Juvenile periodontitis. Some microbiological, histopathological and clinical characteristics.

The microflora of periodontal pockets and some histopathological characteristics of adjacent tissues from individuals with clinical signs of juvenile periodontitis were studied. Adult individuals with ordinary, rapidly advancing periodontitis served as controls. All of the patients had been referred for specialist treatment. Using criteria defined by Baer (19z1), the patients were assigned to one juvenile periodontitis (eight patients), one post-juvenile periodontitis (seven patients) and one adult periodontitis group (seven patients). Only lesions around the first molars and central incisors were studied. Bacterial samples were obtained from each site and were examined by darkfield microscopy and different morphological forms identified. The soft tissue of the diseased sites was excised. The biopsies were placed in a fixative, cut in 1-mm-thick blocks and embedded in Epon. In semithin sections the infiltrated connective tissue (ICT) was identified and the ICT portion further processed for electron microscopy. The numeric and volumetric densities of different cells and structures of the ICT were determined using a morphometric point-counting procedure. The results showed that juvenile periodontitis lesions are associated with a subgingival microflora, the composition of which is different from that of adult periodontitis. Thus, in patients belonging to the adult periodontitis and post-juvenile periodontitis groups, motile microorganisms dominated the subgingival plaque samples, whereas deep pockets in juvenile periodontitis lesions contained a flora dominated by coccoid cells and straight non-motile rods. The most pronounced difference in the composition of ICT between the juvenile on one hand and the post-juvenile and adult periodontitis lesions on the other, was related to the amount of extracellular structures. Thus, in post-juvenile and adult periodontitis lesions, collagen and residual tissue made up around 50% of the infiltrate. In the juvenile periodontitis lesions, however, extracellular structures occupied only around 20% of the volume. In the ICT of the juvenile periodontitis sites, around 70% of the volume was occupied by plasma cells and blast cells. The corresponding figures for the post-juvenile and adult periodontitis sites were 50 and 30%.