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PubMed2005

Bond strengths of nine current dentine adhesive systems to primary and permanent teeth.

The aim of this study was to compare the shear bond strength (SBS) of nine dentine bonding systems (DBS) of different classes to human primary and permanent dentine. Flat dentine occlusal surfaces were produced on human molars (100 primary, 100 permanent) by wet grinding on a 800-grit SiC paper. Nine DBS were applied following the manufacturers' instructions: One total etch multi-step system: Scotchbond Multipurpose Plus (3M/ESPE); Four total etch one-bottle system: Prime &Bond 2.1 (Dentsply), One Step (Bisco), Scotchbond 1 (3M/ESPE), and OptibondSolo Plus (Kerr); Three two-step self-etching primer systems: Clearfil Liner Bond 2 (Kuraray), Clearfil SE Bond (Kuraray), and Prime &Bond NT with NRC (Dentsply); An 'all-in-one' self-etching system: Prompt L-Pop (3M/ESPE). Composite (Z100; 3M/ESPE) cylinders (2 mm diameter, 3 mm high) were polymerized on the treated dentine surfaces and the specimens were stored at 37 degrees C for 24 h prior to testing. Twenty experimental groups were produced and tested. Statistical analysis revealed both a substrate and a bonding system effect. Two adhesive systems (One Step, Prime &Bond NT) had significantly higher bond strengths on permanent than on primary dentine. There was an effect of dentine bonding system on the mode of fracture. Although eight of the 10 DBS tested exhibited higher median SBS values on permanent dentine than on primary dentine, the dependent pairwise comparison identified a significant difference only for two groups. The use of simplified bonding systems does not necessarily result in improved bond strength to primary or to permanent dentine.

Acetone↗

PubMed1997

Dentin bonding: effect of tubule orientation on hybrid-layer formation.

In an attempt to compare the morphology of the resin-dentin interface in areas where the dentinal tubules run perpendicularly or at an angle to the cavity surface with that of areas where they run parallel to it, we studied a dentin adhesive system using transmission electron microscopy and fluorescence confocal laser scanning microscopy. The design of the study included the simulation of the normal hydrostatic pressure within the pulp and the dentinal tubules. Following acid etching of the dentinal surface with maleic acid/HEMA, the smear layer was removed, and a superficial zone was demineralized in such a way that the exposed collagenous dentin matrix retained its integrity. Confocal laser scanning microscopal investigations using primer labeled with rhodamine B showed that the penetration of the primer occurred not only vertically via surface porosities, but mainly laterally, via the dentinal tubules. The adhesive resin labeled with fluorescein completely infiltrated the demineralized layer, thereby forming a hybrid layer. The orientation of the dentinal tubules had a profound effect on the formation of the hybrid layer. In areas with perpendicular tubule orientation, the layer was 3.2 +/- 0.8 microns thick, showing solid 27.2 +/- 0.8 microns long resin tags in the dentinal tubules, and a network of tiny tags in their side-branches. In areas with parallel tubule orientation the layer was significantly thinner (1.3 +/- 0.6 microns) and resin tags were absent.

Acid Etching, Dental↗

PubMed2004

Influence of hydration and mechanical characterization of carious primary dentine using an ultra-micro indentation system (UMIS).

The conditions under which mechanical properties of dentine are tested influence the values recorded. The aims of this study were to examine the effect of hydration on the mechanical properties of primary carious dentine and to provide information on changes in hardness and modulus of elasticity change caused by the demineralizing caries process in dentine. Three primary molar teeth with untreated carious dentine were prepared for nano-indentation tests under both wet and dry conditions. Further tests were conducted on eight primary molars with untreated carious dentine under hydrated conditions. The mechanical properties of dehydrated carious dentine increased approximately 10-fold for hardness and 100-fold for the modulus of elasticity compared with hydrated dentine. The hardness and elastic modulus of the carious primary dentine deteriorated progressively toward the lesion cavity floor, ranging from 0.001 to 0.52 GPa and from 0.015 to 14.55 GPa, respectively, and could be fitted to a simple linear relationship when plotted in logarithmic scale vs. distance. The total depth of dentine affected was around 1100 microm parallel to the tubule direction. This depth was significantly greater than observed subjectively, implying that the demineralization process is more advanced than might be suspected on simple clinical examination.

