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Introduction: It is important to take into account variations in structures related to dental pulp for planning the most adequate endodontic treatment management. The objective of this study was to determine the morphology of roots and canals of maxillary first premolars (MFPs) using cone-beam computed tomography (CBCT). Materials and Methods: This retrospective study included a sample of 392 CBCTs of Peruvian adults proportionally selected by sex, age, and quadrant. One MFP per individual was selected for evaluation by a calibrated evaluator based on the number of roots and canal configuration according to the Vertucci classification (VC; Cohen's κ ≥ 0.834). Pearson's χ 2 and Kruskal-Wallis tests were used with a significance level of P < 0.05. Results: Most MFP presented double roots (59.9%) and were VC type IV (52%). Morphology showed a nonsignificant difference by quadrants (P=0.994). A significant positive association was found between the presence of double roots and type IV in men and with older age, while single roots and type I and II were associated with women and younger age (P < 0.05). Double roots were associated with VC type IV (86%) and single roots with types III (34%), II (32%), and I (26%; P < 0.001). Conclusions: MFPs in a Peruvian sample presented a higher frequency of double roots with two separate canals. The morphology of root and canals was associated with age and sex.

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Este Estudio tuvo por objetivo determinar la incidencia de reabsorción radicular externa en premolares superiores e inferiores permanentes al finalizar el tratamiento de ortodoncia. Esta investigación fue realizada en pacientes entre 18 y 35 años que recibieron tratamiento de ortodoncia, sin extracciones, con técnica de autoligado en la ciudad de Guadalajara. Se consideraron 120 premolares, realizando mediciones longitudinales en las tomografías computarizadas de haz cónico al inicio y término del tratamiento. Utilizando el software Implant Viewer 3. Los valores registrados en el primer y segundo premolar superior tanto del lado derecho como izquierdo al inicio y término del tratamiento fluctuaron entre -4.946 y -7.801; p ≤ 0.0005 encontrándose diferencias estadísticas significativas. Mientras que en el primer y segundo premolar inferior tanto del lado derecho como izquierdo, fluctuaron entre -4.864 y -5.28; p ≤ 0.0005 encontrándose diferencias estadísticas significativas. Se concluye en este estudio que los dientes sometidos a movimientos durante el tratamiento de ortodoncia sufren modificaciones en el contorno de la raíz, cambios con consecuencias mínimas que no comprometen la funcionalidad del diente. Los premolares superiores presentaron mayores rangos de reabsorción radicular que los premolares inferiores.

The aim of this study is to determine the incidence of root resorption in permanent upper and lower premolars at the end of an orthodontic treatment. This research was carried out in patients aged between 18 and 35 years old who received orthodontic treatment, without extractions, with a self-ligating technique in the city of Guadalajara, Mexico. In this study, 120 premolars were considered, making longitudinal measurements with cone beam computed tomography at the beginning and the end of the treatment, using the Implant Viewer 3 software. The values recorded in the upper first and second premolars on both the right and left sides at the beginning and the end of the treatment fluctuated between -4.946 and -7.801; p ≤ 0.0005, finding statistically significant differences. In the lower first and second premolars on both the right and left sides, they fluctuated between -4.864 and -5.28; p ≤ 0.0005, also finding statistically significant differences. It is concluded that teeth subjected to movements during orthodontic treatment suffer modifications in the contour of the root, changes with minimal consequences that do not compromise their functionality. The upper premolars showed higher ranges of root resorption than the lower premolars.

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RESUMEN El sistema de conductos radiculares es complejo. En él podemos encontrar piezas dentales como los premolares, cuya anatomía interna es variable. Así pues, en las piezas premolares superiores predominan tres conductos, mientras que en las piezas premolares inferiores se observa un menor porcentaje de incidencia. Hoy en día, el uso de las tomografías computarizadas es indispensable ya que estas nos brindan imágenes tridimensionales que nos ayudan a generar un correcto diagnóstico, garantizar un adecuado procedimiento y lograr el mejor pronóstico favorable para una endodoncia. El propósito del presente artículo de revisión es compendiar información en una búsqueda manual de artículos diferentes de investigación científica de PubMed y Google Académico, donde se describirán las variaciones anatómicas, el diagnóstico y el tratamiento de los dientes premolares con tres conductos.

ABSTRACT The root canal system is complex. In it we can find dental pieces such as premolars, whose internal anatomy is variable. Thus, in the upper premolars three canals predominate, while in the lower premolars there is a lower percentage of incidence. Nowadays, the use of CT scans is indispensable since they provide us with three-dimensional images that help us to generate a correct diagnosis, guarantee an adequate procedure and achieve the best favorable prognosis for endodontics. The purpose of this review article is to summarize information in a manual search of different scientific research articles from PubMed and Google Scholar, where the anatomical variations, diagnosis, and treatment of premolar teeth with three canals will be described.

