title: Changes in lower incisor irregularity during treatment with oral sleep apnea appliances.
abstract: OBJECTIVE
  The purpose of this study is to test the hypothesis that a flexible oral appliance without incisor coverage (OAFlex) increases the irregularity of the front teeth compared with a rigid appliance with incisor coverage (OARigid) in patients treated for obstructive sleep apnea (OSA).
  
  
  METHODS
  Nineteen patients (10 men) who had used OARigidand 22 patients (19 men) who had used OAFlexwith a median age of 61 years (IQR of 56 to 67 years) who had been treated during a median period of 2.9 years (IQR of 2.7 to 3.1 years) were included in the study. There was no difference in age (p = 0.601) or treatment time (p = 0.432) between the two appliance groups. The patients had clinical examinations, responded to a questionnaire, and had impressions taken for plaster casts. The irregularity of the front teeth was measured by Little's Index, where the combined linear displacement of all the front teeth is assessed. Changes between baseline and follow-up were compared between the two groups.
  
  
  RESULTS
  The OAFlexgroup increased the irregularity of their lower front teeth by 0.3 mm (p = 0.018), while the OARigidgroup had unchanged frontal irregularity (p = 0.717). The difference between the groups was significant (p = 0.035). There were no changes in the irregularity of the upper front teeth in either group. Patient satisfaction with treatment did not differ between the two appliances.
  
  
  CONCLUSIONS
  The present results support the hypothesis that a flexible OA without incisor coverage increases the irregularity of the lower front teeth compared with a rigid OA with incisor coverage.
authors.affiliation: Department of Odontology, Umeå University, SE-901 87, Umeå, Sweden.|Centrum för specialisttandvård, ortodonti, Folktandvården Skåne, SE-222 21, Lund, Sweden.
authors.forename: Niclas
authors.initials: N
authors.lastname: Norrhem
authors.affiliation: Department of Odontology, Umeå University, SE-901 87, Umeå, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Nemeczek
authors.affiliation: Department of Odontology, Umeå University, SE-901 87, Umeå, Sweden. marie.marklund@umu.se.
authors.forename: Marie
authors.identifier: http://orcid.org/0000-0003-0667-3698
authors.initials: M
authors.lastname: Marklund
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007180:Incisor / Q000503:physiopathology*; D008297:Male; D008310:Malocclusion / Q000209:etiology* / Q000503:physiopathology; D008875:Middle Aged; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000628:therapy*
keywords: Appliance design; Mandibular advancement devices; Oral appliances; Side effects