A comparison of the effect of modified and nonmodified instrument tips on apical canal configuration. Part II

Flexibility and Torsional Strength of ProTaper and ProTaper Universal Rotary Instruments Assessed by Mechanical Tests

“…The reduction in tip angle from 66°to 39°found here for the ProTaper Universal shaping instruments should favor the maintenance of the instrument centered within the canal space (23,24), thus reducing the risk of canal transportation. In the case of the new finishing instruments, the increase in tip angle from 66°to 95°found in the present work would give rise to the opposite effect (22)(23)(24)(25). Although no clinical tests were actually performed, one can speculate that the concept of round tip geometry (25), which is the kind of tip used in the new system, has the potential to counterbalance this tendency.…”

“…As pointed out in early studies (22,23) and recognized in a recent review (24), specific design features of the tip, such as tip angle, tip length, cross-section, and tip geometry, significantly influence the cutting efficiency of endodontic instruments. The reduction in tip angle from 66°to 39°found here for the ProTaper Universal shaping instruments should favor the maintenance of the instrument centered within the canal space (23,24), thus reducing the risk of canal transportation. In the case of the new finishing instruments, the increase in tip angle from 66°to 95°found in the present work would give rise to the opposite effect (22)(23)(24)(25).…”

Ledge Formation: Review of a Great Challenge in Endodontics

“…If the tip angle is reduced, the file tends to stay centered within the original canal space and will cut all sides (that is, circumferentially) more evenly (13). Hence, the modified-tip files tend to maintain the original canal curvature better and more frequently than unmodified-tip files (31).…”

Changes in root canal morphology in simulated curved canals o ver‐instrumented with a variety of stainless steel and nickel titanium files

“…Instrumentation was carried out using seven types of file as shown in Table 1. Thirty-five sets of files comprising six sizes of each file type (15,20,25,30,35,40) were randomly allocated, one set to each block, so that during the course of the experiment each instrument was used only once. Files were operated through prefabricated brass stops to ensure that the working length of the instrument was always 1 mm longer than the length of the canal.…”