Analysis of Variance↗

PubMed2001

Tensile bond strengths of fourth- and fifth-generation dentin adhesives with packable resin composites.

PURPOSE: Placement of packable composites would be simplified if a single-bottle dentin bonding agent, rather than the more complex, multiple-bottle dentin bonding agents, involving multiple steps, could be used successfully with adequate bond strength. This study was designed to compare the tensile bond strengths to extracted human dentin of four single-bottle (fifth-generation) and four multiple-bottle (fourth-generation) dentin bonding agents with four packable composites. MATERIALS AND METHODS: Packable composites (P60, 3M Dental Products Division; ALERT, Jeneric-Pentron; Pyramid Dentin, Bisco; and Clearfil AP-X, Kuraray America) were tested for in vitro tensile bond strength to human dentin with their single-bottle and their multiple-bottle dentin bonding agents. Bond strengths were measured using a truncated cone tensile test, with a bonding diameter of 3 mm, after storage of specimens in water at 37 degrees C and 100% relative humidity for 24 hours, and using a testing machine at a crosshead speed of 0.5 mm per minute. RESULTS: Means and standard deviations (n = 10) of tensile bond strengths (MPa) for the single-bottle system were P60, 21.3 MPa (6.7); ALERT, 26.6 MPa (4.2); Pyramid Dentin, 14.8 MPa (4.4); and Clearfil AP-X, 18.6 MPa (3.7). For the multiple-bottle system they were P60, 20.0 MPa (8.6); ALERT, 20.6 MPa (6.2); Pyramid Dentin, 16.0 MPa (3.4); and Clearfil AP-X, 17.8 MPa (6.0). Two-way analysis of variance showed significant differences among composites but no significant differences between single-bottle and multiple-bottle bonding agents. The Tukey-Kramer interval (p < .05) for comparisons of bond strengths among composites was 4.8 MPa. CONCLUSIONS: For single-bottle agents, bond strengths were ranked as ALERT > P60, P60 = Clearfil, P60 > Pyramid, and Clearfil = Pyramid. For multiple-bottle agents, there were no significant differences in bond strengths among the composites. CLINICAL SIGNIFICANCE: Single-bottle bonding agents provide similar in vitro bond strengths for use with packable composites as do the same manufacturers' multiple-bottle bonding agents.

Analysis of Variance↗

PubMed2005

An in vitro model to measure the effect of a silver fluoride and potassium iodide treatment on the permeability of demineralized dentine to Streptococcus mutans.

BACKGROUND: Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been used to reduce the incidence of caries in primary dentitions but has been limited by the associated staining of both teeth and restorative materials. The application of potassium iodide (KI), following AgF prevents staining but its effects on the ability of AgF to reduce caries are not known. The aim of this study was to develop an in vitro model that would provide an indication of the permeability of demineralized dentine to Streptococcus mutans after treatment of the dentine with AgF followed by KI. METHODS: Forty dentine discs were bonded to the base of forty 5mL polycarbonate screw top vials (that had had their bases removed), filled with nutrient medium, sterilized and placed into a continuous culture of S. mutans. Samples were divided into four groups as follows: 10 samples of demineralized dentine as a control, 10 samples of demineralized dentine treated with AgF/KI, 10 samples of demineralized dentine treated with KI and 10 samples of demineralized dentine treated with AgF. After two weeks the optical density of the growth medium chambers was measured to determine bacterial penetration and growth. Cultures were plated out to determine migration through the discs by S. mutans. RESULTS: S. mutans migrated through all dentine discs. However, the samples treated with AgF and AgF/KI had significantly lower optical densities than the corresponding controls. The range of optical densities was least amongst demineralized samples treated with AgF/KI. CONCLUSIONS: Under the conditions of this study, treatment of demineralized dentine discs with AgF followed by KI allowed the penetration of S. mutans. Based on optical density measurements, the treatment resulted in significantly fewer microorganisms being present subjacent to the discs treated with AgF and KI than the control discs at the end of the experimental period.

Bacteriological Techniques↗

PubMed1986

The effects of calcium hydroxide on dentin permeability.

