Effects of etchants and primers on shear bond strength of a self-ligating esthetic orthodontic bracket.

INTRODUCTION: Damon 3 orthodontic brackets (Ormco, Orange, Calif), combining a self-ligating bracket with a composite bracket pad were the subject of an in-vitro bonding study to determine the shear bond strength to enamel and adhesive remaining on the teeth with various enamel and bracket preparation procedures. METHODS: A 3 x 2 factorial design was selected with the following factors as variations of the enamel preparation: liquid phosphoric acid etchant followed by primer (Ortho Solo; Ormco), gel phosphoric acid etchant followed by primer, and self-etching primer (Transbond Plus; 3M Unitek, Monrovia, Calif). The second factor was a primer (Ortho Solo) either applied to the bracket pad or absent as a control. RESULTS: No statistically significant differences were observed in shear bond strengths, with group average estimates ranging from 14.5 to 16.6 MPa. Debonding predominantly occurred at the bracket-pad interface with no significant differences in adhesive remaining on the teeth. CONCLUSIONS: This in-vitro study indicated that self-etching primer, gel etchant, and liquid etchant produce equal and sufficient bond strengths. Furthermore, application of primer to the bracket pad does not improve bond strength.

Effect of water quality on the bonding of resin to moist dentin.

PURPOSE: To test the effect of different water samples, used for rinsing the dentin, following acid conditioning, on the bond strength of a resin-based composite (RBC) restorative material (Z100), to dentin using a one-bottle dentin adhesive (Single Bond). MATERIALS AND METHODS: In preliminary experiments two experimental shear bond strength methods were compared, and one was selected which was deemed to permit more uniform application of the adhesive and better light curing. In the definitive experiments there were five experimental groups, according to rinsing water used (1) distilled water as control, (2) water with 3.5 ppm iodine, (3) water 3.0 ppm sodium hypochlorite, (4) water with 2% ethanol, (5) water contaminated with 6 x 10(4) cfu/mL of E. coli BH5V. For each experimental group the shear bond strength to moist dentin from 10 human intact impacted third molars was measured. The dentin samples were etched, washed and gently blotted to leave the dentin moist. Following application of the adhesive and resin, specimens were stored at 37 degrees C for 24 hours prior to testing in an Instron testing machine at a rate of 0.5 mm/minute. RESULTS: Data (in MPa +/- standard deviation) were: Group 1: 21.2 +/- 4.1; Group 2: 20.8 +/- 5.6; Group 3: 21.8 +/- 6.2; Group 4: 22.9 +/- 5.9; Group 5: 19.6 +/- 5.5. These data support the null hypothesis that the water types used in this work had no significant effect on the bonding of a resin composite to dentin (P= 0.74, ANOVA).