• Pintu-on Chantarawaratit D.D.S.
• Somsak Chengprapakorn D.D.S., M.D.Sc. (Orthodontics), Diplomate, Thai Board of Orthodontics

Objective To investigate and compare the levels of static frictional forces between stainless steel
brackets and two types of orthodontic wires after immersion in three types of solutions which contained
fluoride products.

Materials and methods Canine standard stainless steel brackets (Dyna-lock, 3M Unitek) with
stainless steel wires (Stainless Steel, Ormco) and beta-titanium wires (TMA, Ormco) were immersed
in three types of the solutions which contained the artificial saliva and fluoride products: fluoride
toothpaste, fluoride mouthwash and fluoride gel (APF) at 37 ÌC. In this study, each group included
25 bracket-wire specimens. The static frictional forces were measured by using a Lloyd Universal
Testing Machine, Model LR 10 K (Lloyd Instruments, UK) with a 5-N load cell. The wires were
ligated by elastomeric rings to the brackets which were attached to the crosshead of the machine.
The brackets were pulled up at a speed of 0.1 mm per minute for a distance of 0.5 mm. The control
tests were performed using specimens that had not been dipped in any solution. Two-way ANOVA
(α = 0.05) was used to test for significant differences among the groups of specimens.

Results When comparing the control groups, only the mean static frictional forces of the
APF-immersed groups in both stainless steel wire group and beta-titanium wire group were
significantly greater than those of their control groups at p = .013 and p = .000, respectively. When
comparing the mean static frictional forces of stainless steel groups to those of beta-titanium groups
which were immersed in the same solution, the mean static frictional forces of stainless steel groups
were lower than those of beta-titanium groups in which the specimens were dipped in the toothpaste
solution and the APF solution at p = .003 and p = .004, respectively. There was no significant
difference between the mean static frictional forces of stainless steel group and beta-titanium group
in the control group and the mouthwash solution-immersed group.

Conclusion Immersion of stainless steel brackets, stainless steel wires and beta-titanium wires in
the APF solution can increase the static frictional forces between brackets and archwires.

(CU Dent J. 2008;31:179-92)