Authors: A.S. Abu Haimed, P.M.H. Dummer, S.T. Bryant
Rubrics: Canal shaping
Keywords: curved canals
Aim To compare the canal shaping ability of two reciprocating instruments: WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) and RECIPROC (VDW, Munich, Germany) versus two rotary instruments: ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) and Mtwo (VDW, Munich, Germany).
Methodology A total of one hundred and sixty simulated root canals in resin blocks with four different shapes in terms of angle and position of curvature were constructed: 1. 20_ curve with 12 mm from canal orifice (n = 40). 2. 20_ curve with 8 mm from canal orifice (n = 40). 3. 40_ curve with 12 mm from canal orifice (n = 40). 4. 40_ curve with 8 mm from canal orifice (n = 40). Each block was marked with four reference points, photographed using a camera (Panasonic F10 CCD, Osaka, Japan) and secured a fixed distance from a microscope stage using analysis software (Image-Pro Plus; Media Cybernetics, Silver Springs, MD, USA). Canals were prepared using rotary (ProTaper Universal, Group 1; Mtwo, Group 2) or reciprocating (WaveOne, Group 3; Reciproc, Group 4) instruments. Each system was used to prepare 10 canals of each shape. The manufacturers’ instructions were followed for each instrument during canal preparation, and the same motor was also used (Silver, VDW, Munich, Germany). Each instrument was used to prepare a single canal only. Post-preparation images were photographed, superimposed on the matching preoperative image and analysed to determine the degree of canal transportation at three levels: canal orifice, beginning of the curve, and halfway between the orifice and the beginning of the curve. Presence of various canal aberrations was also noted along with instrument fractures and time of preparation. Data were analysed using ANOVA in SPSS (SPSS Inc, Chicago, IL, USA).
Results Mtwo was associated with greater transportation values. The greatest transportation values were associated with the 40_/08-mm canal type. Canal aberrations were limited to rotary instruments (Mtwo and ProTaper); seven canals had outer widening, and seven had danger zones; all were in canals with 40_ curves. Zipping occurred with ProTaper instrument only in one 20_/12-mm canal. The reciprocating instruments prepared canals significantly more rapidly than rotary systems.
Conclusion Rotary NiTi instruments are associated with more canal transportation and canal aberrations than reciprocating instruments. The 40_/08-mm canal type was associated with more canals transportation and aberrations with all instruments