title: Analysis of daytime variations in gingival crevicular fluid: a circadian periodicity?
abstract: BACKGROUND
  Volumetric alterations in gingival crevicular fluid (GCF) are widely accepted to be associated with periodontal health/disease. The volume/flow of GCF was shown to be affected by an array of methodological factors. However, relatively limited information is available on whether GCF is subject to circadian rhythm. The main aim of the present study is to assess the possible presence/absence of GCF circadian rhythm. The impact of the sampling technique on daytime volumetric variations is also analyzed.
  
  
  METHODS
  The possible daily volumetric variations of GCF with 2-hour intervals (from 08:00 to 18:00 hours) were assessed in 100 tooth sites and 600 GCF samples. Only maxillary incisors were included to eliminate any potential volumetric differences due to tooth dimensions. To analyze the potential impact of sampling technique on GCF volume and daytime variations, at one site modified intracrevicular sampling technique (MIST) was used, whereas the contralateral site was sampled with a deep intracrevicular sampling technique (DIST). Clinical periodontal parameters of the GCF sites were also recorded.
  
  
  RESULTS
  No significant daily variations in GCF volume could be detected. Higher volumetric measures were observed in inflamed subgroups compared with healthy subgroups (P <0.05). MIST was equivalent to DIST with regard to mean GCF volumes and the possible daytime volumetric alterations.
  
  
  CONCLUSIONS
  Within the limits of the present study, it can be suggested that daytime variations did not have significant impact on GCF volume. The sampling methodology had no apparent impact on the circadian periodicity of GCF.
authors.affiliation: Department of Periodontology, Faculty of Dentistry, Hacettepe University, Ankara, Turkey.
authors.forename: Sevim
authors.initials: S
authors.lastname: Günday
authors.forename: Ali Orkun
authors.initials: AO
authors.lastname: Topcu
authors.forename: Esra
authors.initials: E
authors.lastname: Ercan
authors.forename: Nermin
authors.initials: N
authors.lastname: Yamalik
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005883:Gingival Crevicular Fluid / Q000378:metabolism*; D005891:Gingivitis / Q000145:classification / Q000378:metabolism; D006801:Humans; D007180:Incisor; D008297:Male; D008437:Maxilla; D008875:Middle Aged; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000145:classification / Q000378:metabolism; D013048:Specimen Handling / Q000379:methods; D013997:Time Factors; D055815:Young Adult