Calcium hydroxide paste was applied to human dentin in vitro to determine its effects on dentin permeability. Discs of dentin were acid-etched on both sides to permit determination of their maximum permeability. Smear layers were then applied to the enamel sides of the discs, thereby reducing dentin permeability 99%. Topical application of Ca(OH)2 paste to the smear layer reduced dentin permeability further, to levels 48% below that of untreated smear layers. When the Ca(OH)2-treated smear layers were exposed to 6% citric acid for two min, dentin permeability returned to the initial acid-etched value, demonstrating that Ca(OH)2 offers little protection to acid challenge. Treatment of acid-etched dentin with Ca(OH)2 produced a similar reduction in dentin permeability, which was restored to normal following acid challenge. Thus, Ca(OH)2 is effective at reducing the permeability of both the smear layer and of acid-etched dentin, in vitro.

Acid Etching, Dental↗

PubMed1988

Effects of distance from the pulp and thickness on the hydraulic conductance of human radicular dentin.

The purposes of this study were: (1) to measure the effect of distance from the pulp on the hydraulic conductance of human radicular dentin; (2) to determine the influence of dentin thickness on the rates of fluid flow; and (3) to attempt to correlate dentinal tubule densities and diameters with root dentin hydraulic conductance. Dentin slabs prepared from extracted, unerupted, human third molar teeth were placed in a split-chamber device to permit quantitation of fluid filtration rate (hydraulic conductance). In the SEM portion of the study, dentinal tubule numbers and diameters were recorded. The results indicated that radicular dentin hydraulic conductance decreased with distance from the pulp and with increasing dentin thickness. Tubule density and diameter correlated well with the measured hydraulic conductances. The relatively low hydraulic conductance of outer root dentin makes it a significant barrier to fluid movement across root structure.

Adult↗

PubMed1994

Occlusion of dentinal tubules with calcium phosphate using acidic calcium phosphate solution followed by neutralization.

The occlusion of dentinal tubules with calcium phosphate, by a calcium phosphate precipitation method (CPP method), was investigated in vitro for evaluation of the potential value of this method for the treatment of dentin hypersensitivity. The method consists of treating the dentinal surface with a CPP solution, i.e., an acidic solution that contains both calcium and phosphate, followed by neutralization with basic post-treatment solution. The CPP solutions used in this study ([Ca] = 0.2 - 1.0 mol/L, [PO4] = 0.2 - 4.0 mol/L) were prepared by dissolving Ca(OH)2 or CaHPO4 x 2H2O in H3PO4 or HCl, and 1 mol/L NaOH solution was used for the post-treatment solution. Sections of human dentin disks treated by the CPP method were observed by scanning electron microscopy, and the precipitate in the dentinal tubules was subjected to x-ray micro-analysis. After treatment by the CPP method, dentinal tubules were occluded to a distance of approximately 15 microns from the surface, and the precipitate showed a Ca/P molar ratio of 1.03 +/- 0.01 To obtain a larger amount of precipitated mineral for further analysis, we used the same procedure with glass tubes (inside diameter, 1 mm). Powder x-ray diffraction analysis and FT-IR measurement revealed that the precipitate was dicalcium phosphate dihydrate (CaHPO4 x 2H2O). The instant precipitation of calcium phosphate mineral in the dentinal tubules demonstrated the potential value of the CPP method for the occlusion of dentinal tubules, this occlusion may be useful for the treatment of dentin hypersensitivity.

Calcium Phosphates↗

PubMed1997

Why do shear bond tests pull out dentin?

It is widely accepted that a dentin shear bond test which pulls out dentin must mean that the adhesive strength is superior to the cohesive strength of the dentin. Using numerical modeling techniques, Van Noort et al. (1988, 1989) and DeHoff et al. (1995) alerted the scientific community that there were massive stress concentrations in the familiar dentin bond test. It is not inconceivable that these localized high tensile stresses could initiate cracks which diverge monolithically into dentin, leaving the interface unchallenged. To test this hypothesis, we developed a failure accumulation simulation program which determined localized failure interactively "on the fly" with a finite element solver, and also included brittle behavior, adhesive and cohesive failure, stochastic response, and dynamic remeshing. All of the familiar dentin bond variables were included in the simulation. A parallel experimental dentin bond test validation was run, and the fractography was examined in the scanning electron microscope for mode of failure. The simulation confirmed the tensile monolithic fracture hypothesis. It is also confirmed that dentin pull-out was partly due to the biomechanics of the test and did not necessarily mean superior adhesive strength or even that the cohesive strength of the dentin was reduced. There is clear need for a new technology for the evaluation of biological interfaces, and the present work has shown the vital role of numerical modeling in the interpretation of such experimental procedures.

