Endodoncia

Aim To evaluate the influence of the location and design of endodontic access cavities on root canal shaping and filling ability, pulp chamber cleaning and fracture resistance of extracted human mandibular incisors.
Methodology After pre-selection using periapical radiographs, forty extracted intact human mandibular incisors were scanned in a micro-computed tomographic device. The teeth were matched based on similar anatomical features of the canals and assigned to four
experimental groups (n=10) according to the endodontic access cavity and root canal preparation protocol: traditional/TRUShape (T/TRU);
traditional/MTwo (T/MT); minimally invasive/TRUShape (MI/TRU); and minimally invasive/MTwo (MI/MT). The samples were scanned after root canal instrumentation and filling procedures. The parameters evaluated were: volume and area of the root canal, non-instrumented canal areas, canal transportation and centering ratio, accumulated hard tissue debris, voids in root canal fillings and root canal filling materials remnants in the pulp chamber. After root canal filling and cavity  restoration procedures, the samples were submitted to the fracture resistance test. Data were statistically analysed using Shapiro–
Wilk, one-way ANOVA and Bonferroni tests with a significance level of 5% (α=0.05).
Results There was no difference regarding all parameters evaluated before and after root canal preparation (volume and area of the root canal, non-instrumented canal areas, canal transportation and centering ratio, and accumulated hard tissue debris) among the groups (P>0.05). MI/TRU and MI/MT groups were associated with significantly more voids in root canal fillings when compared to the T/TRU and T/MT
groups (P<0.05). Percentage of root canal filling material remnants in the pulp chamber after cleaning procedures and mean fracture resistance values were not ssignificantly different among the four
experimental groups (P>0.05).
Conclusions The location and design of the endodontic access cavity did not impact on the root canal preparation and resistance to fracture of extracted mandibular incisors, regardless of the instrument used.
Minimally invasive access cavities were associated with significantly more voids in root canal fillings.

To evaluate the incidence of dentinal microcracks formation after root canal shaping procedures with HyFlex EDM and Vortex Blue rotary systems comparing with that of hand instrumentation using micro-computed tomography. Mandibular first molar teeth (n=60) having 50 to 200mesial root curvature were scanned using high resolution micro-CT imaging before root canal preparation to identify the presence of dentinal defects. Post-instrumentation cross-sectional images were taken and increased number and type of root defects were assessed and recorded. The data was statistically analysed by using chi-square test and McNemar&#39;s test at a significance level of 5%. HyFlex EDM has shown greater increase in post instrumentation dentinal defects. Both rotary systems exhibited increased dentinal defects formation at coronal, middle regions which is statistically significant (P=0.042) when compared to apical region. HyFlex EDM has shown greater increase in post instrumentation dentinal defects f...

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 to 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 anatomic 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 were
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 analyzed. Data were analyzed 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.

In the last decade, several access cavity designs with minimal removal of tooth tissue have been described for gaining entry to pulp chambers during root canal treatment. The premise behind this concept assumes that maximum preservation of as much of the pulp chamber roof as possible during access preparation would maintain the fracture resistance of teeth following root canal treatment. However, the smaller the access cavity, the more difficult it may be to visualise and debride the pulp chamber as well as locate, shape, clean and fill the canals. At the same time, a small access cavity may increase the risk of iatrogenic complications as a result of poor visibility, which may negatively impact the treatment outcome. This study aimed to critically analyse the literature on minimal access cavity preparations, propose new nomenclature based on self-explanatory abbreviations, and highlight
the areas in which more research is required. The search was conducted without restrictions using specifics terms and descriptors in four databases. A complementary screening of the references within the selected studies, as well as a manual search in the highest impact journals in Endodontics, namely International Endodontic Journal and Journal of Endodontics, were also performed. The initial search retrieved 1,831 publications. The titles and abstracts of these papers were reviewed and the full text of 94 studies assessed. Finally, a total of 28 studies were identified as evaluating the influence of minimally invasive access cavity designs on the fracture resistance of teeth and at different stages of
root canal treatment (orifice location, canal shaping, canal cleaning, canal filling and retreatment). Overall, the studies had major  methodological drawbacks and reported inadequate and/or inconclusive
results on the utility of minimally invasive access preparations. Furthermore, they offered limited scientific evidence to support the use of minimally invasive access cavities to improve the outcome of root canal treatment and retreatment, as well as, to preserve the fracture resistance of root filled teeth to a greater extent than traditional access cavity preparations. It was concluded that, at present, there is a lack of supporting-evidence for the introduction of minimally invasive access cavity preparation into routine clinical practice and/or training of undergraduate and postgraduate students.