RESUMO O sistema de canais radiculares é complexo. Inclui dentes como os pré-molares, cuja anatomia interna é variável. Assim, nos pré-molares superiores predominam os três canais, enquanto nos inferiores observa-se uma menor percentagem de incidência. Hoje em dia, a utilização da tomografia computadorizada é indispensável, uma vez que nos fornece imagens tridimensionais que nos ajudam a gerar um diagnóstico correto, a garantir um procedimento adequado e a obter o melhor prognóstico favorável em endodontia. O objetivo deste artigo de revisão é compilar informação proveniente de uma pesquisa manual de diferentes artigos de investigação científica da PubMed e do Google Scholar, descrevendo as variações anatómicas, o diagnóstico e o tratamento de dentes pré-molares com três canais.

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Introducción: El análisis más utilizado por los ortodoncistas para predecir el espacio ideal del canino y premolares es el Gold Standard de Tanaka-Johnston. Sin embargo, la utilización de este análisis en otros grupos poblacionales a nivel mundial puede ser cuestionable. Objetivo: Predecir el espacio ideal para la erupción del canino y premolares utilizando el análisis de Tanaka y Johnston y el de Ramos, et al. Material y métodos: Fue un estudio descriptivo. Se utilizaron 110 pares de modelos de estudio con dentición permanente, recolectados durante 2018 y 2019. Los anchos mesiodistales fueron medidos con un vernier digital marca UBERMANN® con una precisión de ± 0,01 mm. A los datos obtenidos se les realizó estadística no paramétrica mediante la prueba de comparación de Kruskal-Wallis. Resultados: El análisis de Tanaka-Johnston mostró una diferencia entre los valores predictivos y reales de -0,50 mm (±1,68) con una diferencia estadística de p=0,0001 y el análisis de Ramos, et al., fue de -0,35 mm (±1,70) con una diferencia estadística de p=0,0001. Conclusiones: Se subestimó el espació ideal para la erupción del canino y premolares con el análisis de Tanaka-Johnston y el análisis validado por Ramos, et al. Sin embargo, el análisis de Ramos, et al., se acercó más a los diámetros mesiodistales reales del canino y premolares.

Introduction: The analysis most commonly used by orthodontists to predict the ideal space of the canine and premolars is the Tanaka-Johnston Gold Standard. However, the use of this analysis in other population groups worldwide may be questionable. Objective: To predict the ideal space for the eruption of the canine and premolars using the Tanaka-Johnston analysis and that of Ramos, et al. Material and Methods: A descriptive study was carried out using 110 pairs of study models with permanent dentition, collected during the period from 2018 to 2019. The mesiodistal widths were measured with a UBERMANN® digital vernier with an accuracy of ± 0.01 mm. Non-parametric statistics were performed on the data obtained using the Kruskal-Wallis comparison test. Results: The Tanaka-Johnston analysis showed a difference between the predictive and real values ​​of -0.50 mm (±1.68) with a statistical difference of p=0.0001, and the Ramos et al. analysis was of -0.35 mm (±1.70) with a statistical difference of p=0.0001. Conclusions: The ideal space for the eruption of the canine and premolars was underestimated with the Tanaka-Johnston analysis and the analysis validated by Ramos, et al. However, the Ramos, et al. analysis was closer to the actual mesiodistal diameters of the canine and premolars.

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El diente evaginado (DE) es una anomalía del desa-rrollo que se define como un tubérculo o protube-rancia que se extiende desde la superficie oclusal del diente afectado. La fractura o desgaste de esta pro-longación, internamente compuesta por tejido pul-par, puede causar diversas enfermedades pulpares, como pulpitis, necrosis pulpar e incluso dar lugar a una periodontitis apical. En el presente caso clíni-co se muestra el tratamiento de DE en un segundo premolar superior izquierdo que presentaba como diagnóstico necrosis pulpar y absceso alveolar cró-nico. El tratamiento consistió en realizar la terapia endodóntica con técnica de apexificación empleando BiodentineTM (AU)

Dens evaginatus (DE) is a dental developmental defect defined as a tubercle or protuberance that extends from the occlusal surface of the affected tooth. Fracture or wear of this extension, internally composed of pulp tissue, can cause diverse pulp diseases, such as pulpitis, pulpal necrosis and it can even induce apical periodontitis.The following clinical case shows the treatment of DE in a maxillary left second premolar diagnosed with pulp necrosis and chronic alveolar abscess. The treatment of choice was endodontic therapy using BiodentineTM (AU)

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The ability to recognize the anatomical variations of the root canal system is crucial before starting endodontic treatment, no less important is being able to carry out these treatments based on current scientific evidence. The premolars are the dental pieces with the greatest complexity in their internal anatomy and the ones that appear in the highest percentage compared to other teeth, if a piece presents accessory anatomy, it is highly probable that the contralateral piece presents the same internal anatomy, to this it is known as symmetrical bilaterality, therefore the radiographic images must be executed with proximal and orthoradial projections in order to approximate the 3D shape that these anatomies present and minimize procedural errors. The use of magnification is essential to be able to address the entire root canal system and perform an adequate endodontic treatment. This case report presents the approach to 2 maxillary first premolars from the same patient with 3-canal anatomy, presenting bilateral symmetry.

