This study evaluated the ability of various chemotherapeutic and mechanical modalities to detoxify endotoxin-contaminated hydroxyapatite-coated dental implant surfaces as determined by the early attachment and growth of human gingival fibroblasts. Hydroxyapatite-coated test strips were contaminated with purified outer membranes of Escherichia coli and treated with citric acid, hydrogen peroxide, stannous fluoride, chlorhexidine gluconate, tetracycline HCl, polymyxin B, a plastic sonic scaler tip, or left untreated (contaminated and sterile controls). Human gingival fibroblasts were then seeded onto the test strips and incubated for 48 hours. The citric acid-treated strips showed greater cell growth than the other treatments. The plastic sonic scaler tip and the polymyxin B-treated samples exhibited greater cell coverage than the sterile control specimens. The use of citric acid and/or a modified plastic sonic scaler tip may be a valuable adjunct when surgical repair of an ailing hydroxyapatite-coated dental implant is contemplated. (Implant Dent 1992;1:195-202)