RESUMEN Objetivo: Efectuar el tratamiento endodóntico en un segundo premolar inferior de dos conductos radiculares. Caso clínico: se presentoá la consulta un paciente de 42 años con caries ocluso distal para realizar el tratamiento endodóntico en el segundo pre-molar inferior izquierdo con diagnóstico de mor-tificación pulpar. Al realizar examen radiográfico se observoía presencia de un conducto radicular que a nivel del tercio medio se bifurcaba en dos conductos finalizando en dos forámenes separa-dos. Se realizoía instrumentación con sistema de limas reciprocante y la obturación se llevoá cabo con conos únicos de gutapercha de acuerdo al sistema de instrumentos utilizados. Conclusiones: la frecuencia de dos conductos ra-diculares en el segundo premolar inferior es rela-tivamente baja. Es importante un minucioso exa-men radiográfico para determinar las estrategias a seguir en caso de la presencia de esta tipología de conductos. Palabras clave: segundo premolar inferior, siste-ma de conductos radiculares. INTRODUCCIÓN La preparación químico-mecánica en Endodoncia tiene como objetivo la limpieza y conformación del sistema de conductos radiculares a través de los instrumentos endodónticos y de las solu-ciones de irrigación. El fracaso en Endodoncia se ha relacionado con diferentes factores como la obturación incomple-ta del sistema de conductos radiculares, filtración CASO CLÍNICO BOLETIN SAE coronaria y fallas del operador en reconocer la presencia de conductos y sus ramificaciones 1. Los premolares inferiores, en su gran mayoría, presentan una sola raíz con un conducto, que al ser único es amplio y de fácil localización. En los casos en que existe más de un conducto, estos presentan diversas formas originando una gran variedad en la morfología interna de estas piezas dentarias como lo describe Vertucci 2 3 (Fig. 1). Greco-Machado Y 1 y col. realizaron un estudio, tanto de premolares superiores como inferiores concluyendo que, de 50 segundos premolares in-feriores, la incidencia de Tipo I (un conducto) fue de 73,91%, mientras que el 26,08% de Tipo IV y V (dos conductos). Labarta 4 y col y un estudio realizado en una po-blación argentina, reportan que la morfología en-contrada con mayor frecuencia en los segundos premolares inferiores es de Tipo I, con un 65%, seguida por el Tipo V, con un 20% y finalmente, el Tipo II, con sólo un 15%. Figura 1: Clasificación de Vertucci.

