Root canal shaping of curved canals by Reciproc Blue system and Pro Taper Gold: A micro-computed tomographic study

BACKGROUND: This study aimed to evaluate the centralization and transportation of ProTaper Gold (PTG) rotary system and Reciproc Blue (RB) reciprocating system in curved canals, by using micro-CT. MATERIAL AND METHODS: Twenty extracted mandibular molars were previously scanned by using the SkyScan 1174 microtomograph to select the Vertucci IV anatomic type. The specimens were divided into two groups (n=10) according to the mechanized system used to prepare the root canals. The teeth were scanned by micro-CT to calculate the increase volume, percentage of dentin removed, remaining dentin thickness, structure model index (SMI), degree of transportation and centering ability of root canals. The Student’s t test was used to evaluate differences between PTG and RB in each measurement evaluated. RESULTS: No significant differences were found between the groups in the increase of the total root canal and apical volume; percentage of dentin removed after preparation; SMI of the mesiolingual canal; degree of transportation of the canal and centering ability of the cervical and middle thirds (P>0.05). There were significant differences in the mesiobuccal canal in SMI and in the centering ability of the apical third (P<0.05). Concerning the remaining dentin thickness, there was also no significant diferences between the groups, except for some regions were RB was observed to have a superior cutting capacity (P<0.05). CONCLUSIONS: Both systems were efficient and safe for performing preparation of the moderately curved root canals of mandibular molars. RB instruments produced more circular and better centralized canals in the apical third of the mesiobuccal canal, with superior cutting action when compared with PTG instruments. Key words:Nickel-titanium instrument, heat treatment, micro-computed tomography, canal transportation