Preliminary Study About Edgewise Structural Changes After Damon-Q Self-locking Braces Sliding Different Rectangular Arch Wire Using An Atomic Force Microscope

Objective To examine the surface topography of different arch wire segments after slide by canine tooth brackets during Damon-Q selflocking braces using an atomic force microscope,explore the best combination of pairing self-ligating bracket and arch wire.Method Two malocclusion patients were recruited who had four first premolars extracted and were treated with a Damon-Q self-locking braces.The upper left canine were retracted to contact the second premolar on segments of 0.018 "×0.025" stainless steel arch wires(thick wire group)and segments of 0.016 "×0.022" stainless steel arch wires(filament group)during treatment.Three-dimensional structures of the four surfaces of arch wire segment that slid by the canine tooth bracket and posterior arch wire segment which was between the upper left bicuspid and first molar and have not been slide by any bracket were scanned using an atomic using microscope before and after sliding canine tooth sliding.Three-dimensional parameters were obtained from the topography data.Independent samples T test or Mann-Whitney U test was used for statistical analysis on SPSS13.0.Results(1)upper and lower surfaces of the arch wire that had contacted the slot walls of canine tooth bracket in the thick wire group became smoother.The internal narrow surface that was at the base of the slot become rougher,the external narrow surface that was not contacted the bracket slot was not significant.upper surfaces of the arch wire that had contacted the slot walls of canine tooth bracket in the filament group became smoother.The internal narrow surface that was at the base of the slot become a little rougher,upper surfaces of the arch wire and internal narrow surface that was not contacted the bracket slot was not significant.(2)Upper surfaces of the arch wire segments between second bicuspid and first molar in the thick wire group became a little smoother and the external narrow surface of the arch wire segments in the filament group became a little rougher after canine tooth sliding.(3)Only was the lower surface difference between the arch wire area slid by the canine tooth bracket and the arch wire area that was between the second bicuspid and first molar had not been slid by any bracket in the thick wire group.and the arch wire area slid by the canine tooth bracket become smooth than before.The internal narrow surface area became a little rougher than the arch wire segments was between second bicuspid and first molar and the external narrow surface between second bicuspid and first molar become a little rougher in the filament group.Conclusion(1)Slide back and forth over the canine fangs,the internal narrow surface of thick and thin arch wire that was at the base of the slot become rougher while three structure unchanged or slightly smoothed.(2)From the structural point of view on the surface of the wire,the segments of 0.018 "×0.025" or0.016 "×0.022" stainless steel arch wires can paired with Damon-Q self-locking braces close the extraction space.