Force Loss During Sliding Tooth Movement With Ceramic Brackets

Objectives: Frictional force are generated between the arch wire and the brackets during sliding teeth movement. Several studies reported that ceramic brackets are associated with higher friction values compared to metal brackets. The aim of this study was to compare the amount of force loss due to friction in a newly introduced ceramic bracket type as compared to metal brackets.
Methods: The test groups included Polycrystalline-Alumina (PCA) ceramic brackets (Clarity Advanced-3M Unitek) and Monocrystalline-Alumina (MCA) ceramic brackets (Inspire Ice, Ormco) which were compared with Metal brackets (Victory Series, 3M Unitek). All brackets groups (n=5) had 0.018 Х 0.025 -inch slot with Roth prescription of maxillary canines. The brackets were mounted on the Orthodontic Measurement and Simulation System (OMSS) simulating canine retraction process into first premolar extraction space. 0.016 x 0.022 stainless-steel arch-wires (Tru-Arch, Ormco) were ligated into the brackets using elastic ligatures (Alastik Easy-To-Tie, 3M Unitek). The retraction force was applied through Nickel Titanium coil spring (GAC, Sentalloy) with approximately constant force of 1-Newton. The OMSS measured the percentage of force loss over the retraction path by the difference between the applied retraction force and the actual force acted on each bracket. Comparison between groups was performed using student t-test.
Results: Victory series metal brackets showed the lowest force loss values among the groups, followed by (PCA) then (MCA) ceramic brackets groups (67.3±9.4 , 68±12.5, 76.1±13.4 ) respectively. There was no significant difference between metal and (PCA) brackets (p=0.84).However, there was significant differences between metal and (MCA) brackets (p=0.005) and between (PCA) and (MCA) ceramic brackets (p=0.04).
Conclusions: MCA brackets showed the highest friction, and PCA showed comparable frictional properties to victory brackets.