Intraradicular Dentinal Changes Following Fiber Postremoval: Micro-computed Tomography Analysis.

Context: Excessive dentine wear during postremoval can occur due to the adhesion between the cement and the post. Aim: The aim is to evaluate dentine wear and microcrack occurrence following the removal of intraradicular fiberglass posts that were previously cemented with two types of resin cement. Methods: Distal roots (n = 38) of lower molars were instrumented, filled, prepared for intraradicular postinstallation, and divided into two groups according to the cement used for the posts: RelyX ARC or RelyX U200. The posts were removed through abrasion using ultrasonic diamond tips, after which the degrees of dentine wear (volume/mm3) and microcrack formation were assessed using microcomputed tomographic imaging. Statistical Analysis Used: The Mann-Whitney U (P ≤ 0.05) and Chi-squared tests (P ≤ 0.05) were used. Results: After the removal of the posts, no statistically significant difference in root canal volume or microcrack occurrence was observed between the groups (P > 0.05). The procedure produced significant dentine wear regardless of the type of cement used (P < 0.05). Conclusions: The removal of fiberglass posts caused extensive dentine wear but did not influence microcrack occurrence. The type of resin cement used did not affect the dentine loss or microcrack appearance that resulted from fiberglass postremoval.

Multimethod analysis of three rotary instruments produced by electric discharge machining technology.

AIM: This study aimed to compare three rotary instruments produced by the EDM process with the heat-treated ProTaper Gold system regarding design, metallurgy, mechanical properties and shaping ability. METHODOLOGY: HyFlex EDM (25/~), Neoniti (25/.06), EDMax (25/.06) and ProTaper Gold (25/.08v) instruments (n = 58 per group) were compared regarding design, metallurgy and mechanical performance. Unprepared canal areas were calculated for each system after preparation of mesiobuccal, mesiolingual and distal canals of mandibular molars (15 canals per group) using micro-CT technology. Statistical analyses were performed using One-way anova post-hoc Tukey and Kruskal-Wallis post-hoc Dunn's tests (α = 5%). RESULTS: All instruments had asymmetrical blades, no radial lands, no major defects and almost equiatomic nickel/titanium ratios, but different cross-section designs, tip geometries and surface appearances. Although instruments had distinct transformation temperature curves, they showed crystallographic martensitic arrangement at 21°C and mixed austenite plus R-phase at body temperature. Neoniti and HyFlex EDM showed similar results in all mechanical tests (p > .05), while EDMax and ProTaper Gold had similar time to fracture (p = .841), maximum bending load (p = .729), and cutting ability (p = .985). ProTaper Gold showed the highest torque to failure (p < .001) and HyFlex EDM had the lowest buckling resistance (p < .001). Mean percentages of unprepared canal areas ranged from 20.4% to 25.7% in the mesial canals, and from 20.8% to 26.2% in the distal canal, with no statistical differences among systems (p > .05). CONCLUSIONS: Instruments' geometry and phase transformation temperatures influenced the results of the mechanical tests, but not their shaping ability.

Unraveling potential enzymes and their functional role in fine cocoa beans fermentation using temporal shotgun metagenomics.

Cocoa beans fermentation is a spontaneous process, essential for the generation of quality starting material for fine chocolate production. The understanding of this process has been studied by the application of high-throughput sequencing technologies, which grants a better assessment of the different microbial taxa and their genes involved in this microbial succession. The present study used shotgun metagenomics to determine the enzyme-coding genes of the microbiota found in two different groups of cocoa beans varieties during the fermentation process. The statistical evaluation of the most abundant genes in each group and time studied allowed us to identify the potential metabolic pathways involved in the success of the different microorganisms. The results showed that, albeit the distinction between the initial (0 h) microbiota of each varietal group was clear, throughout fermentation (24-144 h) this difference disappeared, indicating the existence of selection pressures. Changes in the microbiota enzyme-coding genes over time pointed to the distinct ordering of fermentation at 24-48 h (T1), 72-96 h (T2), and 120-144 h (T3). At T1, the significantly more abundant enzyme-coding genes were related to threonine metabolism and those genes related to the glycolytic pathway, explained by the abundance of sugars in the medium. At T2, the genes linked to the metabolism of ceramides and hopanoids lipids were clearly dominant, which are associated with the resistance of microbial species to extreme temperatures and pH values. In T3, genes linked to trehalose metabolism, related to the response to heat stress, dominated. The results obtained in this study provided insights into the potential functionality of microbial community succession correlated to gene function, which could improve cocoa processing practices to ensure the production of more stable quality end products.

