Effect of ferric chloride/citric acid/phosphoric acid conditioner on adhesion of 4-META/MMA-TBB resin to the tooth.
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The aim of this study was to examine the effects of ferric chloride/citric acid/phosphoric acid conditioners on the surface morphology of enamel and dentin and on the adhesion of 4-META/MMA-TBB resin to conditioned tooth surfaces. Seven conditioners, including phosphoric acid and its mixture with citric acid and ferric chloride, were prepared and used for treating bovine teeth before bonding with the resin. The effects of the conditioners on the surface morphology and adhesion were examined by scanning electron microscopy and by atomic force microscopy and by tensile bond strength tests, respectively. The maximum bond strengths to tooth surfaces were obtained by using 3% ferric chloride/5% citric acid/10% phosphoric acid conditioner. Thus, enamel and dentin can be treated simultaneously with this conditioner before bonding with the 4-META/MMA-TBB resin system. (+info)
Transarterial embolization with HEMA-MMA of variant convexity-superior sagittal sinus dural arteriovenous fistula--case report.
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A 62-year-old male presented with a variant dural arteriovenous fistula (DAVF) within the wall of the convexity-superior sagittal sinus, fed by branches of the bilateral external carotid arteries and only cortical venous drainage despite the presence of a patent sinus. Transarterial embolization with poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (HEMA-MMA) was performed, resulting in complete obliteration of the DAVF. Embolization with HEMA-MMA is an effective and safe procedure for the treatment of DAVF. (+info)
Splinting teeth--a review of methodology and clinical case reports.
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Splinting teeth to each other allows weakened teeth to be supported by neighbouring teeth, although the procedure can make oral hygiene procedures difficult. Several methods for splinting teeth, both extracoronal and intracoronal, as well as the materials commonly used for splinting, are described and illustrated. Two case reports are used to demonstrate the situations in which splinting might be appropriate. (+info)
Addition of antibacterial agents to MMA-TBB dentin bonding systems--influence on tensile bond strength and antibacterial effect.
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To produce a bonding system which has both high bond strength and antibacterial properties, an antibacterial agent (vancomycin: VCM or metronidazol: MN) was added to the PMMA powder of 4-META/MMA-TBB resin (CB). The influence of the addition of an antibacterial agent on tensile bond strength to dentin and the antibacterial effect were investigated in this study. Forty-seven freshly extracted bovine first or second incisors were used to measure the tensile bond strength to dentin. The bond strengths to bovine dentin were not significantly decreased by addition of VCM (1%, 2%, 5%), or MN (1%) to CB (p < 0.05). The antibacterial effect of CB containing antibacterial agent on six strains of bacteria was investigated by the agar plate diffusion method, analyzing the appearance of the inhibition zone around a resin disk following anaerobic culturing. The resin disks containing VCM showed antibacterial effects on all of the strains examined; the widths of the inhibition zones were 4-15 mm. The resin disks containing MN showed antibacterial effects on three strains; the widths of the inhibition zones were 0-4 mm. It was thus possible to produce a bonding system with both antibacterial effect and high tensile bond strength by addition of VCM to PMMA powder. (+info)
Effect of the adhesive layer thickness on the fracture toughness of dental adhesive resins.
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We investigated how the thickness of an adhesive layer between two Co-Cr alloy plates affected the mode I fracture toughness of dental adhesive resin by varying the type of resin using a double cantilever beam (DCB) test. Two typical adhesive resins (PV and SB) were used. The adhesive layers of the DCB test specimens were 20, 100 and 200 microns thick. The fracture modes of PV differed with the thickness of the adhesive layer, such as interface fracture at 20 microns thickness, and similar cohesive fracture at 100 and 200 microns thickness. In the case of SB, crack-propagating areas were observed as cohesive fractures in all test specimens with different adhesive layer thickness, and the surfaces of these areas became remarkably rougher as the thickness of the adhesive layer increased. The fracture toughness of PV was not affected by the differences in thickness between the 100 and 200 microns adhesive layers, but there was a notable decrease in fracture toughness when the adhesive layer decreased to a thickness of 20 microns. That of SB showed a tendency to increase as the adhesive layer became thicker. (+info)
Restoration of endodontically treated teeth with carbon fibre posts--a prospective study.
