Many new species have been isolated from subgingival periodontal pockets, for example Wolinella recta and Bacteroides forsythus, reflecting better basic microbiological techniques. Other species were created from existing species as a result of better characterization methods, i.e. Bacteroides buccae and Bacteroides oris. We can recognize different types of periodontal disease and can find differences relating to the progressive compared to inactive lesions. Data illustrated in this presentation suggest that potential pathogens within new species include B. forsythus, W. recta and quite probably Selenomonas noxia. Methods that are rapid and sensitive for these new species include the use of protein profiles determined using SDS-PAGE, and DNA probes.