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Results for “Dentin Permeability”

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PubMed1999

In vitro permeability and scanning electron microscopy study of acid-etched and ground enamel surfaces protected with dental adhesive coating.

Clinical procedures, such as acid etching and reshaping of the teeth supporting removable partial dentures by grinding off some enamel surface, increase the permeability of dental enamel. Teeth take several months in vivo to partially recover from such damage. In the meantime, the tooth is more susceptible to carious decay. To prevent this the ground or etched enamel should be effectively protected. Using electron paramagnetic resonance (EPR) and a two-chamber diffusion cell the authors studied the influence of adhesive resin applied to the ground and acid-etched enamel surfaces on the diffusion of spin label TMAPO (2,2,6-6 tetramethyl-4-acetamido-piperidine-1-oxyl) molecules through the enamel. The enamel permeability was measured in samples exposed to 1-min etching with 37% phosphoric acid, in samples etched for 5 min, and in samples ground with a diamond bur. Next, all the treated enamel surfaces were coated with Scotchbond Multi-Purpose Plus(R) dental adhesive system and the permeability measurements repeated. Scanning electron microscopy (SEM) was used to study the porosity of enamel surfaces. The adhesive resin film covering the etched or ground enamel surfaces was found to decrease significantly the diffusion through dental enamel. This finding confirms the clinical value of dental adhesives used to protect ground or accidentally acid-etched enamel surfaces. SEM analysis showed that adhesive resin covers the porous surface of the acid-etched and ground enamel tightly.

Acid Etching, Dental↗
PubMed2006

Progression of sealed initial bovine enamel lesions under demineralizing conditions in vitro.

The use of sealants for the infiltration of proximal enamel lesions could be a promising alternative to the common strategies of remineralization and operative treatment. The aim of the present study was to compare the progression of sealed initial enamel lesions after exposure to a demineralizing solution in vitro. In each of 54 bovine enamel specimens three subsurface lesions were created. Two of the lesions were etched with phosphoric acid and sealed with either a fissure sealant or with various adhesives (1-5) for 15 s or 30 s, respectively, whereas one lesion remained as the untreated control. Subsequently, half of each specimen was covered with nail varnish (baseline) and the other half was reexposed to a demineralizing solution for 14 days (experimental). The specimens were cut perpendicularly to the surface, infiltrated with a low-viscosity fluorescent resin and observed with a confocal laser scanning microscope (CLSM). For lesions sealed with the fissure sealant and adhesives 1-3, the progression of lesion depth (0-31 microm) was significantly decreased (p<0.01; paired t test) compared with the untreated control (57 microm). For the fissure sealant and adhesives 1 and 3 extended penetration times (30 s) resulted in significantly reduced lesion progression compared to 15 s. It can be concluded that filling of the pores in initial enamel lesions with the fissure sealant and adhesives 1-3 can inhibit further demineralization in vitro.

Acrylates↗
PubMed1999

Effect of saliva contamination on micromorphological adaptation of single-bottle adhesives to etched enamel.

This study explored the topography of the interface of composite resin bonded with four single-bottle adhesives and enamel under salivary contaminated conditions. Prime & Bond 2.1, One Step, Tenure Quik and Syntac Single Component were evaluated. Thirty six sound molars were divided into three subgroups for each of the four adhesives. Small flat areas on the buccal and lingual surface were wet ground in enamel. The adhesives were tested under: uncontaminated condition (Group 1), contamination of the bonding site with fresh whole saliva for 20 seconds (Group 2) and rinsing the saliva for 20 seconds before adhesive application and after enamel etching (Group 3). After adhesive application button of composite resin was applied and light cured. The roots of the teeth were removed and the crowns with the bonded composite immersed in HCl acid till the composite resin buttons become free of enamel. The buttons were immersed in NaC10(4) and prepared for SEM examination. The bonding surface of the composite resin buttons revealed the formation of resin tags reflecting the different etching pattern of enamel. Saliva contamination either washed or unwashed did not affected the resin tags formation except for Syntac Single Component with contaminated unwashed enamel. The clinical significance of this in vitro research was that saliva contamination did not affect the resin tags formation of Prime & Bond 2.1, One Step, and Tenure Quick. For Syntac Single Component, only contaminated unwashed enamel decreased resin tags formation.

Acid Etching, Dental↗
PubMed1998

Interfacial ultrastructure of the resin-enamel region of three adhesive systems.

