O estudo da anatomia interna do complexo sistema de canais radiculares (SCR), é de fundamental importância no diagnóstico, planejamento e plano de tratamento endodôntico. O objetivo deste estudo foi avaliar a anatomia do SCR de pré-molares inferiores com sulcos radiculares, por meio de microtomografia computadorizada (μTC). Foram usados 69 primeiros pré-molares inferiores (1°PMI) e 14 segundos pré-molares inferiores (2ºPMI), escaneados no microtomógrafo SkyScan 1174. Os espécimes foram reconstruídos e analisados os parâmetros bidimensionais (número, área, circularidade, diâmetro maior, diâmetro menor e fator de forma) a 1, 2 e 3 mm do forame apical e tridimensionais (volume, área de superfície, SMI, número e localização de canais acessórios), bem como as características anatômicas externas das raízes (presença, localização, profundidade e extensão dos sulcos e espessura interna e externa da dentina radicular) e análise qualitativa da anatomia interna dos modelos tridimensionais. Os resultados bidimensionais mostraram que o número máximo de canais encontrados no terço apical foi quatro. O diâmetro maior apresentou valores, em média, duas vezes maiores que o diâmetro menor nos dois grupos dentais avaliados. Os valores de circularidade e fator de forma variaram, respectivamente, de 0,43±0,25 a 0,61±0,17, e 0,59±0,26 a 0,80±0,13 evidenciando uma forma levemente achatada, com tendência circular destes canais, tanto para os primeiros quanto para os segundos pré-molares inferiores. A análise tridimensional demonstrou que as médias do volume (mm3), de SMI e da área de superfície (mm²) foram, respectivamente, 10,78±5,42, 2,84±0,61 e 58,51±16,41 para os 1°PMI e de 10,89±5,77, 2,46±0,31 e 60,64±17,46 para os 2°PMI. Os canais acessórios foram observados, nos terços apical e médio em 56,62% dos 1º PMI e 64,28% dos 2º PMI. Na análise radicular externa, observou-se a presença de 182 sulcos radiculares nos 1º PMI e 44 nos 2º PMI, com maior prevalência na face mesial das raízes estudadas. A maior profundidade do sulco encontrou-se na secção correspondente à metade da extensão total do mesmo e a espessura da dentina nas faces interna e externa das raízes na região dos sulcos radiculares decresceu no sentido coroa-ápice sendo a menor média de espessura interna encontrada no valor de 1 mm caracterizando a presença de uma zona de perigo. Os modelos tridimensionais mostraram maior prevalência de canais únicos que deixam a câmara pulpar e se dividem em dois canais distintos e separados (59,42%) em 1ºPMI e canais únicos desde a câmara pulpar ao ápice (35,70%) em 2ºPMI. Conclui-se que a microtomografia possibilitou o estudo de anatomia interna e externa, sendo identificados dois novos tipos morfológicos de SCR de pré-molares inferiores. / The study of the internal anatomy of the complex root canal system (RCS) is of utmost importance for the diagnosis, planning and endodontic treatment plan. The aim of this study was to evaluate the anatomy of the RCS of mandibular premolars with radicular grooves by computed microtomography (μTC). Image acquisition of 69 mandibular first premolars (1PM) and 14 mandibular second premolars (2PM) was performed using the SkyScan 1174 microtomography device. The specimens were scanned and images were reconstructed in order to analyze two-dimensional parameters (number, area, roundness, major diameter, minor diameter, and shape factor) at 1, 2 and 3 mm of the apical foramen; three-dimensional parameters (volume, surface area, SMI, number and location of accessory canals), and the external anatomic characteristics of the roots (presence, location, depth and extension of grooves and internal and external root dentin thickness). A qualitative analysis of the internal anatomy of the three-dimensional models was also performed. In the apical third, it was found up to four root canals; the major diameter presented values, on average, twice greater than those of the minor diameter in both dental groups; the values of roundness and shape factor ranged from 0.43±0.25 to 0.61±0.17, and from 0.59±0.26 to 0.80±0.13, respectively, demonstrating the slightly flattened shape with circular tendency of these canals, in the 1MP and 2MP. The three-dimensional analysis showed that the mean volume (mm³), SMI and surface area (mm²) were, respectively, 10.78±5.42, 2.84±0.61 and 58.51±16.41 for the 1MP and 10.89±5.77, 2.46±0.31 and 60.64±17.46 for the 2MP. The accessory canals were observed mostly in the apical and middle third in 56.62% of 1MP and 64.28% of 2MP. In the analysis of the external root surface, 182 radicular grooves were observed in the 1MP and 44 in the 2MP, with prevalence in the mesial face of the examined roots. The deepest groove was found in the region corresponding to half of its total length and the dentin thickness on the internal and external faces of the roots in the region of the radicular grooves decreased in a corono-apical direction, the smallest internal thickness being 1 mm, which characterizes the presence of a danger zone. The three-dimensional models showed a prevalence of single canals leaving the pulp chamber and dividing into two distinct and separate canals (type 1-2) (59.42%) in the 1MP and single canals starting from the pulp chamber up to the apex (type 1) (35.70%) in 2MP. It may be concluded that μTC allowed the study of the internal and external anatomy of the roots, with identification of two new morphological types of SCR in mandibular premolars.

