Microtomographic Analysis of the Biomechanical Performance of Thermally Treated Instruments in Flattened and Curved Root Canals.

INTRODUCTION

This study aimed to evaluate, using microcomputed tomography, the impact of various mechanized systems on the geometry of the root canal system and dentin thickness in mandibular first molars. The hypothesis proposed that different systems would produce significant variations in root canal system preparation.

METHODS

Mesial and distal canals of mandibular molars were selected and divided into 5 groups (n = 10) based on the system used: 2Shape (25.06), Reciproc Blue (25.08), ProTaper Ultimate (25.08), ProTaper Next (25.06), and Univy New (25.06). Biomechanical preparation was performed following each manufacturer's instructions. Microcomputed tomography scans were conducted before and after preparation to assess 3-dimensional parameters (volume, surface area, Structural Model Index, and prepared root canal walls) and 2-dimensional parameters (area, perimeter, diameters, roundness, and transportation).

RESULTS

ProTaper Ultimate exhibited the greatest volume increase in mesial canals (1.73 ± 0.19), while ProTaper Next demonstrated the highest increase in distal canals (1.95 ± 0.25). Furthermore, ProTaper Ultimate resulted in the greatest dentin removal and the largest postpreparation area. Reciproc Blue achieved the best results for roundness and had the lower unprepared walls (15.3 ± 6.97).

CONCLUSIONS

All systems produced comparable outcomes, with ProTaper Ultimate yielding the greatest volume increase and dentin removal, indicating a less conservative preparation. Reciproc Blue provided optimal roundness and minimized unprepared root canal wall surfaces.