Improved instrumentation to reduce endodontic complications
BUSAN, South Korea: Reducing complications in root canal therapy is in the best interests of dentists as well as patients. To improve the clinical performance of endodontic files, a research team led by Dr Sang Won Kwak from Pusan National University tested instruments with specially designed rotary motion.
Over the years, root canal preparation has been improved by the use of engine-driven NiTi files. Compared with stainless-steel manual files, NiTi instruments offer better flexibility and cutting efficiency in addition to reduced iatrogenic errors. However, the NiTi files may have cyclic fatigue and torsional failure problems during root canal preparation. To reduce the risk of file fracture, Kwak and his team tested heat-treated NiTi alloy files with specially designed rotary motion.
The scientists tested three combinations of instruments and motions for root canal preparation. These were the K3XF rotary system with continuous rotary motion, the K3XF rotary system with adaptive motion and the Twisted File system with adaptive motion (TFA), all from the endodontic product manufacturer Kerr Endodontics. Adaptive motion combines continuous and reciprocating motion, rotating 600° and stopping when the file is exposed to minimal or no load. “Adaptive movement helps to reduce torque generation during instrumentation with NiTi rotary files,” said Kwak. Torque generation occurs while removing root dentine by engine-driven NiTi files. The generated torque indicates the energy required to cut the root dentine, but also represents the reaction stress on NiTi files as well as the root dentine.
To ensure consistent test conditions, endodontic training resin blocks were used. Each block contained an S-shaped artificial canal, with a working length of 16 mm. The instrumentation was performed for a total of 45 tests (15 per instrument) by a single experienced endodontist in order to reduce operator errors.
The researchers found that TFA generated the lowest torque. Kwak and his colleagues thus concluded that the adaptive motion for NiTi files may reduce torque generation without increasing preparation time. Kwak also suggested that the “torque generation is more likely to be affected by the cross-sectional area rather than the movement of the file system”. A smaller cross-sectional area may account for the lower torque generation by the TFA file system.
These findings are promising for instrumentation in the future. The next step would be to assess the feasibility of these improved files in real-life situations in patients in the operating room, as opposed to the well-controlled laboratory conditions of this study.
The study, titled “Comparison of in vitro torque generation during instrumentation with adaptive versus continuous movement”, was published in the June 2019 issue of the Journal of Endodontics.