Influence of access cavity preparation on the dentine thickness of mesial canals of mandibular molars prepared with reciprocating instruments.

AIM: To evaluate the influence of traditional and conservative access cavity preparations on the remaining dentine thickness in the coronal third of mesial canals of extracted mandibular molars prepared with reciprocating instruments using micro-computed tomography as the analytical tool. METHODOLOGY: Seventy extracted mandibular molars were scanned at a pixel size of 19 µm. From this initial sample, 20 teeth were selected, pair-matched and distributed into two groups (n = 10) according to the access cavity preparation: traditional (TradAC) or conservative (ConsAC). The root canals were sequentially enlarged with Reciproc Blue R25 (size 25, 0.08v taper) and R40 (size 40, 0.06v taper) instruments. A new scan was performed and the postoperative stacks were coregistered with their respective preoperative datasets. A colour-coded cross sections of the roots were created and used to identify and measure the smallest dentine thickness related to both MB and ML canals at 1.0-mm intervals from the furcation level of up to 5 mm in the apical direction, in both mesial and distal aspects of the roots, before and after preparation. The statistical analyses were performed with paired-samples t-test, independent-samples Student T-test and Chi-Square test with a significance level of 5%. RESULTS: At all levels of both groups, dentine thickness before preparation was greater than after preparation (p < .05). No difference in the percentage of dentine reduction was observed between TradAC and ConsAC groups (p > .05), but a significantly greater reduction was observed to the distal aspect of the roots (p < .05). After root canal preparation, dentine thinner than 0.5 mm was observed mostly along the distal aspect of the root (10% to 15%) of the MB and ML canals, with no influence of the access cavity type on its incidence to either mesial (X2  = 1.66; p = .2) or distal (X2  = 0.40; p = .5) directions. In the TradAC group, dentine thickness in most slices was greater than 1.0 mm after preparation (n = 124) whilst, in the ConsAC, it ranged from 0.5 to 1.0 mm (n = 136). CONCLUSION: Traditional or conservative access cavity preparation in extracted mandibular molars did not influence the remaining dentine thickness in the coronal third of mesial canals enlarged with thermomechanically treated nickel-titanium reciprocating instruments.

Efficacy of an arrow-shaped ultrasonic tip for the removal of residual root canal filling materials.

This study aimed to evaluate the efficacy of supplementary methods to remove the remaining root filling material from root canals. Twenty mandibular single-rooted teeth were instrumented with Reciproc 25/0.08 and filled with gutta-percha and AH-Plus sealer, followed by a micro-CT scanning. The retreatment procedures were performed, the samples were rescanned and divided into two groups (n = 10) according to the supplementary method: XP-endo Finisher R and Clearsonic tip. The samples were rescanned and the volume of remaining root filling material was quantified. Data were analysed statistically (P < 0.05). The amount of filling material removed after supplementary methods was higher compared with retreatment procedure (P < 0.05). XP-endo Finisher R promoted a greater percentage of filling materials reduction in the entire root canal and apical third compared with Clearsonic tip (P < 0.05). Supplementary methods were effective in the reduction of root filling materials. XP-endo Finisher R removed more root filling material than Clearsonic tip.

Shaping ability of reciprocating and rotary systems in oval-shaped root canals: a microcomputed tomography study.

This study compared the shaping ability of single-file reciprocating (WaveOne Gold) and multifile rotary (Mtwo) systems on mandibular oval-shaped canine root canals, using microcomputed tomography (micro-CT). Thirty mandibular canines were scanned by micro-CT and assigned to one of two groups (n=15) according to the system used for root canal preparation: WaveOne Gold or Mtwo. After preparation, the teeth were rescanned, and the percentage of untouched canal area, apical transportation and centering ability were analyzed. The data was evaluated using Kruskal and Mann- Whitney tests (p<0.05). No difference was found in percentage of unprepared canal area between groups in the entire root canal or the apical third, or in centering ability (p>0.05). WaveOne gold had less canal transportation than MTwo at the 5 mm section (p<0.05). WOG and Mtwo systems presented similar shaping ability and centering ability in oval-shaped canals. However, WOG presented less transportation than Mtwo at 5 mm from the apex.