Adhesiveness↗

PubMed2003

Patterns of fluoro-gold entry into rat molar enamel, dentin, and pulp.

Permeabilities of enamel and dentin are not fully understood despite their importance for caries, restorative materials, and pulp-dentin-enamel interactions. We have found that Fluoro-Gold is useful for examining tooth permeability, and we designed studies to test the effects of aging, injury, neural function, and dentinal repair on its influx into vital rat teeth. We used fluorescence microscopy and immunocytochemistry to show that Fluoro-Gold rapidly penetrates enamel, the dentin-enamel junction, and outer dentinal acellular tubules, and then concentrates in odontoblasts, where it remains for weeks. As predicted, influx was greatest in immature teeth, and formation of reparative dentin impeded it. We expected that denervation would disrupt influx, because of neural regulation of dentinal fluid movement, but it did not. Damage to odontoblasts under injured dentin caused increased influx and efflux of Fluoro-Gold. Analysis of our data suggests that permeabilities of enamel and dentin to Fluoro-Gold are age-related, inter-dependent, and regulated by odontoblasts.

Aging↗

PubMed1999

Microhardness evaluations of resin-dentin bonding areas by nano-indentation.

The purpose of this experiment was to determine the hardness values of the hybrid layer and its surroundings through the continuous use of a microhardness measuring device. Black's Class V cavities were prepared in nine dog teeth. The cavities were divided into four groups according to the dentin adhesive system applied. The adhesive systems were: "Bond One System", "Liner Bond II sigma System", "One Step System", and "Single Bond System". The treated teeth were observed at seven days post-application. Specimens were cross-sectioned perpendicularly or horizontally to the resin-dentin interface and embedded in epoxy resin. Their surfaces were polished. The microhardness of the resin-dentin bonding area was measured with a nano-indentation tester. The hardness values at a point of 10 microns distant from the interface in the direction of the dentin differed between systems. It appeared that this was influenced by the presence of the decalcified dentin not impregnated by resin, differences in the chemistry forming the hybrid layer, and the composition of the bonding resin. The hardness of the dentin-bonding interface and its surroundings was determined, and these areas were observed using SEM. Three layers were confirmed the healthy dentin layer, the composite resin layer, and the hybrid layer, (in which decalcified dentin impregnated by resin and that not impregnated by resin are considered to be mix). In the hybrid layer, no impression was found by SEM although the hardness in the bonding interface was significantly different. These layers appear to be more elastic and softer than the healthy dentin.

Animals↗

PubMed2006

Shear bond strengths of self-etching adhesives to caries-affected dentin on the gingival wall.

The purpose of this study was to evaluate the bonding ability of five current self-etching adhesives to caries-affected dentin on the gingival wall. Seventy extracted human molars with approximal dentin caries were employed in this study. In order to obtain caries-affected dentin on the gingival wall, grinding was performed under running water. Following which, specimens mounted in acrylic blocks and composite resins of the bonding systems were bonded to dentin with plastic rings and then debonded by shear bond strength. With Clearfil SE Bond, bonding to caries-affected dentin showed the highest bond strength. With Optibond Solo Plus Self-Etch, bonding to caries-affected dentin showed higher shear bond strength than AQ Bond, Tyrian SPE & One-Step Plus, and Prompt-L-Pop (p<0.05). Further, the bond strengths of Clearfil SE Bond and Optibond Solo Plus Self-Etch to sound dentin were higher than those of Prompt-L-Pop, AQ Bond, and Tyrian SPE & One-Step Plus (p<0.05). In conclusion, besides micromechanical interlocking through hybrid layer formation, bond strength of self-etch adhesives to dentin may be increased from additional chemical interaction between the functional monomer and residual hydroxyapatite. The results of this study confirmed that differences in bond strength among self-etching adhesives to both caries-affected and sound dentin were due to chemical composition rather than acidity.

