The effect of a transpalatal or nance palatal arch on sliding mechanics with varying degrees of molar rotations

[摘要] Aims: To determine if the use of a transpalatal (TPA) or Nance palatal arch with varying degrees of molar rotations significantly affects resistance to sliding during sliding mechanics. Also, to establish if there is reduced resistance to sliding using the extraoral tube (EOT) on molar bands opposed to the straight wire tube when using a TPA or Nance- palatal arch with rotated molars Materials and method: A custom made experimental apparatus approximating the transpalatal arch, allowing for 1-degree incremental changes to molar rotation was designed. A 0.019 x 0.025” stainless steel archwire was displaced through the molar tubes to determine the effect of molar rotation on resistance to sliding, determined as work. Unilateral and bilateral palatal rotations were evaluated as well as comparison of the extraoral and straight wire tube. Results: The work required to achieve a constant archwire displacement was significantly increased for bilaterally, palatally rotated molars compared with a unilateral rotation (p<0.05 for displacement of both 0.5 and 0.1mm). Pearson correlation analysis identified a significant association between extent of molar rotation and difference in work between unilateral and bilateral rotated molars (p-value 0.002 and 0.01 for displacement of 0.5 and 0.1mm respectively). Placement of the archwire in the extraoral tube significantly reduced the work required for a fixed displacement compared with the straight wire tube. The magnitude of the effect was greatest for bilateral palatal rotated molars and was highly significant (p <0.001 for 0.5mm). Conclusion: The relationship between work and molar rotation was found to be non-linear, with an exponential increase in work with increasing palatal rotations. Bilaterally, palatally rotated molars resulted in a significantly increased amount of work for all amounts of displacement of the archwire compared with a unilateral rotation. Use of the EOT significantly reduced the work required to displace the archwire compared with the straight wire tube.

[发布机构] University:University of Birmingham;Department:School of Dentistry

[关键词] R Medicine;RK Dentistry