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Objetivo: analizar, mediante tomografía computarizada de haz cónico (TC o CBCT [Cone Beam Computed Tomograph]) la frecuencia del tipo de morfología interna de los conductos radi- culares según la clasificación de Vertucci y el número de raíces de los primeros premolares superiores. Material y métodos: en una población argentina de 50 pacientes, 30 de sexo femenino y 20 masculino, que concurrieron a la Cátedra de Diagnóstico por Imá- genes de la Facultad de Odontología de la Universidad de Buenos Aires, se evaluaron 100 primeros premolares superiores con CBCT. Se estudiaron las variables: número de raíces, tipo de morfología interna, edad, sexo y lado. Fueron seleccionadas las tomografías de maxilar superior que incluyeron ambos primeros premolares en salud dental, periodontal y con ápice cerrado. Se realizó una adquisición volumétrica 100 × 90 mm y tamaño de vóxel de 150 µm. Se realizó la exploración de las imágenes en el plano axial de los tercios apical, medio y cervical de las piezas 1.4 y 2.4. Se utilizó un corte axial, observando en él, el tercio apical, medio y cervical de las piezas 1.4 y 2.4. Cada premolar fue analizado con 30 cortes transversales. Se utilizó la clasificación de Vertucci para agrupar las distintas variables anatómicas de los conductos radiculares de los primeros premolares superiores, la cual consta de VIII tipolo- gías. Resultados: el tipo más representativo entre los 100 primeros premolares superiores, dentro de la clasificación de Vertucci, fue el tipo IV (dos conductos separados desde la cámara al ápice). La coincidencia de tipos entre los lados derecho (78%; IC 95%: 65 a 87%) e izquierdo (70%; IC 95%: 56 a 81%) fue significativa. La distribución según el número de raíces en el lado derecho (χ 2 = 2.88) e izquierdo (χ2 = 0.72) no presentó una heterogeneidad significativa. La coincidencia del número de raíces entre los lados derecho e izquierdo fue significativa. Conclusión: se comprobó el tipo de morfología interna más frecuente, el número de raíces y su variabilidad de acuerdo al lado, sexo, y edad; lo cual es de una relevante importancia para realizar una correcta instrumentación y obturación del sistema de conductos radiculares (AU)

Objective: to analyze, using cone beam computed tomography (CBCT), the frequency of the type of internal morphology of the root canals according to the Vertucci classification and the number of roots of the first upper premolars. Material and methods: 100 first upper premolars were evaluated with CBCT, which corresponded to 30 female and 20 male patients in the Chair of Diagnostic Imaging of the Faculty of Dentistry, University of Buenos Aires. Variables were studied: number of roots, type of internal morphology, age, sex and side. The tomography of the upper jaw with both first premolars in dental, periodontal and closed apex health, a 100 × 90 mm volumetric acquisition and a voxel size of 150 µm were selected. An axial cut was used, observing the apical, middle and cervical third of pieces 1.4 and 2.4. Each premolar was analyzed with 30 paraxial cuts. The Vertucci classification was used to group the different anatomical variables of the root canals of the first upper premolars which consists of VIII typologies. Results: the most representative type among the top 100 upper premolars within the Vertucci classification was type IV (two separate ducts from the chamber to the apex). The type coincidence between the right (78%; 95% CI: 65 to 87%) and left (70%; 95% CI: 56 to 81%) los primeros premolares superiores, la cual consta de VIII tipolo gías. Resultados: el tipo más representativo entre los 100 primeros premolares superiores, dentro de la clasificación de Vertucci, fue el tipo IV (dos conductos separados desde la cámara al ápice). La coincidencia de tipos entre los lados derecho (78%; IC 95%: 65 a 87%) e izquierdo (70%; IC 95%: 56 a 81%) fue significativa. La distribución según el número de raíces en el lado derecho (χ 2 = 2.88) e izquierdo (χ2 = 0.72) no presentó una heterogeneidad significativa. La coincidencia del número de raíces entre los lados derecho e izquierdo fue significativa. Conclusión: se comprobó el tipo de morfología interna más frecuente, el número de raíces y su variabilidad de acuerdo al lado, sexo, y edad; lo cual es de una relevante importancia para realizar una correcta instrumentación y obturación del sistema de conductos radiculares (AU))

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The aim of this study was to investigate the internal root canal anatomy of maxillary and mandibular premolars in a Brazilian subpopulation, in order to establish the prevalence of the different configurations proposed by Vertucci. Three hundred and ninety-eight cone-beam computed tomography scans were collected from a private imaging clinic database in Rio de Janeiro, including 217 maxillary and 226 mandibular scans. A total 1316 premolars (594 maxillary and 722 mandibular) were evaluated using an image viewer, and classified according to Vertucci. Two calibrated examiners determined the frequency of each morphological Type. A third examiner reviewed discordant cases. The Kappa test was applied to verify inter-rater agreement, and Fisher's Exact Test to verify gender-related differences. The most frequent root canal configurations of maxillary first and second premolars were Type IV (73.86%) and Type I (47.18%), respectively. Type I was the most prevalent in mandibular first and second premolars (80.59% and 95.86%, respectively). Only Types I and VIII presented a statistically significant difference between sexes. Type I was more frequent in females and Type VIII in males. A highly significant frequency of Type I was found in both mandibular first and second premolars, whereas the most frequent maxillary premolar root canal configuration was Type IV for first premolars and Type I for second premolars.

