MOLECULAR EPIDEMIOLOGY OF ORAL TREPONEMES ASSOCIATED WITH PERIODONTAL-DISEASE

Periodontitis, a disease responsible for tooth loss worldwide, is char acterized by chronic inflammation of the periodontium, eventually lead ing to destruction of periodontal ligaments and supporting alveolar bo ne. Spirochetes, identified by dark-field microscopy as being the most predominant bacteria in advanced lesions, are thought to play a causa tive role. Various spirochetal morphotypes were observed, but most of these morphotypes are as yet uncultivable. To assess the role of these organisms we designed oligonucleotide probes for the identification o f both cultivable and so far uncultivable spirochetes in periodontitis patients, Subgingival plaque specimens taken from diseased sites (n = 200) and healthy control sites (n = 44) from 53 patients with rapidly progressive periodontitis (RPP) were submitted to direct in situ hybr idization or dot blot hybridization after prior amplification with eub acterial primers. Spirochetes were found in all patients, but their di stributions varied considerably. Parallel use of oligonucleotide probe s specific for cultivable or so far uncultivable treponemes suggested the presence of novel Set unknown organisms at a high frequency, These uncultivable treponemes were visualized by fluorescence in situ hybri dization, and their morphologies, sizes, and numbers could be estimate d. All RPP patients included in this study harbored oral treponemes th at represent either novel species, e.g., Treponema maltophilum, or unc ultivable phylotypes. Therefore, it is necessary to include these orga nisms in etiologic considerations and to strengthen efforts to cultiva te these as yet uncultivable treponemes.