A comparison of dentine removal using safety or conventional Hedstrom files

Mandibular molars (n = 20) were divided and the mesial roots mounted in an acrylic mould which allowed them to be removed, sectioned horizontally and then reassembled. The furcal root canal wall thickness 7 mm from the apex was measured prior to instrumentation. The roots were allocated to two groups (n = 10). One group was instrumented using the step back technique with safety Hedstroms in one canal and conventional Hedstrom files in the other canal. The second group was instrumented using a crown down approach (using files and Gates Glidden drills to provide early radicular access). The furcal root canal wall thickness was then remeasured and the amount of dentine removed calculated. The results showed that the safety Hedstrom file removed less dentine from the furcal region of the canal compared to the conventional Hedstrom file. This however was not statistically significant (Paired t test, n = 10, p > 0.05). The amount of dentine removed using the crown down technique was significantly greater than that using the step back technique (Two sample t, n = 20, p < 0.01). In conclusion, less dentine was removed from the furcal region with safety Hedstrom files compared to conventional Hedstrom files; however, Gates Glidden drills removed more dentine than either type of hard file.