title: A premolar extraction case using the Invisalign system.
abstract: BACKGROUND
  Invisalign therapy is an orthodontic treatment method using removable transparent polyurethane splints. Its applicability in extraction cases is limited. This case report documents the treatment with Invisalign of a patient in whom four premolars had to be extracted due to dental crowding.
  
  
  RESULTS
  The patient's primary objective was to undergo treatment to resolve her anterior crowding as esthetically inconspicuously as possible. Diagnostic findings were: constriction of the maxillary and mandibular arch with anterior dental crowding; proclination and anteposition of the anteriors; neutroclusion with an overjet of 6 mm and an overbite of 1 mm. The radiographs showed a mesial tilt of the lower canines and premolars and a mild skeletal Class II relationship with a vertical craniofacial configuration.
  Treatment was initiated by extracting the four first premolars and placing the attachments (Tetric Ceram composite). After the Invisalign aligners had been worn, the anterior segment was uprighted and retracted, the crowding resolved, and the arches well-aligned. The patient's neutroclusion was maintained, physiological anterior relations in the sagittal and vertical planes were achieved, and the lower canines and premolars were uprighted. Active treatment lasted 1 year and 8 1/2 months and involved 43 maxillary and 28 mandibular aligners.
  
  
  CONCLUSIONS
  Particularly in cases with an extended indication for this new treatment modality, due consideration must be given to the importance of comprehensive and meticulous diagnostics and treatment planning, and a solid grasp of the biological and mechanical fundamentals.
authors.affiliation: Eberhard-Karls-Universität Tübingen, Klinik für Zahn-, Mund- u. Kieferheilkunde, Abteilung für Kieferorthopädie, Osianderstr. 2-8, 72076 Tübingen, Germany. mirjam.hoenn@med.uni-tuebingen.de
authors.forename: Mirjam
authors.initials: M
authors.lastname: Hönn
authors.forename: Gernot
authors.initials: G
authors.lastname: Göz
mesh_terms: D000328:Adult; D001641:Bicuspid / Q000601:surgery*; D003131:Combined Modality Therapy; D004867:Equipment Design; D006801:Humans; D008310:Malocclusion / Q000628:therapy*; D009968:Orthodontic Appliances, Removable; D009971:Orthodontics, Corrective / Q000295:instrumentation*; D014081:Tooth Extraction; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D016896:Treatment Outcome