INCIDENCE OF APICAL ROOT CRACK FORMATION AFTER ROTARY ROOT CANAL INSTRUMENTATION AT DIFFERENT INSTRUMENTATION LENGTHS USING PROTAPER UNIVERSAL, PROTAPER NEXT AND PROTAPER GOLD FILES - AN IN-VITRO STUDY

Aim: To evaluate the incidence of apical root crack formation after root canal preparation using ProTaper Universal (PTU), ProTaper Next (PTN) and ProTaper Gold (PTG) rotary file systems and compare the crack formation at various instrumentation lengths. Subjects and Methods: One hundred single rooted extracted mandibular premolar teeth were mounted in acrylic resin blocks after simulating periodontal ligament. The teeth were divided into four groups. Group I was instrumented using PTU, group II using PTN and group III using PTG rotary files, while group IV was left untreated, serving as a negative control group. Each group was subdivided into three subgroups: A, B and C instrumented till root canal length (RCL), RCL-1 and RCL+1. Root apex was sectioned horizontally 1-2mm from apical foramen and was stained with 1% methylene blue dye followed by stereomicroscopic evaluation to determine apical root cracks. The data was analyzed using chi-square, Shapiro Wilkinson and Cramers phi test. The significance level was set at P