title: In situ chlorhexidine substantivity on saliva and plaque-like biofilm: influence of circadian rhythm.
abstract: BACKGROUND
  The aim of the present study is to assess in situ substantivity of a single mouthrinse with 0.2% chlorhexidine (CHX) on saliva and on undisturbed de novo plaque-like biofilm (PL-biofilm), differentiating between two times of application: 1) CHX mouthrinse in the morning; and 2) CHX mouthrinse at night.
  
  
  METHODS
  The study participants were 10 healthy volunteers who wore an individualized splint with glass disks for 48 hours to boost the growth of PL-biofilm. Saliva samples were collected, and two disks were removed from each volunteer's splint at 8, 10, and 12 hours after performing a mouthrinse with 0.2% CHX at 7:00 am (M-0.2% CHX-diurnal) and 1:00 am (M-0.2% CHX-nocturnal). The saliva and plaque samples were analyzed by epifluorescence and confocal laser scanning microscopy, respectively, using a green fluorescent nucleic acid stain/propidium iodide staining.
  
  
  RESULTS
  With M-0.2% CHX-diurnal, the frequency of vital bacteria in saliva was significantly higher than in the PL-biofilm at 8, 10, and 12 hours after mouthrinse. After M-0.2% CHX-nocturnal, the frequency of vital bacteria in saliva was significantly lower than in the PL-biofilm at 8 hours and higher than in the PL-biofilm at 12 hours after mouthrinse.
  
  
  CONCLUSIONS
  These results support the more active physiologic dynamics of the salivary flora and the possible reservoir function associated with the structure of undisturbed de novo PL-biofilm.
authors: Oral Sciences Research Group, Department of Stomatology, School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain.
authors: Inmaculada
authors: I
authors: Tomás
authors: Lucia
authors: L
authors: García-Caballero
authors: Elena
authors: E
authors: López-Alvar
authors: Mercedes
authors: M
authors: Suárez-Cunqueiro
authors: Pedro
authors: P
authors: Diz
authors: Juan
authors: J
authors: Seoane
mesh_terms: D000328:Adult; D000891:Anti-Infective Agents, Local / Q000008:administration & dosage*; D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002710:Chlorhexidine / Q000008:administration & dosage*; D002940:Circadian Rhythm; D018592:Cross-Over Studies; D003773:Dental Plaque / Q000382:microbiology*; D004311:Double-Blind Method; D005260:Female; D005456:Fluorescent Dyes; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D050296:Microbial Viability / Q000187:drug effects; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009067:Mouthwashes / Q000008:administration & dosage*; D012463:Saliva / Q000187:drug effects / Q000382:microbiology*; D055815:Young Adult
chemical_list: D000891:Anti-Infective Agents, Local; D005456:Fluorescent Dyes; D009067:Mouthwashes; D002710:Chlorhexidine