Evaluation of Shaping Ability of MPro and ProTaper Next NiTi Rotary Instruments Using Cone Beam Computed Tomography

Aim: present study was intended to compare the mechanical behavior of PTN and MPro NiTi rotary systems and the associated canal volumetric changes in curved root canals.Materials and methods: 50 freshly extracted permanent first mandibular molars were collected then reduced to 19 mm length and the distal roots were dissected. Mesial roots were then embedded in upright positions within acrylic resin blocks. The samples were randomly assigned into 2 groups (n=25) and prepared with either ProTper Next to X2 file or with MPro files to 25/0.06 file. CBCT scans were performed on the samples before and after root canal preparation with the NiTi rotary systems. Root canal transportation, instrument centering ability and remaining dentine thickness were calculated at 1, 3, 5, 7, and 9 mm from the root apex. Additionally, pre and post instrumentation root canal space through the apical 9 mm of the root were segmented and measured. Results: MPro system significantly transported the root canals at all tested levels compared to the PTN system. Roots prepared with PTN had significantly more dentin thickness at the distal canal wall at levels 5, 7, and 9 mm from the apex, than those prepared with the MPro system. MPro rotary system removed dentin volume in apical 9 mm significantly more than ProTaper Next system and created larger post-instrumentation canal volume.Conclusion: The ProTaper Next system prepared the mesiobuccal root canals of extracted mandibular molar with more uniform and centered instrumentation across the canal length than MPro rotary system.