Three-Dimensional Structure of Connective Tissue Papillae in the Human Gingiva

Three-dimensional structures of connective tissue papillae of the human gingiva were studied by scanning electron microscopy. Specimens were obtained from human cadavers fixed with 10% formaldehyde. The free gingiva, attached gingiva and alveolar mucosa were excised from the incisor, canine and molar regions. They were further fixed with 2.5% glutaraldehyde and treated with 2 N NaOH for 2 weeks at 20 ̊C to remove the epithelium followed by routine specimen preparation methods. Consequently, the connective tissue papillae were observed three-dimensionally and were classified into three types as follows. Type I was an elongated papilla with a pointed tip, which was usually observed in the free gingiva. Type II was a bud-like papilla whose tip was forked into several tips and usually found in the attached gingiva. Type III was a platelike papilla chiefly located in the alveolar mucosa. In general, pointed elongated papillae (type I) in the free gingiva reduced in height changing into type II papillae towards the attached gingiva, and eventually sparsely distributed changing into type III papillae. These findings were commonly observed both in the upper and lower jaws. Lots of small holes, measuring 10 to 30 μm in diameter, were observed at the incisor and canine regions. Functional significance and origin of the holes remain unknown.