Comparison Between Radiographs, White and Fluorescent Images in the Diagnosis and Treatment Decisions for Occlusal Caries: An Ex Vivo Study

ABSTRACT Objective: To compare the agreement of images in white light (WL), fluorescence (FL), and digital radiographs (DR), on the diagnosis and treatment decisions for occlusal caries lesions against a micro-CT gold standard. Material and Methods: Ten extracted third molars, with enamel and/or dentin caries (ICDAS 2-4), were included. Occlusal surface images were acquired with an intraoral camera (SoproLife®) in WL and FL modes. DR was obtained using an intraoral X-ray and a semi-direct digital system. A total of 780 images were needed, organized in a template, to be later examined by twenty-six dentists invited to compose the study. The Generalized Estimation Equations model was used to compare the proportions of the correct answers between the three methods and the gold standard. When significant, Bonferroni post-hoc test was used to identify differences (α=5%). Results: Most of the examiners were specialists (76.9%) with 14.5 years of experience. All diagnostic methods were similar and showed low agreement (DR 12.7%, WL 16.5%, and FL 16.5%) compared with gold standard caries diagnostic scores. Regarding treatment decisions, mean agreement for all diagnostic methods was higher (43.2%; p<0.001), and among all methods, WL (48.1%) and FL (51.2%) modes performed better than DR (30.4%, p<0.001). Conclusion: SoproLife® images could help clinicians to propose rational, minimally invasive treatments for occlusal caries lesions.

Methodological considerations for a model of endodontic treatment in Wistar rats / Consideraciones metodológicas para el modelo de tratamiento endodóntico en ratas Wistar

ABSTRACT The use of correctly designed animal models is a fundamental step prior to clinical trials in humans. Although rats are easy to house and handle, and have molars that resemble those of humans, very few researchers use them as a model for root canal treatment, probably due to their small size and the lack of relevant data necessary to reproduce the model. Our aims were to describe the anatomic and histologic characteristics of the mandibular first molar of the Wistar rat and present a standardised model for its experimental endodontic treatment. Twenty female rats were used. The characteristics of the mesial and distal roots were described histologically and the quality of the results achieved following the treatment protocol presented herein was assessed by means of digital radiographs, micro-CT and histological sections. The age of 55 days was found to be the most adequate for performing this technique, but we consider the interval of 50 to 60 days to be suitable. Both canals are oval, although in opposite planes, and the furcating-facing walls present the minimum dentine thickness. It was essential to become familiar with these aspects in order to decide upon the most appropriate instrumentation and obturation techniques that would enable replication of this model in basic science research.

RESUMEN El uso de modelos animales correctamente diseñados es un paso fundamental previo al desarrollo de ensayos clínicos en humanos. A pesar de resultar fáciles de criar y manipular y de poseer molares que se asemejan a los humanos, muy pocos grupos utilizan a la rata como modelo experimental para el tratamiento endodóntico probablemente debido a su pequeño tamaño y a la escasa información disponible para poder aplicar los modelos existentes. Nuestros objetivos fueron describir las características anatómicas e histológicas del primer molar inferior de la rata Wistar y presentar un modelo estandarizado para el tratamiento endodóntico experimental de esta pieza. Se utilizaron 20 ratas hembra. Las características de las raíces mesial y distal fueron descritas histológicamente y los resultados obtenidos fueron evaluados mediante radiografías digitales, microCTy cortes histológicos. La edad de 55 días demostró ser la más adecuada para ejecutar la técnica, pero consideramos que el intervalo de 50 a 60 días puede resultar apropiado. Se observó que ambos canales presentan una morfología oval, aunque en direcciones opuestas, y que las paredes furcales resultaron ser las que presentan el menor espesor de dentina. Familiarizarse con estos aspectos de la anatomía e histología del molar de la rata resultó fundamental para decidir sobre las técnicas de preparación y obturación más apropiadas que permitieran la replicación de este modelo en el campo de las ciencias básicas.

Avaliação in vitro da microdureza e porosidade de duas resinas compostas fotopolimerizáveis / Evaluación in vitro de la microdureza y porosidad de dos resinas compuestas fotopolimerizables / In vitro evaluation of the microhardness and porosity of two photopolymerizable composite resins

RESUMO Introdução: Os estudos científicos acerca das propriedades físicas e mecânicas apresentadas pelas resinas compostas são cada vez mais necessários diante da grande variedade de produtos disponíveis no mercado atual, resultante do aumento de sua demanda dentro da odontologia que preza por preparos minimamente invasivos com a devolução das características estéticas e funcionais do elemento dentário. Objetivo: Avaliar e comparar a microdureza e porosidade das resinas compostas fotopolimerizavéis Filtek Z350 XT 3M e Zirconfill Technew. Métodos: Foram confeccionados 10 corpos de prova por amostra (n= 10) submetidos a teste microdureza Vickers e porosidade por microtomografia computadorizada. Resultados: Com relação à presença de porosidades, dada em porcentagem, o grupo da Filtek apresentou os menores valores médios. Quando comparado estatisticamente, os grupos apresentaram diferença estatística (p= 0,019), com uma magnitude de efeito alta. Com relação aos valores de microdureza, o grupo da Filtek apresentou os maiores valores médios. Quando comparados estatisticamente, os grupos não apresentaram diferença estatística (p > 0,05). Conclusões: A porosidade foi significativamente diferente entre os grupos estudados, sendo o grupo Filtek Z350XT de menor percentual. No entanto, os grupos não apresentaram diferença estatística para microdureza, apesar do grupo Filtek Z350XT ter apresentado maior valor médio(AU)

