Aggregatibacter actinomycetemcomitans and Its Relationship to Initiation of Localized Aggressive Periodontitis: Longitudinal Cohort Study of Initially Healthy Adolescents

Abstract

ABSTRACT Aggregatibacter actinomycetemcomitans is frequently associated with localized aggressive periodontitis (LAP); however, longitudinal cohort studies relating A. actinomycetemcomitans to initiation of LAP have not been reported. A periodontal assessment was performed on 1,075 primarily African-American and Hispanic schoolchildren, ages 11 to 17 years. Samples were taken from each child for A. actinomycetemcomitans . A cohort of 96 students was established that included a test group of 38 A. actinomycetemcomitans -positive students (36 periodontally healthy and 2 with periodontal pockets) and 58 healthy A. actinomycetemcomitans -negative controls. All clinical and microbiological procedures were repeated at 6-month intervals. Bitewing radiographs were taken annually for definitive diagnosis of LAP. At the initial examination, clinical probing attachment measurements indicated that 1.2% of students had LAP, while 13.7% carried A. actinomycetemcomitans , including 16.7% of African-American and 11% of Hispanic students ( P = 0.001, chi-square test). A. actinomycetemcomitans serotypes a, b, and c were equally distributed among African-Americans; Hispanic students harbored predominantly serotype c ( P = 0.05, chi-square test). In the longitudinal phase, survival analysis was performed to determine whether A. actinomycetemcomitans -positive as compared to A. actinomycetemcomitans -negative students remained healthy (“survived”) or progressed to disease with attachment loss of >2 mm or bone loss (failed to “survive”). Students without A. actinomycetemcomitans at baseline had a significantly greater chance to remain healthy (survive) compared to the A. actinomycetemcomitans -positive test group ( P = 0.0001). Eight of 38 A. actinomycetemcomitans -positive and none of 58 A. actinomycetemcomitans -negative students showed bone loss ( P = 0.01). A. actinomycetemcomitans serotype did not appear to influence survival. These findings suggest that detection of A. actinomycetemcomitans in periodontally healthy children can serve as a risk marker for initiation of LAP.