Scanning electron microscopy (SEM) of the subgingival plaque in HIV-serumpositive subjects

Introduction Periodontal diseases are part of the expected range of HIV associated oral conditions. The reviewed classification of oral lesions in HIV infection (EEC-CO-PRHIV, 1993) comprises among these (a) the linear gingival erythema, (b) the necrotizing gingivitis, (c) the necrotizing periodontitis plus (d) the chronic marginal gingivitis and adult periodontitis altered or exaggerated as a result of immunosuppression. The ethiologic periodontal microflora was studied by several Authors: the microbiology of HIV-associated gingivitis with bandshaped and/or punctate erythema is similar to that of conventional periodontitis and different from conventional gingivitis, with C. albicans isolated by culture in about 50% of sites (Murray 1988, 1989, 1991). However, no data exist on the ultrastructure of dental plaque in HIV-serumpositive patients. Patients and Methods We studied 20 teeth extracted for caries and/or periodontal reasons from 16 HIV-serumpositive patients in CDC stages II, III and IV. Four patients had a diagnosis of linear gingival erythema (LGE), seven patients had chronic periodontal disease (CP) with probing depth 4 to 8 mm and the other five ones showed no periodontal involvement (NoPI) - see Table for details. When feasible, biopsies were obtained from the gingival margin (pts: f-g-h-l-p). Immediately after extraction, the teeth and soft tissues were rinsed with saline, cold fixed at 4°C with 2.5% glutaraldheyde in phosphate buffer, dehydrated in graded ethanol, critically point dried, mounted on brass stubs and coated with sputtered gold. The observations were performed with a JEOL JSM 840A SEM. Results The morphology of dental plaques in the crevicular zones of periodontally sound teeth was similar to that previously described in non-HIV+ individuals. However, spec#2 showed intrasulcularly a colonizing front almost exclusively composed by short rods. In teeth from patients with chronic periodontal disease many subgingival sites were extensively colon¬ized by long and thick filamentous organisms, similar to Actinomyces and Bacterionema. A great number of corn-cob and test-tube brush bacterial associations were seen, but straight and curved rods were few or absent. Such an uncommon morphostructure of the middle and apical plaque zones may be explained by interference in periodontal colonization from antibacterial medications cronically assumed to control systemic infection by those CP patients. Several colonies of yeasts in blastoconidial and pseudohyphal forms were found on the root surfaces of teeth from three patients with linear gingival erythema, at the level of the gingival margin. Moreover, epithelial colonization by yeasts in the corresponding gingival tissues was evident. Microbiological (Murray,1988) and clinical (Winkler,1988) studies have previously related the yeast Candida albicans with bandshaped and/or punctate gingival erythema in HIV+ subjects. The present investigation clearly evidentiates by scanning electron microscopy the presence of yeasts located in the subgingival plaque and in the marginal gingiva of HIV+ subjects with linear gingival erythema. This finding furtherly supports the theory that yeasts could be the ethiologic organisms of the linear gingival erythema, hence explainable as a gingival erythematous candidiasis.