In this study, 11 permanent teeth and their associated soft tissues from an 11-year-old boy with PLS were examined. Plaque, cementum and periodontal tissues were examined by scanning (SEM) and transmission electron microscopy (TEM). Except for depressed lymphocyte transformation, there were no abnormal haematological data. Local findings included abnormally thin cementum, extensive destruction of the periodontal ligament were still attached to the root, and severe inflammation of the soft tissues. Few bacteria were found in any of the soft tissue layers. The apical border plaque was restricted to gram- cocci and rods. The features observed in this case of PLS may indicate primary defects of cementum or ligament attachment, or disruption of fibroblast and cementoblast function due to the rapid advance of the disease process. Lack of bacterial invasion in the pocket soft tissue casts doubt on its involvement in the present case of severe periodontitis. The restricted range of morphotypes observed suggests a limited range of associated organisms. Further research is required to clarify the rôle of the host response and to identify the organisms involved.

HCS periodontitis is associated with an unpredictable and uneven, rapid rate of periodontal destruction of unknown etiology. Further research is required to identify the role of the possible pathogenic factors involved.

Background: The aim of the present study was to evaluate temporal changes on oral health knowledge and attitudes among two populations of young Greek males (age 19-29 years) undergoing their military training. A secondary aim was to identify socioeconomic trends that may have influenced the above.

This study concerns the apical border (AB) plaque in relation to severe forms of periodontitis (SP), including juvenile, post‐juvenile, and rapidly progressing periodontitis. Twenty‐four (24) teeth from 16 patients with SP were examined by transmission electron microscopy (TEM). The AB was not discrete, with islands of bacteria in the so‐called plaque‐free zone (PFZ). Coronal to the AB the established plaque consisted of a layer of Gram‐positive cocci and ghost cells and a superficial layer mainly of Gram‐negative morphotypes, including cocci, rods, filaments, fusiforms, and spirochetes. The most apical apparently intact organisms in the PFZ were in bacterial islands or in isolation and were predominantly Gram‐negative cocci and rods, with ghost cells in abundance. Ruthenium red, alcian blue‐lanthanum nitrate, and safranin O were used to label matrix polyanionic macromolecules, and periodic acid (thiosemicarbazide) silver proteinate for intracellular polysaccharide (IPS). The matrix components were mainly fibrillar. Many intact bacteria exhibited extracellular polysaccharides or glycocalyces associated with their cell wall, and cytoplasmic IPS granules. The latter varied in distribution and were evident even in the most apically advanced intact microorganisms. The results indicate that IPS and some matrix features of the apical border plaque in severe periodontitis in certain aspects resemble those of sub‐contact area plaque on children's teeth, in health or associated with early chronic gingivitis, and with those in chronic adult periodontitis. They also suggest the establishment of acidic regions in the microniche at the bottom of the periodontal pocket in the various forms of periodontitis differing in rate of progression. It was concluded that there was a limited range of intact bacterial morphotypes in the apical border plaque in severe periodontitis, similar to those in chronic adult periodontitis. J Periodontol 1995;66:113–124.