Influence of Kinematics of Nickel-Titanium Instruments on Root Canal Preparations of Dental Students –A Micro CT Evaluation

Abstract

Introduction:One of the most important steps in endodontic treatment includes the shaping and instrumentation of the root canal system. If not done properly, it may lead to errors including canal transportations and uncentered preparations. Over the last decades, nickel-titanium (NiTi) rotary instruments have enhanced the quality of root canal shaping for clinicians. Currently, two common NiTi rotary instruments, WaveOne Gold and ProTaper Gold, function by two different forms of kinematics: a reciprocating and rotating movement respectively. Currently, preclinical curricula in dental schools do not have a standardized rotary file in which dental students are introduced into endodontics with. This study looks at the use of these two rotary systems by novice sophomore dental students on the quality of their root canal preparations. Purpose: This study aims to examine the influence of kinematics of nickel-titanium instruments (reciprocation vs rotation) on the shaping ability, canal transportation and centering ratio, of novice pre-doctoral sophomore dental students and their preference after its use. Materials and Methods: Forty two identical pre-accessed mandibular left first molar 3-dimensional printed replicas’ mesial canals (TrueTeeth; PlanBDental) were instrumented by 21 novice pre-doctoral sophomore dental students. Each canal was previously hand instrumented to a size #15 K file by a single provider. The students were recruited using a random number generator. The teeth were divided up into 2 groups for each rotary file system being used: ProTaper Gold (PTG) (n=21) and WaveOne Gold (WOG) (n=21). Each student instrumented both the mesiobuccal (MB) and mesiolingual canals (ML) using each system. The total instrumentation time was recorded. Micro-computed tomography was used to scan the teeth before and after instrumentation. Centering ratios and canal transportation were calculated at the apical, middle and coronal levels. A questionnaire was completed after instrumentation regarding students’ perception with a 5-point Likert scale: ease of use, flexibility, cutting efficiency, screwing effect and overall impression. Conclusion: Compared to a rotation NiTi file system, reciprocation NiTi file system was preferred by novice sophomore dental students, and it also showed less canal transportation and better centering ability with shorter instrumentation times. Future studies are still needed in order to assess if there are further advantages to training novice dental students with reciprocating rotary systems when learning endodontics, but this study can serve as a framework to answer the question.