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BACKGROUND: A prospective study was started in 1995 to evaluate the success of carbon fibre reinforced epoxy resin (CFRR) posts used to restore endodontically treated teeth. All the teeth in the study had lost more than 50% of their coronal structure. METHODS: Fifty-nine carbon fibre Composiposts cemented with Metabond and built up with Core Paste cores were placed into the teeth of 47 patients. Each tooth received a full-coverage restoration (porcelain fused to metal crown) and was followed for 6.7-45.4 months (average = 28.0 months, standard deviation = 10.7). RESULTS: Results for 52 teeth in 42 patients were analyzed. There were no fractures. The overall failure rate was 7.7% and the cumulative survival rate was 89.6% at the end of the follow-up period. The only statistically significant finding (p = 0.04) was that posts in lower premolars were at higher risk of failure. CONCLUSION: CFRR posts are among the most predictable systems available today. CFRR posts in the upper anterior teeth are associated with a higher success rate and longer life than those placed in premolars, especially lower premolars. This study contributes to the growing body of evidence that supports the use of CFRR posts in the restoration of endodontically treated teeth. (+info)
Serotonin increases the incidence of primary afferent-evoked long-term depression in rat deep dorsal horn neurons.
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5-hydroxytryptamine (5-HT) is released in spinal cord by descending systems that modulate somatosensory transmission and can potently depress primary afferent-evoked synaptic responses in dorsal horn neurons. Since primary afferent activity-induced long-term potentiation (LTP) may contribute to central sensitization of nociception, we studied the effects of 5-HT on the expression of sensory-evoked LTP and long-term depression (LTD) in deep dorsal horn (DDH) neurons. Whole cell, predominantly current clamp, recordings were obtained from DDH neurons in transverse slices of neonatal rat lumbar spinal cord. The effect of 5-HT on dorsal-root stimulation-evoked synaptic responses was tested before, during, or after high-frequency conditioning stimulation (CS). In most cells (80%), 5-HT caused a depression of the naive synaptic response. Even though 5-HT depressed evoked responses, CS in the presence of 5-HT was not only still capable of inducing LTD but also increased its incidence from 54% in controls to 88% (P < 0.001). Activation of ligands selective for 5-HT(1A/1B) and 5-HT(1B), but not 5-HT(2A/2C) or 5-HT(3) receptors, best reproduced these actions. 5-HT also potently depressed postconditioning synaptic responses regardless of whether the induced plasticity was LTP or LTD. Our results demonstrate that in addition to depressing the amplitude of evoked sensory input, 5-HT can also control the direction of its long-term modifiability, favoring the expression of LTD. These findings demonstrate cellular mechanisms that may contribute to the descending serotonergic control of nociception. (+info)
XPS study on the weakest zone in the adhesion structure between resin containing 4-META and precious metal alloys treated with different surface modification methods.
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Three precious metal alloys, Type IV gold alloy, 14 K gold alloy, and silver-based alloy, were treated with different surface modifications including a metal primer (VBATDT) application, a SiOx coating method, high-temperature oxidation, modification method with a liquid Ga-Sn alloy, and tin electroplating. Then thin PMMA films were bonded with a resin containing 4-META. Water durability at the adhesion interface was evaluated after water immersion, followed by thermal cycling used liquid nitrogen. The weakest zone at the interface was investigated using XPS only for the Ag-Pd alloy specimens that had been surface-treated with as-polishing, adhesive primer, and the SiOx coating method, since peeling of the PMMA film on the surface of specimens surface-treated by other methods was not observed. Metal elements were detected from the resin side at the adhesion interface. The chemical states of Cu in the resin before argon ion etching were characterized as metal oxides and/or states of chemical interaction with 4-META, VBATDT, or SiOx. (+info)