PURPOSE: To observe the resin/enamel interface produced by different adhesive systems. MATERIALS AND METHODS: A conventional three-step smear layer removing adhesive system (Scotchbond Multi-Purpose), a two-step smear layer removing adhesive system (Prime & Bond), and a two-step smear layer dissolving adhesive system containing a self-etching primer (Panavia 21) were evaluated. Flat enamel surfaces were obtained from approximal surfaces of 18 extracted human molars. A total of 36 surfaces were collected and divided into three groups of 12 samples. One-half of each specimen in each group was etched with 35% phosphoric acid prior to the application of each adhesive system, with the second half being kept unetched. Subsequently, resin composite was placed and polymerized for 40 seconds. The samples were fractured and immersed into HCl and NaOCl solutions, followed by critical point drying and sputter coating for examination with a field emission scanning electron microscope. RESULTS: In the etched samples, Panavia 21 and Scotchbond Multi-Purpose showed more consistent resin tag penetration than did Prime & Bond. Unetched Prime & Bond and Scotchbond Multi-Purpose samples showed minimal or no adhesive penetration in enamel surfaces.

Acid Etching, Dental↗
PubMed2000

Analysis of sealing vs tensile bond strength of eight adhesive restorative material systems.

PURPOSE: Using a simulated perfusion system, the intent was to determine: 1) the sealing ability of eight restorative materials (five composite resins and three compomers) used together with their corresponding dentin bonding systems, 2) their tensile bond strength, and 3) the correlation (if any) between both parameters. MATERIALS AND METHODS: Permeability in crown segments from sound human third molars (n = 140) subjected to simulated perfusion (32 cm of distilled water) was measured before and after restoring with each material, and the percentage of decrease in permeability (PPD) was recorded. Specimens were later subjected to tensile tests to determine the tensile bond strength (TBS) of the interface. Finally, parameters were analyzed for correlation. RESULTS: For the eight adhesive systems, the percentage of reduction in permeability was relatively high [mean in %, (SD)]: F2000 93.6 (5.7), SB1 88.6 (11.3), SSC 86.0 (5.7), PB20 81.1 (15.9), COM 77.5 (10.8), OPTS 75.3 (20.6), DYR 73.7 (12.7), SSPR 65.5 (19.8). TBS values were relatively low [mean (SD)], in MPa: F2000 1.8 (0.7), SB1 4.9 (1.4), SSC 2.6 (1.4), PB20 4.3 (1.2), COM 2.4 (1.1), OPTS 4.5 (1.7), DYR 1.6 (0.6), SSPR 4.2 (1.5). We could not demonstrate any statistically significant correlation between both parameters for these results (maximum significance [F2000]: r = 0.39, p = 0.206). CONCLUSION: No material completely ceased to filtrate through the interface. The low TBS values were probably due to the large size of adhesive areas. No significant correlation was found between PPD and TBS for the materials tested. There was a statistically significant relationship (r2 = 0.063, p = 0.018) between TBS and TBA (total bonded area), described by the equation TBS = 5.9 - 0.03.TBA.

Adhesives↗
PubMed1989

Permeability of apical barriers.

The purpose of this work was to measure the permeability (hydraulic conductance) of root canal apical barriers in vitro. In 30 extracted teeth, the pulp tissue was removed and the apical opening standardized and enlarged using endodontic files. One-millimeter thick barriers of either autogenous dentin chips, calcium hydroxide powder, or durapatite particles were placed just inside the apical opening. The prepared teeth were mounted in a special chamber, fluid pressure applied, and the resultant flow measured. The permeability of dentin chip barriers in 10 additional teeth with nonstandardized apical openings was measured also. The standardized canals with the autogenous dentin chip barriers had a mean permeability of 0.0010 microliter/s/psi at 20 psi applied pressure. Teeth with calcium hydroxide barriers averaged 0.0012 microliter/s/psi. The durapatite particle barriers were much more permeable and averaged 0.0220 microliter/s/psi. It was concluded that this technique is useful in evaluating the effectiveness of apical barrier materials. For the materials tested, autogenous dentin chips and calcium hydroxide barriers have significantly lower permeability than durapatite barriers (p = 0.05).

Calcium Hydroxide↗
PubMed1992

Calcium oxalate smear layer: mineralogical and crystallographic study.

Different methods to reduce dentine hypersensitivity have been tested by means of oxalate treatments. Natural material (20 teeth) and commercial oxalates have been employed. As a result the dentinal tubules are filled by small crystals preventing dental disease. Permeability measurements have been performed in order to quantify results. The composition of the synthetic smear layer produced after oxalate treatment have been investigated by powder diffraction method suggesting calcium oxalate formation.

Calcium Oxalate↗
PubMed2001

Sealing and dentin bond strength of adhesive systems in selected areas of perfused teeth.

