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Results for “Dentin Solubility”

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PubMed2002

A comparative study of fluoride-releasing adhesive resin materials.

One of the most important and exciting properties of recently introduced dental restorative materials is their ability to release fluoride ions, as this has several advantageous effects on tooth structures. They have been extensively used as fluoride-releasing filling and luting materials. Recently, fluoride-releasing adhesive resins and fluoride-releasing adhesive resin cement have been developed and introduced for clinical use. The purpose of this study was to evaluate the fluoride release from these adhesive resins and the fluoride uptake by both enamel and dentin, as well as the acid-resistance of these tooth structures. Based on our results, we conclude that fluoride-releasing adhesive resins and luting cements are useful for the prevention of initial or secondary caries, especially along the margins of restorations.

Cariostatic Agents↗
PubMed1978

Type-I trimer and type-I collagen in neutral-salt-soluble lathyritic-rat dentine.

Triple-helical collagen molecules have been obtained from EDTA-demineralized lathyritic rat incisors by neutral buffer extraction. Component alpha chains, isolated by sequential ion-exchange and gel-filtration chromatography, were shown to be alpha1 I and alpha2 chains by cyanogen bromide peptide analysis. The alpha1 I:alpha2 chain ratio was approximately 3:1, which is greater than expected for type I collagen. The excess of alpha1 I chains over that required for type I collagen was due to the presence of type I trimer molecules. Fractional salt precipitation separated type I collagen from type I trimer. It is not known at present if type I trimer synthesis also occurs in normal rat tissues.

Animals↗
PubMed1999

Effect of chloroform, xylene, and halothane on enamel and dentin microhardness of human teeth.

OBJECTIVE: The purpose of this study was to assess in vitro the effect of commonly used gutta-percha solvents on the microhardness of human enamel and dentin. STUDY DESIGN: Crowns of human teeth were cut and treated with chloroform, xylene, and halothane. Treatment consisted of exposing the specimens for 5 or 15 minutes to the test solvents. Acid-treated and saline-treated specimens served as controls. After each treatment period, the specimens were rinsed, dried, and prepared for Vicker's microhardness analysis. Vicker's microhardness values for each specimen were recorded before and after treatment, and the differences were statistically compared. RESULTS: A statistically significant decrease in enamel and dentin microhardness was found in most solvent-treated groups; the amount of the decrease was directly related to the exposure time. CONCLUSIONS: Chloroform, xylene, and halothane may cause a significant softening effect on both enamel and dentin. This softening is already apparent after 5 minutes of treatment.

Adult↗
PubMed1995

Synergistic effects of magnesium and carbonate on properties of biological and synthetic apatites.

Magnesium (Mg) and carbonate (CO3) are minor elements associated with enamel, dentin and bone apatite. The purpose of this study was to determine the effect of Mg and CO3 on some properties of synthetic apatites to gain insights on their effects on biological apatites. Biological apatites from human enamel and dentin and from bovine bone and synthetic apatites with/without Mg or CO3 were characterized using x-ray diffraction, infrared absorption, thermogravimetry and chemical analyses. Dissolution in acidic buffer was also determined. Results from this study demonstrated: (1) the synergistic effects of Mg and CO3 on reducing the crystallinity and increasing the extent of dissolution of synthetic apatites; (2) dentin and bone, compared to enamel apatite contained higher levels of Mg and CO3; had lower crystallinity and higher extent of dissolution. The lower crystallinity and higher extent of dissolution of dentin and bone compared to enamel apatite may be partly attributed to their higher Mg and CO3 concentrations.

Animals↗
PubMed2006

Acid susceptibility at various depths of pH-cycled enamel and dentine specimens.

pH-cycling and in situ studies have shown that fluctuations in de-/remineralisation conditions or in fluoride usage can lead to laminations inside enamel or dentine lesions. Layers with different mineral content are thought to reflect the history of fluoride administrations. Studying the dissolution properties of such lesions at various depths -- using bulk specimens -- is presumably hampered by limited diffusion of acids through the lesion pores. Therefore, in this study the acid susceptibility of enamel and dentine lesions and the underlying sound tissues was studied by exposing sections to acid buffers from the cut rather than from the external surface. Specimens were obtained from a previous study of the effects of high-fluoride (0, 1,000, 2,000, 3,000/5,000 ppm F) toothpastes on enamel and dentine de-/remineralisation. Sections were subjected to acid buffers for 3 and 7 days and the changes in mineral content were monitored by contact microradiography. For enamel lesions a significant difference in dissolution over depth was observed between the groups subjected to the different fluoride schemes. At 7 days a dose response was found between the different fluoride groups and the lesion parameters. In the no-fluoride group dissolution in the original lesion and the sound tissue were similar. All dentine lesions which had been treated with fluoride showed inhibition of dissolution, but the inhibition did not increase with higher fluoride concentrations. Deeper into the dentine tissue there was some protection, but it was not statistically significant. We conclude that penetration of fluoride through the lesion pores determines the dissolution pattern of a lesion at various depths.

