A New One-Part Self-Etching Orthodontic Primer

Orthodontic primers have evolved from total-etch primers requiring prior acid etch/rinse multisteps to self-etch primers incorporating all in one step. 

Objective: This study compares the shear bond strength of a new one-part self-etch primer with a commercially available two-part self-etch primer and a total-etch primer on bovine uncut enamel.

Methods: The new one-part self-etching primer (3M Unitek) was compared to Transbond Plus Self Etching Primer (3M Unitek) and Transbond MIP Moisture Insensitive Primer (3M Unitek) for bond strength.  Transbond XT Adhesive (3M Unitek) or Transbond PLUS Color Change Adhesive (3M Unitek) was pasted onto Victory Series upper central brackets (3M Unitek, REF 017-401) and bonded to bovine teeth, which had been pumiced, rinsed and etched/primed with one of the primers according to manufacturer's instructions.  For the new self-etching primer, the same instruction for Transbond Plus Self Etching Primer was followed except that mixing two parts was not needed.  An Ortholux LED Curing Light (3M Unitek) was used to cure the brackets with a 5x5-second curing time.  The bonded teeth were stored overnight in 37șC water.  Bond strength was tested in a shear-peel mode at a crosshead speed of 0.2 inch/minute using a MTS QTest/5 Universal Test Machine (MTS Systems Corporation).  Bond strength was converted to MPa by dividing the force by the bracket base area. 

Results: mean bond strength ± standard deviation

Analysis of Variance showed that bond strengths were not statistically different in all pairwise comparisons among all three primers with either of the two adhesives.

Conclusion: The new one-part self-etching primer has bond strength comparable to Transbond Plus Self Etching Primer and Transbond MIP Moisture Insensitive Primer.  All primers combined with Transbond XT Adhesive or Transbond PLUS Color Change Adhesive provide good bond strengths on bovine uncut enamel.