title: Second molar impaction associated with lip bumper therapy.
abstract: BACKGROUND
  Although lip bumpers (LBs) provide significant clinical gain of mandibular arch perimeter in mixed-dentition patients, orthodontists are reluctant to use them due to the possibility of permanent second molar eruptive disturbances.
  
  
  OBJECTIVE
  The present study was conducted to assess second molar impaction associated with the use of LBs, and to investigate how they can be solved.
  
  
  METHODS
  Lateral and panoramic radiographs of 67 patients (34 females and 33 males) were assessed prior (T₁) and post-LB treatment (T₂). LB therapy lasted for approximately 1.8 ± 0.9 years. Concomitant rapid palatal expansion (RPE) was performed in the maxilla at LB treatment onset. Impaction of mandibular second molars was assessed by means of panoramic radiographs in relation to the position of first mandibular molars. Horizontal and vertical movements of first and second molars were assessed cephalometrically on lateral cephalometric radiographs based on mandibular superimpositions.
  
  
  RESULTS
  Eight (11.9%) patients had impacted second molars at the end of LB therapy. Two patients required surgical correction, whereas five required spacers and one patient was self-corrected. Mandibular first molar tip and apex migrated forward 1.3 mm and 2.3 mm, respectively. Second molar tip showed no statistically significant horizontal movement.
  
  
  CONCLUSIONS
  Although LB therapy increased the risk of second molar impaction, impactions were, in most instances, easily solved.
authors: Texas A&M University Baylor College of Dentistry.
authors: Helder Baldi
authors: HB
authors: Jacob
authors: Texas A&M University Baylor College of Dentistry.
authors: Shawn
authors: S
authors: LeMert
authors: Department of Orthodontics, Texas A&M University Baylor College of Dentistry.
authors: Richard G
authors: RG
authors: Alexander
authors: Texas A&M University Baylor College of Dentistry.
authors: Peter H
authors: PH
authors: Buschang
mesh_terms: D002508:Cephalometry / Q000379:methods; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007180:Incisor / Q000473:pathology; D008137:Longitudinal Studies; D008297:Male; D008334:Mandible / Q000473:pathology; D008963:Molar / Q000473:pathology*; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances / Q000009:adverse effects*; D010155:Palatal Expansion Technique / Q000295:instrumentation; D011862:Radiography, Panoramic; D012189:Retrospective Studies; D014078:Tooth Eruption / Q000502:physiology; D014087:Tooth Movement Techniques / Q000295:instrumentation; D014095:Tooth, Impacted / Q000209:etiology*
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