Finite element analysis of stress distribution in anchor teeth in surgically assisted rapid palatal expansion.

The treatment of a transverse maxillary deficiency in skeletally mature individuals should include surgically assisted rapid palatal expansion. This study evaluated the distribution of stresses that affect the expander's anchor teeth using finite element analysis when the osteotomy is varied. Five virtual models were built and the surgically assisted rapid palatal expansion was simulated. Results showed tension on the lingual face of the teeth and alveolar bone, and compression on the buccal side of the alveolar bone. The subtotal Le Fort I osteotomy combined with intermaxillary suture osteotomy seemed to reduce the dissipation of tensions. Therefore, subtotal Le Fort I osteotomy without a step in the zygomaticomaxillary buttress, combined with intermaxillary suture osteotomy and pterygomaxillary disjunction may be the osteotomy of choice to reduce tensions on anchor teeth, which tend to move mesiobuccally (premolar) and distobuccally (molar).

[Acute paraplegia. A rare complication of aortic dissection]. / Paraplegia aguda. uma complicação rara da dissecção aórtica.

A 67 year-old normotensive woman had a syncope followed by shock and remained anuric after hemodynamic stabilization. Paraplegia and paresis of the right upper limb, as well as signs of ischemia of the distal lower limbs were noted. The possibility of acute aortic dissection was raised and confirmed by computed tomography. The paraplegia was attributed to an ischemic infarction of the spinal cord. The patient died on the fourth hospital day due to a pericardial temponade. This rare and not well recognized complication of aortic dissection is briefly reviewed.