In the present investigation an attempt was made to follow the sequence of events occurring in the gingival tissues of dogs reacting to the reaccumulation of microbial plaque. The experiment was performed on 5 young dogs which twice a day during a preparatory period of 5-6 months had been treated with a 2% chlorhe.xidine mouthrinse. When the eruption of the permanent teeth was in a final phase a clinical examination (Plaque Index, Gingival Index, Gingival exudate measurements) was performed, biopsies sampled from predetermined tooth regions and the chlorhexidine regimen terminated. On days 1, 3, 5, 7, 14, and 28 the clinical examinations were repeated and biopsies of buccal gingival tissues taken from incisors, canines, and premolars. The gingival tissues were subjected to a stereologic analysis based on morphometric point counting procedures. On day zero small amounts of plaque were detected on most teeth. Following the termination of the chlorhexidine regimen plaque accumulation as well as gingival exudation increased. The morphometric data revealed that (I) all biopsies contained a small portion of ICT (infiltrated connective,tissue) which did not increase in size with time (2) the cellular composition of ICT fluctuated but did not change its general pattern with time (3) immunoblasts were rarely seen but an unusual lymphoid cell (X-lymphocyte) was regularly present in ICT. The possibility was discussed that chlorhexidine not only interferes with plaque formation but also may suppress some aspects of the inflammatory and immunopathologic response of the gingiva.

SUMMARY Stereologic point counting procedures were applied to estimate volumetric and numerical densities of tissue components residing in and forming a defined, simplified model of human marginal gingiva. This included the quantitative characterization of inflammatory cell infiltrates occurring in the epithelial as well as the connective tissue fractions of this model. The gingival tissue was harvested from defined intraoral sites of 9–15 year‐old children and processed under standardized conditions for light and electron microscopic observation. Random cross‐sections of this tissue were subjected to morphometric analysis based on a multistage sampling technique. At each sampling level, tests were performed to study (1) the suitability of different test systems, (2) the parameter variation within one and between different biopsies and (3) the comparability and reliability of the data obtained. Based on these tests, a morphometric technique was designed which resulted in an accurate estimation of the various parameters characterizing the model tissue. These parameters were the volumetric densities of the following constituents: oral epithelium, junctional epithelium and its leucocyte content, infiltrated and non‐infiltrated connective tissue, and its respective collagen fibre content. Infiltrated and non‐infiltrated connective tissue fractions were analysed for their respective volumetric and numerical densities of fibroblasts, neutrophilic granulocytes, monocytes, macrophages, small and medium‐sized lymphocytes, immunoblasts, plasma cells and mast cells. Sampling technique, test procedures and the design and results of the morphometric system are discussed.

SUMMARY Stereologic point‐counting procedures were applied to estimate quantitative tissue and cytoplasm parameters of the oral and the junctional epithelium of the human gingiva. Three gingival biopsies of female children, obtained and processed under standardized conditions, served (1) to determine the minimal sample size of cytoplasmic area required for estimating representative volumetric parameters in different strata of both epithelia, and (2) to compare average volume and surface density data derived from standardized samples in epithelial cross sections cut at two planes orientated perpendicular to each other. Sampling of electron micrographs, performed at two levels of magnifications according to a systematic stratified random sampling procedure consisted of recording field strips parallel to the epithelial or tooth surface within each of the various strata. The optimal sample size required varied for different organelles and epithelial strata. Minimal sample size of cytoplasmic area per biopsy were 300–440 μm2 for basal, and 450 μm2 for stratum spinosum cells of oral epithelium, and 130–185 μm2 for basal cells of the junctional epithelium. Average morphometric parameters for gross tissue components (cells, nuclei, cytoplasm, intercellular space) which resulted from analysing 4900 μm2 tissue area in each of the epithelia in each biopsy, were almost identical when determined in two different section planes. Volume and surface density data of cytoplasmic organelles (mitochondria, rough and smooth endoplasmic reticulum, cytoplasmic filaments) resulting from a sample of 280 μm2 cytoplasmic area per stratum and biopsy, revealed differences of varying magnitude, when determined in the two section planes. These differences were markedly smaller than those between comparable strata of both epithelia. Discussion of sampling procedures concluded that the type of sampling used for the present study is suitable for comparative morphometric studies.