RESUMEN Introducción: Los estudios científicos sobre las propiedades físicas y mecánicas presentadas por las resinas compuestas son cada vez más necesarios ante la gran variedad de productos disponibles en el mercado actual, resultante del aumento de su demanda dentro de la odontología que aprecia por preparaciones mínimamente invasivas con la devolución de las características estéticas y funcionales del elemento dental. Objetivo: Evaluar y comparar la microdureza y porosidad de las resinas compuestas fotopolimerizables Filtek Z350 XT 3M y Zirconfill Technew. Métodos: Se han confeccionado 10 cuerpos de prueba por muestra (n= 10) sometidos a prueba de microdureza Vickers y porosidad por microtomografía computarizada. Resultados: Con respecto a la presencia de porosidades, dada en porcentaje, el grupo de Filtek presentó los menores valores medios. Cuando se comparó estadísticamente, los grupos presentaron una diferencia estadística (p= 0,019), con una magnitud de efecto alto. Con respecto a los valores de microdureza, el grupo de Filtek presentó los mayores valores medios. Cuando se comparó estadísticamente, los grupos no presentaron una diferencia estadística (p> 0,05). Conclusiones: La porosidad fue significativamente diferente entre los grupos estudiados, siendo el grupo Filtek Z350XT de menor porcentaje. Sin embargo, los grupos no presentaron diferencia estadística para microdureza, a pesar de que el grupo Filtek Z350XT presentó un valor medio más alto(AU)

ABSTRACT Introduction: Scientific studies about the physical and mechanical properties of composite resins are increasingly needed in view of the wide variety of products available in the market today, resulting from the increase in their demand for dental care purposes, with a preference for minimally invasive preparations aimed at restoring the esthetic and functional characteristics of the treated element. Objective: Evaluate and compare the microhardness and porosity of the photopolymerizable composite resins Filtek Z350 XT and Zirconfill Technew. Methods: Ten test bodies were developed per sample (n= 10) and subjected to Vickers microhardness and porosity testing by computerized microtomography. Results: With respect to the presence of porosity, expressed in percentages, the Filtek group had the lowest mean values. When compared statistically, the two groups showed a statistical difference (p= 0.019) with a high effect magnitude. Regarding microhardness, the Filtek group had the highest mean values. Statistical comparison did not find any difference between the groups (p> 0.05). Conclusions: Porosity was significantly different in the groups studied, the Filtek Z350XT group exhibiting the lowest percentage. However, the groups did not show any statistical difference concerning microhardness, despite the fact that the Filtek Z350XT group had a higher mean value(AU)

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.

A micro-CT study of different regions of the atlas / Un estudio de micro-CT de diferentes regiones del atlas

This study aimed to examine the differences in bone microarchitecture between different regions of the atlas in 28 dry atlas specimens using micro-CT, in order to explain the mechanism of the predilection sites of atlas fractures from the morphological point of view. A total of 28 dry specimens of intact adult atlas were randomly selected, scanned by micro-CT, and divided into a region from the anterior arch midpoint (AAM) to the lateral masses (LM), a LM region, and a region from the LM to the posterior arch midpoint (PAM). Trabecular thickness, separation, number, connectivity, and structure model index were measured for each of the three regions using the built-in software of the CT scanner. Trabecular thickness was all measured to be 0.11 ± 0.00 mm for AAM to LM, LM, and LM to PAM. Trabecular separation: AAM to LM > LM to PAM > LM. Trabecular number: LM > LM to PAM > AAM to LM. Connectivity: LM > LM to PAM > AAM to LM. Structure model index: LM > LM to PAM > AAM to LM. A lower trabecular number and connectivity and higher trabecular separation were seen in the anterior and posterior arches of the atlas, in which higher fracture rates were reported. By contrast, a higher trabecular number and connectivity and lower trabecular separation were seen in the lateral masses, in which lower fracture rates were reported.

Este estudio tuvo como objetivo examinar las diferencias en la microarquitectura ósea entre diferentes regiones del atlas en 28 muestras de atlas secas utilizando micro-CT, con el fin de informar el área de mayor frecuencia en las fracturas de atlas, desde el punto de vista morfológico. Se seleccionaron al azar un total de 28 muestras secas de atlas adultos intactas las que se escanearon por micro-CT y se dividieron en una región desde el punto medio del arco anterior (MAA) hasta las masas laterales (ML), una región ML y una región desde el ML hasta el punto medio del arco posterior (MAP). Se midió el grosor trabecular, la separación, el número, la conectividad y el índice del modelo de estructura para cada una de las tres regiones utilizando el software incorporado del escáner CT. El grosor trabecular se midió en 0,11 ± 0,00 mm para MAA a ML, ML y ML a MAP. Separación trabecular: MAA a ML> ML a MAP> ML. Número trabecular: ML> ML a MAP> MAA a ML. Conectividad: ML> ML a MAP> MAA a ML. Índice del modelo de estructura: ML> ML a MAP> MAA a ML. Se observó un menor número de estructuras trabeculares y conectividad y una mayor separación trabecular en los arcos anterior y posterior del atlas, en los que se informaron tasas de fracturas más altas. Por el contrario, se observó un mayor número de estructuras trabeculares y conectividad, y una menor separación trabecular en las masas laterales, en las que se observó un número menor de fracturas.

Micro-computed tomographic assessment of the variability and morphological features of root canal system and their ramifications

Abstract Objectives This study assessed the incidence and variability features of root canals system (RCS) and their ramifications according to Pucci & Reig (PR) (1944) and the American Association of Endodontists (AAE) (2017) by micro-computed tomography (μCT). Methodology 500 representative extracted human teeth of each tooth group (n=50) (maxillary/mandibular central and lateral incisors, canines, first and second premolars and molars) were scanned by μCT with a resolution of 26.70 μm. The reconstructed cross-sections images and the visualization of the continuous slices in the transversal axis were performed using DataViewer software. RCS were classified according to Pucci & Reig (main canal, collateral canal, lateral canal, secondary canal, accessory canal, intercanal, recurrent canal) and AAE (main canal, accessory canal, lateral canal). The apical deltas were assessed for both classifications. The prevalence of apical deltas was evaluated using the Chi-squared test (p<0.05). Results According to PR, a higher incidence of lateral canals was observed in maxillary canines (10%), central incisors (8%) and first premolars (6%). Using AAE, the highest incidence of lateral canals was observed in the mandibular first premolars (85%), first and second molars (84%), lateral incisors (67%), canines (59%), and in maxillary first premolars (52%). Regarding accessory canals, the PR showed a frequency in 2% of the maxillary lateral incisors and maxillary and mandibular first premolars and 3% of mandibular first and second molars. On the other hand, the AAE showed the highest incidence of accessory canals in 86% of the maxillary first premolars, 71% in mandibular lateral incisors, 69% in mandibular first premolars, 65% in mandibular canines, and 56% in maxillary canines. The PR showed the lowest incidence of apical deltas for all dental groups when compared with AAE (p=0.004). Interestingly, distal canals in maxillary molars showed a significant discrepancy between classifications (p=0.027). Conclusions μCT enabled accurately describing the RC system and related ramifications, adding to the PR and AAE classifications, with some discrepancies reported for maxillary molars. Clinical Relevance This μCT study enabled a thorough description of the variability among root canals and their ramifications, including clinically relevant details on the presence and location of lateral canals and accessories in all human tooth groups, beyond the currently existing classification systems.

