Root canal therapy（RCT） has long been accepted as an effective resolution against the endodontic disease. However cases exist which can not heal after conventional RCT. They are known as refractory periapical periodontitis. Recent years, numerous studies had been done in order to uncover the causes of refractory periapical periodontitis and to find available treatment options for it. We here reviewed current opinions on the etiology and therapy of refractory periapical periodontitis.
