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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study investigated adhesion to dentin of a modified 4-META/MMA-TBB resin (4-methacryloxyethyl trimellitate anhydride in methyl methacrylate initiated by tri-n-butyl borane) which does not require PMMA powder to polymerize. Ground bovine dentin specimens were pre-treated with an aqueous solution of 10% citric acid and 3% ferric chloride (10-3). This solution removes the smear layer and demineralizes the dentin, exposing collagen. Improved bond strengths were obtained when a HEMA-primer was applied to 10-3 pre-treated dentin. SEM examination revealed the formation of a transitional zone of resin-reinforced-dentin (hybrid layer) in 10-3 pre-treated, HEMA-primed samples. The adhesive monomer impregnated exposed collagen fibrils and, upon polymerization, became entangled with them to create the hybrid layer, essential in achieving significantly high tensile bonding strengths. HEMA enhanced the penetration capability of dentinal substrates. After polymerization and formation of the hybrid layer, auto-cured acrylic resin, photo-cured composite and amalgam were all capable of adhering to the dentin. The modified 4-META/MMA-TBB resin created significant adhesive bonds to 10-3 pre-treated ground bovine dentin.
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PMID:Dentin adhesion of "modified" 4-META/MMA-TBB resin: function of HEMA. 129 94

The purpose of this study was to observe the interfaces between (1) dentin and amalgam and (2) freshly placed amalgam and existing amalgam using various adhesive liners. Specimens were randomly assigned to four equal groups for liner placement: Group I--control, no liner used; Group II--copal varnish; Group III--4-META adhesive; Group IV--dentin bonding agent. After liner placement and amalgam replacement, specimens set for 24 hours and were then thermocycled in 0.5% basic Fuchsin dye, sectioned, and SEM analyses performed. Microgaps appeared in a disjointed fashion at the interface between freshly placed and existing amalgam. The 4-META adhesive appeared to establish a bond between amalgam and tooth structure and, thus, diminished the microgap between amalgam and dentin.
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PMID:Addition of fresh amalgam to existing amalgam utilizing various adhesive liners: a SEM study. 138 43

Research into improved adhesion of resins to tooth substrates has found that methacrylates with both hydrophobic and hydrophilic groups, like 4-methacryloxyethyl trimellitate anhydride (4-META), enhance monomer penetration into dentin pretreated with 10% citric acid and 3% ferric chloride (10-3). Scanning and transmission electron microscope (SEM and TEM) examinations revealed the formation of a transitional zone of resin-reinforced dentin, termed the hybrid layer. The 4-META adhesive resin impregnated the exposed collagen bundles with which it entangled to create the hybrid, essential to attaining high tensile bond strengths.
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PMID:Adhesive bonding with 4-META. 147 May 41

A new, simple surface modification method for adherend metals has been developed. It gives high bond strength and superior water durability to dental precious-metal alloys bonded with 4-META/MMA-TBB resin. However, there was no effect on the bonding of Ag-In-Zn alloy and base-metal alloys. In the present study, the alloy surfaces modified by the new method were analyzed by ESCA and SEM for determination of details of the modification effect. A new alloying layer containing Ga and Sn was formed on the precious-metal alloys. The main factor for excellent adhesion to be achieved was the formation of a very thin layer of Ga2O3 and SnO2, less than 1-2nm thick, on the alloy surface. A thicker modified layer, as formed on the Ag-In-Zn and Ni-Cr alloys, led to low bonding ability.
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PMID:ESCA study on dental alloy surfaces modified by Ga-Sn alloy. 161 84

The objective of this study was to determine the shear bond strength of dental amalgam bonded to dentin with adhesives. Four groups of 15 permanent posterior teeth were used in this study. The occlusal enamel of the teeth was removed to produce a flat dentin surface. The teeth were embedded in phenolic rings with acrylic resin. Vinyl polysiloxane ring molds 4 mm thick with 4.5 mm circular openings were attached to the exposed dentin surface. Adhesives applied to the dentin surfaces prior to amalgam placement and condensation included: Amalgambond, a 4-META/TBB-MMA, HEMA based system (A), Panavia EX, a modified phosphate ester of Bis-GMA luting system (P), and Ketac-Cem, a glass ionomer luting cement (K). A dentin bonding agent and composite resin restoration system (Scotchbond 2/Silux Plus) was included for comparison. The specimens were stored in 37 degrees C water for 7 days prior to testing. Shear bond tests were done in an Instron machine at a crosshead speed of 0.02 inches per minute. The data were analyzed by ANOVA at 5% level of significance. The differences in shear bond strengths of the four test groups were not statistically significant (P = 0.115). Fracture patterns of the bonded amalgams, examined by SEM, were adhesive in appearance for Groups A and K and cohesive for Group P.
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PMID:Shear bond strength of dental amalgam bonded to dentin. 190 Jun 93

