title: Biomechanical analysis of maxillary expansion in CLP patients.
abstract: OBJECTIVE
  To carry out a comparative biomechanical analysis of maxillary low force expansion using the quadhelix appliance in cleft and noncleft patients. We also intended to determine whether a sufficient transverse skeletal effect could be achieved among cleft patients using the quadhelix appliance.
  
  
  METHODS
  Three finite element models of the viscerocranium and neurocranium were established in which a transverse expansion of the maxilla using a quadhelix (transverse force of 2 N) was simulated.
  
  
  RESULTS
  The skeletal effects at the anatomic structures of the midface and the cranial base were far more marked in the simulation models with clefts compared to the morphologically normal state. The highest expansions were measured for bilateral cleft palates. Thus, the expansion measured at the supraorbital margin was 4.7 mustrain with a bilateral cleft, 2.1 mustrain with a unilateral cleft, and only 0.2 mustrain with the morphologically normal state. For bilateral and also for unilateral bone clefts, the skeletal effect of a maxillary low force expansion with a quadhelix on the anatomical structures of the viscerocranium and neurocranium is very much larger than is the case for individuals without clefts.
  
  
  CONCLUSIONS
  In the presence of a continuous cleft in the jaw and palate area, orthodontic forces (quadhelix) are apparently already sufficient to allow a skeletal expansion of the maxilla. Maxillary expansion using the quadhelix appliance represents a reasonable alternative to using conventional rapid maxillary expansion appliances among cleft patients.
authors.affiliation: Department of Orthodontics, University of Munich, Germany. christof.holberg@med.uni-muenchen
authors.forename: Christof
authors.initials: C
authors.lastname: Holberg
authors.forename: Nikola
authors.initials: N
authors.lastname: Holberg
authors.forename: Katja
authors.initials: K
authors.lastname: Schwenzer
authors.forename: Andrea
authors.initials: A
authors.lastname: Wichelhaus
authors.forename: Ingrid
authors.initials: I
authors.lastname: Rudzki-Janson
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002508:Cephalometry; D002972:Cleft Palate / Q000628:therapy*; D005147:Facial Bones / Q000033:anatomy & histology*; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009967:Orthodontic Appliances; D010155:Palatal Expansion Technique / Q000295:instrumentation*