Transporte y centricidad de los sistemas mtwo y twisted file evaluados mediante tomografía computarizada cone-beam

Objective: To determine the amount of transportation and the centering ability by nickel titanium rotary systems Mtwo and Twisted File, in mesial roots of lower molars using Cone Beam computed tomography. Materials and Methods: Sixty mesial canals of mandibular molars with severe angles of curvature were divided into two groups. After the instrumentation with rotary systems Mtwo and Twisted File, the amount of transportation and centering capacity were evaluated using cone beam computed tomography. Two sections from middle and cervical levels of the canal were recorded. Student t-tests and U by Mann Whitney tests were used for statistical analysis. Results: Less transportation and better centering ability occurred with Twisted File rotary instruments. However, there was no statistically significant difference between the systems (p≤0.05). Canals were transported mostly towards the mesial aspect in the cervical third of the roots, and towards the distal aspect in the mesial third. Conclusions: The rotary instruments Mtwo and Twisted File behaved similarly about the canal transportation and centering, allowing the preparation of curved canals with little deviation.Objetivos: Determinar la cantidad de transporte y capacidad de centrado de los sistemas rotatorios Mtwo y Twisted File, en raíces mesiales de molares inferiores usando tomografía computarizada Cone Beam. Materiales y Métodos: Sesenta conductos mesiales de molares inferiores con ángulos severos de curvatura fueron divididos en dos grupos. Después de la instrumentación con los sistemas rotatorios Mtwo y Twisted File, se evaluó la cantidad de transporte y capacidad de centrado mediante tomografía computarizada Cone Beam. Se registraron dos secciones a nivel del tercio medio y cervical del conducto. Pruebas de T de Student y U de Mann Whitney se utilizaron para el análisis estadístico. Resultados: Menor transporte y mejor centricidad se obtuvieron con los instrumentos rotatorios Twisted File. Sin embargo, no hubo diferencias estadísticamente significativas entre los sistemas (p≤0.05). Los conductos se transportaron principalmente hacia mesial en el tercio cervical de la raíz y hacia distal en el tercio medio. Conclusiones: Los instrumentos rotatorios Mtwo y Twisted File se comportaron de manera similar en cuanto al transporte y centricidad, permitiendo la preparación de conductos curvos con poca desviación

Evaluation of different techniques and materials for filling in 3D printed replicas of teeth with perforating internal resorption by means of microcomputed tomography

O presente estudo teve como objetivo avaliar a capacidade de preenchimento de duas técnicas de obturação em dentes impressos com reabsorção interna perfurante (RIP). Inicialmente, a partir de um incisivo central superior humano hígido, foi realizado um escaneado por microtomografia computadorizada (micro-CT) para aquisição de um modelo 3D no formato estereolitográfico (.stl). Em seguida, a etapa de modelagem foi realizada com o auxílio do software Blender, no qual foi desenhada uma reabsorção interna perfurante no terço médio do canal radicular. A partir do desenho final obtido, foram impressas 33 réplicas em resina cirúrgica que foram distribuídas em 4 grupos de acordo com a técnica de preenchimento e material utilizado (n= 8): GI - técnica híbrida com Bio-C Sealer/guta-percha + Bio-C Repair, GII - técnica híbrida com BioRoot/gutapercha + Biodentine, GIII - técnica incremental com condensador manual e Bio-C Repair, GIV - técnica incremental com condensador manual e Biodentine. Foi realizada micro-CT pós-obturação, para mensurar o volume percentual de espaços vazios, e microscopia confocal a laser para mensurar a rugosidade da superfície dos cimentos reparadores (Bio-C Repair e Biodentine). Os dados foram comparados por testes ANOVA e Kruskal-Wallis. No terço apical, os grupos GI (89,70±5,15), GII (87,70±8,43) e GIII (84,20±9,00) mostraram as maiores porcentagens de volume de preenchimento em relação ao GIV (69,70±6,88) (P<0,05). Na área de reabsorção interna os grupos GI (96,00±2,64) e GIII (95,30±2,93) apresentaram as maiores porcentagens de volume de preenchimento em relação ao GII (91,50±1,35), sendo que o GIV (92,60±3,39) apresentou resultados hora semelhantes ao GI e GII e hora semelhante ao GIV (P<0,05). Quanto à qualidade do preenchimento na área de perfuração, o cimento Bio-C Repair apresentou melhores resultados quando comparado ao cimento Biodentine (P<0,001). Quanto à rugosidade, o cimento Bio-C Repair (1,66±0,65) apresentou menor rugosidade superficial em relação ao cimento Biodentine (2,51±0,89) (P<0,05). A capacidade de preenchimento e qualidade da obturação em dentes com reabsorção interna perfurante foi superior com a técnica incremental com Bio-C Repair e híbrida com Bio-C Sealer/guta-percha + Bio-C Repair.The present study aims to evaluate the filling ability of two filling techniques in teeth impressed with perforating internal resorption (RIP). A healthy human maxillary central incisor was instrumented to an apical diameter of 600 &micro;m and scanned by microcomputed tomography (micro-CT). The 3D model was reconstructed in stereolithographic (.stl) format and, with the aid of Blender software, a perforating internal resorption in the middle third of the root canal was designed. Thirty-three replicas were printed in surgical resin and distributed in 4 groups according to the filling technique and material used (n= 8): GI- incremental technique with manual condenser and Bio-C Repair, GII- hybrid technique with Bio-C Sealer/gutta-percha + Bio-C Repair, GIII- incremental technique with manual condenser and Biodentine, GIV- hybrid technique with BioRoot/gutta-percha + Biodentine. Post-obturation micro-CT was performed to measure the percentage volume of voids, and laser confocal microscopy was used to measure the surface roughness of the repair cements (Bio-C Repair and Biodentine). Data were compared using ANOVA and Kruskal-Wallis tests. In the apical third, groups GI (89.70±5.15), GII (87.70±8.43) and GIII (84.20±9.00) showed the highest percentages of filling volume compared to GIV (69.70±6.88) (P<0.05). In the area of internal resorption, groups GI (96.00±2.64) and GIII (95.3 ±2.93) showed the highest percentages of filling volume compared to GII (91.50±1.35), and GIV (92.60±3.39) showed results similar to GI and GII and similar to GIV (P<0.05). As for the quality of the filling in the drilled area, Bio-C Repair cement showed better filling capacity when compared to Biodentine cement (P<0.001). Regarding roughness, Bio-C Repair (1.66±0.65) cement showed lower surface roughness compared to Biodentine cement (2,51±0,89) (P<0.05). The filling capacity and quality of the filling in teeth with perforating internal resorption was superior with the incremental technique with Bio-C Repair and hybrid technique with Bio-C Sealer/gutta-percha + Bio-C Repair