Adhesion durability between dentin pretreated with 10-3 and 4-META/MMA-TBB resin was studied. Reduction of etching periods with 10-3 was not so effective as expected. The weakening of bond strength during immersion in water at 37 degrees C to the dentin pretreated for 1 sec occurred faster than those for either 5 sec or 10 sec. The strength decreased from 12 MPa at 1 day to 9 MPa at 3 months, 3 MPa at 6 months and finally 2 MPa at 1 year in the case of 1 sec pretreated dentin. On the other hand, the strength became half after the storage in water for 1 year in the cases of 5 and 10 sec pretreated dentins. Combination of 10-3 pretreatment and subsequent glutaraldehyde treatment could stabilize the decrease but not completely. SEM and TEM examinations suggested that dentinal collagen exposed by the etching but not entangled and impregnated by poly (4-META-co-MMA) easily deteriorated by water during the longer immersion. Collagen modified with 10-3 and then with glutaraldehyde was also changed by the longer immersion.
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PMID:[Durability of bonding between 4-META/MMA-TBB resin to dentin pretreated with 10-3. The effect of 10-3 pretreating period and subsequent glutaraldehyde treatment]. 213 46

EDTA 3-2 (Fe.NH4), EDTA 3-2 (Co.NH4) and EDTA 3-2 (Cu.NH4) at pH 7.4 were investigated to determine effective pretreatment to promote strong adhesion of 4-META/MMA-TBB resin to enamel with minimum demineralization. EDTA 5-0 (NH4) solution which does not contain a metal salt was also investigated as a control. The amount of Ca2+ demineralized during the pretreatment and the tensile bond strength to enamel were measured. The pretreated enamel surface and the resin surface of the adhesion junction were observed with SEM. When the enamel surface was pretreated with EDTA 3-2 (Fe.NH4) for 60 seconds, the tensile bond strength of the resin to enamel was 7.1 MPa after the thermal cycling test. No direct correlation was observed between the amount of Ca2+ demineralized and the tensile bond strength. The stable and strong bonding to enamel was taken place without strong mechanical retention.
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PMID:[Adhesion of 4-META/MMA-TBB resin to enamel treated with EDTA metal ammonium solutions. Effect of Fe.NH4, Co.NH4 and Cu.NH4 salts]. 251 67

EDTA metal ammonium salt solution containing Fe3+, Co3+ or Cu2+ was studied to determine the pretreatment reagent that causes no denaturation of dentin collagen and promotes good adhesion to dentin. After application of EDTA 3-2 (Fe.NH4), EDTA 3-2 (Co.NH4) or EDTA 3-2 (Cu.NH4) at pH 7.4 on the dentin surface, the amount of Ca2+ demineralized and the tensile bond strength were measured. The pretreated dentin surfaces were also observed with SEM. No correlation was obtained between the amount of Ca2+ demineralized and the tensile bond strength. On the EDTA 3-2 (Fe.NH4) treated dentin a small amount of smear remained partially, but the tensile bond strength of 4-META/MMA-TBB resin to the dentin was higher than 13 MPa. This indicates that complete removal of the smear on dentin is not always necessary for better bonding.
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PMID:[Adhesion of 4-META/MMA-TBB resin to dentin treated with EDTA metal ammonium solutions. Effect of Fe.NH4, Co.NH4 or Cu.NH4 salts]. 251 58

The tensile median fatigue limits and fracture mode of 4-META cement were evaluated after bonding Ni-Cr, Ni-Cr-Be, and Co-Cr alloys to enamel. Alloy surfaces, 6 mm in diameter, were grit blasted with 50 microns Al2O3 and cemented to etched bovine enamel under a 2 kg load. Samples were cycled in tension to failure or 10(6) cycles at 5 Hz in Ringer's solution at 37 degrees C. Two-point strategy was used to determine median fatigue limits (S50). Fracture modes were evaluated by SEM on samples failing before 10(6) cycles. Results indicated differences between all sample groups where S50 (Ni-Cr-Be) > S50 (Co-Cr) > S50 (Ni-Cr). Failure analysis revealed mixed cohesive fractures near both interfaces with small areas of delamination within the cement. Comparison to reported median fatigue limits of two commercially available cements were discussed.
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PMID:Tensile fatigue of 4-META cement bonding three base metal alloys to enamel and comparison to other resin cements. 778 18

In vitro localized wear testing was completed on several commercially available and experimental resin composites to evaluate the loss of occlusal contact wear. Marginal deterioration after localized stressing was also evaluated by SEM observation. The compositions containing zirconium silicate and quartz exhibited the least amount of wear. However, an experimental 4-META bonding resin exhibited the best marginal integrity.
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PMID:Localized wear and marginal integrity of posterior resin composites. 780 9


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