Browsing by Subject "Forces"
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Item Bracket, ligation, and misaligned straight wires effects on load systems during orthodontic sliding mechanics(2015-07) Hannah, Richard D.; Katona, Thomas R.Objective: The objectives of this study were to measure and compare the complete, not solely friction, load components (forces and moments) experienced by brackets as they slide along straight wires that are angled relative to the path of bracket travel. Materials and Methods: Three types of brackets (stainless steel mandibular canine and central incisor, and an all-ceramic mandibular canine) were ligated with stainless steel or elastomeric modules to 2 sizes of stainless steel wire (0.021” x 0.021” and 0.016” x 0.016”) at 0°, 1° and 2° bracket-wire misalignments. All 3 force and 3 moment components experienced by the brackets were measured as they slid along the wire. Results: Overall, all 36 permutations of the 3 brackets, 2 ligations, 2 wires and 3 alignments produced statistically different (predominantly P < .0001) load components on the bracket. Conclusions: The type of bracket, wire, ligation, and relatively small misalignments (1° and 2°) between bracket and wire affect all force and moment components applied to the bracket. Traditional friction-focused “pull through” studies miss the attendant effects on the other 5 load components.Item The effects of bracket, wire conformation and size on the load systems during orthodontic sliding mechanics(2015-07) Mika, David E.; Katona, Thomas R.Objective: The purpose of this laboratory study was to compare all 6 load components (3 force and 3 moment) acting on 2 different stainless steel brackets as they slide along 3 sizes of stainless steel archwires with 3 different conformations. Materials and Methods: Brackets were attached to a load cell and elastomeric ligated to the wires. As the load cell was pulled along a precision track, the 6 load components (forces and moments in the 3 orthogonal coordinate system) acting on the bracket were recorded. ANOVA was applied to the data. Results: Overall, there were significant differences for all effects (bracket, wire size and wire configuration), for all outcomes (the loads), except the effect of bracket on the force of friction and one of the moment components. Conclusion: The results demonstrate that the force of friction associated with sliding mechanics should not be considered in isolation, because factors that affect it also affect the other 5 load components.Item Loads applied to the supporting structures of teeth during orthodontic bracket debonding(2015-07-22) Cardo, Gretter M.; Katona, Thomas R.Objective: The purpose of this study was to measure, and compare, the loads applied by operators with different levels of experience during a laboratory simulation of orthodontic bracket debonding. Materials and Methods: A 2 load cell device was designed and built to simultaneously measure the 3 force and 3 moment components experienced concomitantly by a simulated bracket and a simulated tooth during debonding. Comparisons were performed using mixed-model ANOVA with a main effect for group, and a random effect for the trials by an individual. Results: Several of the load components applied by the most inexperienced group were significantly higher than those applied by the 2 more experienced groups. Conclusion: Minimal experience with LODI (Lift-Off-Debonding Instrument) seems to bestow the ability to deliver lower loads to the structures.