RESUMEN La instrumentación de conductos curvos siempre ha sido un reto para el Odontólogo, aún para el más experimentado. Los cambios en la morfología interna son mucho más rápidos y peligrosos en los conductos curvos y pueden conducir al fracaso. El propósito de este estudio fue evaluar el grado de curvatura de la raíz mesio vestibular del primer molar inferior con el propósito de planificar el tratamiento endodóntico a fin de conservar dicha curvatura. Se utilizaron 50 imágenes obtenidas con radiovisiografía, elegidas al azar de primeros molares inferiores y de acuerdo al Método de Schneider se clasificaron con respecto a grado de curvatura radicular, en leve, moderado y severo. Este método de evaluación se puede utilizar para todas las piezas dentarias que presenten algún grado de curvatura radicular. El análisis estadístico descriptivo se realizó mediante la distribución de frecuencia utilizando el programa Excel 2016, el cual arrojó como resultado que el 53% de dichas raíces presentó curvatura severa, el 37% moderada y el 10% leve. La conservación de la curvatura en el sistema de conductos radiculares es fundamental en endodoncia. Si no se realizan los recaudos pertinentes a conservarla se pueden producir accidentes operatorios como el transporte apical, entre otros, que pueden llevar al fracaso del tratamiento endodóntico. Palabras clave: Primer Molar Inferior. Curvatura Radicular. Educación en Odontología. RESUMO A instrumentação de condutos curvos sempre foi um desafio para o cirurgião-dentista, mesmo para os mais experientes. Alterações na morfologia interna são muito mais rápidas e mais perigosas em condutos curvos e podem levar ao fracasso. O objetivo deste estudo foi avaliar o grau de curvatura da raiz mesio vestibular do primeiro molar inferior com o objetivo de planejar o tratamento endodôntico, a fim de preservar a referida curvatura. Foram utilizadas 50 imagens obtidas por radiovisiografia, escolhidas aleatoriamente entre os primeiros molares inferiores e, segundo o método de Schneider, classificadas quanto ao grau de curvatura radicular, em leve, moderada e severa. Este método de avaliação pode ser usado para todos os dentes que possuem algum grau de curvatura da raiz. A análise estatística foi realizada por meio do programa Excel 2016, que mostrou que 53% dessas raízes apresentavam curvatura severa, 37% moderada e 10% leve. A conservação da curvatura no sistema de canais radiculares é essencial na endodontia, caso as coletas pertinentes não sejam realizadas para conservá-la, acidentes operatórios como o transporte apical podem ocorrer, entre outros, o que pode levar ao insucesso do tratamento endodôntico. Descritores: Primeiro Molar Inferior. Curvatura da raiz. Educação em Odontologia.

La instrumentacion de conductos curvos siempre ha sido un reto para el Odontologo, aun para el mas experimentado. Los cambios en la morfologia interna son mucho mas rapidos y peligrosos en los conductos curvos y pueden conducir al fracaso. El proposito de este estudio fue evaluar el grado de curvatura de la raiz mesio vestibular del primer molar inferior con el proposito de planificar el tratamiento endodontico a fin de conservar dicha curvatura. Se utilizaron 50 imagenes obtenidas con radiovisiografia, elegidas al azar de primeros molares inferiores y de acuerdo al Metodo de Schneider se clasificaron con respecto a grado de curvatura radicular, en leve, moderado y severo. Este metodo de evaluacion se puede utilizar para todas las piezas dentarias que presenten algun grado de curvatura radicular. El analisis estadistico descriptivo se realizo mediante la distribucion de frecuencia utilizando el programa Excel 2016, el cual arrojo como resultado que el 53% de dichas raices presento c...

Resumen
Objetivo: Valorar la concordancia entre las mediciones realizadas
con un dispositivo de localización apical electrónica y las
registradas mediante conductometría radiográfica.
Materiales y métodos: Fueron determinadas las longitudes
de trabajo de manera electrónica (RayPex 6, VDW, Alemania) y
radiográfica de 249 conductos radiculares correspondientes a 125
pacientes a los que se había indicado tratamiento endodóntico. Éstos
fueron atendidos según los protocolos clínicos habituales.
Resultados: La prueba de t utilizada demostró que la diferencia
media entre las mediciones no era significativamente
distinta de 0. Los resultados para el coeficiente de correlación
intraclase y el correspondiente intervalo de confianza indican
una concordancia de 0,991 para un intervalo de confianza del
95%.
Conclusiones: Bajo las condiciones en que fue realizado
este estudio, la concordancia entre los valores obtenidos con los
métodos de determinación de la longitud de trabajo electrónico y
radiográfico fue muy buena.
Palabras clave: Foramen apical, localizador apical electrónico,
longitud de trabajo.

