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Biomedical subjects

D H Retief

Publications and source records attributed to D H Retief.

At least 73 records · Page 4Linked to original sources
PubMed1987

Tensile bond strengths of orthodontic bonding resins and attachments to etched enamel.

The purpose of this in vitro study was to determine the tensile bond strengths (TBS) of several orthodontic bonding systems and orthodontic brackets to enamel surfaces exposed to different etching procedures. The TBS of four bonding systems were determined by a test method developed by Kemper and Kilian. Twelve test specimens were prepared for each procedure. The test system was modified to determine the TBS of orthodontic brackets bonded to enamel surfaces by six bonding procedures and the TBS were evaluated 15 minutes and 24 hours after specimen preparation. The specimens were loaded to failure in an Instron machine operated at a crosshead speed of 0.02 inch/min. The TBS were expressed in MN.m-2. The TBS of the four bonding systems to etched enamel were not significantly different (P = 0.2528). The TBS of bonded brackets determined 24 hours after specimen preparation were not significantly different than the TBS recorded after 15 minutes except for brackets bonded with Lee Cleanse and Bond I to enamel surfaces etched with 15% H3PO4 for 30 seconds. The TBS of brackets to enamel etched with 15% H3PO4 for 30 seconds were not significantly different from the TBS to enamel surfaces etched with 5% H3PO4 for 15 seconds except for brackets bonded with Lee Cleanse and Bond II and tested 24 hours after bonding.

Acid Etching, Dental↗
PubMed1986

The effect of fluoride in phosphoric acid on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin.

Decalcification that occurs adjacent to bonded orthodontic brackets is of great concern to orthodontists. Among the many procedures suggested to overcome this problem is the addition of fluoride to the phosphoric acid (H3PO4) etching solution. The purposes of this study were to determine the loss of fluoride from the acidic etching solutions, to evaluate the effect of various fluoride concentrations in H3PO4 on the tensile bond strength of an orthodontic bonding resin, to determine the amount of total and bound fluoride acquired by etched enamel, and to evaluate the effect of these etching solutions on enamel by scanning electron microscopy. Solutions of 50 m/m% H3PO4 containing 0 and approximately 0.01, 0.04, 0.08, 0.2, 0.4 and 0.9% fluoride were prepared. The fluoride concentrations in the etching solutions remained stable up to 3 months after preparation. The tensile bond strengths of the bonding resin to the etched enamel surfaces were not significantly different. Enamel acquired the greatest amount of total fluoride from H3PO4 solutions containing 0.215% fluoride while the bound fluoride acquired by enamel from the fluoride-containing etching solutions was not significantly different. The addition of fluoride to H3PO4 did not impede the etching effect on enamel.

Acid Etching, Dental↗