ANALYSIS OF FORCES DEVELOPED DURING ROOT-CANAL PREPARATION WITH THE BALANCED FORCE TECHNIQUE

The aim of this study was to examine the forces and torque developed d uring root canal preparation with the balanced force technique using a recently described force-analyser device. A tooth tvas placed in a ho lder within the Endograph and forces and torques exerted were recorded , These parameters, which can be studied during preparation (on-line) or stored and examinated subsequently (off-line) generated endograms, which showed the forces generated with time, In addition, the endogram s of preparations performed by students and endodontists, as well as d eliberately induced failures in preparation technique (broken instrume nts), were compared, The values for the forces and torques depended on the size of the instruments and were related to the phase of the prep aration. For the endodontists. the vertical and horizontal forces vari ed, respectively, From 0.08 +/- 0.01 kg for a size 15 to 0.65 +/- 0.10 kg for a size 45, and from 0.01 +/- 0.005 kg for a size 15 to 0.4 +/- 0.1 kg for a size 40. The torque varied from 0.08 cl kg mm(-1) for a size 15 to 1.6 +/- 0.4 kg mm(-1) for a size 45. With the Endograms use d as a reference, the relation between the developed vertical forces a nd the torque became more similar between the groups of endodontists a nd students, The Endograph provides a new approach to the analysis of preparation technique because it depicts the relationships between the different parameters of the preparation.