Cone-beam and micro-computed tomography for the assessment of root canal morphology: a systematic review

Abstract This study presents an overview of the accuracy of cone beam computed tomography (CBCT) compared with micro-computed tomography (μCT) in the assessment of root canal morphology of extracted human permanent teeth. A database search in PubMed, PubMed Central, Embase, Scopus, Opengrey, Scielo and Virtual Health Library was conducted which compared root canal morphology of extracted human permanent teeth on the accuracy of CBCT with μCT. In accordance with PRISMA statement guidelines, data were extracted on study characteristics, target mediators, sampling and assay techniques and the parameters associated with obtaining the image and ability to identify the root canal morphology. Amongst 2734 records, ten fulfilled the inclusion criteria. Four studies compared the accuracy of CBCT and μCT in the assessment of root canal morphology using Vertucci's classification, with at least one CBCT group or subgroup of each study presented high agreement compared to the μCT. Six studies assessed more detailed root canal morphology, including two articles that found a lack of agreement between these imaging systems. Risk of bias was deemed low in three studies, moderate in four and high in three. CBCT can be as accurate as μCT in the assessment of several morphological features of extracted human permanent teeth; however there are some exceptions related to the more detailed morphological aspects. Voxel size likely influences the ability to detect these features, though the different aspects of exposure setting used in studies components may be confounding factors. CBCT may be considered for the assessment of root canal morphology ex-vivo.

A micro-CT evaluation of the performance of rotary and reciprocating single-file systems in shaping ability of curved root canals

Abstract To compare the shaping ability of different single-file systems in the preparation of mesial curved canals of mandibular molars using micro-CT technology. Fifteen mesial roots of mandibular molars with two independent and curved canals (n = 30) were selected, scanned at a resolution of 26.7 μm anatomically matched, and distributed into three groups (n = 10), according to the preparation system: WaveOne 25.08, Reciproc 25.08, and OneShape 25.06. A final micro-CT scanning was performed, data sets were registered with their respective counterparts, and compared regarding the three-dimensional (volume, surface area, and structure model index - SMI) and two-dimensional (perimeter, area, roundness, major and minor diameters) parameters, as well as, canal transportation, using ANOVA and post hoc Tukey tests (α = 5%). Overall, no difference was observed between groups regarding area, perimeter, volume, surface area, and canal transportation (p > 0.05). Within group, no canal transportation was significantly higherobserved in the apical third (0.10 ± 0.05 mm) compared to coronal (0.08±0.040 mm) and middle (0.07 ± 0.03 mm) thirds (p < 0.05). Structure model index (SMI) was statistically higher after preparation with OneShape instrument (0.36 ± 0.26) compared to other systems (p < 0.05). Within the parameters of this study, similar shaping ability was observed in the preparation of mesial curved root canals of mandibular molars with Reciproc, OneShape and WaveOne systems.

A Radiographic Comparison of Two Methods of Hand and Automated Instrumentation for Preparations of Simulated Curved Root Canals / Comparación Radiográfica de Dos Métodos de Instrumentación Manual y Automatizado para Preparaciones de Canales Radiculares Curvos Simulados

ABSTRACT: The present study evaluated the presence of apical deviation and tapering in preparations performed with the use of the automated handpieces with continuous motion, the K3 Endo system (Group 1) and instrumentation manually with Protaper (Group 2). 30 simulated roots were divided into two groups and prepared according each technique. The alteration caused by root canal preparation was analyzed by radiographs obtained on a radiographic desk fabricated for the study. The results (X2), demonstrated that the K3 Endo produced a smaller incidence of apical deviation and Protaper produced a greater tapering of the root canals.

RESUMEN: El objetivo de este trabajo fue evaluar la presencia de desviación y conicidad adecuada apical con el uso del sistema de instrumentación de movimiento continuo K3 Endo (Grupo 1) respecto a la instrumentación manual realizada con Limas Protaper (Grupo 2). Treinta canales curvos simulados fueron divididos aleatoriamente en dos grupos e instrumentados por los diferentes sistemas. La alteración causada por la preparación de los canales fue analizada en radiografías obtenidas, en placas ad hoc. Los resultados (X2) demostraron que el K3. Endo produjo una menor incidencia de desviación apical y Protaper produjo una mayor conicidad de los canales radiculares.

Micro-architecture study of the normal infant auditory ossicles with micro-computed tomography / Estudio de microarquitectura de los osículos auditivos infantiles normales con tomografía microcomputarizada

This study aimed to investigate the micro-anatomical morphology of ossicular chain in term fetus using micro-CT, in order to analyze the parameters of internal ossicular structure that may affect sound conduction.Four ossicular chains from two term fetuses were scanned by micro-CT. The related structural parameters of the trabeculae within the incus and malleus were calculated and compared. The fine anatomical structure of the auditory ossicles was analyzed.The microstructure of each auditory ossicles in term fetuses was clearly revealed by micro-CT. A marrow cavity was observed in the incus and malleus. In statistical analysis of the structural parameters of trabeculae in the incus and malleus, significant differences were found in BS/BV and Tb.Th (P < 0.05). Micro-CT enables the visualization of internal ossicular structure. The auditory ossicles in term fetus has good bone quality. The obtained bone structure data will help to clarify the physiological functions of normal fetal auditory ossicles.

