Evaluation of the internal anatomy and instrumentation techniques with new mechanized instrumentation systems in second mandibular molars with fused roots

• Autor(a) principal: Silva, Pablo Andres Amoroso
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/25/25147/tde-15122021-123212/
• topic: Dente molar; Endodontia; Endodontics; Microtomografia por Raio-X; Molar; Preparo de Canal Radicular; Root canal preparation; X-Ray Microtomography

The present study evaluated the morphometric aspects of the internal anatomy of the root canal and the effect of 90º-oscillatory instrumentation with hand files on volume, surface area and uninstrumented surface after shaping procedures with Self adjusting file and Reciproc in mandibular second molars with C-shaped canals. 52 extracted mandibular second molars with C-shaped canals were scanned with a micro-computed tomography scanner. The root canal cross-sections were recorded according to the modified Melton classification. Morphometric parameters and the tridimensional configuration, were evaluated. Afterwards, 20 teeth with merging type canals and C1 internal configuration were divided in two groups (n = 10) and instrumented with Reciproc and SAF instruments respectively. Then, a size 30 Niti hand K-file used in 90º-oscillatory was used as a final instrumentation. The specimens were scanned using Micro-CT after all procedures. Morphometric parameters were analyzed using CTAn software. Also, the uninstrumented root canal surface was calculated for each canal third. The results indicated an even distribution within the sample. Also, the cross-sectional configuration analysis revealed predominance of the C4 and C3 configurations at 1 mm from the apex and the C1 and C2 configurations in the cervical third. According to the morphometric parameters, the C1 and the distal aspect of the C2 exhibited the lowest roundness values and higher values for the area, major diameter and aspect ratio in the apical third. All values were compared between groups using the MannWhitney test and within groups using the Wilcoxons signed-rank test. The significance level was set at 5%. Instrumentation with Reciproc significantly increased canal volume compared to SAF and the canal volumes were significantly increased after 90º-oscillatory instrumentation (P < 0.05). After all instrumentation protocols the surface area increase only revealed significant differences in the within groups comparison (P < 0.05). Reciproc and SAF instrumentation yielded a uninstrumented root canal surface of 28% and 34%, respectively, without differences (P > 0.05). Final oscillatory instrumentation reduced the uninstrumented root canal surface from 28% to 9% (Reciproc) and from 34% to 15% (SAF; P < 0.05). The apical and middle thirds exhibited higher uninstrumented root canal surfaces after the first instrumentation that was significantly reduced after oscillatory instrumentation (P < 0.05). Mandibular molars with C-shaped root canals exhibited similar distributions of symmetrical, asymmetrical and merging-type canals. The C1 configuration and the distal aspect of the C2 configuration exhibited the highest area values and large apical diameters. Furthermore, the final use of 90º-oscillatory instrumentation using NiTi hand files significantly decreased the uninstrumented canal walls that remained after Reciproc and SAF instrumentation. Finally, the combination of two instrumentation systems/techniques proved to be effective in achieving better instrumentation results in C-shaped mandibular second molars.