Effect of different instrumentation techniques on students’ performance and outcomes of nonsurgical root canal treatment

This study compared, retrospectively, the incidence of clinical errors and effects on treatment outcomes, when students were exposed to two different instrumentation techniques: a hybrid rotary technique (HYB), consisting of both hand instrumentation with hand stainless steel and Ni‐Ti files plus the use of a rotary system (Vortex Blue, Dentsply Sirona), versus a full reciprocation instrumentation technique (WaveOne Gold [WOG], Dentsply Sirona). A total of 368 endodontic cases (n= 184) in anterior and premolar teeth, completed by dental students at the University of Michigan School of Dentistry from 2013 to 2022, were used for the study. The groups were evaluated by two calibrated clinicians, observing the incidence of clinical errors: file separations, over‐instrumentation, ledges and transportations. Treatment outcomes were also observed. Data were analyzed statistically by Fisher's exact test and Mann–Whitney Utest (p< 0.05). No significant difference in file separations, ledges, and transportation was observed between the two groups. However, the WOG Group experienced significantly more over‐instrumentation than HYB group, although this did not significantly affect tooth survival or periapical index (PAI). Cases with PAI scores of 5 were found to have significantly less tooth survival compared to the other PAI scores. It can be concluded that both techniques in our study are well suited to advancing the endodontic dental education of students and novice operators, anticipating relatively successful outcomes of tooth survival, as long as the cases selected are less severe in progression preoperatively.