O presente estudo teve como objetivo investigar a anatomia interna de pré-molares superiores e inferiores em uma subpopulação brasileira para estabelecer a prevalência das diferentes configurações propostas por Vertucci. Trezentos e noventa e oito exames de tomografia computadorizada de feixe cônico foram coletados de um banco de dados de uma clínica privada de imagem no Rio de Janeiro, incluindo 217 exames maxilares e 226 mandibulares. Um total de 1.316 pré-molares (594 superiores e 722 inferiores) foram avaliados usando um visualizador de imagens e categorizados de acordo com a classificação de Vertucci. Dois examinadores calibrados determinaram a frequência de cada tipo morfológico. Um terceiro examinador revisou os casos discordantes. O teste Kappa foi aplicado para verificar a concordância entre os avaliadores e o Teste Exato de Fisher para verificar diferenças relacionadas ao gênero. A configuração do canal radicular mais frequente dos primeiros e segundos pré-molares superiores foi Tipo IV (73,86%) e Tipo I (47,18%), respectivamente. O tipo I foi o mais prevalente nos primeiros e segundos pré-molares inferiores (80,59% e 95,86%, respectivamente). Os tipos I e VIII foram os únicos que apresentaram diferença estatisticamente significativa entre os sexos. O tipo I foi mais frequente nas mulheres e o tipo VIII nos homens. Uma frequência altamente significativa do Tipo I foi encontrada em ambos os primeiros e segundos pré-molares inferiores, enquanto a configuração do canal radicular dos pré-molares superiores mais frequente foi o Tipo IV para os primeiros pré-molares e o Tipo I para os segundos pré-molares.

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ABSTRACT The aim of this study was to investigate the internal root canal anatomy of maxillary and mandibular premolars in a Brazilian subpopulation, in order to establish the prevalence of the different configurations proposed by Vertucci. Three hundred and ninety-eight cone-beam computed tomography scans were collected from a private imaging clinic database in Rio de Janeiro, including 217 maxillary and 226 mandibular scans. A total 1316 premolars (594 maxillary and 722 mandibular) were evaluated using an image viewer, and classified according to Vertucci. Two calibrated examiners determined the frequency of each morphological Type. A third examiner reviewed discordant cases. The Kappa test was applied to verify inter-rater agreement, and Fisher's Exact Test to verify gender-related differences. The most frequent root canal configurations of maxillary first and second premolars were Type IV (73.86%) and Type I (47.18%), respectively. Type I was the most prevalent in mandibular first and second premolars (80.59% and 95.86%, respectively). Only Types I and VIII presented a statistically significant difference between sexes. Type I was more frequent in females and Type VIII in males. A highly significant frequency of Type I was found in both mandibular first and second premolars, whereas the most frequent maxillary premolar root canal configuration was Type IV for first premolars and Type I for second premolars.

RESUMO O presente estudo teve como objetivo investigar a anatomia interna de pré-molares superiores e inferiores em uma subpopulação brasileira para estabelecer a prevalência das diferentes configurações propostas por Vertucci. Trezentos e noventa e oito exames de tomografia computadorizada de feixe cônico foram coletados de um banco de dados de uma clínica privada de imagem no Rio de Janeiro, incluindo 217 exames maxilares e 226 mandibulares. Um total de 1.316 pré-molares (594 superiores e 722 inferiores) foram avaliados usando um visualizador de imagens e categorizados de acordo com a classificação de Vertucci. Dois examinadores calibrados determinaram a frequência de cada tipo morfológico. Um terceiro examinador revisou os casos discordantes. O teste Kappa foi aplicado para verificar a concordância entre os avaliadores e o Teste Exato de Fisher para verificar diferenças relacionadas ao gênero. A configuração do canal radicular mais frequente dos primeiros e segundos pré-molares superiores foi Tipo IV (73,86%) e Tipo I (47,18%), respectivamente. O tipo I foi o mais prevalente nos primeiros e segundos pré-molares inferiores (80,59% e 95,86%, respectivamente). Os tipos I e VIII foram os únicos que apresentaram diferença estatisticamente significativa entre os sexos. O tipo I foi mais frequente nas mulheres e o tipo VIII nos homens. Uma frequência altamente significativa do Tipo I foi encontrada em ambos os primeiros e segundos pré-molares inferiores, enquanto a configuração do canal radicular dos pré-molares superiores mais frequente foi o Tipo IV para os primeiros pré-molares e o Tipo I para os segundos pré-molares.