Acids↗

PubMed1999

Demineralizing effect of dental cements on human dentin.

OBJECTIVE: This study was undertaken to verify the hypothesis that dentin surfaces are demineralized during placement of four kinds of chemically setting cements (zinc phosphate cement, luting glass-ionomer cement, restorative glass-ionomer cement, and zinc polycarboxylate cement). METHOD AND MATERIALS: Sixty cemented dentin disks were observed under scanning electron microscopy and with confocal laser scanning microscopy after use of an argon-ion etching technique. To determine the surface effects of the cements, 30 dentin surfaces were treated with 1 of 6 freshly mixed cements (5 per group) for 60 seconds. The disks were subjected to rinsing with a water spray and ultrasonic washing prior to scanning electron microscopic observation. RESULTS: Observation of cemented dentin specimens revealed that the dentin was not completely demineralized at the interface formed by the cement and dentin and that the extent and depth of demineralization along the interface tended to be nonuniform. Zinc phosphate cement caused the greatest demineralization of dentin, followed by luting glass-ionomer cement. The extent of demineralization with restorative glass-ionomer cement or zinc polycarboxylate cement was less discernible. Confocal laser scanning microscopy generally confirmed scanning electron microscopic observations and revealed that most of the specimens showed close adaptation of the cements to the dentin surfaces. CONCLUSION: Acid-containing cements have self-etching properties that are effective, to various degrees, in removing the smear layer and promoting close adaptation to dentin surfaces.

Acid Etching, Dental↗

PubMed1999

Bonding to caries-affected dentin using self-etching primers.

PURPOSE: To evaluate resin bond strengths to caries-affected versus normal dentin using three self-etching primer adhesive systems. MATERIALS AND METHODS: Carious lesions were excavated and then bonded with one of three self-etching primer adhesive systems (Clearfil Liner Bond 2, Clearfil Liner Bond 2V, A.R.T. Bond). A crown was then built up using a resin composite to a height of 4 mm. Five to six serial slabs approximately 0.7 mm thick were sectioned perpendicular to the bonded surface. The bonded caries-affected or normal dentin areas were isolated to create an hourglass configuration with a cross-sectional area of approximately 1 mm2. The specimens were subjected to tensile stress at a crosshead speed of 1.2 mm/min. The bonded interfaces to caries-affected and normal dentin were examined with an SEM. RESULTS: Clearfil Liner Bond 2 and Clearfil Liner Bond 2V produced high bond strengths to normal dentin, but significantly lower bonds than to caries-affected dentin. (P < 0.05). For A.R.T. Bond, there was no statistically significant difference between types of dentin. All three bonding systems produced thin (+/- 0.5-1.5 microns) hybrid layers in normal dentin. When used on caries-affected dentin, all self-etching primer systems produced hybrid layers that were twice as thick as those produced in normal dentin.

Acid Etching, Dental↗

PubMedDate not supplied

Comparison of conventional vs self-etching adhesive bonds to caries-affected dentin.

The mechanism of resin adhesion to caries-affected dentin is still unclear. This study evaluated the interfacial morphology of two bonding systems to caries-affected dentin, coupled with the measurement of microtensile bond strengths (mu TBS). Carious human molars were prepared as previously described in Nakajima and others (1995) and were bonded with Single Bond (SB) or FluoroBond (FB) according to the manufacturer's instructions, followed by creation of AP-X composite buildups. After one day of storage in 37 degrees C water, the teeth were serially sectioned vertically into 0.8 mm slabs, trimmed to yield a 1 mm2 test area, and tested to failure in a Bencor device used in an Instron machine operated at 1 mm/min. Resin-dentin interfaces were observed with SEM before or after acid/base challenge. Bonding to normal dentin with the two bonding systems (SB and FB) showed tensile bond strengths significantly higher than those to caries-affected dentin. The moist bonding technique significantly increased bond strength of SB to normal and caries-affected dentin. SEM examination revealed that typical hybrid layer and resin tags could not be formed to caries-affected dentin. The results suggested that resin penetration may be prevented by occlusion of dentinal tubules by mineral deposits that may also impart acid-resistance to the intertubular matrix of caries-affected dentin.

Acid Etching, Dental↗

PubMed2003

Effect of EDTA conditioning on bond strength to bovine dentin promoted by four current adhesives.

