(PR24) Micro–Computed Tomographic Evaluation of Shaping Ability by Novice Dental Students and Their Preference of Nickel-Titanium File; Rotation Versus Reciprocation System

This study examined the influence of kinematics of nickel-titanium instruments (reciprocation vs rotation) on the shaping ability of novice dental students and their preference after its use. Mesial canals of 42 3D printed mandibular molars (TrueTooth, PlanBDental) were prepared with ProTaper Gold (PTG) and WaveOne Gold (WOG) by 21 sophomore dental students. Micro–computed tomography was used to scan teeth before and after instrumentation to compare centering ratio and canal transportation at the apical, middle, and coronal levels. Total instrumentation time was also recorded. 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. Their preference between two files was also asked. Statistical analysis was completed using two-way ANOVA with Tukey’s tests (p < 0.05). PTG showed significantly more canal transportation than WOG in both apical and middle thirds of the mesio-lingual canals (p < 0.05).The centering ratios of WOG were also significantly higher at apical and middle thirds of mesio-lingual canal but lower at apical thirds of mesio-buccal canal. 19/21 students (90.48%) preferred WOG to PTG. WOG had significantly higher scores in the categories of ‘ease of use’, ‘screwing effect’, and ‘overall impression’ (p < 0.05) than those of PTG. The time for WOG instrumentation was shorter than for PTG (218± 83.6 vs 446.6±231.4 seconds, P<0.05).

Conclusion: Compared to rotation system, reciprocation system was preferred by novice dental students, which showed less canal transportation and better centering ability with shorter instrumentation time.