ANTIMICROBIAL PROPERTIES OF HUMAN DENTIN IMPREGNATED WITH TETRACYCLINE HCL OR CHLORHEXIDINE - AN IN-VITRO STUDY

Substantivity of tetracycline HCl and chlorhexidine digluconate to hum an root dentin was assessed in vitro. 51 extracted single-rooted teeth , their crowns removed, were assigned to 1 of 4 treatments in groups o f 12. A control groups included 3 roots. Each group was divided into 3 subgroups to allow evaluation of drug exposure for 1, 3 or 5 min. The roots were immersed in tetracycline HCl (10 or 50 mg/ml) or chlorhexi dine digluconate (0.12 or 0.2%) solutions following root planing. Cont rol roots were immersed in sterile saline (0.9%). Following drug immer sion, the roots were transferred to tubes containing 2 ml tris buffere d saline. The tubes were incubated at room temperature for 22 days. De sorption media were replaced at 24-h intervals. Removed media were exa mined for antimicrobial activity using a microtiter assay in which bac terial growth was evaluated by optical density readings. Roots immerse d in tetracycline HCl 50 mg/ml released antimicrobial activity to succ essive desorption media for 14 days. Tetracycline HCl 10 mg/ml activit y lasted 4 days. Roots subjected to chlorhexidine digluconate released antimicrobial activity for 24 h only. Within each treatment, there we re no differences between the 3 exposure intervals of 1, 3 or 5 min. O ur findings suggest usage of the periodontally exposed instrumented ro ot as a depot for sustained release of tetracycline HCl, but not chlor hexidine digluconate, to the subgingival environment. The substantiven ess of tetracycline HCl seems related to drug concentration rather tha n the exposure interval. Clinical trials are needed to confirm the cli nical significance of these in vitro observations.