El concepto de síndrome metabólico fue introducido por vez primera en 1923 por Kylin.
Las dos características más constantes de personas con el síndrome son resistencia a la insulina y obesidad abdominal central.
FISIOPATOLOGÍA
MANIFESTACIONES CLÍNICAS

Objetivo: Identificar y analizar en la literatura científica reciente el
uso de la oximetría de pulso como método diagnóstico de vitalidad
pulpar. Metodología: En este trabajo se llevó a cabo una revisión de
la literatura en las plataformas de PubMed y Google Académico, en
la cual se analizó el uso de la oximetría de pulso en el diagnóstico y
monitoreo odontológico del estado pulpar. Resultados: Después de
una exhaustiva revisión, y de acuerdo con los criterios de inclusión
y exclusión, se analizaron 21 artículos. La mayoría de los trabajos
consideran la oximetría de pulso un método alternativo de diagnóstico
indoloro, seguro y eficaz; sin embargo, la adaptación de un instrumento
de uso exclusivo odontológico es necesaria para una medición exacta de
la saturación de oxígeno en la pulpa dental. Los avances tecnológicos
en el campo clínico de la odontología nos han llevado a la búsqueda
de nuevas técnicas diagnósticas clínicas para mejorar la atención y
los tratamientos de los pacientes que acuden día con día a recibir una
consulta odontológica. Conclusiones: En los últimos años la oximetría
de pulso ha demostrado ser una herramienta de diagnóstico eficaz para
el diagnóstico de la vitalidad pulpar. El análisis de los artículos incluidos
en esta revisión concluye que la oximetría de pulso es una técnica
innovadora que puede ser utilizada como una herramienta diagnóstica
adyuvante en el diagnóstico de la vitalidad pulpar.

De la fisiología al metaboloma, de la etiología bacteriana al concepto del biofilm y la disbiosis en el microbioma humano. La caries y las enfermedades periodontales son infecciones donde el biofilm es un reconocido factor de riesgo microbiano que determina el inicio y progresión de una lesión. Las bacterias que causan estas enfermedades están organizadas en estructuras denominadas biofilm, que son comunidades de complejos microbianos compuestos por una gran variedad de microorganismos con diferentes requerimientos ecológicos y un alto potencial patogénico. El biofilm es un neologismos científico que no merece ser traducido y sobre todo mal interpretado. La placa bacteriana es en realidad un biofilm microbano...
V 2018 REVISTA DE LA ASOCIACIÓN DE ENDODONCISTAS DEL AZUAY.

Los selladores endodóncicos pueden causar citotoxicidad en los
tejidos periapicales después de un tratamiento de conductos. En
general, las pruebas de biocompatibilidad in vitro realizadas a los
selladores evalúan su citotoxicidad cuando éstos ya endurecieron, lo que limita la evaluación de sus efectos durante la aplicación aguda; condición observada en la clínica. En el presente trabajo se evaluó la citotoxicidad de tres selladores: AH-Plus,RoekoSealAutomix® (RSA) y Roth Root utilizando un dispositivo que permite evaluar los efectos de los selladores durante su fase de polimerización. Cultivos de fibroblastos murinos fueron expuestos a los distintos selladores durante 6, 12, 24, 36, 48 y 72 horas. Después de cada periodo de tiempo se evaluó la morfología celular por microscopia de luz y la viabilidad mediante la prueba de exclusión del azul tripano. La morfología de fibroblastos expuestos al RSA no se altera. Sin embargo, al exponerlos a los otros dos selladores la mayor parte de los fibroblastos se despegan después de las primeras 6 horas. El ensayo de viabilidad muestra que el número de fibroblastos fue muy parecido entre el grupo control y el grupo expuesto a RSA a lo largo del curso temporal.
En contraste, la muerte de fibroblastos es evidente desde
las primeras 6 horas de exposición al AH-Plus y al Roth Root.
En conclusión, debido a que el RSA no mostró citotoxicidad, parece que los selladores con base de silicona constituyen la primera elección para el tratamiento de conductos.

In the last decades, the move of medicine towards minimally invasive treatments is notorious and scientifically grounded. As dentistry naturally follows in its footsteps, minimal access preparation have also becume a trend topic in the endodontic field. This procedure aims to maximize preservation of dentine tissue backed up by the idea that this is an effective way to reduce the incidence of post-treatment tooth fracture. However, with the assessment of the body of evidence on this topic, it is possible to observe some key points (a) the demand for nomenclature standardization, (b) the TRADITIONAL ACCESS CAVITY PREPARATION Access cavity preparation is defined as "the opening prepared in a tooth to gain entrance to the root canal

