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 1,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influences of nine dentin surface treatments were evaluated on the shear bond strength of a new light-cured glass-ionomer cement (GIC) and on the SEM morphology of the treated dentin surfaces. The following treatments were performed: saline solution (control), NaOCl, acidic glycine, EDTA, malic acid, malic acid plus glycine, polyacrylic acid, tannic acid, and neutral+acidic oxalate solutions. Buccal dentin surfaces were polished with #320-grit abrasive paper, treated with one of the chemicals, washed, and air-dried. Cylindrical GIC samples were then applied to the dentin surface, stored in 100% humidity, and tested after 24 h. SEM observations demonstrated no effect of saline or NaOCl treatment on the smear layer but its complete removal with exposure of collagen fibrils after malic or malic acid plus glycine treatment. Partial removal of the smear layer occurred following glycine treatment and with tannic or polyacrylic acids. Complete removal of the smear layer was seen after EDTA or pyruvic acid treatment. Oxalate treatment produced a layer of crystals, which completely covered the dentin surface. Shear bond strength of GIC was significantly increased only by treatment with the oxalate solutions.
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PMID:Effects of dentin surface treatments on the shear bond strength of Vitrabond. 152 80

The present study investigated the effectiveness of treating dentin with 2-hydroxyethyl methacrylate (HEMA) prior to application of an adhesive resin. The adhesive resin was 5% 4-methacryloxyethyl trimellitate anhydride (4-META) in methyl methacrylate (MMA) combined with poly-MMA powder. Polymerization of this resin was initiated by tri-n-butyl borane (TBB). Bovine dentin samples were ground with 600-grit Carbimet paper discs, and demineralized with either an aqueous solution of 10% citric acid/3% ferric chloride (10-3) or an aqueous solution of 10% citric acid (10-0). Improved bond strengths were achieved with HEMA treatment of bovine dentin samples, and improvement of bond strengths was dependent upon the time period of HEMA application. Scanning electron microscope (SEM) examination revealed the formation of a transitional zone of resin-reinforced dentin, termed the "hybrid" layer, in those specimens receiving 10-3 pre-treatment. The adhesive resin impregnated the exposed collagen bundles with which it entangled to create the "hybrid", essential in the attainment of high tensile bond strengths. Specimens pre-treated with 10-0 did not readily form "hybrid" layers. However, if HEMA application followed the 10-0 pre-treatment, "hybrids" were demonstrated on SEM, and bond strength increased to 13 MPa. The ferric ions in the 10-3 effectively improved the diffusivity of dentinal substrates, as did HEMA. This study indicates that HEMA applied to dentinal substrates enhances monomer diffusion and entanglement with dentinal components, and facilitates the formation of a "hybrid" layer.
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PMID:Effect of HEMA on bonding to dentin. 152 92

Research into polymer systems capable of bonding to dentin and enamel have resulted in improved bond strengths that allow more conservative restoration and strengthening of teeth. However, pretreatment of the dentin and enamel of various sorts, including exposure to laser energy, have been espoused to enhance this bonding. This study investigated the effects of two pretreatments, acid and CO2 laser exposure, both alone and in combination, on the surface topography of prepared dentin specimens as observed by scanning electron microscopy. Eighteen dentin specimens were flat-sanded with 600 grit sandpaper and exposed to 10% maleic acid and CO2 laser both alone and in combination. SEM observation suggested that laser treatment prior to acid etching could increase the resistance of the smear layer to acid removal, that laser exposure after acid treatment could expose a porous topography suggestive of the underlying dentin inorganic structure by way of vaporization of the collagen surface left after acid demineralization, and that these effects varied in degree with the laser exposure energy.
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PMID:SEM comparison of acid-etched, CO2 laser-irradiated, and combined treatment on dentin surfaces. 783 Apr 72

Phenotypic responses of rat calvarial osteoblast-like cells (RCOB) were evaluated on commercially pure titanium (cpTi) surfaces when cultured at high density (5100 cells/mm2). These surfaces were prepared to three different clinically relevant surface preparations (1-micron, 600-grit, and 50-microns-grit sand-blast), followed by sterilization with either ultraviolet light, ethylene oxide, argon plasma-cleaning, or routine clinical autoclaving. Osteocalcin and alkaline phosphatase, but not collagen expression, were significantly affected by surface roughness when these surfaces were altered by argon plasma-cleaning. In general, plasma-cleaned cpTi surfaces demonstrated an inverse relationship between surface roughness and phenotypic markers for a bone-like response. On a per-cell basis, levels of the bone-specific protein, osteocalcin, and the enzymatic activity of alkaline phosphatase were highest on the smooth 1-micron polished surface and lowest on the roughest surfaces for the plasma-cleaned cpTi. Detectable bone cell expression can be altered by clinically relevant surfaces prepared by standard dental implant preparation techniques.
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PMID:Bone cell expression on titanium surfaces is altered by sterilization treatments. 800 33

