Effect of retained fractured instruments on tooth resistance to vertical fracture with or without attempt at removal

Madarati AA, Qualtrough AJE, Watts DC. Effect of retained fractured instruments on tooth resistance to vertical fracture with or without attempt at removal. International Endodontic Journal, 43, 1047–1053, 2010. Aims To investigate the effect of retained fractured endodontic instruments on root strength and to evaluate the effectiveness of several root filling materials in reinforcing roots that had undergone unsuccessful attempt at removal of fractured instruments. Methodology Seventy five mandibular premolar roots were divided into five groups. In group A (control), canals were prepared to a size F5‐ProTaper instrument and filled with gutta‐percha and TubliSeal sealer fragments. In the experimental groups (B, C, D and E), 4 mm of F5‐ProTaper instruments were fractured in the apical one‐third of the canal and then treated as follows: in group B, the fragments were left in situ without attempt at removal, and canals were filled with gutta‐percha and TubliSeal sealer (GP No Removal). In groups C, D and E, an attempt at removal of the fragment was simulated by preparing a staging platform coronal to the fragment using modified Gates Glidden burs (No 2–5). Canals in group C were filled with gutta‐percha and TubliSeal sealer (GP Removal), group D filled with Resilon (Resilon Removal) and group E with mineral trioxide aggregate (MTA Removal). Roots then underwent vertical fracture. Data were analysed using the one‐way anova at P