This is a successfully managed clinical case report of a young lady whose tooth # 11 was root treated in 2010 which reinfected after three years. The root treatment was repeated but was iatrogenically perforated because of the operating dentist's error. The tooth was therefore opened for surgical correction. During the procedure, it was found that labial wall of the tooth was missing in the mid-root area. The labial wall was built using glass ionomer cement keeping the endodontic file in the canal to avoid obliteration of canal space by glass ionomer. The rebuilt canal was treated with Calcium Hydroxide dressings at an interval of 7 days. In two weeks as the sinus healed, swelling subsided and the canal became effortlessly dryable using just two absorbent points, the canal was obturated with a custom made gutta percha cone, employing glass ionomer as a canal sealer.

Introducción: Se ha reportado la formación de precipitados color marrón y presencia de PCA al mezclar NaOCl y CHX experimentales. Sin embargo, no hay reportes al mezclar soluciones comerciales.

Objetivo: Analizar la formación y coloración de precipitados de Para-cloroanilina (PCA) su coloración y pH al mezclar NaOCl y CHX de uso clínico y comercial.

Metodología: Se formaron ocho grupos de estudio, utilizando diferentes presentaciones y concentraciones de NaOCl y CHX, a fin de evaluar la formación de precipitados y lograr describir sus características físicas. La presencia de PCA fue determinada por espectroscopia de resonancia magnética nuclear de hidrógeno (RMN de 1H).

Resultados: No se observaron precipitados en los grupos I, III, V, VII. Precipitados de color marrón mostraron los grupos II, IV. Los grupos VI y VIII mostraron precipitados azules. La presencia de PCA se observó en los grupos II, IV, V, VI, VII, VIII.

Conclusiones: Las concentraciones de NaOCl y CHX fueron determinantes en la formación de precipitados y PCA. Aditivos no específicos en NaOCl dental podrían ser responsables de la formación de precipitados azules, que a la fecha no han sido reportados en otros estudios.

Introduction: A prospective, multicentered, random-ized clinical trial was designed to assess if controlled irrigation with cold saline could result in less incidence and intensity of postoperative pain in patients presenting with pulp necrosis and symptomatic apical periodontitis. Methods: A total of 210 patients (presenting with necrotic uniradicular teeth with a diagnosis of symptomatic apical periodontitis and a preoperative visual analog scale (VAS) score higher than 7) were randomly allocated in the control or experimental group after the completion of shaping and cleaning procedures. The experimental group received a final irrigation with 20 mL sterile cold (2.5 C) saline solution delivered to the working length with a sterile, cold (2.5 C) Endovac microcannula (Kerr Endo, Orange Country, CA) for 5 minutes. The same protocol was used in the control group with room temperature saline solution. Patients were instructed to record the presence, duration and level of postoperative pain, and analgesic medication intake. A logistic regression was used to compare the incidence of postoperative pain and the need for painkillers between groups. Differences in general pain intensity between groups were analyzed using the ordinal (linear) chi-square test. Postoperative pain after 6, 24, and 72 hours (recorded in a VAS scale) and the need for analgesic medication intake between the 2 groups were assessed using the Mann-Whitney U test. Results: Patients in the control group presented a significantly higher incidence of postoperative pain, intensity, and need for medication intake (P < .05). Conclusions: Cryotherapy reduced the incidence of postoperative pain

Introducción: Se ha reportado la formación de precipitados color marrón y presencia de PCA al mezclar NaOCl y CHX experimentales. Sin embargo, no hay reportes al mezclar soluciones comerciales.

Objetivo: Analizar la formación y coloración de precipitados de Para-cloroanilina (PCA) su coloración y pH al mezclar NaOCl y CHX de uso clínico y comercial.

Metodología: Se formaron ocho grupos de estudio, utilizando diferentes presentaciones y concentraciones de NaOCl y CHX, a fin de evaluar la formación de precipitados y lograr describir sus características físicas. La presencia de PCA fue determinada por espectroscopia de resonancia magnética nuclear de hidrógeno (RMN de 1H).

Resultados: No se observaron precipitados en los grupos I, III, V, VII. Precipitados de color marrón mostraron los grupos II, IV. Los grupos VI y VIII mostraron precipitados azules. La presencia de PCA se observó en los grupos II, IV, V, VI, VII, VIII.