The purpose of this study was to evaluate the usefulness of resorbable collagen membrane for guided tissue regeneration. Dehiscences were surgically induced in dog mandibles. Hydroxyapatite-coated or grit-blasted implants were then placed in a random pattern in both sides of the mandibles (two of each type of implant in each side of the mandible). A resorbable collagen barrier membrane was placed around one pair of implants on each side. The other two implants on each side served as controls. The sites were examined clinically and histologically after 4 or 8 weeks to assess bone regeneration. Sites around experimental hydroxyapatite-coated and grit-blasted implants showed significantly more bone fill than did control sites. In addition to its apparent ability to encourage bone regeneration, the collagen membrane is resorbable, obviating the need for a second surgery to allow removal. (Int J Periodont Rest Dent 1993; 13:71-83.)
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PMID:Regeneration of dehisced alveolar bone adjacent to endosseous dental implants utilizing a resorbable collagen membrane: clinical and histologic results. 833 Sep 47

The purpose of this pilot study was to determine how lactic acid solution at various concentrations and etching times affected prepared human enamel and dentin surfaces and to assess whether it could be used in place of phosphoric or maleic acid as an etchant. The occlusal surfaces of extracted molar teeth were ground wet with 600-grit silicon carbide paper and treated with various aqueous solutions of lactic acid. Random samples were prepared for observation by scanning electron microscopy. The rest were used to determine shear bond strength of bonded dental composite cylinders. The micrographs revealed that lactic acid dissolved the smear layer with various degrees of etching and demineralization. The degree of smear layer and matrix removal was proportional to the concentration of the acid and the length of application time. A 20% lactic acid concentration applied for 10 seconds produced a clearly etched surface with minimal demineralization. A 30% concentration not only removed the smear layer and enlarged the dentin tubule orifices but also appeared to affect the collagen matrix. The shear bond strength to enamel treated with 50% lactic acid (17.5 +/- 1.5 MPa) and All-Bond 2 etchant (18.9 +/- 1.3 MPa) were not significantly different (p > 0.05). However, mean dentin bond strengths for all groups of lactic acid etchant and All-Etch etchant (10% phosphoric acid) were statistically similar.
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PMID:A pilot study of lactic acid as an enamel and dentin conditioner for dentin-bonding agent development. 888 97

The purpose of this study was (1) to evaluate the effect of a 2-minute exposure of 5% NaOCl following acid conditioning of the dentin on the shear bond strength for two adhesive systems and (2) to examine the ultrastructure of the resindentin interface under SEM. The mesial and distal surfaces of 28 extracted human third molars were ground to expose dentin, then polished with 600-grit SiC. Teeth were randomly assigned to four test groups (n = 14) and received the following treatments: Scotchbond Multi-Purpose (SBMP)--Samples were conditioned with 37% phosphoric acid, rinsed and left moist, SBMP primer and adhesive were applied according to the manufacturer's directions, and Restorative Z-100 composite resin was bonded to the dentin surface. SBMP/NaOCl--The same procedures were followed as for SBMP except the surfaces were treated with 5% NaOCl for 2 minutes, after acid conditioning. All-Bond 2 (AB2)--The same technique was followed as for SBMP, using AB2 according to the manufacturer's recommendations. AB2/NaOCl--The same procedure was followed as for SBMP/NaOCl, using AB2. Specimens were thermocycled in a water bath 300 times between 5 degrees-55 degrees C, then sheared in a Zwick Universal Testing Machine. A one-way ANOVA and Duncan's Multiple Range Test were used for statistical analysis of the data. A 2-minute exposure of dentin to 5% NaOCl following acid conditioning of the dentin had no significant effect on the dentin shear bond strength for Scotchbond Multi-Purpose, but significantly increased the bond strength of All-Bond 2 specimens. The interfacial structure of the dentin to resin bond for two dentin treatments and two adhesive systems was studied morphologically under the scanning electron microscope. Argon ion beam etching and acid demineralization clearly revealed the hybrid layer for the conventional treatment with phosphoric acid and indicated an absence of this resin-impregnated collagen network in those specimens treated with both phosphoric acid and NaOCl.
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PMID:Resin-dentin shear bond strength and interfacial ultrastructure with and without a hybrid layer. 948 56

