A longitudinal study of Actinobacillus actinomycetemcomitans in army recruits

During recruiting examinations 201 recruits, 18-25 yr old, were examined for subgingival and extracrevicular Actinobacillus actinomycetemcomitans. The organism was isolated in 55 subjects, most often at low levels. Cluster analysis revealed 3 clusters with no (A, n = 86) or minor (B, n = 92) periodontal disease and low DMF-S, as well as established periodontitis, increased D + DF-S and high DMF-S (C, n = 22). When leaving the 12-months' service, 105 recruits were re-examined (54 cluster A, 41 cluster B, 9 cluster C subjects, 1 recruit who was not clustered). An increase of periodontal probing depth (PPD) of > or = 3 mm at 1 or more sites occurred in 33 subjects: 9 (17%) in cluster A, 16 (39%) in cluster B, 7 (78%) in cluster C and in the not-clustered recruit. Considerable variation in frequency distributions of PPD alterations was observed, therefore significant (p < 0.1) mean increase (1-sample t-test) and skew g1 (S-statistic) were additionally considered to define an "active" case. A total of 7 recruits (6.7%) met the criteria. Logistic regression analysis revealed a significant influence of self-reported smoking habits on activity status. Thus, heavy smokers (> 20 cigarettes/d) had a 14-fold higher risk (p = 0.030) for developing or progressing periodontitis compared to non- or light smokers (< 10 cigarettes/d). In particular, cluster B recruits appeared to have a lower risk (p = 0.11) for developing periodontitis than cluster C recruits (established periodontitis, high DMF-S). A. actinomycetemcomitans was isolated in 29 recruits (27.6%) at baseline and 30 recruits (28.6%) after 12 months. Presence of the organism was not a risk factor for periodontitis. However, in active subjects, significantly more samples were only A. actinomycetemcomitans-positive at re-examination compared to inactive recruits. It was concluded that smoking is a significant risk factor for periodontitis. Subjects with established periodontitis tend to deteriorate further. A. actinomycetemcomitans seems not to increase the risk for developing or progressing periodontitis in this age group. Longer studies involving larger populations are needed to confirm these observations.