• Puntip Dongpaiboon D.D.S.
• Paiboon Techalertpaisarn D.D.S., Ph.D., Diplomate, Thai Board of Orthodontics

Objective To study the effect of liquid resin on initial shear bond strength between bracket and
enamel in 3 groups using different adhesives

Materials and methods Sixty human premolars were divided into 3 groups of 20 each. Tooth surface
was treated with phosphoric acid, then rinsed and blown to dry. Brackets were bonded to tooth surface
with light cured adhesives as following: group 1 Transbond XT^TM (3M Unitek, CA, USA), group 2
(G) Grengloo^TM (Ormco, Glendora, CA, USA), and group 3 (P) Padlock^TM (Reliance Orthodontic
Product, Inc., Itasca, IL, USA). Each group was divided into 2 subgroups of control and test. In test
subgroups (T1, G1, P1), brackets were bonded to tooth surface without the use of liquid resin, whereas
those in the control subgroups (T2, G2, P2) were bonded with the use of liquid resin in accordance
with manufacturerûs instruction. Shear bond strengths of 9 specimens from each subgroup were tested
after light activation for 5 minutes by universal testing machine. One remaining specimen from each
subgroup was used for investigation of resin penetration pattern into enamel under scanning electron
microscope. The means of bond strength between test and control subgroups were compared using
unpaired t-test, while the means of bond strength among subgroup were compared by one-way
ANOVA. The adhesive remnant indices in each subgroup were measured and tested by the Chi-square
at 95% confidence interval.

Results Mean shear bond strengths and standard deviations of test subgroups T1, G1, and P1 were
10.18 ± 2.33, 10.72 ± 3.21 and 11.61 ± 3.67 MPa, respectively. Those of control subgroups were 12.12 ±
3.29, 11.94 ± 3.20 and 10.44 ± 3.47 MPa, respectively. There is no significant difference between test and
control subgroups of each adhesive. There is no significant difference among all subgroups in test and
control groups. Also, no significant difference between ARI scores among subgroups is noted. For the
pattern of resin penetration into enamel during bracket bonding procedure, it was found that subgroups
without liquid resin represented less penetration of resin than those with liquid resin.

Conclusion The use of liquid resin in bracket bonding procedure does not affect initial shear bond
strength of all adhesives tested in this study.

(CU Dent J. 2015;38:11-20)