongly with the demineralization period. The previously published diol treatment is capable of reducing the relative lesion shrinkage in thick dentine slabs to negligible values.

Dentin↗
PubMed1994

An in vitro model for studying the efficacy of fluoride dentifrices in preventing root caries.

This investigation tested and validated an in vitro model for studying the effects of fluoride on human dentin mineral content and fluoride uptake. Four studies examined the effects of different concentrations of fluoride, established dose-response profiles with NaF and Na2PO3F, and tested commercial dentifrices. A 7- or 14-day cyclic treatment regimen involved four 1-min exposures of sound human dentin specimens to the treatment agents, a 4-hour acid challenge period, and 20 h in human saliva daily. Mineral content was analyzed by image analysis microradiography and fluoride assays were performed using a microdrill biopsy technique. Data from these studies established the ability of the in vitro model to provide reproducible results, to demonstrate significant dose-related differences in the effects of both NaF- and Na2PO3F-containing treatments on dentin fluoride uptake and demineralization, and to detect a fluoride-induced reduction in dentin caries, relative to a nonfluoride control, similar to results established in a clinical trial.

Biopsy↗