Twenty-seven patients with a recent history of
periodontal abscesses and/or loss of gingival attachment level (GAL) despite active periodontal
therapy were enrolled in a double-blind, randomized, placebo-controlled trial. Clinical measurements and
subgingival scaling were performed every 2 months. When a site exhibited greater than or equal to 2 mm loss of GAL or a
periodontal abscess, patients were administered either
doxycycline at a dosage of 200 mg to start and 100 mg per day for 3 weeks, or a placebo. Clinical measurements of GAL and microbial analysis of subgingival plaque at study and control sites were made at the time of active disease and at intervals of 1 week and 7 months after completion of the
drug regime. Plaque samples were screened for the presence of Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Bacteroides intermedius (Bi), Eikenella corrodens (Ec) and Fusobacterium nucleatum (Fn) by indirect immunofluorescence antibody technique and for spirochetes (Sp) using Ryu's
stain. Based on presence or absence analysis of the sum scores of the 6 pathogens, both the placebo (n = 10) and the
doxycycline groups (n = 17) exhibited similar scores at the time of detection of active disease (mean placebo = 2.38 +/- 0.32; mean
doxycycline = 2.95 +/- 0.27; P = 0.18). One week
after treatment, the probability of detection was unchanged in the placebo group (mean placebo = 3.14 +/- 0.47), but was significantly reduced in the
doxycycline group (mean
doxycycline = 1.77 +/- 0.26; P = 0.0002). Study (active) sites exhibited scores 2 to 3 times higher than control (inactive) sites before
doxycycline treatment.(ABSTRACT TRUNCATED AT 250 WORDS)