title: Effects of facial tooth movement on the periodontium in rats: a comparison between conventional and low force.
abstract: BACKGROUND
  Bone dehiscences and gingival recession have been associated with orthodontic arch expansion. The aim of this study was to assess and compare periodontal modelling during application of two force levels.
  
  
  METHODS
  The second and third upper molars were orthodontically moved buccally with conventional or low forces for 60 or 90 days in 32 rats. Ten non-treated animals were used as controls. The influence of force level and time on dental, skeletal and periodontal parameters (i.e. height and thickness of gingiva and bone) was assessed on histomicrographs using a mixed linear model.
  
  
  RESULTS
  Facial tooth position (725 μm, CI 379-1072 μm, distal root of the third molar) and maxillary skeletal width (295 μm, CI 168-421 μm) differed significantly between force groups. Despite bone apposition at the facial aspects of the moved roots, bone dehiscences were developing and bone thickness was decreasing during facial tooth movement. Development of gingival recession was scarce and in cases with extreme facial tooth movement. No remarkable differences between force levels were found for any of the periodontal parameters.
  
  
  CONCLUSIONS
  Facial tooth movement with conventional or low forces resulted in similar modelling of facial alveolar bone and gingiva.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Bern, Switzerland.|Department of Dentistry, Aarhus University, Aarhus, Denmark.
authors.forename: Jan C
authors.initials: JC
authors.lastname: Danz
authors.affiliation: Department of Public Health, Institute of Biostatistics, Aarhus University, Aarhus, Denmark.
authors.forename: Bo M
authors.initials: BM
authors.lastname: Bibby
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, University of Bern, Bern, Switzerland.
authors.forename: Christos
authors.initials: C
authors.lastname: Katsaros
authors.affiliation: Department of Periodontology and Community Dentistry, Faculty of Odontology, Malmö University, Malmö, Sweden.
authors.forename: Andreas
authors.identifier: http://orcid.org/0000-0001-8161-3754
authors.initials: A
authors.lastname: Stavropoulos
mesh_terms: D000818:Animals; D005881:Gingiva; D005889:Gingival Recession; D010513:Periodontal Ligament; D010519:Periodontium; D051381:Rats; D014087:Tooth Movement Techniques
keywords: animal; bone dehiscence; force level; gingival recession; orthodontics; tooth movement