PURPOSE: To investigate the effect of disodium dihydrogen ethylenediamine tetraacetate dihydrate (EDTA) conditioning prior to the application of adhesive systems on the bond strength of resin composite to dentin. METHODS: 80 bovine teeth were ground with 600-grit SiC paper to obtain flat dentin surfaces. Half of the specimens were conditioned with 0.5 mol EDTA aqueous solution (pH 7.4) for 60 seconds, water-rinsed and air-dried, and the other half were used without any treatment. The specimens were randomly divided in four groups of 10 each. The dentin surfaces were treated with each of two "all-in-one" adhesive systems (One-up Bond F, OB; Reactmer Bond, RB), a self-etching priming system (Clearfil SE Bond, SE), and a total-etch one-bottle bonding system (Single Bond, SB). For SB, the adhesive was applied on EDTA-conditioned dentin without H3PO4 etching. Then a layer of resin composite was placed and light-cured for 40 seconds. The tensile bond strength was measured and the resin-dentin interface was observed using a scanning electron microscope. RESULTS: The mean and standard deviation of tensile bond strength in MPa to ground dentin were 9.3+/-3.5/OB, 11.6+/-2.0/RB, 23.2+/-4.9/SE and 19.7+/-4.1/SB. Bond strengths to EDTA-conditioned dentin were 15.0+/-3.0/OB, 16.8+/-3.6/RB, 22.8+/-5.2/SE and 19.4+/-5.1/SB. Duncan's Multiple Range test revealed that the EDTA-conditioned dentin showed significantly higher tensile bond strength than the non-conditioned one for "all-in-one" adhesive systems (P < 0.05) but no significant difference was found for the self-etching priming and total-etch one-bottle bonding systems. At the resin-dentin interface, EDTA-conditioned specimens formed thicker hybrid layers than non-conditioned ones for all systems except for SB.

Analysis of Variance↗

PubMed1992

Effect of aging and caries on dentin permeability.

Extracted human teeth were collected from young (20-28 yrs) versus old (45-69 yrs) patients. The teeth were divided into carious and noncarious groups. Slabs were created from the mid-coronal occlusal dentin. Carious lesions were excavated and the smear layers on both normal and excavated carious dentin were removed with 37% phosphoric acid (1 min). The permeability (hydraulic conductance) of old normal dentin was only 20% of that obtained in young normal dentin but all of the specimens were permeable. Young carious dentin was only 14% as permeable as young normal dentin and only 1 out of 7 specimens was not permeable. All 7 specimens of old carious dentin were impermeable. Scanning electron microscopy of old and carious dentin exhibited far more intratubular crystals than normal dentin, providing a structural basis for the functional observation.

Adult↗

PubMedDate not supplied

An in vitro study of dentin exposure during resin-bonded fixed partial denture preparation.

OBJECTIVES: The aim of this in vitro study was to investigate whether dentin is exposed during tooth preparation for resin-bonded fixed partial dentures and, if so, to quantify the amount of dentin exposure. METHOD AND MATERIALS: Twenty extracted premolars were prepared in the following manner: The palatolingual and proximal axial surfaces were reduced by 0.50 mm. Mesial and distal grooves, 1.00 mm in depth, and mesial and distal occlusal rest seats, measuring 2.00 mm buccolingually x 1.50 mm mesiodistally x 1.00 mm deep, were prepared. The specimens were stained with a modified van Gieson's stain to identify dentin exposure, mounted on a jig to allow standardization, and photographed after 30-degree rotation to create a panoramic image of each tooth. The image was modified and analyzed to measure the percentage of the preparation area that exhibited dentin exposure. RESULTS: Dentin exposure was noted in all specimens. The mean area of dentin exposure was 11.06 mm2 (16.15% of the preparation area). The minimum and maximum areas of dentin exposure were 4.07 mm2 (7.03%) and 19.73 mm2 (27.28%), respectively. CONCLUSION: Dentin is exposed during resin-bonded fixed partial denture preparation if current tooth preparation guidelines are followed, despite the commonly made recommendation that the preparation remain within enamel. The region of the grooves consistently exhibited exposed dentin; exposure at the cervical margin was variable.

Bicuspid↗