• Buntoon Chotiwannaporn D.D.S., M.D.Sc. (Orthodontics)
• Porntip Chiewcharat D.D.S. (Hons), M.D.Sc. (Orthodontics), Diplomate, Thai Board of Orthodontics
• Niramol Chamnannidiadha D.D.S. (Hons), Dr.med.dent. (Orthodontics), Diplomate, Thai Board of Orthodontics

Objective The purpose of this study was to compare the frictional resistance of two types of passive
self-ligating brackets and a conventional bracket. The two passive self-ligating brackets were Damon
3MX that kept the wire inside the slot by a sliding door and Smartclip that held the wire by two slipping
clips while the conventional bracket (Gemini) kept the wire inside the slot by an elastomeric ring.

Materials and methods Three experimental groups were tested by using three different materials in
active configuration. Each group consisted of 30 samples. At critical angle 3 degrees, static frictional
resistance was evaluated by Lloyd universal testing machine while the 0.019 inch x 0.025 inch stainless
steel wire was moved in the bracket slot. One-way analysis of variance and multiple comparisons with
Tamhaneûs T2 were used to analyze the difference of the static frictional resistance among three groups
at statistically significant level 0.05.

Results The findings revealed that Damon 3MX showed the lowest frictional resistance (0.203 ± 0.083
newton) followed by Smartclip (0.297 ± 0.074 newton) and Gemini (1.865 ± 0.404 newton), respectively.
There were statistically significant differences of the frictional resistance among three groups at
level 0.05.

Conclusion In the active configuration, Damon 3MX bracket and Smartclip bracket produced lower
frictional force than the conventional bracket did. Between two self-ligating brackets, Damon 3MX
demonstrated lower frictional force than that of Smartclip with statistical significance.

(CU Dent J. 2008;31:159-68)