Este estudio tuvo como objetivo investigar la morfología microanatómica de la cadena osicular en el feto a término con micro-CT, con el fin de analizar los parámetros de la estructura osicular interna que pueden afectar la conducción del sonido. Cuatro cadenas osiculares de dos fetos a término fueron examinadas por micro-CT. Se calcularon y compararon los parámetros estructurales relacionados de las trabéculas dentro de los incus y malleus. Se analizó la estructura anatómica fina de los osículos. Se observó claramente la microestructura de cada osículo en los fetos y la cavidad medular en el incus y el malleus. En el análisis estadístico de los parámetros estructurales de las trabéculas en el incus y el malleus, se encontraron diferencias significativas en BS / BV y Tb.Th (P <0,05). Micro-CT permite la visualización de la estructura osicular interna. Los osículos en el feto a término tienen buena calidad ósea. Los datos obtenidos de la estructura ósea ayudarán para aclarar las funciones fisiológicas de los osículos auditivos fetales normales.

Ultrasonic tips as an auxiliary method for the instrumentation of oval-shaped root canals

Abstract To evaluate the influence of novel ultrasonic tips as an auxiliary method for the rotary preparation of flattened/oval-shaped canals. Forty-five mandibular incisors were selected and divided into one of three experimental groups (n = 15): Group PFCP - ProDesign Logic 25/.05 + Flatsonic + Clearsonic + Prodesign Logic 40/.01; Group FCP - Flatsonic + Clearsonic + ProDesign Logic 40/.01; and Group PP - Prodesign Logic 25/.05 + Prodesign Logic 40/.05. The teeth were scanned preoperatively and postoperatively using microcomputed tomography. The percentage values for increase in volume, non-instrumented surface area, dentin removal, degree of canal transportation, and centering ratio between the experimental groups were examined. Data were analyzed using the non-parametric Kruskal-Wallis and Dunn's tests (p < 0.05). Group PFCP showed the greatest volume increase in the total portion of the root canal and the lowest percentage of non-instrumented surface area. Regarding the degree of transportation in the buccolingual direction, statistically significant differences between groups PFCP and PP were observed at the coronal third of the canal. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. As for the centering ratio, statistically significant differences were found in the buccolingual direction. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. The use of novel ultrasonic tips combined with rotary instruments in group PFCP provided a significant increase in volume and reduced the percentage of non-instrumented areas during the preparation of flattened/oval-shaped canals.

Evaluation of flow and filling of root canal sealers using different methodologies / Avaliação do escoamento e preenchimento de cimentos obturadores utilizando diferentes metodologias

Abstract Introduction Flow and filling ability of root canal sealers are indispensable for hermetic sealing of the root canal. Micro-computed tomography (micro-CT) can be used as a complementary methodology to evaluate such properties. Objective To evaluate the flow and filling ability of AH Plus, Endofill and Sealapex by conventional methodology and micro-CT. Material and method The flow of the sealers was analyzed according to ISO 6876/2012 and complemented by the area evaluation. Glass plates were manufactured with diameters of 1×1×2 mm and 1×1×1 mm (length, width and height), with a central cavity and four grooves in the horizontal and vertical directions. Each material was placed in the central cavity. Another glass plate and a metal weight were placed on the cement and kept for 10 minutes. The glass plate/sealer set was scanned using micro-CT. The flow was calculated by linear measurement of the material in the grooves. The central filling (mm3) was calculated in the central cavity and the lateral filling was measured up to 2 mm from the central cavity. Data were submitted to ANOVA/Tukey tests (α=0.05). Result All evaluated sealers presented flow according to ISO 6876 standards. The materials showed central cavity filling capacity higher than 80% and lateral filling greater than 75%. There was no difference in flow (mm and mm2) and in the filling ability (mm3) provided by the materials (p>0.05). Conclusion All evaluated root canal sealers showed adequate flow and filling capacity, suggesting their clinical application.

Resumo Introdução Escoamento e capacidade de preenchimento de cimentos obturadores são indispensáveis para um selamento hermético do canal radicular. Microtomografia computadorizada (micro-CT) pode ser utilizada como uma metodologia complementar para avaliação de tais propriedades. Objetivo Avaliar escoamento e capacidade de preenchimento de AH Plus, Endofill e Sealapex, por meio de metodologia convencional e micro-CT. Material e método O escoamento dos cimentos foi analisado de acordo com as normas ISO 6876/2012 e complementado pela avaliação em área. Placas de vidro foram confeccionadas nos diâmetros de 1×1×2 mm e 1×1×1 mm (comprimento, largura e altura), com uma cavidade central e quatro canaletas nas direções horizontal e vertical. Cada material foi colocado na cavidade central. Outra placa de vidro e um peso de metal foram colocados sobre o cimento e mantidos por 10 minutos. O conjunto placa de vidro/cimento foi escaneado usando micro-CT. O escoamento foi calculado por medição linear do material nas canaletas. O preenchimento (mm3) central foi calculado na cavidade central e o preenchimento lateral foi medido até 2 mm a partir da cavidade central. Os dados foram submetidos aos testes ANOVA/Tukey (α=0.05). Resultado Todos os cimentos avaliados apresentaram escoamento de acordo com as normas ISO 6876. Os materiais mostraram capacidade de preenchimento da cavidade central superior a 80% e preenchimento lateral superior a 75%. Não houve diferença no escoamento (mm e mm2) e na capacidade de preenchimento (mm3) proporcionada pelos materiais (p>0.05). Conclusão Todos os cimentos obturadores avaliados mostraram adequado escoamento e capacidade de preenchimento, sugerindo a aplicação clínica dos mesmos.