Conclusiones: Las concentraciones de NaOCl y CHX fueron determinantes en la formación de precipitados y PCA. Aditivos no específicos en NaOCl dental podrían ser responsables de la formación de precipitados azules, que a la fecha no han sido reportados en otros estudios.

Resumen
Los selladores endodónticos a base de metacrilatos, han demostrado poseer una importante capacidad
adhesiva con la dentina de las paredes del conducto radicular pero no con los conos de gutapercha.
Esto indujo la reciente aparición en el mercado de conos de gutapercha recubiertos con
una resina del mismo tipo. La resina tiene por objeto permitir una adhesión más efectiva entre conos
y selladores. El propósito de este estudio fue observar por medio del microscopio electrónico
de barrido la conformación estructural a nivel del tercio apical de conos de gutapercha Nº 40 (taper
.02) recubiertos con resina y comprobar si la misma es regular, continua y sin interrupciones. Para
el estudio morfológico, se observaron los tercios apicales de 20 conos nuevos. Los conos presentaron
alteraciones estructurales, especialmente en el extremo más apical, y cierta cantidad de partículas
adheridas a la superficie. Para el estudio de la capa de resina que cubre la superficie de los
conos se analizaron cortes transversales realizados a 1,0, 5,0 y 16,0 mm del extremo apical de los
mismos. La capa de resina resultó ser continua y sin interrupciones alrededor de toda la circunferencia
de los conos. Sin embargo no fue regular y presentó variaciones de espesor, especialmente
a nivel del tercio apical. Los resultados enfatizan la necesidad de un control de calidad más exhaustivo
por parte del fabricante a efectos de que la cobertura de resina no aparte a este tipo de
conos de las especificaciones de estandarización requeridas para obtener una obturación más
precisa a nivel del tercio apical.
PALABRAS CLAVE: conos de gutapercha, metacrilatos, obturación.
Summary
Unused resin-coated gutta-percha cones (size #40 .02 taper) were randomly selected from a proprietary
standardized system. Their morphological variations at the areas of their apical thirds as
well as the structure of the resin that covers the gutta-percha cone surfaces were analyzed with the
scanning electron microscope. SEM examination showed the presence of many morphologic irregularities.
The resin coat was continuous and without interruptions around the full perimeter of the
cones. However, the thickness of the resin was irregular and showed the most higher variations at
the level of the apical third. Our results emphasize the need for more precise criteria to fulfill the
conditions of standardization required for this type of root canal filling material.
KEY WORDS: gutta-percha, methacrylate, root canal filling

Aim To validate a new method for the evaluation of pulp tissue debridement in the root canals of extracted teeth using an impregnation protocol involving potassium triiodide, a radiocontrast solution known as
Lugol’s, combined with micro-computed tomographic (micro-CT) imaging.
Methodology The impact of NaOCl on the radiopacity of Lugol’s solution was assessed using a series of 1:1 dilutions of Lugol in distilled water and 5.25% NaOCl, which were then pipetted into transparent dishes
and radiographed. To verify the influence of Lugol on the oxidizing ability of NaOCl, a dissolution test was performed using fresh bovine meat. Ten slices did not undergo any tissue processing, whilst twenty slices
were fixed in formaldehyde for 24 h. After that, 10 of them were immersed in Lugol for another 24 h. Then, all specimens were placed in NaOCl and the time required for a complete pulp tissue dissolution was
recorded. For the last experiments (histological validation and micro-CT assessment), 8 extracted mandibular premolars with vital pulps were immersed in buffered formalin, scanned in a micro-CT device,
accessed, immersed in Lugol for 7 days and scanned again. Then, the root canals of 5 teeth were prepared, scanned, and the volume of remaining pulp tissue identified and quantified, whilst 3 teeth were
histologically processed. The same specimens were subjected to histological assessment and the images of the histologic sections were registered with the corresponding micro-CT images to qualitatively verify
whether the pulp tissue in the histological sections matched its counterpart in the Lugol-impregnated tissues identified in the micro-CT slices.
Results There was no discernible effect on radiopacity when NaOCl was mixed with Lugol. Tissue processing did not affect the time required for the complete dissolution of fresh bovine meat. Histological evaluation revealed a correlation between micro-CT and histological images confirming the identification of Lugol-impregnated pulp tissue in micro-CT images.
Conclusions The radiocontrast Lugol’s solution was unaffected by NaOCl and did not interfere with its pulp tissue dissolution capability. The pulp tissue impregnation protocol using Lugol allowed the visualization of pulp tissue on micro-CT images and the identification of remaining pulp tissues during the evaluation of chemical-mechanical canal procedures.

