Comparison of the maintenance of root canal anatomy in severely curved resin blocks using RaCe and Flexmaster rotary systems

Dr. S. Khedmat* - Dr. M. Vahdatifar**

 *- Associate Professor of Endodontics Dept. - Faculty of Dentistry – Tehran University of Medical Sciences.

**- Endodontist.

 Background and Aim: Various rotary systems are available on the market, therefore selection of a proper instrument for root canal therapy is difficult. The aim of this study was to compare the maintenance of working length and original shape of curved canals and the incidence of procedural errors, using the newly introduced Race and the older Flexmaster rotary systems.

 Materials and Methods: In this experimental study, 40 resin blocks with a 45° curvature were randomly divided into two groups. After determination of the working length and staining with methylen blue, photographs were obtained. All root canals were prepared using Flexmaster and Race rotary systems according to the manufacturers’ insructions. The working lengths were determined once more and the prepared canals were stained with Eosin and photographs were taken. Pre- and post-preparation images were superimposed and changes in the canal walls were evaluated. Data were analyzed using Mann-Whitnney and student t-tests.

Results: The mean canal transportation (determined from the inner and outer width measurements) was higher for Race as compared to Flexmaster. The mean loss of working length in the Race (0/54mm) and Flexmaster groups (0/59 mm) was similar. The incidence of zips and elbows was %20 and %35 in the Race and Flexmaster groups, respectively.

Conclusion: Based on the results of this study, Race instruments produce more changes in the anatomy of severely curved simulated root canals, as compared to Flexmaster instruments.

Key words: Curved resin blocks - Rotary system – Flexmaster – Race.