Darkfield microscopic spirochete count in the differentiation of endodontic and periodontal abscesses.

A previous experimental study indicated that a darkfield microscopic spirochete count of 0 to 10% was indicative of a lesion entirely of endodontic origin and a count between 30 and 58% suggested a purely periodontal lesion. Two clinical cases are described where the differentiation of an endodontic lesion from a periodontal lesion was difficult and the traditional diagnostic indicators either could not be used or gave conflicting results. In these cases the percentage of spirochetes in the exudates of the lesions was used as an aid to diagnosis with successful treatment results.