原子力显微镜下Damon-Q托槽滑过不同方丝后方丝表面结构变化的初步研究

Preliminary study on edgewise structural changes after Damon-Q self-locking braces sliding different rectangular arch wire using an atomic force microscope

目的探讨在牙齿移动过程中Damon-Q自锁托槽滑过不同方丝表面对方丝结构产生的影响,从弓丝结构损坏方面探寻最佳的自锁托槽与弓丝的配对组合。方法对2例已拔除4个第一前磨牙、戴用Damon-Q自锁托槽矫治器治疗的错牙合畸形患者,分别使用0.018″×0.025″(粗丝组)、0.016″×0.022″(细丝组)不锈钢片段弓拉尖牙远移关闭拔牙间隙。在原子力显微镜下观察测量托槽滑过段弓丝、未有托槽滑过的磨牙前段弓丝于托槽滑动前后四个面三维结构的改变情况。结果 (1)尖牙滑动前后粗丝组托槽滑过段弓丝上下宽面、内窄面的St值差异有统计学意义(P<0.05),滑动前后上宽面的St(峰沟总高度)为(625.5±346.2)nm和(244.4±134.4)nm,下宽面的为(628.5±258.7)nm和(329.5±137.4)nm,内窄面的为(275.5±306.0)nm和(480.2±153.5)nm,外窄面结构无变化。细丝组托槽滑过段弓丝滑前后下宽面St值分别为(223.8±110.1)nm和(122.7±52.8)nm,内窄面的为(391.9±133.2)nm和(775±267.1)nm,上宽面、外窄面结构无变化。(2)粗丝组磨牙前段弓丝在尖牙滑动前后上宽面St值差异有统计学意义(P<0.05),为(385.9±238.2)nm和(157.5±40.5)nm。细丝组外窄面St值差异亦有统计学意义(P<0.05),为(41.5±183.7)nm和(175.0±199.1)nm。结论 (1)尖牙滑动前后尖牙滑过段粗、细弓丝内窄面均变粗糙,其余三个面结构不变或略变光滑。(2)从对弓丝表面结构影响趋势来看,Damon-Q自锁托槽均可与0.018″×0.025″或0.016″×0.022″方丝配对来关闭拔牙间隙,效果接近。

Objective To examine the surface topography of different arch wire segments after slide by canine tooth brackets during Damon-Q self-locking braces using an atomic force microscope,and to explore the best combination of pairing self-ligating bracket and arch wire. Methods Two malocclusion patients were recruited who had four first premolars extracted and were treated with a Damon-Q self-locking brace. The upper left canine teeth 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 the 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 had not been slid by any bracket were scanned using an atomic force microscope before and after canine teeth slid. The 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 became rougher. The external narrow surface that was not contacted the bracket slot was not significant. The lower surface 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 on the base of the slot became a little rougher,and the upper surfaces of the arch wire and external narrow surface that was not contacted the bracket slot was not significant.（ 2） The upper surface of the arch wire segments between the 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 the canine tooth slid. Conclusion（ 1） Slide back and forth over the canine fangs,the internal narrow surface of thick and thin arch wire that is on the base of the slot becomes rougher while the structures on the other three sides are unchanged or slightly smooth.（ 2） From the view of structural changes on the surface of the wire,the segments of 0. 018″ × 0. 025″or 0. 016″ × 0. 022″ stainless steel arch wires can be paired with Damon-Q self-locking braces before closing extraction space for similor effect.