Este estudo comparou a capacidade de modelagem dos sistemas reciprocante de lima única (WaveOne Gold) e rotatórios com múltiplas limas (Mtwo) em caninos ovais inferiores, usando microtomografia computadorizada (micro-CT). Trinta caninos inferiores foram escaneados por micro-CT e divididos em dois grupos (n = 15) de acordo com o sistema usado durante o preparo do canal radicular: WaveOne Gold (WOG) e Mtwo. Os dentes foram reeescaneados e a porcentagem de área do canal não preparada, transporte apical e capacidade de centralização foram analisados. Os dados foram avaliados pelos testes de Kruskal Wallis e Mann-Whitney (p<0,05). Nenhuma diferença foi encontrada na porcentagem de área não preparada entre os grupos em todo o canal radicular e no terço apical e na capacidade de centralização (p>0,05). O sistema WOG promoveu menor transporte do canal do que o sistema Mtwo na região de 5mm aquém do ápice (p<0,05). Os sistemas WOG e Mtwo apresentaram capacidade de modelagem e capacidade de centralização semelhantes em canais ovais. No entanto, WOG promoveu menor transporte do que Mtwo a 5 mm do ápice.

Integrating microbial metagenomics and physicochemical parameters and a new perspective on starter culture for fine cocoa fermentation.

Cocoa beans used for chocolate production are fermented seeds of Theobroma cacao obtained by a natural fermentation process. The flavors and chemical compounds produced during the fermentation process make this step one of the most important in fine chocolate production. Herein, an integrative analysis of the variation of microbial community structure, using a shotgun metagenomics approach and associated physicochemical features, was performed during fermentation of fine cocoa beans. Samples of Forastero variety (FOR) and a mixture of two hybrids (PS1319 and CCN51) (MIX) from Bahia, Brazil, were analyzed at 7 different times. In the beginning (0 h), the structures of microbial communities were very different between FOR and MIX, reflecting the original plant-associated microbiomes. The highest change in microbial community structures occurred at the first 24 h of fermentation, with a marked increase in temperature and acetic acid concentration, and pH decrease. At 24-48 h both microbial community structures were quite homogenous regarding temperature, acetic acid, succinic acid, pH, soluble proteins and total phenols. During 72-96 h, the community structure resembles an acidic and warmer environment, prevailing few acetic acid bacteria. Taxonomic richness and abundance at 72-144 h exhibited significant correlation with temperature, reducing sugars, succinic, and acetic acids. Finally, we recommend that dominant microbial species of spontaneous fine cocoa fermentations should be considered as inoculum in accordance with the farm/region and GMP to maintain a differential organoleptic feature for production of fine chocolate. In our study, a starter inoculum composed of Acetobacter pausterianus and Hanseniaspora opuntiae strains is indicated.

Shaping ability of reciprocating and rotary systems in oval-shaped root canals: a microcomputed tomography study / Capacidade de modelagem dos sistemas reciprocante e rotatório em canais radiculares ovais: um estudo de microtomografia computadorizada

ABSTRACT This study compared the shaping ability of single-file reciprocating (WaveOne Gold) and multifile rotary (Mtwo) systems on mandibular oval-shaped canine root canals, using microcomputed tomography (micro-CT). Thirty mandibular canines were scanned by micro-CT and assigned to one of two groups (n=15) according to the system used for root canal preparation: WaveOne Gold or Mtwo. After preparation, the teeth were rescanned, and the percentage of untouched canal area, apical transportation and centering ability were analyzed. The data was evaluated using Kruskal and Mann- Whitney tests (p<0.05). No difference was found in percentage of unprepared canal area between groups in the entire root canal or the apical third, or in centering ability (p>0.05). WaveOne gold had less canal transportation than MTwo at the 5 mm section (p<0.05). WOG and Mtwo systems presented similar shaping ability and centering ability in oval-shaped canals. However, WOG presented less transportation than Mtwo at 5 mm from the apex.

RESUMO Este estudo comparou a capacidade de modelagem dos sistemas reciprocante de lima única (WaveOne Gold) e rotatórios com múltiplas limas (Mtwo) em caninos ovais inferiores, usando microtomografia computadorizada (micro-CT). Trinta caninos inferiores foram escaneados por micro-CT e divididos em dois grupos (n = 15) de acordo com o sistema usado durante o preparo do canal radicular: WaveOne Gold (WOG) e Mtwo. Os dentes foram reeescaneados e a porcentagem de área do canal não preparada, transporte apical e capacidade de centralização foram analisados. Os dados foram avaliados pelos testes de Kruskal Wallis e Mann-Whitney (p<0,05). Nenhuma diferença foi encontrada na porcentagem de área não preparada entre os grupos em todo o canal radicular e no terço apical e na capacidade de centralização (p>0,05). O sistema WOG promoveu menor transporte do canal do que o sistema Mtwo na região de 5mm aquém do ápice (p<0,05). Os sistemas WOG e Mtwo apresentaram capacidade de modelagem e capacidade de centralização semelhantes em canais ovais. No entanto, WOG promoveu menor transporte do que Mtwo a 5 mm do ápice.