Acetic Acid↗
PubMedDate not supplied

Preliminary in vitro assessment of erosive potential using the ultra-micro-indentation system.

The aim of this study was to measure the change in hardness and modulus of elasticity of enamel and dentine in primary teeth using the ultra-micro-indentation system (UMIS) after exposure to potentially erosive beverages and to relate the changes to the chemical composition of the test beverages. Primary molar teeth were sectioned and polished. Indentations were made in enamel and dentine prior to and then after exposure to one of four beverages: distilled water (control), orange juice, Orange Cordial, Fanta((R)) and a 'toothfriendly' Tropical Orange Cordial (Ribena((R))). Each beverage was then analysed. Fanta and Orange Cordial were the only test beverages to show a statistically significant reduction in the enamel hardness in comparison to the control and only Fanta showed a significant reduction in dentine hardness. None of the test beverages significantly reduced the modulus of elasticity of either enamel or dentine. Statistically the pH, phosphate and fluoride concentrations of the beverages were correlated with softening of enamel. Calcium concentration and titratable acidity were correlated with softening of dentine. The UMIS offers another method of measuring the basic mechanical properties of enamel and dentine. This is useful in predicting the erosive potential of substrates. It is likely that the pH, titratable acidity, fluoride, phosphate and calcium content of beverages are all important in determining the potential erosiveness of beverages.

Acids↗
PubMed2000

Erosion of dentine and enamel in vitro by dietary acids: the effect of temperature, acid character, concentration and exposure time.

Sales of soft drinks has been increasing by 56% over the last 10 years and are estimated to keep rising at about 2-3% a year. Further, the reported incidence of tooth erosion has been increasingly documented. Whilst these factors could well be linked, many individuals with erosive diets are not presenting with erosion. This would suggest the effects of many variables, hence the aim of these investigations. Methodologies included preparing enamel and dentine samples from unerupted human third molars. Groups of five specimens were placed in citric acid over a temperature range of 5-60 degrees C for 10-min exposures; placed in citric, lactic, malic or phosphoric acid (0.05, 0.1, 0.5, and 1% (w/v)) for 10-min exposures; and placed in the same three organic hydroxy acids at 0.3% (w/v) or phosphoric acid at 0.1% (w/v) for 3 x 10-min exposures. Tissue loss was determined by profilometry. Results showed that increasing temperature, concentration and exposure time increased the erosion of dentine and enamel. This study has shown that under highly controlled conditions, erosion of dentine and enamel by dietary acids can be greatly influenced in vitro by temperature, concentration, type of acid and exposure time. These factors could be employed in order to reduce the erosivity of soft acidic drinks.

Adolescent↗
PubMedDate not supplied

A study in vitro of the abrasive effect of the tongue on enamel and dentine softened by acid erosion.

The palatal aspect of upper anterior teeth appears to be one site of predilection for erosion. This raises the question of whether abrasion of softened enamel and dentine by the tongue has a role in this process. The aim of this study in vitro was to determine whether enamel and dentine specimens licked by the tongue after exposure to acid lost more tissue than when exposed to acid alone. Flat enamel and dentine specimens were prepared from human third molars and taped to expose a window of tissue. Three groups of specimens were exposed to citric acid for 10 min followed by 60 s tongue licking, ultrasonication or immersion in water. Two further groups of enamel specimens were placed in a low erosive drink for 10 min with or without licking. At the end of 5, 10 and 15 treatment cycles tissue loss was measured by profilometry. Enamel loss was significantly greater with licking and ultrasonication compared to water immersion. Dentine loss was greater with licking and ultrasonication compared to water immersion, but differences only reached significance for ultrasonication. The low erosive drink produced one third of the citric acid erosion and licking had no effect. The results suggest that the tongue could exert an abrasive effect on dental tissues softened by erosion, thereby increasing the overall loss of tooth substance.

Adolescent↗
PubMedDate not supplied

The effect of window width on the demineralization of human dentine and enamel.

