A controlled clinical trial was carried out to compare the clinical effect of combined antimicrobial-mechanical treatment modalities on moderate-to-deep periodontal pockets in patients with adult periodontitis. Twelve patients having at least three nonadjacent sites of periodontitis were included in the split-mouth study. Gingival Index, Plaque Record, bleeding on probing, probing depth, attachment level, and recession depth were recorded immediately before treatment. In the control site, supragingival and subgingival scaling was performed with an ultrasonic scaler. One experimental site received supplemental irrigation with 15 mL of a 100-mg/mL tetracycline solution, while the other received a tetracycline-loaded fiber after mechanical instrumentation. Fibers were left in place for 10 days. Reevaluation 30 to 60 days after treatment showed that all three treatment modalities were effective in improving clinical parameters. No adjunctive effect on the healing response was obtained by augmenting mechanical debridement with tetracycline.