Flow cytometry as a new method to quantify the cellular content of human saliva and its relation to gingivitis

Abstract Background : Determining the cellular content of saliva by means of conventional microscopy chamber counting is a very time-consuming and operator-sensitive procedure. This study concentrated on the use of flow cytometry to examine the cellular content of saliva. Erythrocytes, leukocytes, epithelial cells and bacteria were quantified and the results were compared with caries experience and the presence of gingivitis. Methods : 258 uncentrifuged vortexed paraffin-stimulated saliva samples (112 males and 146 females) were analyzed with the UF-100® flow cytometer. Salivary reference values were established for erythrocyte, leukocyte, epithelial cell and bacterial count. Caries experience (DMF) and the presence of gingivitis were recorded. Results : Caries experience or caries risk could not be assessed with flow cytometry. However, salivary flow cytometry may be useful in determining an individual's risk for gingivitis: a significant increase in salivary leukocytes was observed in individuals with gingivitis. At a cut-off level of 10 3 leukocytes μl −1 saliva, a sensitivity of 76% and a specificity of 45% was obtained. Other analytes were not significantly different between individuals with and without gingivitis. Conclusion : Flow cytometry of paraffin-stimulated human saliva seems a promising diagnostic or predictive tool and further investigations of diseases of the oro-pharyngeal loge, such as tonsillitis and periodontitis, should be carried out in the future.