Date of Award

Spring 2011

Document Type


Degree Name

Master of Science (MS)



First Advisor

Berzins, David

Second Advisor

Bradley, Gerard

Third Advisor

Liu, Dawei


Objective: To determine if American Orthodontics' (AO) new, experimental ligature demonstrates less friction in vitro when compared to four other ligatures on the market.

Methods: Four brackets were mounted on a custom metal fixture allowing an 0.018-in stainless steel wire attached to an opposite fixture with one bracket to be passively centered in the bracket slot. The wire was ligated to the bracket using one of five types of ligatures including the low friction test ligatures (AO), conventional ligatures (AO), Sili–TiesTM, Silicone Infused Ties (GAC), Synergy® Low-Friction Ligatures (RMO), and SuperSlick ligatures (TP Orthodontics). Resistance to sliding was measured over a 7 mm sliding distance using a universal testing machine (Instron) with a 50 Newton load cell and a crosshead speed of 5 mm/min. The initial resistance to sliding (static) was determined by the peak force needed to initiate movement and the kinetic resistance to sliding was taken as the force at 5 mm of wire/bracket sliding. Fifteen unique tests were run for each ligature group in both dry and wet (saliva soaked for 24 hours with one drop prior to testing) conditions.

Results: In the dry state, the SuperSlick ligature demonstrated more static friction than all of the other ligatures, while SuperSlick and Sili–Ties demonstrated more kinetic friction than the AO conventional, AO experimental and Synergy ligatures. In the wet condition, SuperSlick and the AO experimental ligature demonstrated the least static friction, followed by the AO conventional and Sili–Ties. The most static friction was observed with the Synergy ligatures. In the wet condition, the SuperSlick, AO experimental and AO conventional exhibited less kinetic friction than the Sili-Ties and Synergy ligatures.

Conclusions: AO's experimental ligature exhibits less friction in the wet state than conventional ligatures, Sili–Ties and Synergy and is comparable to the SuperSlick ligature. These preliminary results suggest that the AO experimental ligature and the SuperSlick ligature create less friction, but direct conclusions regarding in vivo performance cannot be made and randomized controlled clinical trials are needed to determine if these ligatures have clinical significance in treatment efficiency.