OBJECTIVES: (1) Test the sealing capacity and tensile strength of various adhesive systems: Scotch Bond 1 (Single Bond in USA)(SB1)+Z100, Syntac Sprint (SYN)+Tetric Ceram, Prime and Bond 2.1 (PB21)+TPH Spectrum, F2000 (Adhesive+Compomer) (F2000) and Optibond Solo (OPT)+Prodigy, to perfused teeth (30 cm distilled H2O), in select areas. (2) Determine the relationship between sealing ability and size of adhesive area (BA) with tensile strength (TS). METHODS: Segments of human third molars (n=67) sealed with amalgam on their coronal side were connected to a perfusion system (30 cm distilled H2O), to measure the basal permeability. Access cavities were drilled through the amalgam to expose dentin (area range: 8.7-20.8 mm2) and measure the permeability of that area. Cavities were sealed with one of the test materials and permeability measured prior to tensile testing. The percentage of decrease in permeability (PPD) that occurred with the different combinations of materials was also measured. RESULTS. TENSILE STRENGTH: there were no statistically significant differences among groups. PERMEABILITY: ANOVA showed that there were statistically significant differences in the mean % decrease in permeability (PPD) among groups (p=0.018). Student-Newman-Keuls test (p<0.05) detected that the mean PPD of F2000 ranked statistically higher than that of SB1. Relationship among variables: a linear correlation was found defined by the formula TS=7.47+0.008 x PPD-0.23 x BA, with a significance of the model p=0.0097. SIGNIFICANCE: None of the materials studied reduced permeability up to 100%. They all produced low tensile bond strengths (maximum mean value of groups: 5.51 MPa (OPT)).

Acetone↗
PubMed2004

Single-step, self-etch adhesives behave as permeable membranes after polymerization. Part III. Evidence from fluid conductance and artificial caries inhibition.

PURPOSE: To test the hypothesis that formation of inhibition zones by bonded restorations in artificially-induced carious dentin lesions is related to the permeability of the self-etch adhesives. METHODS: Fluid conductance of four single-step self-etch adhesives (Prompt L-Pop, Etch&Prime 3.0, One-Up Bond F and Reactmer Bond), and a control two-step self-etch adhesive (UniFil Bond) were measured after sound dentin surfaces were:(1) acid-etched; (2) polished to produce smear layers; (3) bonded with the adhesive; each at 20 cm hydrostatic pressure (hp). Osmotic fluid conductance was also determined for the bonded dentin after immersion in 4.8 M CaCl2 at 0 cm hp. For artificial caries inhibition, a non-fluoride releasing (NFR) two-step self-etch adhesive (UniFil Bond) and a fluoride-releasing (FR) single-step adhesive (Reactmer Bond) were used in combination with a NFR composite (Metafil CX) or a FR restorative material (Reactmer Paste). Artificial caries were induced in these restorations, from which 120 +/- 10 microm thick sections and the effect of caries inhibition were quantitatively assessed with polarizing light microscopy and image analysis. RESULTS: Fluid conductance after bonding with the single-step adhesives Prompt L-Pop and Etch&Prime 3.0 were not significantly different from those recorded from smear layer-covered dentin. Although better seals were achieved with One-Up Bond F and Reactmer Bond, fluid conductance at 20 cm hp was significantly higher than the two-step self-etch adhesive UniFil Bond. Osmotic conductance at 0 cm hp were not significantly different from normal fluid conductance at 20 cm hp. The sizes of artificial carious lesions in UniFil Bond were significantly higher irrespective of whether a FR or NFR composite was used. Significant reduction in lesion size occurred in Reactmer Bond with the use of a NFR composite, and even more so with the use of a FR composite.

Acid Etching, Dental↗
PubMed1989

[Transparent dentinal sclerosis and its clinical significance].

Localisation, extension, age dependence and permeability of the translucent zones in different progression stages of the dentine caries were examined by light microscopy, histochemical methods and dye penetration on ground sections, thin-ground sections and decalcified material of extracted human teeth. This phenomenon is observed in every age and more interpreted as a passive chemical precipitation than a protective activity of the pulp-dentine-system. As it is developed incompletely, it represents at most a relative, but not a proof protection from penetrating noxious actions.

Aging↗
PubMedDate not supplied

The influence of various conditioner agents on the interdiffusion zone and microleakage of a glass lonomer cement with a high viscosity in primary teeth.

The smear layer, which occurs during cavity preparation procedures, does not constitute a stable substructure in the bond of restorative material to dental hard tissues. Depending on the dissolution of this material in the course of time, microleakage occurs between the tooth and restorative material. This study evaluated the effects of different conditioner agents (Fuji Cavity Conditioner, 10% maleic acid, 35% phosphoric acid and 3% hydrogen peroxide) on Fuji IX microleakage, Fuji IX-enamel and Fuji IX-dentin combination in Class I cavities prepared to standards having the dimensions of 4x3x2 mm3 in extracted primary molars. The restorations were then subjected to thermocycling procedures and soaked in the 0.5% basic-fuchsin dye for 24 hours. Some sections were taken, parallel to the long axis of the tooth in a mesio-distal direction, and evaluated under a stereo-microscope for leakage. Also, two samples of Fuji IX-enamel and dentin combinations were chosen randomly from each group for evaluation in scanning electron microscopy (SEM). The distribution of microleakage occurred as follows: Control Group > Hydrogen Peroxide > 10% Maleic acid > Fuji Cavity Conditioner = Phosphoric acid. The difference between microleakage scores obtained from the groups was statistically significant (p<0.05). The SEM evaluation revealed a close interface connection in all groups except for the control and hydrogen peroxide groups in the Fuji IX-enamel combination. In the Fuji IX-dentin combination, however, a close interface connection was observed except in the control group. In conclusion, the application of conditioner agents to Class I cavities restored with glass ionomer cement with a high viscosity in vitro either diminishes or completely eliminates microleakage.

