Removal of intracanal smear by doxycycline in vitro

Cleansing and shaping result in a smear layer on the instrumented canal wall surfaces. The smear layer may inhibit close contact between sealers and dentin, and inhibits diffusion of medicaments. Objective. This study assessed the effect of doxycycline hydrochloride (DH) on smear layer on intracanal walls. Study design. Scanning electron microscopy was used to evaluate the remaining smear layer using different concentrations of DH. Single-canal palatal roots of extracted maxillary molars were irrigated with saline - 15% EDTA; saline - 25 mg/ml DH; saline - 50 mg/ml DH; saline - 100 mg/ml DH; NaOCl - 15% EDTA; NaOCl - 25 mg/ml DH; NaOCl - 50 mg/ml DH; and NaOCl - 100 mg/ml DH. The roots were fractured into halves and the amount of smear layer assessed in the middle and apical third. Results. Doxycycline-HCl of 100 mg/ml was the most effective in removing smear layer. In the saline group, 100 mg/ml of DH was more effective than EDTA. In the hypochlorite group, 50 mg/ml and 100 mg/ml of DH were more effective than EDTA ( p < 0.05). Conclusion. Doxycycline solution may be an effective irrigant.