Polymerization shrinkage of bulk fill composites and its correlation with bond strength

Abstract The present study aimed to evaluates polymerization shrinkage (PS) using microcomputed tomography (μCT) and microtensile bond strength (μTBS) in bulk fill composites (BFC) and conventional class I restorations as well as the correlation between these factors. Class I cavities (4 x 5 x 4 mm), factor-C = 4.2, were created in third molars that were free of caries, which were randomly divided in 4 groups (n = 6): XTI (Filtek Supreme XTE: incremental technique); XTB (Filtek Supreme XTE: single fill technique); TBF (Tetric Bulk Fill); and SF (SonicFill). Each tooth was scanned twice in μCT: T0 was after filling the cavity with composite, and T1 was after light curing. The data were analyzed by subtracting the composite volume for each time (T1 - T0). After 1 week, the teeth were sectioned crosswise in the buccolingual and mesiodistal directions to obtain specimens with approximately 1 mm² thickness and fixed in a universal testing machine to perform μTBS. The Kruskal-Wallis and Dunn tests showed a statistically significant difference for shrinkage in µCT among the XTI and XTB and between the SF and XTB. Regarding the μTBS, all the groups differed from XTB. Bulk fill composites type presents a PS similar to that of the conventional nanoparticulate composite inserted using the incremental technique, but the bond strength was higher for the incremental group, which presented a lower number of pre-test failures when compared to BFC. No correlation was observed between the polymerization shrinkage and bond strength in the studied composites.

Resumo O presente estudo teve por objetivo avaliar a contração de polimerização (CP) usando microtomografia computadorizada (µCT) e a resistência de união por microtração (µTBS) em restaurações classe I de compósitos bulk fill (CBF) e convencional, assim como a correlação entre esses fatores. Cavidades classe I (4 x 5 x 4 mm), fator C=4,2, foram feitas em terceiros molares livres de cárie que foram randomizados e divididos em 4 grupos (n = 6): XTI (Filtek Supreme XTE: técnica incremental); XTB (Filtek Supreme XTE: técnica de preenchimento único); TBF (Tetric Bulk Fill); E SF (SonicFill). Cada dente foi escaneado duas vezes em μCT: T0 -após o preenchimento da cavidade com compósito, e T1 - após a cura à luz. Os dados foram analisados subtraindo o volume do compósito para cada tempo (T1 - T0). Após 1 semana, os dentes foram seccionados transversalmente no sentido vestíbulo-palatino e mesio-distal para obter espécimes com aproximadamente 1 mm² de espessura e fixados em uma máquina de ensaio universal para teste de μTBS. Os testes de Kruskal-Wallis e Dunn mostraram diferença estatisticamente significante para a contração em μCT entre XTI e XTB, e entre SF e XTB. Em relação à μTBS, todos os grupos diferiram do XTB. Compósitos do tipo bulk fill apresentam uma CP similar ao compósito convencional nanoparticulado inserido usando a técnica incremental, porém a resistência de união foi maior para o grupo incremental, que apresentou um menor número de falhas pré-teste quando comparado aos CBF. Não foi observada correlação entre a contração de polimerização e a resistência de união nos compósitos estudados.

Use of micro-computed tomography for bone evaluation in dentistry

Abstract Micro computed tomography (µCT) follows the same principle of computed-tomography used for patients, however providing higher-resolution. Using a non-destructive approach, samples can be scanned, and each section obtained is used to build a volume using tridimensional reconstruction. For bone analysis, it is possible to obtain information about the tissue's microarchitecture and composition. According to the characteristics of the bone sample (e.g. human or animal origin, long or irregular shape, epiphysis or diaphysis region) the pre-scanning parameters must be defined. The resolution (i.e. voxel size) should be chosen taking into account the features that will be evaluated, and the necessity to identify inner structures (e.g. bone channels and osteocyte lacunae). The region of interest should be delimited, and the threshold that defines the bone tissue set in order to proceed with binarization to separate the voxels representing bone from the other structures (channels, resorption areas, and medullary space). Cancellous bone is evaluated by means of the trabeculae characteristics and their connectivity. The cortex is evaluated in relation to the thickness and porosity. Bone mineral density can also be measured, by the amount of hydroxyapatite. Other parameters such as structure-model-index, anisotropy, and fractal dimension can be assessed. In conclusion, intrinsic and extrinsic determinants of bone quality can be assessed by µCT. In dentistry, this method can be used for evaluating bone loss, alterations in bone metabolism, or the effects of using drugs that impair bone remodeling, and also to assess the success rate of bone repair or surgical procedures.

Resumo A microtomografia computadorizada segue o mesmo princípio da tomografia computadorizada utilizada para avaliação dos pacientes, mas neste caso, é empregada para pequenas amostras com alta resolução. De forma não destrutiva, as amostras podem ser escaneadas, e cada fatia obtida é organizada de forma seriada para formar um volume tridimensional (3D). Para análise óssea, é possível obter informações de microarquitetura e composição mineral, permitindo avaliação distinta entre diferentes sítios. De acordo com as características de cada amostra óssea, como amostras de humanos, animais, ossos longos ou achatados, epífise ou diáfise, etc, devem ser definidos os parâmetros pré-escaneamento com a resolução desejada, levando em consideração quais informações serão extraídas da avaliação. Depois do escaneamento e da reconstrução, deve-se proceder com a seleção da região de interesse (ROI), e depois seguir com o processo de binarização, que se caracteriza pela escolha de um limiar que define os voxels que compõem a região de osso e àqueles que compõem a região dos buracos (canais, áreas de reabsorção e espaço medular). No osso trabecular e no reparo os parâmetros avaliados se baseiam nas características das trabéculas e sua conectividade. No osso cortical os parâmetros estão relacionados com a espessura e porosidade. Além dos parâmetros de microarquitetura, também é possível avaliar a densidade mineral óssea, calculada por volume de hidroxiapatita. Outros parâmetros também podem ser mensurados, utilizando técnicas computacionais como a análise de textura. Parâmetros intrínsecos e extrínsecos da qualidade óssea podem ser avaliados pela microtomografia computadorizada. Na odontologia, este método pode ser empregado em estudos que objetivem avaliar doenças, alterações metabólicas e medicamentos com repercussão no metabolismo ósseo, e na avaliação do processo de reparo e de técnicas cirúrgicas.