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Abstract Complex anatomical variations on root canals morphology are one of the most arduous challenges in the endodontic practice. The objective of this case report is to discuss the clinical management of a mandibular left second premolar with four root canals and four distinct apical foramina. This case report has been written according to Preferred Reporting Items for Case reports in Endodontics (PRICE) 2020 guidelines. A 74-year-old patient was referred to retreat a left mandibular second premolar. The patient complained of discomfort when chewing hard food. After obtaining consent from the patient to investigate the symptoms, a thorough clinical and radiographic examination was performed. The main clinical findings observed were a moderate sensitivity to vertical percussion and mild discomfort at palpation. The periapical radiograph showed a fusion-like root with multiple canals and unsatisfactory root canal fillings associated with apical radiolucency. Based on this investigation, a diagnostic of persistent apical periodontitis was made to the tooth, and nonsurgical root canal re-treatment was proposed to the patient. After written informed consent was obtained, the procedure was performed under magnification provided by a dental operating microscope with the aid of ultrasonic tips. During the access opening and fillings removal, four root canal orifices were observed. Therefore, state-of-the-art technology such as the dental operating microscope, ultrasonics, and cone-bean computed tomography image are strong allies to manage anatomical variations.

Resumen Las complejas variaciones anatómicas en la morfología de los conductos radiculares son uno de los desafíos más arduos en la práctica de la endodoncia. El objetivo de este reporte de caso es discutir el manejo clínico de un segundo premolar mandibular izquierdo con cuatro conductos radiculares y cuatro agujeros apicales distintos. Este informe de caso se ha escrito de acuerdo con Preferred Reporting Items for Case reports in Endodontics (PRICE) 2020. Paciente de 74 años que fue remitido para retirada de un segundo premolar mandibular izquierdo. El paciente se quejaba de malestar al masticar alimentos duros. Después de obtener el consentimiento del paciente para investigar los síntomas, se realizó un examen clínico y radiográfico completo. Los principales hallazgos clínicos observados fueron una sensibilidad moderada a la percusión vertical y una leve molestia a la palpación. La radiografía periapical mostró una raíz similar a una fusión con múltiples conductos y empastes de conductos radiculares insatisfactorios asociados con radiolucidez apical. Con base en esta investigación, se realizó un diagnóstico de periodontitis apical persistente en el diente y se propuso al paciente un nuevo tratamiento del conducto radicular no quirúrgico. Una vez obtenido el consentimiento informado por escrito, el procedimiento se realizó con un aumento proporcionado por un microscopio quirúrgico dental con la ayuda de puntas ultrasónicas. Durante la apertura del acceso y la remoción de los empastes, se observaron cuatro orificios del conducto radicular. Por lo tanto, la tecnología de punta, como el microscopio de operación dental, los ultrasonidos y la imagen de tomografía computarizada de haz cónico, son fuertes aliados para manejar las variaciones anatómicas.

Resumo Variações anatômicas complexas na morfologia dos canais radiculares são um dos desafios mais árduos na prática endodôntica. O objetivo deste relato de caso é discutir o manejo clínico de um segundo pré-molar inferior esquerdo com quatro canais radiculares e quatro forames apicais distintos. Este relato de caso foi escrito de acordo com as diretrizes do Preferred Reporting Items for Case reports in Endodontics (PRICE) 2020. Um paciente de 74 anos foi encaminhado para retirada de um segundo pré-molar inferior esquerdo. O paciente queixou-se de desconforto ao mastigar alimentos duros. Após obter o consentimento do paciente para investigar os sintomas, foi realizado um exame clínico e radiográfico completo. Os principais achados clínicos observados foram sensibilidade moderada à percussão vertical e leve desconforto à palpação. A radiografia periapical mostrou uma raiz fusionada com múltiplos canais e obturações de canais radiculares insatisfatórias associadas à radioluscência apical. Com base nesta investigação, um diagnóstico de periodontite apical persistente foi feito ao dente, e um retratamento não cirúrgico do canal radicular foi proposto ao paciente. Após a obtenção do termo de consentimento livre e esclarecido, o procedimento foi realizado sob magnificação fornecida por microscópio cirúrgico odontológico com auxílio de pontas de ultrassom. Durante a abertura do acesso e retirada das obturações, foram observados quatro orifícios do canal radicular. Portanto, tecnologia de ponta, como microscópio cirúrgico odontológico, ultrassom e imagem de tomografia computadorizada de feixes cônico, são fortes aliados para o gerenciamento de variações anatômicas.

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The presence of deciduous premolars and erupting C1, P2, P4, I1, I2, I3, P2, and P4 in Nesophontidae is established for the first time on the fossil remains of Nesophontes major Arredondo, 1970, and N. micrus Allen, 1917 from El Abrón Cave (Republic of Cuba, Pinar del Río Province, Late Pleistocene). During ontogenesis, the replacement of teeth (except P1 and P1) occurred after the molar eruption, but before the animal reached adult size. By the dental replacement pattern nesophontids differ from most members of Lipotyphla and are close to Solenodontidae.

