Effect of Rotational Speed on Root Canal Preparation with Hero 642 Rotary Ni-Ti Instruments

Abstract

The purpose of this study was to evaluate the influence of Hero 642 rotary Ni-Ti instruments driven at 300, 400, or 600 rpm on root canal straightening, loss of working length, and instrument breakage. Sixty mesial root canals from extracted human mandibular molars were divided into 3 groups of 20 each and were instrumented at the aforementioned rotational speeds with a crown-down technique. Using a digital intraoral radiography system directly on the images of pre- and postoperative radiographs, degrees of canal curvatures were measured and recorded. Statistical analysis showed that final canal curvatures and working lengths were significantly reduced compared with those of original values in each group (p < 0.001). However, using Hero 642 rotary Ni-Ti system at different rotational speeds had no effect on canal curvature and working length alterations (p > 0.05). No file breakage was observed in any of the groups.

Effect of instrument speed when used in reciprocating motion on root canal transportation and centering ability

“…Karagöz-Küçükay et al[ 10 ] evaluated the influence of Hero 642 rotary NiTi instruments driven at 300, 400, or 600 rpm on root canal straightening using digital intraoral radiography system. According to the results, using Hero 642 rotary NiTi system at different rotational speeds had no effect on canal curvature.…”

Factors contributing to the separation of endodontic files

“…However, it should be noted that file fracture was consid ered as a main criterion for failure of instruments while deformed instruments should be considered as failed also. 41 Dif ferent methodologies were used, which may explain the different conclusions reported. However, it is imperative that clinicians always adhere to the speed recommended by the manufacturer for each rotary system and sometimes for each specifi c fi le.…”

Influence of rotational speed on the cyclic fatigue of Mtwo instruments

“…For the most part, the influence of rotational speed on fatigue fractures has been investigated using standardized canals made with a stainless steel apparatus (Pruett et al 1997, Kitchens et al 2007, Lopes et al 2009) or canals of extracted human teeth (Gabel et al 1999, Yared et al 2001, Karag€ oz-K€ uc ߀ ukay et al 2003, Gao et al 2010. Other studies have investigated cyclic fatigue after pre-stressing of files following instrumentation of various numbers of clinical cases using the same rotational speed (Gambarini 2001, Fife et al 2004).…”