Numerous experimental studies have examined how much orthodontic force is needed to move teeth more smoothly; however, no reports have examined this clinically in individual, living subjects. We aimed to… Click to show full abstract
Numerous experimental studies have examined how much orthodontic force is needed to move teeth more smoothly; however, no reports have examined this clinically in individual, living subjects. We aimed to develop a method for quantifying the force exerted on individual teeth by an orthodontic wire to measure how loads placed on crowded teeth change dynamically over time. Accordingly, we fabricated a series of dental casts of patients undergoing orthodontic treatment (using optical impressions and a three-dimensional printer), fitted these models with nickel-titanium wire, and subjected them to bending load tests. During leveling, nickel-titanium wire is generally considered to exert a weak force due to its low elastic modulus, with a weak orthodontic force applied over a long period of time due to its superelasticity; however, we found that the actual energy exerted by nickel-titanium wire is also largely affected by other factors (e.g., amount of crowding).
               
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