Permeability of the gingival tissues to IgM during an experimental gingivitis study in man

Changes in the permeability of the underlying vasculature of the gingival crevice region may occur either as part of an inflammatory response during gingivitis or as a response to trauma during collection of gingival crevicular fluid. IgM was selected as a marker of permeability and the concentration in gingival crevicular fluid was determined immunochemically by dot blotting, using rabbit antihuman IgM specific for μ chain. Gingival crevicular fluid samples were derived from experimental (non-cleaning) and control (cleaning) sites in six individuals participating in a 28-day experimental gingivitis study using a split-mouth protocol. The fluid was collected by a filter-paper method. At each site, four gingival crevicular fluid samples were collected for 5 s each over a 3-min period and a fifth sample was collected after a further 6 min. IgM was detected in 7/30 experimental strips at baseline (after intensive professional prophylaxis) and this increased to 21/30 by 24 days: control values were 13/30 and 12/30, respectively. The data indicate that IgM was detected with greater frequency as gingivitis becomes evident, suggesting increased permeability in response to plaque accumulation. IgM was detected in 17/120 of the first strip samples, collected over the 66-day study period, whereas in the fifth strip samples IgM was detected in 68/120, and the concentration of IgM-in gingival crevicular fluid also increased, indicating that sequential collection induced permeability. It is concluded that the permeability of the gingiva changes in response to both an inflammatory stimulus and trauma due to collection.