Exploration of uninstrumented areas and volumetric precision of ProTaper Ultimate versus ProTaper Next file systems: A micro-computed tomography study.

Context: Root canal shaping is critical in endodontic treatment, aiming to maintain canal anatomy while effectively removing infected tissue.

Aim: The aim of this study was to compare the volumetric changes and uninstrumented areas in root canals prepared with ProTaper Ultimate (PTU) and ProTaper Next (PTN) file systems using micro-computed tomography (CT).

Settings and design: This was an in vitro comparative study using fifty extracted human mandibular premolars with moderate canal curvature (10°-35°).

Materials and methods: Pre- and postinstrumentation micro-CT scans were performed at 13 µm resolution. Canal preparation was done with PTU (n = 25) (up to F2) without prior glide path and PTN (n = 25) (up to X2) with hand file glide path. Volume changes and uninstrumented surface areas were analyzed using specialized software.

Statistical analysis used: Unpaired t-test for volume changes, Kruskal-Wallis test for inter-comparison of uninstrumented areas, and Mann-Whitney U test for intragroup comparison, with significance level set at P < 0.05.

Results: PTU demonstrated significantly lower canal volume gain (13.20% ±1.95% vs. 21.12% ±2.7%) and tooth volume loss (0.588% ±0.18% vs. 0.95% ±0.12%) compared to PTN.

Conclusions: The PTU system demonstrated superior preservation of tooth structure with less canal enlargement while maintaining effective instrumentation of canal surfaces compared to PTN, likely due to its enhanced flexibility, smaller core diameter, and improved metallurgy.