Segmentation methods for micro ct images: a comparative study using human bone samples

Abstract X-ray microtomography (microCT) is a nondestructive technique used to assess bone morphometry. For an accurate analysis, it is necessary to segment the bone tissue from the background images, avoiding under- or overestimation of the real bone volume. Thus, segmentation methods for microCT can influence the accuracy of bone morphometry analysis. The purpose of this study was to compare two different image segmentation methods available on microCT software (subjective and objective) regarding to the human bone morphometric analysis. Sixteen samples containing a fixation screws covered by 0.5-1mm of bone were scanned using the SkyScan 1173 scanner. Three examiners segmented the microCT images subjectively and recorded the threshold values. Subsequently, an objective segmentation was also done. The 3D analysis was performed for both images using the values​ previously determined in CTAn software. Five bone morphometric parameters were calculated (BV/TV, Tb.Th, Tb.N, Tb.Sp, Conn.Den) and used as dependent variables. ANOVA showed no significant differences between the methods concerning BV/TV (p=0.424), Tb.N (p=0.672), Tb.Th (p=0.183), Tb.Sp (p=0.973) and Conn.Den (p=0.204). Intra- and interobserver agreement ranged from satisfactory to excellent (0.55-1 and 0.546-0.991, respectively). Therefore, results obtained with subjective threshorlding were similar to those obtained with objective segmentation. Since objective segmentation does not have human input and it is a truly objective method, it should be the first choice in microCT studies that concern homogeneity and high resolution human bone sample.

Resumo A microtomografia computadorizada (microTC) é uma modalidade de imagem não destrutiva utilizada para avaliar a morfometria óssea. Para análise acurada, faz-se necessário segmentar o tecido ósseo do fundo (background) da imagem, evitando assim, sub ou sobre estimação do volume ósseo real. Desta forma, fica evidente que os métodos de segmentação em análise de microTC podem influenciar a precisão dos cálculos da morfometria óssea. A realização do presente estudo teve como objetivo comparar o desempenho de dois diferentes métodos de segmentação de imagem de microTC, subjetivo e objetivo, através da avaliação dos resultados das análises morfométricas obtidas de ossos humanos. Dezesseis amostras contendo parafusos de fixação cobertos por 0,5- 1 mm de osso humano foram escaneados usando o microtomógrafo SkyScan1173. Três examinadores realizaram a segmentação das imagens de forma subjetiva (visualmente) obtendo seus respectivos valores de threshold. Em seguida, a segmentação objetiva (automática) foi realizada. As análises tridimensionais foram obtidas utilizando os valores determinados por ambos os métodos no software CTAn. Cinco parâmetros morfométricos do osso foram calculados (BV / TV, Tb.Th, Tb.N, Tb.Sp, Conn.Den) e usados ​​como variáveis ​​dependentes. O teste ANOVA não mostrou diferenças estatisticamente significantes entre os métodos comparados: BV / TV (p=0,424), Tb.N (p=0,672), Tb.Th (p=0,183), Tb.Sp (p=0 973) e Conn.den (p=0,204). A concordância intra e interobservardores variou entre satisfatória e excelente (0,55-1 e 0,546-0,991, respectivamente). Portanto, os resultados obtidos com a segmentação subjetiva foram semelhantes aos obtidos com a automática. Entretanto, a segmentação automática dispensa intervenção humana, sendo um método verdadeiramente objetivo e deve ser a primeira escolha em estudos microTC que objetivam avaliar a morfometria óssea humana.

The influence of new heat­treated NiTi alloy on shaping ability and apical transportation of maxillary molars. The evaluation of the larger apical preparation on mesiobuccal and distobuccal canals of maxillary molars: a micro-computed study / Influência de diferentes tratamentos na liga de Ni-Ti no preparo e transporte apical de molares superiores. Avaliação do efeito da variação do diâmetro do preparo apical de canais mesio-vestibulares e disto-vestibulares de molares superiores: análise por meio de microCT

The aim of this study was to evaluate canal transportation; centering ability; dentin thickness; change in volume, and time spent on shaping ability of maxillary molars prepared with mechanized NiTi file systems composed of a conventional NiTi alloy (Mtwo), a CM-Wire (Prodesign R and Hyflex CM) NiTi alloy, R-phase (Twisted File Adaptive) and an M-Wire (Reciproc) NiTi alloy]. With the purpose of understanding the role of new treated NiTi alloys in larger apical preparations, this type of preparation was evaluated in the mesiobuccal (MB) and distobuccal canal (DB) of maxillary molars, as well as, in the second mesiobuccal (MB2) canals in extracted maxillary first molars by means of micro-computed tomographic (micro- CT) imaging. For the second mesiobuccal canal (MB2) evaluation, thirty maxillary molars with Vertucci type IV canal configuration were selected and randomly divided into 3 groups (n = 10): Reciproc [REC; VDW, Munich, Germany], Prodesign R [PDR; Easy, Belo Horizonte, Brazil] and Mtwo [MO; VDW, Munich, Germany]. To assess the mesiobuccal and distobuccal canals, a total of 45 extracted maxillary molars were selected according to the following criteria: MB canals exhibiting curvatures according to the Weine classification in the 20-30 degree range; and DB canals presenting curvatures in the 0-5 degree range. These teeth were randomly assigned to three groups, Reciproc (REC) [40.06]; Hyflex CM (HF) [40.06] [Coltene, Cuyahoga Falls, OH, USA] and Twisted file Adaptive (TFA) [35.04]. After root canal preparation, all the teeth were scanned to evaluate parameters previously cited. In particular, the percentage of negotiability of the MB2 canal was evaluated. All parameters were statistically compared using the Kruskal-Wallis and Dunn's Multiple comparison tests within groups with a significance level of 5%. For MB2 canals, no statistically significant difference was observed among the three groups with regard to the values of canal transportation, centering ability, remaining dentin thickness in the coronal third, number of specimens with thickness under 0.5 mm in the danger zone, and apical volume (P>0.05). However, the entire volume of the canal in Group MO differed statistically from that of Group PDR (P<0.05), but Group REC did not differ statistically from Groups MO and PDR (P>0.05). Group PDR demanded more time to reach WL than use of the MO and REC systems. For MB and DB canals, the trend of canal transportation was towards inner curvature in apical third, while in the coronal third it was towards the outer curve. There was no difference in apical transportation values in the first apical millimeters for both canals. In MB canal, at 3 and 4 mm, the Reciproc transportation value was significantly lower than that of Hyflex CM(P<0.05). In the DB canal, at 2 and 4 mm, Reciproc showed substantially higher values than Group TFA (P<0.05). There was no statistically significant difference between the two canals among the three systems for centering ability in the apical third and the remaining dentin thickness (RDT). For DB canal, there was no significant difference in shaping time, but in the MB canal, Group TFA was swifter than Reciproc and Hyflex CM. The initial changes in volume (apical/entire) after canal preparation was statistically significant within groups in MB and DB canals for percentage and volume of dentin removed. TFA had the lowest values for the apical and entire volumes of dentin removed in both canals compared with Reciproc and Hyflex CM (P<0.05). TFA had the lowest percentage of dentin removed from the entire MB canal, and from the apical and entire volume of DB canal. For negotiating and shaping the MB2 canal, the three file systems had similar performance. However, the REC system reached the full working length faster than PDR. The MO and REC systems removed more dentin in the inner furcation area when compared with PDR. For MB and BD canals, the heat treated NiTi alloy systems used for larger apical preparation evenly maintained the morphology of the MB and DB canals of maxillary molars. In shaping procedures, the larger apical preparation produced slight canal transportation without evidence of significant preparation errors. However, these variations may not be feasible of clinical significance. Use of TFA was swifter for preparing the MB canal and produced fewer changes in volume parameters. The TFA system was able to preserve the original canal anatomy with less canal transportation than the Reciproc and Hyflex CM systems.(AU)

