Darkfield microscopy as a diagnostic aid in differentiating exudates from endodontic and periodontal abscesses.

It was the purpose of this study to determine if a periodontal abscess could be differentiated from an endodontic abscess by the types and proportion of microorganisms found in the abscess exudate in darkfield microscopic examination. Dental abscesses with draining sinus tracts in 17 patients were studied. Eight of the abscesses were diagnosed clinically to be of endodontic origin and nine periodontal origin. When the occurrence of motile lads in endodontic and periodontal abscesses were Compared, the differences were not significantly different (mean, 12.1 __. 10.8% and 7.5 +_. 3.9%, l l lpectively). In abscesses diagnosed clinically as tedodontal, spirochaetes were the predominant cell (mean, 40.6 + 10.9%) with coccoid cells present in eignificantly lower numbers (mean, 19.7 __. 10.9%). In endodontic abscesses the reverse was true. CocImid ceils dominated (mean, 44.3 __. 19.7%) and only #lw spirochetes were present (mean, 5.6 4.7%). 1111e range of percentages for coccoid cells was 7 to 40% in periodontal abscesses and 24 to 84% in endodontic abscesses. The overlap of range of 25 to 40% limited the use of these organisms for diagnostic purposes. For the spirochetes, on the other hand, there was a distinct difference in the range of percentages in the two types of abscesses. In peri~lontal abscesses the occurrence of spirochetes tanged from 30 to 60%, whereas in endodontic abY s s e s the range was 0 to 10%. Thus, the perr of spirochetes as seen by darkfield microsCopy may be of value in the differential diagnosis of I~dodontal and endodontic abscesses.