Observations on the structural changes according to aging of oral mucous membrane in the elderly--structure of buccal mucous membrane in the vicinity of angulus oris

The purpose of this research was to clarify the structural changes according to the aging of the buccal mucous membrane in the elderly. Thirty-eight Japanese adult cadavers (62-98 years) which dental students had used for anatomy practice were used as materials. Serial sections were made from the specimens of the buccal mucous membrane in the vicinity of angulus oris removed from the cadavers, and the sections were observed with a light microscope. The results were as follows: 1) As for the buccal mucous membrane in the vicinity of angulus oris in the elderly, the thickness decreases significantly with aging. 2) In the buccal mucous membranes of the elderly, the functional arrangement of the collagenous and elastic fibers distributed in the lamina propria and the submucous membrane disappears with aging, and the fibrosis tendency generally becomes remarkable. 3) The number of blood vessels distributed in the mucous membrane in the vicinity of angulus oris of the elderly decreases with aging, and the distribution of blood vessels changes, too. It seems that these changes suppress the circulatory system of the buccal mucous membrane in the very elderly. 4) The fatty change and the fibrosis of the small salivary gland progress among the very elderly. It seems that the structural change of such a glandular tissue causes dryness in the mouth. 5) The change in the thickness of the tunica muscularis according to aging was hardly seen among the elderly. However, the tendency toward thinness with aging was seen, as for the muscular fiber. The structural change of such a muscular fiber seems to cause depression such as that of the orbicular muscle of the mouth in the elderly.