O estudo da anatomia interna do complexo sistema de canais radiculares (SCR), é de fundamental importância no diagnóstico, planejamento e plano de tratamento endodôntico. O objetivo deste estudo foi avaliar a anatomia do SCR de pré-molares inferiores com sulcos radiculares, por meio de microtomografia computadorizada (μTC). Foram usados 69 primeiros pré-molares inferiores (1°PMI) e 14 segundos pré-molares inferiores (2ºPMI), escaneados no microtomógrafo SkyScan 1174. Os espécimes foram reconstruídos e analisados os parâmetros bidimensionais (número, área, circularidade, diâmetro maior, diâmetro menor e fator de forma) a 1, 2 e 3 mm do forame apical e tridimensionais (volume, área de superfície, SMI, número e localização de canais acessórios), bem como as características anatômicas externas das raízes (presença, localização, profundidade e extensão dos sulcos e espessura interna e externa da dentina radicular) e análise qualitativa da anatomia interna dos modelos tridimensionais. Os resultados bidimensionais mostraram que o número máximo de canais encontrados no terço apical foi quatro. O diâmetro maior apresentou valores, em média, duas vezes maiores que o diâmetro menor nos dois grupos dentais avaliados. Os valores de circularidade e fator de forma variaram, respectivamente, de 0,43±0,25 a 0,61±0,17, e 0,59±0,26 a 0,80±0,13 evidenciando uma forma levemente achatada, com tendência circular destes canais, tanto para os primeiros quanto para os segundos pré-molares inferiores. A análise tridimensional demonstrou que as médias do volume (mm3), de SMI e da área de superfície (mm²) foram, respectivamente, 10,78±5,42, 2,84±0,61 e 58,51±16,41 para os 1°PMI e de 10,89±5,77, 2,46±0,31 e 60,64±17,46 para os 2°PMI. Os canais acessórios foram observados, nos terços apical e médio em 56,62% dos 1º PMI e 64,28% dos 2º PMI. Na análise radicular externa, observou-se a presença de 182 sulcos radiculares nos 1º PMI e 44 nos 2º PMI, com maior prevalência na face mesial das raízes estudadas. A maior profundidade do sulco encontrou-se na secção correspondente à metade da extensão total do mesmo e a espessura da dentina nas faces interna e externa das raízes na região dos sulcos radiculares decresceu no sentido coroa-ápice sendo a menor média de espessura interna encontrada no valor de 1 mm caracterizando a presença de uma zona de perigo. Os modelos tridimensionais mostraram maior prevalência de canais únicos que deixam a câmara pulpar e se dividem em dois canais distintos e separados (59,42%) em 1ºPMI e canais únicos desde a câmara pulpar ao ápice (35,70%) em 2ºPMI. Conclui-se que a microtomografia possibilitou o estudo de anatomia interna e externa, sendo identificados dois novos tipos morfológicos de SCR de pré-molares inferiores. / The study of the internal anatomy of the complex root canal system (RCS) is of utmost importance for the diagnosis, planning and endodontic treatment plan. The aim of this study was to evaluate the anatomy of the RCS of mandibular premolars with radicular grooves by computed microtomography (μTC). Image acquisition of 69 mandibular first premolars (1PM) and 14 mandibular second premolars (2PM) was performed using the SkyScan 1174 microtomography device. The specimens were scanned and images were reconstructed in order to analyze two-dimensional parameters (number, area, roundness, major diameter, minor diameter, and shape factor) at 1, 2 and 3 mm of the apical foramen; three-dimensional parameters (volume, surface area, SMI, number and location of accessory canals), and the external anatomic characteristics of the roots (presence, location, depth and extension of grooves and internal and external root dentin thickness). A qualitative analysis of the internal anatomy of the