O objetivo deste estudo foi avaliar o transporte do canal, a centralização do canal, a espessura dentinária, a alteração volumétrica e o tempo de trabalho de diferentes sistemas mecanizados de níquel-titânio compostos por ligas convencional (Mtwo) e tratados termicamente (CMWire (Prodesign R e Hyflex CM), M-Wire (Reciproc) e fase-R (Twisted file adaptive) em preparos de canais em molares superiores. O papel dos novos instrumentos de níquel titânio tratados termicamente em preparos apicais mais amplos de canais mésio-vestibulares e distovestibulares dos molares superiores foi avaliado, como também o preparo do canal mésiopalatino (CMP), por meio da microtomografia computadorizada (µ-CT). No estudo do canal mésio-palatino, 30 primeiros molares superiores com configuração tipo IV de Vertucci foram selecionados e divididos em 3 grupos (n = 10): Reciproc [REC; VDW, Munich, Germany], Prodesign R [PDR; Easy, Belo Horizonte, Brazil] and Mtwo [MO; VDW, Munich, Germany]. No estudo dos canais mésio-vestibulares e disto-vestibulares, o total de 45 molares superiores foram selecionados com angulação da raiz mésio vestibular de 20 a 30 graus e apresentando a raiz disto-vestibular com angulação de 0 a 5 graus, de acordo com a classificação de Weine. Os dentes foram aleatoriamente distribuídos em 3 grupos (n=15): Reciproc (40.06) [REC, VDW, Munich, Germany]; Hyflex CM (40.06) [HF, Coltene, Cuyahoga Falls, OH, USA]; e Twisted file Adaptive (35.04) [TFA, SybronEndo, Orange, CA]. Após o preparo dos canais mésio-palatino, mésio-vestibular, e disto-vestibular, todos os dentes foram escaneados para avaliação dos parâmetros previamente citados. Especificamente, na avaliação do canal mésiopalatino, foi avaliada a porcentagem de canais que alcançaram patência. Todos os parâmetros foram avaliados estatisticamente pelo teste de Kruskal-Wallis e pelo teste Dunn's de múltipla comparação entre grupos, com nível de significância de 5%. O canal mésio-palatino não apresentou diferença estatisticamente significante em relação ao transporte, centralização, remanescente de dentina no terço cervical, quanto ao número de espécime abaixo de 0,5 mm de espessura na zona de perigo e no volume apical (P>0.05). O volume total do canal no grupo MO diferenciou-se do volume total do grupo PDR (P<0.05), enquanto essa diferença não foi evidenciada entre os grupos REC comparado aos grupos MO e PDR (P>0.05). O grupo PDR demandou maior tempo para atingir o comprimento de trabalho comparado aos sistemas MO e REC. Na análise dos canais MV e DV dos molares superiores, o transporte coronal direcionou-se para o interior da curvatura do canal, enquanto no terço apical o transporte direcionou-se para o lado externo da curvatura. O transporte apical no primeiro milímetro de ambos os canais (MV e DV) foi equivalente entre os grupos (P>0.05). O canal MV apresentou nos níveis 3 e 4 mm transporte do grupo Reciproc significantemente menor do que no grupo Hyflex CM (P<0.05). Em relação ao transporte apical, no canal DV, nos milímetros 2 e 4 apicais do grupo Reciproc transportou significantemente mais comparado ao grupo TFA (P<0.05). Contudo, a centralização apical de ambos os canais e a quantidade de remanescente dentinário apical não se diferiram estatisticamente (P<0.05). O preparo do canal MV foi mais rápido com o sistema TFA comparado ao Reciproc e do Hyflex CM (P<0.05), enquanto no canal DV não foi evidenciado diferenças em relação ao tempo de preparo (P>0.05). A porcentagem e o volume de dentina removida em todo o canal e na região apical, após o preparo do canal apresentou diferenças significantes entre os grupos. O grupo TFA teve as menores porcentagens e valores de dentina removida no volume total do canal e no volume apical, em ambos os canais, comparado com os sistemas Reciproc e Hyflex CM (P<0.05). No canal MP, os três sistemas avaliados prepararam e patenciaram semelhantemente os canais MP. Contudo, o sistema Reciproc foi mais rápido para alcançar o comprimento de trabalho do que o sistema Prodesign R. Os grupos Mtwo e Reciproc removeram mais dentina na região voltada para o interior da furca quando comparado ao Prodesign R. Os sistemas compostos por ligas tratadas termicamente em preparos com maior ampliação apical mantiveram a morfologia dos canais MV e DV. Os sistemas promoveram discretos transportes, sem evidência de erros no preparo. Contudo, essas variações não são passíveis de significância clínica. O grupo do TFA foi mais rápido e promoveu menores alterações nos parâmetros volumétricos. O grupo do TFA foi capaz de preservar a anatomia original do canal com menor grau de transporte comparado ao Reciproc e Hyflex CM.(AU)

