Optimization of unilateral molar rotation correction by a trans-palatal bar: A three dimensional analysis using the finite element method

摘要

The derotation of a single molar prior to placing orthodontic appliances is a clinical problem that has been encountered by orthodontists many times. Methods of derotation have included the use of quadhelices, transpalatal bars, removable and fixed appliances. The problem with such devices is how to minimise the stress and to maximise the moment required to produce rotation in the desired molar, at the same time keeping the mechanics as simple as possible. Minimal mesial movement of the rotated molar is also desirable. In theory, the simplest design would be a transpalatal bar with no coils or loops but this would be extremely difficult to place if derotation was desired, and this would cause very high stresses (and discomfort) in the teeth concerned.