title: Nicotine effect on bone remodeling during orthodontic tooth movement: histological study in rats.
abstract: BACKGROUND
  Nicotine is harmful to angiogenesis, osteogenesis and synthesis of collagen.
  
  
  OBJECTIVE
  The aim of this study was to investigate the effect of nicotine on bone remodeling during orthodontic movement in rats.
  
  
  METHODS
  Eighty male Wistar rats were randomly divided into three groups: Group C (control), group CM (with orthodontic movement) and group NM (nicotine with orthodontic movement) groups. The animals comprising groups C and CM received 0.9% saline solution while group NM received nicotine solution (2 mg/kg). A nickel-titanium closed-coil spring was used to induce tooth movement. The animals were euthanized and tissue specimens were histologically processed. Blood vessels, Howship's lacunae and osteoclast-like cells present in the tension and compression areas of periodontal ligaments were quantified. The extent of bone formation was evaluated under polarized light, to determine the percentage of immature/mature collagen.
  
  
  RESULTS
  It was observed lower blood vessel densities in the NM group in comparison to the CM group, three (p < 0.001) and seven (p < 0.05) days after force application. Osteoclast-like cells and Howship's lacunae in the NM group presented lower levels of expression, in comparison to the CM group, with significant differences on day 7 (p < 0.05 for both variables) and day 14 (p < 0.05 for osteoclast-like cells and p < 0.01 for Howship's lacunae). The percentage of immature collagen was increased in the NM group in comparison to the CM group, with a statistically significant difference on day 3 (p < 0.05), day 7 (p < 0.001), day 14 (p < 0.001) and day 21 (p < 0.001).
  
  
  CONCLUSIONS
  Nicotine affects bone remodeling during orthodontic movement, reducing angiogenesis, osteoclast-like cells and Howship's lacunae, thereby delaying the collagen maturation process in new bone matrix.
authors.forename: Ricardo Lima
authors.initials: RL
authors.lastname: Shintcovsk
authors.forename: Luégya
authors.initials: L
authors.lastname: Knop
authors.forename: Orlando Motohiro
authors.initials: OM
authors.lastname: Tanaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maruo
mesh_terms: D000539:Alveolar Process / Q000098:blood supply / Q000187:drug effects*; D000818:Animals; D016723:Bone Remodeling / Q000187:drug effects*; D001862:Bone Resorption / Q000473:pathology; D003094:Collagen / Q000187:drug effects; D003722:Dental Alloys / Q000737:chemistry; D003739:Dental Cementum / Q000098:blood supply / Q000187:drug effects; D008297:Male; D008963:Molar / Q000098:blood supply / Q000187:drug effects; D018919:Neovascularization, Physiologic / Q000187:drug effects; D009532:Nickel / Q000737:chemistry; D009538:Nicotine / Q000494:pharmacology*; D009969:Orthodontic Wires; D010010:Osteoclasts / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects; D010513:Periodontal Ligament / Q000098:blood supply / Q000187:drug effects*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D014087:Tooth Movement Techniques / Q000295:instrumentation; D014092:Tooth Root / Q000098:blood supply / Q000187:drug effects
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009538:Nicotine; D009532:Nickel; D003094:Collagen; D014025:Titanium
keywords: Blood vessels; Bone formation; Bone resorption; Nicotine; Tooth movement