Recent study shows that doxycycline is effective in removing the smear layer from the cervical and middle third of the root canal. The study was conducted in four groups comprising of G1- Doxycycline, G2- Ethylenediaminetetraacetic acid + Sodium hypochlorite, G3- Doxycycline + Sodium hypochlorite, G4- Water.
Ref: Australian Endodontic Journal
DOI 10.1111/j.1747-4477.2009.00191.x