Mechanical Tests, Metallurgical Characterization, and Shaping Ability of Nickel-Titanium Rotary Instruments: A Multimethod Research.

INTRODUCTION: This study aimed to compare the mechanical and metallurgical properties and shaping ability of different rotary systems using a multimethod approach. METHODS: New NeoNiti A1 (Neolix SAS, Châtres-La-Forêt, France), HyFlex EDM One File (Coltène/Whaledent, Altstätten, Switzerland), ProTaper Gold F2 (Dentsply Maillefer, Ballaigues, Switzerland), and ProTaper Universal F2 (Dentsply Maillefer) rotary instruments were tested regarding cyclic fatigue, torsional resistance, design, and morphologic characteristics using scanning electron microscopy, metal alloy characterization using differential scanning calorimetry, and energy-dispersive X-ray spectroscopy. Additionally, their shaping ability on the preparation of 48 canals of maxillary molars was evaluated using micro-computed tomographic technology. Mechanical and metallurgical analyses were compared using analysis of variance post hoc Tukey tests, whereas the independent Student t test was used to compare the shaping ability of the ProTaper systems or the thermomechanically treated instruments. The significance level was set at 5%. RESULTS: The highest cyclic fatigue was observed with the NeoNiti and HyFlex EDM instruments (P > .05), whereas HyFlex EDM had the highest angular rotation to fracture (P < .05). Scanning electron microscopic/energy-dispersive X-ray spectroscopic analyses confirmed similarities in the instruments' design and an almost equiatomic composition of the systems. Differential scanning calorimetry showed that ProTaper Gold had higher transformation temperatures than ProTaper Universal, whereas a similar transformation was observed between NeoNiti and HyFlex. Micro-computed tomographic analysis revealed that, despite the fact that none of the systems was able to prepare all root canal walls, no statistical differences were observed in either ProTaper systems (P > .05) or the thermomechanically treated instruments (P > .05). CONCLUSIONS: Apart from differences in the mechanical tests and metallurgical characterization, systems with comparable instrument dimensions and preparation protocols showed a similar percentage of untouched surface areas in the root canal preparation of maxillary molars.

Radiographic Diagnosis of Simulated External Root Resorption in Multi-Rooted Teeth: The Influence of Spatial Resolution.

The aim of this study was to evaluate the influence of spatial resolution (line pairs per millimetre - lp/mm) on the diagnosis of simulated external root resorption (ERR) in multi-rooted teeth by using digital periapical radiography. Forty human mandibular molars (80 roots) were used. The roots were divided into the following groups (n = 10): control without root filling (WORF), control with root filling (WRF), small ERRWORF, small ERR-WRF, moderate ERR-WORF, moderate ERR-WRF, extensive ERR-WORF and extensive ERR-WRF. Four digital radiographs (phosphor storage plates - PSP system) were taken of each tooth in three angulations. The PSPs were scanned with 10, 20, 25 and 40 lp/mm. All images were assessed by three endodontists who used a five-point scale for presence and absence of ERR and classified its location (cervical, middle or apical third). ROC curves and one-way ANOVA were performed (p < 0.01). Diagnosis of ERR in nonroot-filled teeth showed higher values of sensitivity for 20 lp/mm and higher values of both specificity and accuracy for 40 lp/mm. In root-filled teeth, sensitivity and accuracy were higher for 25 lp/mm and spatial resolution had no influence on specificity. The best resolution for diagnosis of small and extensive ERR was 25 lp/mm, whereas for moderate ERR, it was 40 lp/mm. Cervical ERR was the most difficult to diagnose, regardless of the spatial resolution. Higher spatial resolutions have improved the radiographic diagnosis of simulated ERR in multi-rooted teeth and this should be considered when performing digital radiographs.

