Biomedical subjects
D R Beech
Publications and source records attributed to D R Beech.
Bond strength of restorative materials to human dentin: influence of post-extraction time.
This study was undertaken to determine if the time after which teeth are extracted influences the tensile bond strength of a glass ionomer (Fuji II: GC) and a dentin bonding agent (Scotchbond Self Cure; 3M) to dentin. Within 20 min of extraction, 14 teeth were bonded with glass ionomer and 13 teeth with Scotchbond Self Cure plus a composite material (Clearfil; Kuraray), by attachment of orthodontic brackets to prepared dentin surfaces. The bonds were fractured in tension, and yielded values of 3.7 MPa for glass ionomer and 1.08 MPa for Scotchbond Self Cure + Clearfil. These data were significantly different (P less than 0.002) from data previously obtained from the use of old teeth, from which values of 2.20 MPa and 1.82 MPa for glass ionomer and Clearfil + Scotchbond Self Cure, respectively, were obtained. It was concluded that the time after extraction can significantly change bond strengths to dentin, but that the direction and magnitude of these changes depend on the adhesive system used.
Mechanism of adhesion of polymers to acid-etched enamel. Effect of acid concentration and washing on bond strength.
The tensile bond strengths of composites to enamel etched with various concentrations of phosphoric acid have been shown to correlate closely with the phase diagram for the system Ca(OH)2/H3PO4/H2O. Bond strengths were independent of the adhesive used and were a maximum when using approximately 20% phosphoric acid as etchant. High bond strengths were obtained with 2% phosphoric acid etchant without 'tag' formation, after short term water immersion. Washing the enamel for 60 s instead of 15 s after etching significantly increased the bond strengths obtained with 16 and 30% acid but not with 2%. Etching enamel with phosphoric acid results in deposition of calcium phosphates, which must be removed to give optimal bonding.
Improving the bond strength of polyacrylate cements to dentine. A rapid technique.
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Polymeric restorative materials.
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Adhesion and adhesives in the oral environment.
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Molecular weight distribution of denture base acrylic.
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