Two years oral use of chlorhexidine in man

Possible changes in the structure of human oral mucosa resulting from exposure to chlorhexidine were examined in biopsy specimens of palatal and gingival mucosa obtained from three groups of young adults who had rinsed for more than 1 year (a) once or (b) twice daily with 0.2 % chlorhexidine solution or (c) with a placebo mouthwash. Specimens were quenched in liquid nitrogen and cryostat sectioned perpendicular to the epithelial surface. Sections stained with hematoxylin and eosin were used to assess the degree of keratinization of epithelia and to measure the width of the stratum corneum. Sections treated with buffered alkaline solutions were used to expand and count the number of layers of cells in the stratum corneum.
All specimens examined showed evidence of keratinization and, in keeping with previous reports, palatal specimens were more frequently orthokeratinized than gingival specimens. Mean width of the stratum corneum of gingival specimens was approximately 13 μ m and of palatal specimens, 23 μ m. The mean number of layers of cells in the stratum corneum of the gingiva was approximately 10 and of the palate, approximately 12. Differences in the degree of keratinization and thickness of the stratum corneum between gingival and palatal specimens was statistically significant, but no statistically significant differences were found between the chlorhexidine-exposed and non-chlorhexidine-exposed palatal tissue in keratinization, layers of cells or thickness of the stratum corneum. Neither was there any statistical difference in the same parameters for the gingival specimens. The methods employed did not therefore detect any changes in the normal structure of keratinizing oral epithelia as a result of prolonged daily exposure to chlorhexidine.