Methodological considerations in the assessment of gingival crevicular fluid volume

In 4 studies on gingival crevicular fluid volume (GCFV) determination, the reliability of measurements, influences of plaque, circadian rhythms and st ability over 24 h were examined. Samples were taken at 2 sites with a modif ied intracrevicular method. Reliability (n=40): repeated GCFV determination s within 5 min revealed good reliablity coefficients (r(tt)>0.80). Influenc es of supragingival plaque (n=80): repeated GCFV determinations within 5 mi n with plaque removal between measurements in fourty subjects, the other su bjects serving as control, revealed no group differences with respect to th e differences between measurements. Circadian rhythms (n=20): GCFV was asse ssed 6x throughout the day. Repeated measures ANOVA revealed no significant time effect. Stability over 24 h under constant clinical conditions (n=20) : measures were taken at 16:00 h on 2 consecutive days, several disturbing variables were kept constant. Retest correlations revealed a low stability (i.e., high variablity) of GCFV measures under constant clinical conditions (r(tt)=0.38 for tooth 11 and r(tt)=-0.25 for tooth 26). It is concluded th at GCFV determination can be done with high reliability the validity of mea surements neither being affected by supragingival plaque nor by diurnal rhy thms. The low stability of measurements questions the validity of GCFV for diagnostic purposes.