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Query: EC:2.3.1.177 (BIS)
 957 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tensile fatigue limits and ultimate tensile strengths of some prosthodontic adhesive systems were determined. Ni-Cr-Be cylinders were: electro-etched, chemically etched, and sand-blasted prior to being bonded end-to-end with BIS-GMA and 4-META adhesives. Bonded specimens were stored in distilled de-ionized water for three days prior to being tested. Fifteen paired specimens per group were subjected to a cyclic tensile load for 1000 cycles. Tensile fatigue limits were determined by the staircase method. Five specimens per group were tested for ultimate tensile strength. In addition, those specimens which survived the 1000 cycles during fatigue testing were also tested for ultimate tensile strength. Statistical evaluations to compare tensile fatigue limits and ultimate tensile strengths for fatigued and non-fatigued specimens were then performed. The results indicated that the tensile fatigue limit and the ratio of fatigue limit to ultimate tensile strength of the sand-blasted, 4-META adhesive system were significantly lower than those of the other systems tested. The application of a cyclic load significantly decreased the ultimate tensile bond strength of the 4-META adhesive. Application of a cyclic load had no significant effect on the ultimate tensile bond strengths of the BIS-GMA systems tested.
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PMID:Tensile fatigue limits of prosthodontic adhesives. 182 69

The adsorption of 4-methacryloxyethyl trimellitate anhydride (4-META) was studied from ethanol and dichloromethane onto synthetic hydroxyapatite (containing about 1.5 monolayers of physisorbed water) in order to study its role in restorative composite bonding to teeth. The adsorption isotherm of 4-META was S-shaped and reversible from ethanol, and followed the Langmuir plot at lower concentrations. The isotherm was irreversible from dichloromethane, and a constant amount of adsorbate was removed from the solutions above a certain concentration. The irreversibly adsorbed compound was completely removed by washing with ethanol. Therefore, the bonding between teeth and the restorative resin containing 4-META as a coupling agent is micromechanical and not chemical in nature. An analysis of isotherms showed that the benzene rings of the adsorbate molecules lie flat on the surface for both solvents. The molecules adsorbed from ethanol rotate about the solvent-modified (esterified) or unmodified carboxylic anhydride moieties with methacrylate hydrocarbon groups which are folded upward. However, the molecules adsorbed from dichloromethane remain fixed to the surface without rotation, and their methacryloxyethyl groups are folded over the rings. The diametral tensile strength of a BIS-GMA polymer with adsorbate-covered apatite was approximately equal to that of the composite filled with untreated apatite.
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PMID:Adsorption of 4-methacryloxyethyl trimellitate anhydride (4-META) on hydroxyapatite and its role in composite bonding. 264 29

Flat tabs of cast gold alloy (n = 156) were subjected to either of three surface treatments: (1) roughening with diamond bur, (2) aluminum oxide sandblasting, and (3) sandblasting plus tin electroplating. Mandibular incisor edgewise brackets were bonded with Concise (BIS-GMA resin) (Unitek, Monrovia, Calif.) or Superbond C&B (4-META metal bonding resin) (Sun Medical Co. Ltd., Kyoto, Japan), or with Concise after application of an intermediate resin. All-Bond 2 Primers A and B (Bisco Dental Products, Itasca, Ill.), or B alone. All specimens were stored in water at 37 degrees C for 24 hours, and 60 were then thermocycled 1,000 times from 5 degrees C to 55 degrees C and back. The tensile bond strength testing was performed in a Lloyd 1,000R machine (Fareham, Hants, England). Alignment and uniform loading during testing were secured by engaging a hook in a circular ring soldered onto the bracket slot before bonding. Similar control brackets (n = 24) were bonded with Concise to extracted human premolars and lower incisors according to a routine procedure. Bond failure sites were classified by a modified ARI system. The results showed that sandblasting produced significantly stronger bonds to gold alloy than roughening with diamond bur. Superbond C&B provided significantly stronger bonds to gold alloy than Concise. There were generally insignificant differences in bond strengths between the water stored and the thermocycled specimens. Bond failures of Concise to sandblasted plus tin-plated gold alloy invariably occurred at the gold/adhesive interface, whereas those of Superbond C&B occurred within the adhesive or in the adhesive/bracket interface.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Improving orthodontic bonding to gold alloy. 748 70