title: Laser-induced alveolar bone changes during orthodontic movement: a histological study on rodents.
abstract: OBJECTIVE
  The aim of this study was to assess by light microscopy changes in alveolar bone during orthodontic movement in rats.
  
  
  BACKGROUND
  Orthodontic movement causes both removal and deposition of bone tissue. The use of laser phototherapy (LPT) is considered an enhancement factor for bone repair.
  
  
  METHODS
  Thirty Wistar rats were divided into two groups (n = 15) and subdivided according to animal death (7,13, and 19 days). Half of the animals in each group were treated with LPT during orthodontic movement. After animal death, specimens were processed and underwent histological and semi-quantitative analyses (HE and Sirius red).
  
  
  RESULTS
  LPT-irradiated specimens showed significantly higher numbers of osteoclasts when compared with controls at both 7 (p = 0.015) and 19 (p = 0.007) days, as well as significant increases in the number of osteoblasts (p = 0.015) between days 7 and 13. The amount of collagen matrix was significantly reduced between days 7 and 13 at both pressure and tension sites in controls (p = 0.015) but not in LPT-treated animals. LPT-treated subjects showed significantly greater deposition of collagen matrix at the pressure site at both the thirteenth (p = 0.007) and nineteenth days (p = 0.001). At the tension site, a significant increase in the amount of collagen matrix was observed in non-irradiated specimens (p = 0.048) between days 7 and 19.
  
  
  CONCLUSIONS
  LPT caused significant histological changes in the alveolar bone during induced tooth movement, including alterations in the number of both osteoclasts and osteoblasts and in collagen deposition in both pressure and tension areas.
authors.affiliation: Centro de Ortodontia e Ortopedia Facial Prof. José Edimo Soares Martins, School of Dentistry, Federal University of Bahia (UFBA), Salvador, Brazil.
authors.forename: Fernando A L
authors.initials: FA
authors.lastname: Habib
authors.forename: Sabrina K C
authors.initials: SK
authors.lastname: Gama
authors.forename: Luciana M P
authors.initials: LM
authors.lastname: Ramalho
authors.forename: Maria Cristina T
authors.initials: MC
authors.lastname: Cangussú
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Santos Neto
authors.forename: Juliana A
authors.initials: JA
authors.lastname: Lacerda
authors.forename: Telma M
authors.initials: TM
authors.lastname: Araújo
authors.forename: Antônio L B
authors.initials: AL
authors.lastname: Pinheiro
mesh_terms: D000539:Alveolar Process / Q000166:cytology* / Q000528:radiation effects*; D000818:Animals; D002452:Cell Count; D003094:Collagen / Q000528:radiation effects; D028022:Low-Level Light Therapy; D008853:Microscopy; D010010:Osteoclasts / Q000166:cytology; D051381:Rats; D017208:Rats, Wistar; D014087:Tooth Movement Techniques
chemical_list: D003094:Collagen