Abstract The present study describes periodontal conditions in 22 adolescents with proximal attachment loss 2 mm (AL) and 22 matched referents without AL, all identified in a cross?sectional study of 570 16- and 18-year-olds. The cases were followed for 3 years and the referents for 1 year while they were in the care of an organized dental health system. With the exception of 1 case with Morbus Hodgkin, the case and referent groups had a similar background with respect to general health and participation in the dental health program. Bleeding on probing was found at AL sites in 12 of the cases and at corresponding sites in 4 referents. 2 cases had a history of eruption disorders at the AL sites, 1 case had experienced a defective filling and 1 had a root fissure at the AL sites. At reexaminations after 1 and 3 years, 10 out of 21 earlier identified AL cases did not meet the criterion of 1 or more sites with AL 2 mm. None of the cases showed progression 2 mm of the lesions. In 1 case, the number of AL sites increased during the period. 4 of the cases harboured Actinobacillus actinomycetemcomitans (A.a.) at AL sites in year 1 and 3 in year 3. 8 of the cases and 4 referents had antibodies specific for A.a.-leukotoxin. The 2 most severe cases, in terms of number of sites with AL, showed bleeding at 1 or more of the AL sites, harboured A.a. at these sites and had serum titers against A.a.-leukotoxin.
