Changes in canal width and angle in curved canals in the resin blocks: Pro taper next versus one shape instruments

Objective:To compare the effect of OneShape and ProTaper Next file on the change in canal width and angle of curvature in simulated curved canal in resin blocks. Methods: The quasi-experimental study was conducted at the Aga Khan University, Karachi, from January to March 2018, and comprised endodontic resin blocks that had inbuilt curved canals. These were randomly divided into 2 equal groups and were subsequently prepared using OneShape in group A, and ProTaper Next rotary instrument in group B followed by staining with red and blue ink for comparison of pre- and post-operative images of canals. Standardised photographs were taken along with reference measuring scale. Independent sample t-test and Paired sample t-test were used to compare the angle of curvature and canal width changes and pre and post instrumentation changes in resin block after using both the instruments, respectively. Intra class correlation was used to determine inter-examiner reliability. The level of significance was kept at p value < 0.01. SPSS 22 was used for data analysis. Results: Of the 60 blocks, 30(50%) were in each of the two groups. The mean pre-instrumentation angle of curvature was 32.3±2.13 and 31.0±3.28 degrees for groups A and B. The mean degree of canal straightening post-intervention was 1.5±0.5 and 3.6±1.38 degrees in groups A and B (p<0.001). In terms of canal width changes, OneShape file removed more resin material from the canal walls compared to the ProTaper Next system (p<0.001). Conclusion: ProTaper Next file significantly altered the angle of curvature in the resin block compared to OneShape file, but the amount of material removed from the canal space was significantly higher with the OneShape file compared to ProTaper Next.