Accuracy of visual and image-based ICDAS criteria compared with a micro-CT gold standard for caries detection on occlusal surfaces

Abstract The aim of this study was to check the in vitro accuracy of ICDAS criteria on digital images compared to visual examination for the diagnosis of occlusal caries against a micro-CT gold standard. ICDAS was scored in 40 extracted permanent molars by means of visual inspection and stereomicroscopic images. Visual examinations were performed in duplicate and at a one-week interval by three different calibrated examiners. The analysis of digital images by ICDAS criteria was also performed in duplicate, 1 month after visual examinations. The detection methods were compared by means of sensitivity, specificity, area under the curve, predictive positive and negative values, and accuracy for two different thresholds (1- sound vs. carious teeth; 2- tooth requiring operative vs. non-operative treatment). Sensitivity and accuracy values for threshold 1 in the visual ICDAS and image-based ICDAS methods were high for sensitivity (0.93 and 0.97) and for accuracy (0.83 and 0.85), but low for specificity (0.55 for both methods). Specificity values for threshold 2 were 0.77 and 0.82, while sensitivity was 0.33 and 0.28 for each method. Spearman's rank correlation coefficient was 0.53 and 0.43 (p<0.05) for visual and image-based ICDAS compared to the gold standard scores. Both visual and image-based ICDAS scores were similar to each other in terms of diagnostic accuracy when compared to the micro-CT gold standard. Low specificity for the presence of caries and sensitivity for the detection of caries requiring operative treatment were found.

Unprepared root canal surface areas: causes, clinical implications, and therapeutic strategies

Abstract: Chemomechanical preparation is intended to clean, disinfect, and shape the root canal. This step is of utmost importance during treatment of infected teeth with apical periodontitis, because treatment outcome depends on how effectively the clinician eliminates bacteria, their products, and necrotic tissue that would serve as substrate for bacterial regrowth. Nonetheless, curvatures and complex internal anatomical variations of the root canal system can pose a high degree of difficulty in reaching these goals. In infected teeth, bacteria may persist not only in difficult-to-reach areas such as isthmuses, ramifications, dentinal tubules, and recesses from C-shaped or oval/flattened canals, but also in areas of the main canal wall that remain untouched by instruments. If bacteria withstand chemomechanical procedures, there is an augmented risk for post-treatment apical periodontitis. This article discloses the reasons why some areas remain unprepared by instruments and discusses strategies to circumvent this issue and enhance infection control during endodontic treatment/retreatment of teeth with apical periodontitis.

Root canal preparation using micro-computed tomography analysis: a literature review

Abstract: This literature review has critically analyzed the published research related to the biomechanical preparation of root canals with three-dimensional analysis using micro-computed tomography (micro-CT). In December 2017, six databases (PubMed, Cochrane, Web of Science, Embase, Scopus, and Science Direct) were accessed using keywords to find articles including the use of the micro-CT analysis in biomechanical root canal preparation. There were 60 full articles that were selected, which were screened and read by two authors. The research that was reviewed and analyzed included root canal anatomy and sample selection, changes in canal shape and untouched canal areas, canal transportation and centering ability, and kinematics (motion). Of the studies selected, 49.18% discussed anatomical characteristics, with 54.1% of these studies describing mesial roots of mandibular molars with moderate curvature. Only 35% used a stratified distribution based on root canal system morphology and quantitative data obtained by micro-CT. The analysis of canal transportation and centering ability showed that transport values in the apical third exceeded the critical limit of 0.3 mm in mesial roots of mandibular molars with moderate curvature, especially in the groups in which a reciprocating system was used. In relation to kinematics, 91.70% of the reviewed studies evaluated continuous rotating instruments, followed by reciprocating rotation (38.33%), vibratory (15%), and the adaptive kinematics, which was in only 8.33%. The reciprocating kinematics was associated with higher canal decentralization and transportation indexes, as well as a greater capacity for dentin removal and debris accumulation. This literature review showed that the anatomy, the type of design and kinematics of instruments, and the experimental design are factors that directly influence the quality of biomechanical preparation of root canals analyzed in a qualitative and quantitative manner by micro-CT.

High-throughput micro-phenotyping measurements applied to assess stalk lodging in maize ( Zea mays L. )

BACKGROUND: The biomechanical properties of maize stalks largely determine their lodging resistance, which affects crop yield per unit area. However, the quantitative and qualitative relationship between micro-phenotypes and the biomechanics of maize stalks is still under examined. In particular, the roles of the number, geometry, and distribution of vascular bundles of stalks in maize lodging resistance remain unclear. Research on these biomechanical properties will benefit from high-resolution micro-phenotypic image acquisition capabilities, which have been improved by modern X-ray imaging devices such as micro-CT and the development of micro-phenotyping analysis software. Hence, high-throughput image analysis and accurate quantification of anatomical phenotypes of stalks are necessary. RESULTS: We have updated VesselParser version 1.0 to version 2.0 and have improved its performance, accuracy, and computation strategies. Anatomical characteristics of the second and third stalk internodes of the cultivars 'Jingke968' and 'Jingdan38' were analyzed using VesselParser 2.0. The relationships between lodging resistance and anatomical phenotypes of stalks between the two different maize varieties were investigated. The total area of vascular bundles in the peripheral layer, auxiliary axis diameter, and total area of vascular bundles were revealed to have the highest correlation with mechanical properties, and anatomical phenotypes of maize stalk were better predictors of mechanical properties than macro features observed optically from direct measurement, such as diameter and perimeter. CONCLUSIONS: This study demonstrates the utility of VesselParser 2.0 in assessing stalk mechanical properties. The combination of anatomical phenotypes and mechanical behavior research provides unique insights into the problem of stalk lodging, showing that micro phenotypes of vascular bundles are good predictors of maize stalk mechanical properties that may be important indices for the evaluation and identification of the biomechanical properties to improve lodging resistance of future maize varieties.