When lesion formation in dental enamel or dentine is studied in vitro, a well-defined area of the material, a 'window', is exposed to the demineralization medium. In the present experiments, we report the effect of window width on lesion formation in enamel and dentine. Rectangular windows, longest dimension always 5 mm and shortest dimension varying from 0.5 to 5 mm, were exposed to demineralization media. Lesions in dentine were formed by placing the specimens in an acidified unstirred 6% carboxymethyl cellulose (CMC) gel, an unstirred 0.5% CMC gel, a mildly stirred 0.5% CMC gel, or in a mildly stirred demineralization solution. Lesions in enamel were formed only in an unstirred acidified 6% CMC gel. pH in the demineralization media was 5.0 in all experiments. The microradiographic technique was used to assess lesion depth and mineral loss (vol% x microm) of lesions formed. Lesions formed in the unstirred gels were deeper, and there was a larger mineral loss, the narrower the window. There was no effect of window size on lesions formed in stirred systems. These effects can be explained by the strong dependence of concentration gradient in stirred gels just outside the exposed window on the window size. The phenomenon found here in vitro may at least partly explain why secondary caries may lead to localized, but relatively deep, lesions.

Carboxymethylcellulose Sodium↗
PubMed1991

Modulatory effect of fluoride and irradiation on rat molar rate of wear.

The hypothesis was tested that fluoride (F-) modulates molar wear rate in the irradiated rat and that enamel solubility and dentin hardness are involved in this process. Seventy five 21 day-old rats were divided into 5 groups. Groups received either F-(25 ppm) in the drinking water or irradiation to the head (15 Gy in a single dose), or a combination of the two. The rate of occlusal wear was assessed by computerized planimetry. The amount of wear was significantly higher in the F- and irradiation monotreated rats, while under combined treatment it did nor differ significantly from the control values. Fluoridation or irradiation suppressed enamel solubility, as measured by calcium release in the etchant. Dentin microhardness, expressed in Vickers hardness number, was enhanced after either treatment, but remained unaffected when F- administration preceded irradiation. Enamel solubility and dentin microhardness did not correlate significantly with the rate of occlusal wear.

Animals↗
PubMed1991

Influence of the solubility parameter of intermediary resin on the effectiveness of the gluma bonding system.

The aim of the present study was to investigate the effect of the solubility parameter of the intermediary resin in the Gluma system on the bonding to dentin. The solubility parameter of the resins was varied between 18.8 x 10(3) and 21.1 x 10(3) J(1/2)/m3/2 by varying the composition of the resin. The efficacy of the bonding system was determined by measurements of marginal gaps formed by polymerization contraction of a restorative resin in dentin cavities treated with the bonding system. The bonding system had maximum efficacy at a solubility parameter of the intermediary resin of delta = 20.0 x 10(3) J(1/2)/m3/2. This finding corroborates a concept of bonding to dentin that involves a mechanical interlocking by interpenetrating resins.

Analysis of Variance↗
PubMed2006

Retention of KOH-soluble fluoride on enamel and dentine under erosive conditions--A comparison of in vitro and in situ results.

OBJECTIVES: Aim of the study was to investigate the stability of CaF(2)-like precipitates on enamel and dentine under neutral or acidic conditions and to compare in vitro and in situ results. METHODS: Human enamel and dentine specimens were fluoridated (Elmex fluid, 5 min) and subjected to erosive demineralisation (Sprite light: 3/day each; 30 s in vitro, 2 min in situ) or stored under neutral conditions for 4 (in vitro) or 7 (in situ) days. KOH-soluble fluoride was determined using an ion selective electrode. Between the acid attacks, specimens were stored in remineralisation solution (in vitro) or retained in the oral cavity (four volunteers for enamel and dentine each). RESULTS: Initially, high amounts of KOH-soluble fluoride were gained (between 77.9+/-12.3 and 96.0+/-46.4 microg/cm2). Under neutral conditions in vitro, a significant decrease on enamel (16.2+/-5.0 microg/cm2) and dentine (18.6+/-10.5 microg/cm2) was found, which was more severe under acidic conditions (6.3+/-3.0 and 5.1+/-2.1 microg/cm2, respectively). Under in situ conditions, KOH-soluble fluoride was strikingly stable on enamel under neutral (42.3+/-12.6 microg/cm2) as well as under acidic conditions (54.1+/-17.4 microg/cm2). On dentine, the dissolution kinetics of KOH-soluble fluoride was similar to the in vitro conditions, but the loss was less severe (45.3+/-12.9 microg/cm2 under neutral and 8.8+/-6.4 microg/cm2 under acidic conditions). CONCLUSIONS: In vitro, more KOH-soluble fluoride was lost under erosive compared to neutral conditions. The intra-oral environment was considerably protective for CaF2-like precipitates especially on enamel.

Amines↗