Rapid maxillary expansion with palatal anchorage of the hyrax expansion screw - Pilot study with case presentation

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Winfried Harzer - , Orthodontic Clinic (Author)
  • Matthias Schneider - , Department of Oral and Maxillofacial Surgery (Author)
  • Tomasz Gedrange - , Department of Orthodontics (Author)

Abstract

Background: Rapid maxillary expansion (RME) with the appliance fixed at the crowns of the first premolars and molars leads not only to transversal expansion but also to tipping of the anchorage teeth and a risk of increased tooth mobility as well as of root and bone resorptions. These disadvantages were to be avoided by fixing the transversal screw directly to the hard palate. Material and Method: Following preliminary experimental work to determine the extent to which the hard palate could be loaded with orthodontic implants, two female patients were treated for extreme transverse maxillary deficiency using a Hyrax expansion screw fixed on one side with an implant with the following dimensions: length 4.0 mm, diameter 3.5 mm, abutment diameter 5.00 mm (EO implant, Straumann, Freiburg i. Br., Germany), and on the other side with a bone screw between the roots of the second premolars and the first molars. Presurgical osteotomy according to Glassmann was followed immediately by loading, i.e. by expansion through activation of the screw several times per day. Additional anterior guidance of the right and left maxilla was provided by crossed segmented archwires and a tension coil spring for space opening in the incisor region. After adequate expansion by 8.0 mm and correction of the position of the buccal teeth, the Hyrax expansion screw and the osteosynthesis screw were removed. The implant served as orthodontic anchorage for a molar-to-molar transpalatal bar aimed at preventing relapse. Results and Conclusions: The tooth axis inclination measured on cut sections of the plaster casts made at the beginning and end of treatment was largely without transversal discrepancies. Direct fixing of the transversal screw in the palatal arch prevents buccal tipping of the posterior teeth, especially in patients with a small apical base. Compared with other direct procedures involving osteosynthesis plates, this technique offers adequate guiding stability and is minimally invasive.

Details

Original languageEnglish
Pages (from-to)419-424
Number of pages6
JournalJournal of orofacial orthopedics
Volume65
Issue number5
Publication statusPublished - Sept 2004
Peer-reviewedYes

External IDs

PubMed 15378196

Keywords

ASJC Scopus subject areas

Keywords

  • Direct rapid maxillary expansion, Hyrax expansion screw, Orthodontic implants, Transverse deficiencies