A histological study of experimental gingivitis in man

Experimental gingivitis was induced in 21 individuals. Oral hygiene was abolished on the buccal and interproximal tooth surfaces of one side of the mouth in the mandibular premolar and molar area. The other tooth surfaces served as controls and were subject to thorough oral hygiene measures. After 15–17 days, when clinically manifest gingivitis had developed in the non-cleansing side of the majority of the subjects, biopsies were obtained from that side as well as from the control side. Histological examination of tissue from the experimental side revealed inflammatory infiltrates largely confined to the connective tissue adjacent to the pocket epithelium. The cells were mainly medium-large and small lymphocytes, macrophages and fibroblasts. A few neutrophilic leukocytes were observed mostly inside the vessels and adjacent to and within the pocket epithelium. Immature and mature plasma cells were seen in the central regions of the connective tissue, but were scant or absent nearer to the pocket epithelium The distribution of the different types of mononuclear cells might be consistent with a transformation of lymphocytes into plasma cells.