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BACKGROUND: Mandibular premolars are complicated teeth to endodontically treat due to the anatomical variations that can present. The purpose of this study was to determine the presence of C-shaped configurations in mandibular premolars by cone-beam computed tomography (CBCT). METHODS: 380 mandibular first premolars and 308 mandibular second premolars cone-beam computed tomographic images were obtained from 292 patients (175 female and 117 male). Tooth position, number of roots, root canals, C-shaped root canal system configuration, level of canal bifurcation and radicular grooves were evaluated by two endodontists trained in CBCT evaluation; previously calibrated between them, and a radiologist with endodontic experience. Data were statistically compared by The Chi-square test (α = 0.05) to examine any significant difference between gender and C-shaped root canal system and any significant difference between C-shaped configuration according to Fan criteria and gender. RESULTS: Overall 100% (n = 688) teeth examined, 19.2% (n = 132) had a C-shaped root canals system. 9.16% (n = 63) in male patients and 10.03% (n = 69) in female patients. The prevalence of C-shaped root canal system in mandibular first premolar was 83.33 and 16.66% in mandibular second premolars. According to Fan classification, the mandibular first premolars showed 3.63% as C1, 9.09% C2, 59.09% C3, 21.81% C4a, 1.8% C4b. Mandibular second premolars showed 13.63% as C1, 18.18% C2, 13.63% C3, 27.27% C4a, 9.09% C4b. Male patients showed 4.54% as C1, 3.78% C2, 22.72% C3, 11.36% C4a, 0.75% C4b, and 4.54% out of classification. Female patients showed 0.75% as C1, 6.81% C2, 30.03% C3, 9.84 C4a, 2.27% C4b, and 2.27% out of classification. The 53.36% canal bifurcation in mandibular first premolars and 50.09% in mandibular second premolars were in the middle third. No statistical differences were found between C-shaped root canal system and gender or C-shaped configuration according to Fan criteria and gender. P was < 0.05. CONCLUSIONS: Within the limitation of this study, the presence of C-shaped anatomical system is relatively low in mandibular second premolars than in mandibular first premolars.

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INTRODUCTION: The purpose of this study was to evaluate the impact of conservative endodontic cavities (CECs) on root canal preparation, restoration, and biomechanical behavior of teeth prepared using different shaping systems and restorative materials. METHODS: Ninety upper premolars with a bifurcated root were matched based on morphology and randomly assigned to a control group (n = 10) or 1 of the following experimental groups (n = 40): traditional endodontic cavity and CEC. Teeth were subdivided according to instrumentation (n = 10) as follows: ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland), Reciproc (VDW GmbH, Munich, Germany), Reciproc Blue (VDW GmbH), and Hyflex EDM (Coltene/Whaledent, Altstätten, Switzerland). After canal obturation, teeth were restored using temporary material, conventional composite, regular bulk fill composite, or bulk fill flow combined with conventional composite. Before and after preparation and after obturation, the teeth were scanned using micro-computed tomographic imaging. Canal transportation (CT), the percentage of untouched canal surfaces (UCSs), voids in restoration (VRs), and residual filling material in the pulp chamber were evaluated. Finite element analysis, fracture resistance, and the failure pattern were recorded. The data were analyzed using analysis of variance and the Tukey and chi-square tests. RESULTS: CECs had greater CT, percentage of filling material, and VRs compared with traditional endodontic cavities (P < .0001). The highest CT and UCSs were observed in CEC with ProTaper Universal. Bulk fill flow combined with conventional composite showed a lower percentage of VRs compared with other restorative materials (P < .05). Finite element analysis, fracture resistance, and failure pattern revealed similar behaviors in all groups (P > .05) . CONCLUSIONS: CECs had a negative impact on root canal centralization, UCSs, cleaning of the pulp chamber, and percentage of VRs. Controlled memory instruments were the most adequate for the root canal preparation of CECs. The endodontic cavity did not influence the biomechanical behavior of restored teeth.

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OBJECTIVE: To evaluate cone-beam computed tomography images in an Argentine population in order to determine the presence of mandibular premolars with C-shaped canal system and classify them. METHODS: 697 images were observed, 170 of them fulfilling the selection criteria. Once established the presence of a C-shaped canal system, premolars were classified using Fan's criteria. Data description was made by frequencies and percentages rates, with a 95% confidence interval according to the score method. Comparisons were assessed by means of the Chi-square test with a significance level equal to 5%. RESULTS: Of 269 first premolars, 27 teeth showed C-shaped canal system, i.e. 10%, and of 231 second premolars, 4 presented C-shaped canal system, i.e. 2%. Out of 17 patients presenting first premolars in both sides, 6 showed a bilateral C-shaped canal system pattern and 11 did not present this condition. When the condition was unilateral (n = 15), 7 patients showed C-shaped canal in the tooth 3.4 and 8 patients showed C-shaped canal in the tooth 4.4. The second premolars showed C-shaped canals unilaterally. Along the canal, configuration variations at the three-thirds have been observed for the first and second mandibular premolars. CONCLUSION: The C-shaped canal system pattern prevalence in mandibular first and second premolars was estimated for the first time in an Argentine population, in vivo. The present report contributes to the epidemiological understanding of the anatomical variable of the inner dental configuration and its extrapolation to the clinical practice.

