title: Dental and skeletal effects of two-piece and three-piece surgically assisted rapid maxillary expansion with complete mobilization: a retrospective cohort study.
abstract: OBJECTIVE
  The aim of this study was to examine the dental and skeletal widening effects of 2 surgically assisted rapid maxillary expansion (SARME) techniques after complete mobilization of the maxilla in patients with transverse maxillary hypoplasia and bilateral crossbite.
  
  
  METHODS
  A retrospective cohort study design was implemented evaluating 2 treatment groups with complete Le Fort I osteotomy and segmentation of the maxilla followed by distraction using a tooth-borne expansion device: patients without crowding of the incisor roots underwent 2-piece SARME and patients with crowding underwent 3-piece SARME. Linear transverse measurements were performed on dental casts (intercanine and inter-second molar distance) and posteroanterior cephalograms (skeletal jugulum distance) before surgery (T1) and at 6 weeks (T2), 6 months (T3), and 12 months (T4) postoperatively.
  
  
  RESULTS
  The study included 24 patients (13 women and 11 men; mean age, 27 yr; standard deviation, 18.5 yr). Significant maxillary expansion was achieved by the 2 surgical techniques (P < .05), especially in the posterior portion. From T1 to T2, widening values (+3.8 mm) at the intercanine level in the 2-piece SARME group were significantly higher (P = .004) than those in the 3-piece SARME group. Distraction effects were mainly skeletal, whereas dental relapse tendencies predominated at T3 and T4.
  
  
  CONCLUSIONS
  The 2 SARME methods ensured sufficient widening with satisfactory results after a 12-month period. To decrease surgical risks to the incisor roots and esthetic impairments, 3-piece SARME with complete mobilization is recommended in cases of transverse posterior maxillary hypoplasia and crowding of the incisor roots.
authors.affiliation: Orthodontist, Private Practice, Weilheim, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Habersack
authors.affiliation: Orthodontist, Private Practice, Weilheim, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Becker
authors.affiliation: Resident, Department of Oral Maxillofacial Surgery, Paracelsus Hospital Munich, Munich, Germany. Electronic address: ristow@aesthetik-muenchen.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Ristow
authors.affiliation: Department Head, Department of Oral Maxillofacial Surgery, Paracelsus Hospital Munich, Munich, Germany.
authors.forename: Gerhard W
authors.initials: GW
authors.lastname: Paulus
mesh_terms: D000328:Adult; D001842:Bone and Bones; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010155:Palatal Expansion Technique; D012189:Retrospective Studies; D014070:Tooth; D055815:Young Adult