O objetivo deste estudo foi avaliar a influência do número de pares de linhas em radiografia intra-oral digital, na precisão da detecção de reabsorção radicular externa. Quarenta molares inferiores (n=80 raízes) foram submetidos ao preparo químico mecânico e em então, metade da amostra foi obturada. Em seguida, as raízes dos dentes foram aleatoriamente divididas de acordo com o tamanho da reabsorção radicular a ser simulada e com a presença e ausência de tratamento endodôntico. As RRE foram realizadas com brocas esféricas diamantadas de tamanhos 1/2, 1, 2. Executou-se radiografias digitais por meio do sistema de aquisição semidireto com a utilização de placas de fósforo fotoestimuladas (PSP). Em cada dente, incidências orto, mésio e distorradial foram repetidas quatro vezes, para que pudessem ser digitalizadas com resoluções de 10, 20, 25, 40 pl/mm. Após análise, verificou-se que dentes obturados apresentaram menores valores de sensibilidade com 10, 20 e 25 pl/mm e maiores valores de especificidade e acurácia para as mesmas resoluções. Dentes sem obturação registraram maiores valores de sensibilidade para resolução 20 e menor para 40; no entanto, a especificidade e a acurácia, foram maiores com 40 e menores em 10. Em RRE pequena, as resoluções 10 e 25 pl/mm foram respectivamente menos e mais acuradas; RRE média, foi maior com 40 pl/mm e RRE grandes foram melhores identificadas com 25. Correlacionando acertos no diagnóstico com localização das RRE, verificou-se que o terço cervical apresentou-se menos detectável. Concluiu-se que resolução espacial influenciou a detecção de RRE simuladas em radiografias periapicais digitais.

Internal Lower Incisor Morphology revealed by Computerized Microtomography.

This study evaluated the internal morphology of lower incisors using computerized microtomography (micro-CT) images. Eighty-nine lower incisors were scanned by micro-CT and reconstructed with NRecon software. 2D parameters (perimeter, root length, circularity and canal diameter) and 3D parameters (volume, surface area and structure model index) were evaluated with CTAn and CTVol software. The results are presented descriptively. It was found that 89.9% of the canals had a single main root canal (type I), followed by type II (6.7%) and III (3.4%), while 5.6% of the specimens presented lateral canals and 1.1% had an apical delta. Mean volume and surface area were 31.80mm³ and 90.58mm², respectively. The most prevalent shape of the root canal at CEJ level was circular (41.6%) and 1mm from the apex, 73% of the samples were classified as oval. Lower incisors with internal anatomical variations may offer a high degree of technical complexity and may result in treatment failure.

Este estudo avaliou a morfologia interna dos dentes incisivos inferiores utilizando imagens de microtomografia computadorizada (micro-TC). 89 incisivos inferiores foram escaneados or micro-CT e reconstruídos com o programa NRecon. Parâmetros 2D - perímetro, comprimento da raiz, circularidade e diâmetro do canal - e parâmetros 3D - volume, área superficial e índice de modelo de estrutura - foram avaliados com os softwares CTAn e CTVol. Os resultados foram apresentados de forma descritiva. 89,9% dos canais apresentaram um único canal radicular principal (tipo I), seguido pelo tipo II (6,7%) e III (3,4%). 5,6% dos espécimes apresentavam canais laterais e 1,1% delta apical. O volume médio e a área de superfície foram 31,80mm³ e 90,58mm², respectivamente. A forma mais prevalente do canal radicular no nível da CEJ foi circular (41,6%) e a 1 mm do ápice, 73% das amostras foram classificadas como ovais. Incisivos inferiores com variações anatômicas internas podem oferecer um alto grau de complexidade técnica e resultar em falha do tratamento.

Radiographic Diagnosis of Simulated External Root Resorption in Multi-Rooted Teeth: The Influence of Spatial Resolution / Diagnóstico radiográfico de reabsorção externa simulada em dentes multiradiculares: influência da resolução especial

ABSTRACT The aim of this study was to evaluate the influence of spatial resolution (line pairs per millimetre - lp/mm) on the diagnosis of simulated external root resorption (ERR) in multirooted teeth by using digital periapical radiography. Forty human mandibular molars (80 roots) were used. The roots were divided into the following groups (n = 10): control without root filling (WORF), control with root filling (WRF), small ERRWORF, small ERRWRF, moderate ERRWORF, moderate ERRWRF, extensive ERRWORF and extensive ERRWRF. Four digital radiographs (phosphor storage plates - PSP system) were taken of each tooth in three angulations. The PSPs were scanned with 10, 20, 25 and 40 lp/mm. All images were assessed by three endodontists who used a fivepoint scale for presence and absence of ERR and classified its location (cervical, middle or apical third). ROC curves and oneway ANOVA were performed (p < 0.01). Diagnosis of ERR in nonrootfilled teeth showed higher values of sensitivity for 20 lp/mm and higher values of both specificity and accuracy for 40 lp/mm. In rootfilled teeth, sensitivity and accuracy were higher for 25 lp/mm and spatial resolution had no influence on specificity. The best resolution for diagnosis of small and extensive ERR was 25 lp/mm, whereas for moderate ERR, it was 40 lp/mm. Cervical ERR was the most difficult to diagnose, regardless of the spatial resolution. Higher spatial resolutions have improved the radiographic diagnosis of simulated ERR in multirooted teeth and this should be considered when performing digital radiographs.

