title: [Comparison of sampling methods and their effects on alkaline phosphatase levels in gingival crevicular fluid].
abstract: OBJECTIVE
  To observe the change of alkaline phosphatase (ALP) after repeat sampling and compare the two sampling methods (orifice method and intra-pocket method).
  
  
  METHODS
  Gingival crevicular fluid (GCF) was sampled repeatedly by the interval of 20 minutes, with orifice and intra-pocket method respectively, and the levels of ALP in GCF were determined.
  
  
  RESULTS
  Mean levels of ALP per site and concentration of ALP are not statistically different between two samples after repeat sampling with-orifice method as well as intra-pocket method (P > 0.05). ALP levels (per site and per microliter) are much higher for intra-pocket method than orifice method (P < 0.001). From the viewpoint of the numbers of recovery sites after repeat sampling, though ALP levels at most sites can't entirely recover to their original levels with both method, intra-pocket method is still a little better than orifice method, and ALP levels per site is better than ALP concentration.
  
  
  CONCLUSIONS
  The interval of repeat sampling should be prolonged more than 20 minutes. It is better to determine the GCF-ALP with intra-pocket method and also the recommended pattern that express enzyme levels is total activity per site but not concentration.
authors.affiliation: School of Stomatology, Beijing Medical University, Beijing 100081.
authors.forename: L
authors.initials: L
authors.lastname: He
authors.forename: Y
authors.initials: Y
authors.lastname: Sha
authors.forename: C
authors.initials: C
authors.lastname: Cao
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000032:analysis*; D005260:Female; D005883:Gingival Crevicular Fluid / Q000737:chemistry*; D006801:Humans; D008297:Male; D013048:Specimen Handling
chemical_list: D000469:Alkaline Phosphatase