Background: Rotary instrument techniques have shown evidence of simultaneously enlarging the root canal and maintaining the canal anatomy. Protocols for the use of rotary systems in primary molars are not well established.
Aims: The aim of the study was to evaluate and compare root canal shape and area after ProTaper and K3 rotary instrumentation in primary molars.
Settings and design: Coronal access cavities with straight-line access into the root canals were prepared on primary mandibular molar teeth, extracted for therapeutic reasons. The teeth were aligned in a prefabricated template in individual self-cure acrylic blocks such that their respective positions could be reproduced later.
Subject and methods: Forty-two primary mandibular molar teeth selected were equally divided into three groups: instruments with stainless-steel (SS) hand K-files, ProTaper, and K3 Endo rotary system. Precomputed tomography (CT) slices were taken at predetermined levels (coronal, middle, and apical third) followed by instrumentation of canals using selected files and post-CT scan.
Statistical analysis used: Data obtained were evaluated using independent t-test with a 0.05 level of significance and ANOVA.
Results: SS hand K-files and rotary ProTaper and K3 Endo of 0.04 taper produced a predominantly round shape at coronal, middle, and apical levels. ProTaper system caused the greatest increase in round-shaped canals and canal area followed by K3 Endo of 0.04 taper.
Conclusions: Shaping abilities of both manual and rotary instrumentation systems in primary molars were similar, whereas for enlarging and maintaining anatomy, rotary systems (ProTaper and K3) were better.
Keywords: Canal area difference; canal shapes; pediatric endodontics; primary mandibular molar; rotary endodontics.