• Nattaporn Laotaveerungrueng D.D.S.
• Paiboon Techalertpaisarn D.D.S., Ph.D., Diplomate, Thai Board of Orthodontics

Objective To study the effect of different enamel conditioners on initial shear bond strength of resinmodified
glass ionomer adhesive to enamel.

Materials and methods Fifty five human premolars were divided into 5 groups (11 samples for each
group). Group 1, 2, 3 and 4 (Experimental groups) were conditioned with no conditioner, 20% polyacrylic
acid, 37% phosphoric acid and self-etching primer, respectively and the brackets bonded with resinmodified
glass ionomer adhesive (Fuji ortho LC). Group 5 (Control group) was conditioned with 37%
phosphoric acid and the brackets bonded with composite resin adhesive (Transbond XT). After light
activation for 5 minutes, shear bond strengths of 10 specimens from each group were tested by
universal testing machine. One remaining specimen from each group was used to investigate of resin
penetration pattern into enamel under scanning electron microscope. The mean of shear bond strength
among groups were compared by one-way ANOVA. The adhesive remnant indices (ARI) in each
group were measured and tested by the Chi-square at 95% confidence interval.

Results Mean of shear bond strengths and standard deviations of test groups 1, 2, 3, 4 and 5 were 8.4
± 2.0, 10.8 ± 0.7, 14.6 ± 3.0, 13.7 ± 1.7 and 21.5 ± 4.0 megapascal, respectively. There is no significant
difference between group 3 and 4 (p = 0.433). Types of enamel conditioners were statistically significant
to ARI scores (p < 0.05). SEM image revealed that the size and number of resin tags in self-etching
primer group are greater than other experimental groups.

Conclusion The use of phosphoric acid or self-etching primer as a conditioner before bonding with
resin-modified glass ionomer adhesive can increase initial shear bond strength.

(CU Dent J. 2015;38:197-208)