title: Histomorphometric study of the periodontal ligament in the initial period of orthodontic movement in Wistar rats with induced allergic asthma.
abstract: BACKGROUND
  Asthma is a common systemic disease occurring in infancy and adolescence, time periods that could encompass orthodontic treatment. Asthma is an inflammatory disease; therefore, it might interfere with orthodontic tooth movement. The purpose of the study was to analyze the histomorphologic aspects of the periodontal ligament of asthmatic Wistar rats in the initial period of orthodontic movement.
  
  
  METHODS
  Thirty-two Wistar rats were divided into 4 groups: 2 control groups consisting of rats without induced allergic asthma, and 2 experimental groups consisting of rats with induced allergic asthma. The animals of the first control and experimental groups did not receive orthodontic forces, whereas those in the second control and experimental groups were subjected to mesial movement of the maxillary left first molar for 3 days. The samples were prepared for histomorphometric analysis of the periodontal ligament. The area of the periodontal ligament was calculated as a function of root length in the cervical and apical regions of the distal face of the maxillary first molar mesial root. The Student t test and the Welch correlation test were applied to the data obtained.
  
  
  RESULTS
  There was a statistically significant difference (P <0.05) between the control and experimental groups. An enhanced response to orthodontic force was observed in the asthmatic animals: the periodontal ligament was more compressed at the pressure area and more stretched in the traction area.
  
  
  CONCLUSIONS
  Our findings indicate that experimental allergic asthma seems to exacerbate orthodontic movement in rats.
authors.affiliation: Department of Orthodontics, School of Dentistry, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Cristiane Correia Pereira
authors.initials: CC
authors.lastname: Machado
authors.forename: Matilde da Cunha Gonçalves
authors.initials: Mda C
authors.lastname: Nojima
authors.forename: Patrícia Machado
authors.initials: PM
authors.lastname: Rodrigues e Silva
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Mandarim-de-Lacerda
mesh_terms: D000818:Animals; D001249:Asthma / Q000276:immunology / Q000473:pathology*; D001696:Biomechanical Phenomena; D001980:Bronchi / Q000473:pathology; D019245:Compressive Strength; D003799:Dental Stress Analysis; D007958:Leukocyte Count; D008963:Molar; D010513:Periodontal Ligament / Q000033:anatomy & histology*; D051381:Rats; D017208:Rats, Wistar; D013718:Tensile Strength; D014087:Tooth Movement Techniques; D014092:Tooth Root / Q000033:anatomy & histology