Acid Etching, Dental↗
PubMed1990

The effect of etching on the dentin of the clinical cavity floor.

The most conservative cavity preparation, which takes full advantage of chemically adhesive composite resin, involves removal of only the infected outer carious dentin that is stainable by the caries detector. This preparation exposes in the cavity floor either the turbid layer at the top of the inner carious dentin or the underlying transparent layer. Examination by scanning electron microscope revealed that etching the cavity floor demineralized the intertubular dentinal surface slightly and produced tapered, cylindrical holes or ring-shaped holes at the dentinal tubule apertures of the turbid or transparent layer, respectively. The holes were blind with solid floors of intratubular crystal deposits of the transparent layer, suggesting that etching increases permeability little. Placement of the adhesive resin on the etched cavity floors produced a resin-impregnated dentinal layer and tapered, cylindrical or tubular-shaped resin tags, which apparently improved the bond and tubule aperture seal.

Acid Etching, Dental↗
PubMed1998

Enamel cracks. The role of enamel lamellae in caries initiation.

Lamellae or cracks are distributed throughout tooth enamel in both deciduous and permanent dentitions. While earlier authors postulated that lamellae may be pathways of entry for caries, no evidence was adduced and the theory appears to have been discounted. The present study seeks to show that, at least in some cases, lamellae are permeable to dyes, may be associated with caries initiated in the dentine, supporting the hypothesis of Hardwick and Manly of lamellae penetration by Streptococcus mutans and lactobacilli. The enamel lamellae are shown to be a permeable pathway allowing caries-producing bacteria access to the dentine-enamel junction. Caries can thus be established within the tooth without visible evidence at the surface.

Azo Compounds↗
PubMed1996

In vitro models of biocompatibility: a review.

The objectives of this paper were to define in vitro biocompatibility of materials, to discuss some of the issues concerning why conclusions from tissue culture are sometimes different from in vivo biocompatibility, to give highlights of the sequence of the development of these in vitro assays from the early 1950s to their present state of development, and to discuss possible future trends for in vitro testing. In vitro biocompatibility tests were developed to simulate and predict biological reactions to materials when placed into or on tissues in the body. Traditional assays have measured cytotoxicity by means of either an end-stage event, (i.e., permeability of cytoplasmic membranes of dead and dying cells, or some metabolic parameter such as cell division or an enzymatic reaction). In vitro assays for initiation of inflammatory and immune reactions to materials have also begun to appear in the literature. More recently, the concept of dentin barrier tests has been introduced for dental restorative materials. Four models which measure both permeability and biological effects of materials are compared and discussed. Future efforts may be directed toward development of materials which will allow or promote function and differentiation of tissues associated with materials. New analytical procedures and understanding of optimal characteristics of materials should improve our ability to develop more biocompatible materials. Both molecular biology techniques, and altered design of material surfaces may make the materials either more or less reactive to the biological milieu. These trends suggest a greater future role of the biological sciences in the development of biomaterials.

Animals↗
PubMed2005

In vivo fluid movement through dentin adhesives in endodontically treated teeth.

Fluid transudation through simplified dentin adhesives can occur in bonded vital crown dentin, since these adhesives behave as permeable membranes after polymerization. The effect of adhesive permeability in endodontically treated teeth is unknown. This study examined the hypothesis that in vivo fluid movement through simplified adhesives occurs when they are applied to root canals. Dowel spaces were prepared in endodontically treated teeth with single root canals. Six adhesives were applied to the intra-radicular dentin of canal walls. Impressions were obtained with polyvinyl siloxane, and replicas were fabricated with the use of polyether impression material. Replica hemisections were gold-coated for SEM examination. Fluid transudation was evident on the adhesive surfaces of all simplified total-etch and self-etch adhesives. Conversely, most of the specimens bonded with the control three-step total-etch adhesive were devoid of fluid droplets. Permeability of simplified adhesives results in water movement, even in root-treated dentin. This may adversely affect the coupling of auto-/dual-cured resin cements.

Acid Etching, Dental↗