three-dimensional models was also performed. In the apical third, it was found up to four root canals; the major diameter presented values, on average, twice greater than those of the minor diameter in both dental groups; the values of roundness and shape factor ranged from 0.43±0.25 to 0.61±0.17, and from 0.59±0.26 to 0.80±0.13, respectively, demonstrating the slightly flattened shape with circular tendency of these canals, in the 1MP and 2MP. The three-dimensional analysis showed that the mean volume (mm³), SMI and surface area (mm²) were, respectively, 10.78±5.42, 2.84±0.61 and 58.51±16.41 for the 1MP and 10.89±5.77, 2.46±0.31 and 60.64±17.46 for the 2MP. The accessory canals were observed mostly in the apical and middle third in 56.62% of 1MP and 64.28% of 2MP. In the analysis of the external root surface, 182 radicular grooves were observed in the 1MP and 44 in the 2MP, with prevalence in the mesial face of the examined roots. The deepest groove was found in the region corresponding to half of its total length and the dentin thickness on the internal and external faces of the roots in the region of the radicular grooves decreased in a corono-apical direction, the smallest internal thickness being 1 mm, which characterizes the presence of a danger zone. The three-dimensional models showed a prevalence of single canals leaving the pulp chamber and dividing into two distinct and separate canals (type 1-2) (59.42%) in the 1MP and single canals starting from the pulp chamber up to the apex (type 1) (35.70%) in 2MP. It may be concluded that μTC allowed the study of the internal and external anatomy of the roots, with identification of two new morphological types of SCR in mandibular premolars.

No description available.

The TRUShape 3D Conforming File (TRUShape), a novel, S-shaped nickel-titanium (NiTi) rotary file, was developed to facilitate cleaning and shaping of irregular-shaped root canals. The purpose of this study was to evaluate the shaping ability of TRUShape compared to Vortex Blue (VB) when used in non-round, oval-shaped root canals by micro-computed tomography (MCT). Thirty single-rooted human mandibular premolar teeth with radiographically similar root canal size and curvature were randomly allocated to two groups (N=15), and mechanically prepared with TRUShape or VB. Each tooth was submitted to MCT at 20 μm resolution at three time intervals: before shaping, and after shaping to an intermediate apical size 30 and a final apical size 40. Three-dimensional data sets were superimposed and evaluated for root canal volume, surface area, and treated surface. Matched axial slices in the apical, middle, and coronal root thirds were evaluated for area, roundness, and canal transportation expressed as center of mass shift (CMS). Data were statistically analyzed using parametric and non-parametric tests. Root canal volumes increased similarly and significantly overall (p< 0.001; from an initial volume of 7.3±3.5 mm3 to an intermediate volume of 8.7±3.1 mm3 and a final volume of 9.9±3.0 mm3). Treated canal surface was significantly larger in the TRUShape group at both apical sizes 30 and 40 with 72±15% vs. 55±23% and 85±12% vs. 71±20% non-static voxels for TRUShape and VB, respectively (p< 0.05). Canal transportation was less than 100 μm in all but 8 out of 90 cross sections and was not significantly different between groups. This MCT study demonstrated the TRUShape 3D Conforming File to be effective in the mechanical preparation, specifically, the surface treatment, of single-rooted premolars with non-round, oval-shaped root canals. Funding was provided by the American Association of Endodontists (AAE) Foundation and the Department of Endodontics at the University of Iowa, College of Dentistry.