RESUMO O objetivo deste estudo foi avaliar a influência do número de pares de linhas em radiografia intraoral digital, na precisão da detecção de reabsorção radicular externa. Quarenta molares inferiores (n=80 raízes) foram submetidos ao preparo químico mecânico e em então, metade da amostra foi obturada. Em seguida, as raízes dos dentes foram aleatoriamente divididas de acordo com o tamanho da reabsorção radicular a ser simulada e com a presença e ausência de tratamento endodôntico. As RRE foram realizadas com brocas esféricas diamantadas de tamanhos 1/2, 1, 2. Executouse radiografias digitais por meio do sistema de aquisição semidireto com a utilização de placas de fósforo fotoestimuladas (PSP). Em cada dente, incidências orto, mésio e distorradial foram repetidas quatro vezes, para que pudessem ser digitalizadas com resoluções de 10, 20, 25, 40 pl/mm. Após análise, verificouse que dentes obturados apresentaram menores valores de sensibilidade com 10, 20 e 25 pl/mm e maiores valores de especificidade e acurácia para as mesmas resoluções. Dentes sem obturação registraram maiores valores de sensibilidade para resolução 20 e menor para 40; no entanto, a especificidade e a acurácia, foram maiores com 40 e menores em 10. Em RRE pequena, as resoluções 10 e 25 pl/mm foram respecti vamente menos e mais acuradas; RRE média, foi maior com 40 pl/mm e RRE grandes foram melhores identificadas com 25. Correlacionando acertos no diagnóstico com localização das RRE, verificouse que o terço cervical apresentouse menos detectável. Concluiuse que resolução espacial influenciou a detecção de RRE simuladas em radiografias periapicais digitais.

Internal Lower Incisor Morphology revealed by Computerized Microtomography / Morfologia interna de incisivos inferiores reveladas por microtomografía computadorizada

ABSTRACT This study evaluated the internal morphology of lower incisors using computerized microtomography (microCT) images. Eightynine lower incisors were scanned by microCT and reconstructed with NRecon software. 2D parameters (perimeter, root length, circularity and canal diameter) and 3D parameters (volume, surface area and structure model index) were evaluated with CTAn and CTVol software. The results are presented descriptively. It was found that 89.9% of the canals had a single main root canal (type I), followed by type II (6.7%) and III (3.4%), while 5.6% of the specimens presented lateral canals and 1.1% had an apical delta. Mean volume and surface area were 31.80mm³ and 90.58mm², respectively. The most prevalent shape of the root canal at CEJ level was circular (41.6%) and 1mm from the apex, 73% of the samples were classified as oval. Lower incisors with internal anatomical variations may offer a high degree of technical complexity and may result in treatment failure.

RESUMO Este estudo avaliou a morfologia interna dos dentes incisivos inferiores utilizando imagens de microtomografia computado rizada (microTC). 89 incisivos inferiores foram escaneados por microCT e reconstruídos com o programa NRecon. Parâmetros 2D perímetro, comprimento da raiz, circularidade e diâmetro do canal e parâmetros 3D volume, área superficial e índice de modelo de estrutura foram avaliados com os softwares CTAn e CTVol. Os resultados foram apresentados de forma descritiva. 89,9% dos canais apresentaram um único canal radicular principal (tipo I), seguido pelo tipo II (6,7%) e III (3,4%). 5,6% dos espécimes apresentavam canais laterais e 1,1% delta apical. O volume médio e a área de superfície foram 31,80mm³ e 90,58mm², respectivamente. A forma mais prevalente do canal radicular no nível da CEJ foi circular (41,6%) e a 1 mm do ápice, 73% das amostras foram classificadas como ovais. Incisivos inferiores com variações anatômicas internas podem oferecer um alto grau de complexidade técnica e resultar em falha do tratamento.