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En los últimos años resulta de elección la utilización de postes de fib ra en la rehabilitación de piezas endodónticamente tratadas. La adhesión entre poste, agente cementante y dentina radicular permitiría lograr una retención de la estructura dentro de las paredes del conducto. El objetivo de este estudio fue comparar la resistencia adhesiva en los tercios cervical, medio y apical, entre la dentina del conducto radicular y el cemento adhesivo utilizado en la cementación de postes de fibra. Se utilizaron 30 premolares inferiores uniradiculares humanos, recientemente extraídos, se realizaron los tratamientos endodónticos, se desobturaron y realizaron las preparaciones con la fresa conformadora número 3 para la cementación de postes White Post DC especial número 3 con cemento Paracore utilizando el protocolo adhesivo del mismo sistema. Las muestras fueron incluidas en acrílico cristal, cortadas en forma perpendicular al eje mayor de la pieza con una máquina de corte y por último se procedió a medir los valores de adhesión de los postes a la superficie interna de los conductos en los tres tercios con la prueba push-out mediante una máquina de ensayo universal. Los resultados arrojaron que las resistencias (media +- DE, MPa) en los tercios cervical, medio y apical, fueron 8,74 +- 3,12, 9,38 +- 2,29 y 11,11 +- 2,95, respectivamente. En el tercio apical se registró mayor resistencia. Considerando las limitaciones de esta investigación, se puede concluir que la cementación de postes de fibra con cementos resinosos, presenta mayores valores en el tercio apical y menores en el tercio cervical del conducto radicular con técnica de Push-out (AU)

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AIM: To evaluate the influence of ultraconservative endodontic access cavities (UEC) on gaps and void formation in resin composite restorations in extracted two-rooted maxillary premolars after root canal treatment. Traditional endodontic access cavities (TEC) were used as a reference for comparison. METHODOLOGY: Two-rooted maxillary premolars were scanned in a micro-computed tomographic (micro-CT) device, matched based on similar anatomical features and allocated into two groups (n = 10) according to the design of the access cavity: TEC or UEC. Teeth were mounted on a mannequin head and a single operator performed the treatment, including endodontic access cavity preparation, root canal detection, preparation, filling and restoration procedures, under magnification. For restorative procedure, a bulk fill flowable layer was applied initially followed by an overlaying of regular composite. After restoration procedures, a new micro-CT scan was performed to check the quality of the coronal restoration by analysing the percentage volume of empty spaces present in the tooth-restoration interface (gaps) and inside the restoration (voids). Data were analysed statistically using Shapiro-Wilk and Student's t tests with a significance level of 5%. RESULTS: All specimens had gaps and voids. There were significant differences between the access cavity designs regarding the formation of voids with significantly more voids associated with the UEC (P < 0.05). Gap formation did not differ between groups (P > 0.05). CONCLUSION: The access cavity design used during root canal treatment interfered with the adaptation of the restorative material. The minimally invasive access cavity design was associated with a significantly greater number of voids within restorations.

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AIM: To evaluate the influence of ultraconservative endodontic cavities (UEC) on canal shaping and filling ability, cleaning of the pulp chamber, time required to perform root canal treatment and fracture resistance of 2-rooted maxillary premolars in comparison with traditional endodontic access cavities (TEC) in extracted teeth placed in a phantom head to simulate clinical conditions. METHODOLOGY: Twenty extracted intact 2-rooted maxillary premolars were scanned in a micro-computed tomographic device, matched based on similar anatomical features of the canals and assigned to UEC or TEC groups (n = 10). Then, teeth were mounted on a mannequin head and their pulp chamber accessed. After canal preparation, filling and cavity restoration, the time required to perform root canal treatment was recorded and the specimens were loaded to fracture in a universal testing machine. The maximum load at fracture was recorded. The sample was scanned after root canal instrumentation, filling and restoration procedures. Untouched canal areas, accumulation of hard-tissue debris (AHTD), voids in root fillings and cleaning of the pulp chamber were analysed. Data were analysed statistically using Shapiro-Wilk and Student's t-tests with a significance level of 5%. RESULTS: The percentage of untouched canal area did not differ significantly between UEC and TEC groups (P > 0.05). However, UECs were associated with a greater percentage of AHTD after canal preparation (P < 0.05). No differences were observed in terms of voids in root fillings between the groups (P > 0.05). Nonetheless, UEC had a greater percentage of root filling remnants in the pulp chamber after cleaning procedures (P < 0.05). The time required to perform root canal treatment was significantly longer in the UEC group (P < 0.05). There was no difference regarding the mean load at fracture between the groups (P > 0.05). Unrestorable fractures were observed in all specimens of both groups. CONCLUSIONS: There was no true benefit associated with ultraconservative endodontic cavities. UEC resulted in more AHTD remaining inside the root canals. UEC did not influence the quality of root fillings; however, UEC made the cleaning procedure of the pulp chamber more difficult, thus increasing the total time required to perform root canal treatment. Moreover, UEC were not associated with an increase in fracture resistance of root filled 2-rooted maxillary premolars.