It was recently reported that removal of the collagen network from etched dentin does not affect dentin bond strengths. The aim of this study was to determine if the removal of the collagen fibers results in changes in dentin roughness and wettability. Twenty cary-free extracted human third molars were sectioned parallel to the occlusal surface to expose either superficial or deep dentin. Dentin was ground flat through 600-grit SiC abrasive paper under water to provide uniform surfaces. Observed contact angle measurements were performed to assess wettability by using the axisymmetric drop shape analysis technique using water and a water-based primer. Average roughness was determined with a profilometer. The specimens were analyzed just after being ground, after etching with 35% H(3)PO(4) gel for 15 s, and after etching and deproteinization with 5% NaOCl for 2 min. Data were analyzed with two-way ANOVA and Newman-Keuls multiple comparison t test procedure. Etching resulted in an increase in surface roughness and dentin wettability. For deep dentin, collagen removal did not influence the average roughness, but it resulted in a significantly greater degree of wettability. The degree of wettability for deep dentin was greater than for superficial dentin.
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PMID:Effect of acid etching and collagen removal on dentin wettability and roughness. 1044 30

Interaction between resin tags and microtags of adhesive systems and dentinal collagen fibrils is a poorly understood aspect of adhesion. This study evaluated this interaction in 25 recently extracted human third molars. Each tooth was embedded in an epoxy resin and cross-sectioned to obtain two 1-mm-thick dentin disks. The outer dentin surfaces were polished with wet 600-grit sandpaper to create a uniform smear layer. After etching with 35% phosphoric acid for 15 seconds, the primer and adhesive of Scotchbond Multi-Purpose and the resin composite Z100 (3M Dental Products, St Paul, MN 55144, USA) were placed on the dentinal surfaces according to the manufacturer's instructions. The disks were left in distilled water at 37 degrees C for two weeks, then fractured perpendicular to the bonded surfaces in order to obtain two hemi-disks. The fractured surfaces were treated with 2N-chloridric acid and processed for scanning electron microscopy. Gold-coated specimens were examined with a JEOL 6100 scanning electron microscope. Results showed a hybrid layer with resin tags of approximately 100 microm in length and numerous and fine branching resin microtags. The tags and microtags created by this three-step adhesive system were observed in intimate contact with the collagen fibrils of dentin, even in deeper zones which were not affected by acid etching. It suggests that adhesion to dentin may include both micromechanical and chemical aspects.
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PMID:SEM evaluation of the interaction between a three-step adhesive and dentin. 1155 Oct 7

Smear layers are generally present on any dentin surface prepared with cutting instruments and are often the only available substrate for bonding. It is commonly reported that acid removes these layers, but to date there has been no chemical evidence to support this observation. Confocal Raman microspectroscopy was used to investigate changes in the composition and molecular structure of acid-treated smear debris and in situ dentin smear layers. The exposed dentin in human molars was abraded with 600-grit silicon carbide sandpaper. Raman spectra were acquired on the smear debris and collected from the sandpaper before and after treatment with 10% citric acid, 35% H3PO4, or 0.5M ethylenediaminetetraacetic acid (EDTA). The resultant smeared dentin samples were treated with one of the aforementioned reagents, and spectra were acquired at 1.0-microm intervals across the interfaces of the smear layers/demineralized dentin/mineralized dentin. Corresponding specimens were morphologically analyzed with scanning electron microscopy (SEM). The results showed that the composition of the smear debris and the in situ smear layers was a mixture of disorganized collagen and mineral. Spectral changes in the smear debris suggested that the disorganized collagen was denatured by acid treatment. The denatured collagen formed a gelatinous matrix around the mineral in the smear layer, thereby shielding it from the acid. The smear layers were not apparent in the SEM micrographs of acid-etched dentin prepared and processed with conventional techniques. The micro-Raman spectroscopic results presented in this study provide the first direct evidence that partially denatured collagen within smear layers is not removed and that the mineral is only partially removed with acids that represent conventional dentin adhesive etchants.
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PMID:Analysis of acid-treated dentin smear debris and smear layers using confocal Raman microspectroscopy. 1185 37


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