Analysis of factors that may affect the enzymatic profile of gingival crevicular fluid: sampling technique, sequential sampling and mode of data presentation.

To evaluate the possible effect of sampling technique and sequential sampling on gingival crevicular fluid (GCF) volume and myeloperoxidase (MPO) activity, 14 patients presenting at least two symmetrical maxillary sites with mild/moderate periodontitis were selected. Two sites in each individual were sequentially sampled using either the deep-intracrevicular or orifice technique. Spectrophotometrically determined MPO levels were presented either as total MPO activity or MPO concentration. Although the clinical periodontal status of the 20 sampling sites were similar, the deep-intracrevicular technique regularly provided larger GCF volumes. With both techniques, the last samples contained the highest GCF volume. During sequential orifice sampling, GCF volume was relatively more stable. In general, a depletion of MPO activity was observed with sequential sampling performed with either of the techniques. Depletion of MPO did not replenish to baseline levels at the end of the 10-min sequential sampling. Although MPO activity showed a general reduction during sequential orifice sampling with both modes of data presentation, total MPO activity and MPO concentration did not match with the deep-intracrevicular technique. Due to the potential of affecting GCF volume/composition, the selection of sampling technique seems to be a critical methodological decision in GCF-profile studies, primarily during sequential sampling. In GCF-profile studies, mode of data presentation should also be considered.