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The maxillary sinus floor location and the buccal bone plate are factors to be considered in the long-term success with implant treatments mainly in the premolar region. the aim of this study was to establish morphometric characteristics of the buccal cortical bone (BCB) thickness of maxillary premolars and its relation to maxillary sinus floor through CBCT. In this study 350 first and second maxillary premolars were analyzed from 110 CBCT images and the buccal cortical bone (BCB) was measured in a coronal view at the major axis level of each premolar. In addition, in 200 first and second maxillary premolars CBCT images were measured the distance from premolar apex to maxillary sinus floor (MSF) in both frontal and sagittal plane. The type of relationship between the apex and MSF was classified according to Ok et al. (2014). The second premolar was observed with higher values of BCB (p<0.001). In first premolar, higher values were observed in the male sex (p>0.05). In second premolar, only significantly higher values were observed in the male sex in MA-MB-MC (p>0.05). Regarding to MSF and its relation to premolar roots, it was observed that 10 % of the sample was classified as type I, 19 % as type II, 55.5 % as type III and 15.5 % as type IV. The BCB of the upper premolar region is thicker in the apical region and decreases toward the coronal region. Almost 50 % of apex of second premolars are closely and risky related MSF (Type I and II).

La localización del piso del seno maxilar (PSM) y la tabla ósea vestibular (TOV) son factores a considerar en el éxito a largo plazo de los tratamientos de implante dental en la región premolar. El objetivo de este estudio fue establecer características morfométricas del grosor de la TOV en los premolares maxilares y su relación con el PSM a través de CBCT. Se analizaron 350 primeros y segundos premolares en 110 CBCT y la TOV fue medida en vista coronal en el eje axial mayor de cada premolar. Además en 200 primeros y segundos premolares maxilares se midió la distancia desde el ápice del diente hasta el PSM en el plano sagital y frontal. El tipo de relación entre el ápice y el PSM se clasificó según Ok et al. (2014). El Segundo premolar obtuvo los mayores valores de grosor de TOV (p<0.001). En primeros premolares se observaron valores altos en el género masculino (p>0.05). En segundos premolares solo se encontraron valores significativamente altos en el género masculino en MA-MB-MC (p>0.05). En la relación con el PSM y ápices de raíces de premolares, el 10% de la muestra se clasificó como tipo I, el 19% como tipo II, el 55,5% como tipo III y el 15.5% como tipo IV. En conclusión la TOV de la región premolares superior es más grueso en la zona apical, decreciendo hacia la zona coronal. Alrededor del 50% de los ápices de raíces de premolares maxilares están cercanas y en relación de riesgo con el PSM (tipo I y II).

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The aim of this study was to evaluate the root canal configuration of maxillary premolars using cone-beam computed tomography (CBCT). CBCT images of 999 maxillary premolars from a database were analysed to determine the frequency of the number of roots, root canals and Vertucci's classification. The associations among these variables were evaluated by Chi-square test (P < 0.05). In the first premolars, 42.2% of single-rooted teeth had a type II configuration, whereas 98.7% of 2-rooted teeth showed type IV. In the second premolars, type I was the most prevalent (49.9%). The presence of two roots was more prevalent in first premolars, and the presence of one root was more prevalent in second premolars (P < 0.05). Male patients had a higher percentage of two roots compared with female patients (P < 0.05). Type IV and I was more prevalent in first and second premolars respectively (P < 0.05). There was a high frequency of 2-rooted and single-rooted teeth among maxillary first and second premolars respectively.

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Objetivo: El objetivo de este estudio fue evaluar la frecuencia con que las raíces de premolares y molares superiores se encuentran dentro del seno maxilar. Conocer la relación entre dichas estructuras es importante para planificar los procedimientos endodónticos y quirúrgicos a ser realizados en esa región. Materiales y métodos: Se realizó el análisis cualitativo dinámico de 82 tomografías computadas de haz cónico (CBCT) unilaterales, analizándose 738 raíces correspondientes a premolares y molares de una sola hemiarcada superior. Se utilizó sala con iluminación controlada y la observación fue realizada por un solo examinador. El criterio de inclusión requería que la cortical inferior del seno maxilar debía ser visible para poder establecer la relación. Se utilizaron los tres planos tomográficos de visualización, permitiendo ajustes de brillo y contraste. La escala de clasificación de cada raíz consideró su relación como: dentro o fuera del seno maxilar. Los datos obtenidos fueron sometidos a las pruebas de Chi-cuadrado y Test Exacto de Fisher. Resultados: el primer premolar superior mostró una proyección hacia el interior del seno maxilar significativamente menor que las otras piezas dentarias posteriores (p>0.05), observándose su raíz vestibular sin proyección. La raíz palatina del primer premolar superior mostró la mayor incidencia dentro del seno maxilar, con un 39,02% del total de las raíces analizadas (p<0,05). El segundo molar superior mostró considerable proximidad con el seno maxilar, pero con menor incidencia con relación a la raíz palatina del primer molar. Conclusión: los procedimientos endodónticos o quirúrgicos a realizarse en cercanía al seno maxilar deben considerar siempre la relación raíz/seno, para evitar maniobras que lo invadan. La raíz palatina del primer molar superior mostró la mayor incidencia dentro del seno maxilar, con un 39,02% (AU)

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