title: Ameliorative effect of quercetin on the destruction caused by experimental periodontitis in rats.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of quercetin, a flavonol that exhibits anti-inflammatory properties, on experimental periodontal destruction in rats.
  
  
  METHODS
  Osteoclast formation on maxillary palatal alveolus was induced with daily lipopolysaccharide (LPS) injections (0, 1 or 5 mg/mL) for 3 d. Five days later, the osteoclasts on bony surfaces were counted after histochemical staining for tartrate-resistant acid phosphatase. The effect of intragastric quercetin on the osteoclast formation was evaluated in the following three groups: quercetin (75 mg/kg/d by oral feeding); LPS (5 mg/mL); and quercetin plus LPS. Moreover, the effect of quercetin on the ligature-induced periodontitis around maxillary second and mandibular first molars was further evaluated by microcomputerized tomography (on days 0, 4, 8 and 12) and by histometry (on day 8).
  
  
  RESULTS
  A dose-dependent increase in osteoclasts occurred after LPS injections. However, quercetin (75 mg/kg) reduced the 5 mg/mL LPS-induced osteoclasts. Using microcomputerized tomography, the bone crest levels at ligation sites were found to be significantly more apical than at the control sites on days 8 and 12; however, the apically located bone crests rebounded in rats from the quercetin-plus-ligation group. Histometry demonstrated significantly more coronal alveolar crest bone levels, less inflammatory cell-infiltrated connective tissue areas and less connective tissue attachments in the ligation-plus-quercetin group compared with those in the ligation group.
  
  
  CONCLUSIONS
  As the quercetin could reduce the LPS-induced osteoclast formation and the ligature-enhanced periodontal inflammation and bone loss, we suggest that it may have an ameliorative effect on periodontal destruction.
authors.affiliation: Department of Periodontology, School of Dentistry, National Defense Medical Center and Tri-Service General Hospital, Taipei, Taiwan.
authors.forename: W-C
authors.initials: WC
authors.lastname: Cheng
authors.forename: R-Y
authors.initials: RY
authors.lastname: Huang
authors.forename: C-Y
authors.initials: CY
authors.lastname: Chiang
authors.forename: J-K
authors.initials: JK
authors.lastname: Chen
authors.forename: C-H
authors.initials: CH
authors.lastname: Liu
authors.forename: C-L
authors.initials: CL
authors.lastname: Chu
authors.forename: E
authors.initials: E
authors.lastname: Fu
mesh_terms: D000284:Administration, Oral; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000188:drug therapy*; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D008026:Ligation; D008070:Lipopolysaccharides; D008297:Male; D010010:Osteoclasts / Q000187:drug effects; D010518:Periodontitis / Q000188:drug therapy*; D011794:Quercetin / Q000008:administration & dosage / Q000627:therapeutic use*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D055114:X-Ray Microtomography
chemical_list: D000975:Antioxidants; D008070:Lipopolysaccharides; D011794:Quercetin