Farklı Nİ-Tİ retreatment sistemlerinin (R-ENDO, MTWO R, D-RACE, protaper universal retreatment) tedavi tekrarı etkinliklerinin in vitro değerlendirilmesi In vitro retreatment evaluation of efficacy of different ni-ti retreatment systems(R-ENDO, MTWO T, D-RACE, protaper uni̇versal retreatment)