Table 1.

Plaque samples for cultivation were collected from 58 of the students examined on the last day of the planned field study. Five samples were discarded due to overgrowth of bacteria and yeast. In 53 of the 58 plaque samples collected, A. actinomycetemcomitans could be detected and isolated in 12 (22.6%) of them. These 12 isolates were serotyped and examined for their leukotoxic activity.

Number	Aa Isolate	Serotype
1	Aa-3-K	f
2	Aa-4-K	f
3	Aa-6-K	c
4	Aa-11-K	a
5	Aa-17-K	f
6	Aa-23-K	c
7	Aa-25-K	c
8	Aa-29-K	a
9	Aa-30-K	a
10	Aa-38-K	c
11	Aa-51-K	a
12	Aa-52-K	a