Canal master instrumentation: an in vitro study of separation frequency

Incidence of Lightspeed separation and the potential for bypassing

It is important for endodontic instruments to have a low fracture rate. If a fracture does occur, it would be desirable to have the ability to bypass the broken segment and complete the root canal treatment. One hundred sixty-two root canals in 52 maxillary and mandibular first molars were cleaned and shaped with Lightspeed instruments by three endodontists in their private practices. The canals were instrumented using the technique recommended by the manufacturer. All canals were instrumented to at least a size 45 at the working length. Six instruments separated during treatment. All six had been used more times than recommended by the manufacturer. Five of the six were easily bypassed and treatment completed.

Torsional and bending properties of stainless steel and nickel titanium Canal Master U and Flexogate instruments

The purpose of this study was to assess and to compare the torsional and bending properties of the Canal Master U (CMU) and Flexogate instruments made of stainless steel and nickel titanium. The bending moment, the torsional moment and angular deflection were measured according to ANSI/ADA specification number 28 and ISO reference number 3630. Ten instruments of each size, sizes 25 to 40 were used for each test. Nickel titanium instruments were significantly more flexible than stainless steel files. With regard to the torsional moment, values obtained were below the standards in all sizes except stainless steel CMU sizes 25, 35 and 40, and nickel titanium CMU size 25. Nickel titanium instrument also showed the highest angular deflection values. There were statistically significant differences between nickel titanium files and stainless steel Flexogates and between stainless steel Flexogates and stainless steel CMU. Based on these findings, the use of nickel titanium CMU and Flexogates is encouraged. Given the perceived advantages of both CMU and Flexogate instruments over conventional files for canal preparation, it would appear desirable to have the torque resistance of these instruments improved.

An evaluation of the Canal Master, balanced force, and step-back techniques

The step-back (SB), balanced-force (BF) , and Canal Master (CM) instrumentation techniques were compared in 53 mesial canals of mandibular molars using two different instrument types: Flex-R and CM. Canal angulation changes from preoperative to postrotary and postinstrumentation were measured using the Schneider technique (ST) and the long-axis technique (LAT). Instrumentation times were recorded, and then the roots were sectioned at 1, 3, and 5 mm from the apex. Measurements were made of the minimal remaining root structures and canal diameter. Rotary instrumentation resulted in a average loss of curvature of 2.37 degrees, as measured by the ST. The ST showed significant changes in canal angulation between CM (-7.74 degrees) and SB (-5.28 degrees) groups, with p < 0.05. LAT showed significant changes for CM versus BF and SB (p<0.001), with a mean change in angulation of -7.69 degrees, -1.68 degrees, and _0.1 degrees respectively. The BF technique (5.5) was significantly faster than either SB (7.1 min) or CM (8.3 min), with p < 0.05. The remaining mesial-distal root structure at all levels was similar among groups.