The effect of using a new experimental self-etch primer/adhesive on the shear bond strength of orthodontic brackets: a comparative study.

S. E. Bishara, R. Ajlouni, G. E. Denehy, J. F. Laffoon, J. J. Warren
Hellenic Orthodontic Review 2002;5:13-20.

Conventional adhesive systems use three different agents, an enamel conditioner, a primer solution, and an adhesive resin during the bonding of orthodontic brackets to enamel. A unique characteristic of some new bonding systems in operative dentistry, is that they combine the conditioning and priming agents into a single application. Combining conditioning and priming saves time and should be more cost-effective to the clinician and indirectly to the patient.
AIM: To assess and compare the effects of using two self-etch primers including an experimental one, on the shear bond strength of orthodontic brackets.
DESIGN: In vitro study.
SETTING: College of Dentistry, University of Iowa.
MATERIAL AND METHOD: The brackets were bonded to extracted human teeth according to one of three protocols;
Group I (Control): Teeth were etched with 37% phosphoric acid. After applying the sealant, the brackets were bonded with Transbond XT (3M Unitek, Monrovia, California, USA) and light cured for 20 seconds.
Group II: A self-etch acidic primer (ESPE Dental AG, Seefeld, Germany) was placed on the enamel for 15 seconds and gently evaporated with air as suggested by the manufacturer. The brackets were then bonded with Transbond XT as in the first group.
Group III: A new experimental self-etch primer EXL# 547 (3M ESPE, St. Paul, Minnesota, USA), was rubbed on the enamel for 10 seconds and left to stand for 20 seconds before it was air-dried and then light cured for 10 seconds. The brackets were then bonded as in groups I and II
RESULTS: The present in vitro findings indicated that the shear bond strengths of the three groups were significantly different (P=0.018). Duncan multiple range tests indicated that Prompt L-Pop had a significantly lower (mean = 7.1 ± 4.4 MPa) shear bond strength than both the new EXL# 547 self- etch primer (mean = 9.7 ± 3.7 MPa) or phosphoric acid and the conventional adhesive system ( mean = 10.4 ± 2.8 MPa).
CONCLUSIONS: The present results indicated that the newly introduced self-etch primers, containing both the enamel etchant and primer have the potential to be successfully used in bonding orthodontic brackets.

Reprint requests to: Dr. Samir E. Bishara, Professor, Department of Orthodontics, College of Dentistry, University of Iowa, Iowa City, Iowa 52242, U.S.A.