Aim To investigate the shaping and cleaning performance of the Clearsonic ultrasonic tip as a supplementary tool during the preparation of long oval-shaped root canals through micro-computed tomographic (micro-CT) imaging technology. Reciproc M-Wire R40 instrument was used as a reference instrumentation technique for comparison.
Methodology Twenty mandibular incisors with a single, straight and long oval-shaped canal were selected and pair-matched by micro-CT scanning. The root canals were prepared with Reciproc R25 and R40 instruments, scanned again in a micro-CT device and randomly allocated into one of the two experimental groups (n = 10), according to the supplementary debridement protocol used: Clearsonic or Reciproc R40 used in brushing motion against buccal and lingual walls. Non-instrumented canal areas, accumulation of hard-tissue debris (AHTD) and volume of removed dentine were assessed using micro-CT imaging after supplementary debridement protocols. Data were analyzed statistically in two phases using t-test with a significance level of 5%.
Results In phase-1, there was significant similarity between the samples regarding the evaluated micro-CT baseline parameters (P > 0.05), validating their anatomical similarity between the pairs. In phase-2, there was significant difference between the groups for canal volume, surface area, non-instrumented root canal walls and the amount of removed dentine for both absolute and percentage values (P < 0.05), but not AHTD (P = 0.759).
Conclusions The Clearsonic tip out-performed the Reciproc R40 instrument as a supplementary debridement protocol as it was associated with significantly greater reduction of non-instrumented root canals walls and consequently a larger amount of removed dentine. Both groups performed similarly regarding accumulated hard-tissue debris.

Aim To investigate the smallest dentine thickness in mesial canals of mandibular molars along the cervical and middle thirds of the root by means of a micro-computed tomographic (micro-CT) technology and digital image analysis.
Methodology Fifty mesial roots of mandibular molars having two independent canals (mesiobuccal and mesiolingual), in the coronal and middle levels, were scanned in a micro-CT device and selected. After reconstruction procedures, approximately 468 slices per root covering the 7 mm below the furcation area of the mesial root were analyzed to measure the smallest dentine thickness (danger zone [DZ]) in each slice from both distal and mesial regions of the mesial canals by an automatic segmentation process.
Results The DZ values in the mesiobuccal canals varied from 0.67 to 1.93 mm, with an average of 1.13 ± 0.21 mm. For the mesiolingual canals, the DZ varied from 0.77 to 1.89 mm with an average of 1.10 ± 0.21 mm. There was no correspondence in the DZ between the mesiobuccal and mesiolingual canals at the same cross-sectional level in 71% of the specimens. Moreover, the smallest dentine thickness was towards the mesial region of the roots in 22% and 18% of the mesiolingual and mesiobuccal canals, respectively.
Conclusions The smallest dentine thickness was on the mesial plane of the roots in about 40% of the canals. The vertical location of the DZ in relation to the furcation area was in the middle third of the root.

Introduction: The aim of this study was to evaluate the influence of rotary (ProTaper Next [PTN; Dentsply Maillefer, Ballaigues, Switzerland] and ProTaper Gold [PTG, Dentsply Maillefer]) and reciprocating (WaveOne Gold [WOG, Dentsply Maillefer]) systems in dentinal microcrack generation after the preparation of curved root canals using micro-computed tomographic analysis. Methods: Twenty-four human mandibular molars with curved roots were scanned in a micro-computed tomographic device using an isotropic resolution of 6.78 mm and randomly assigned into 1 of 3 experimental groups (n 5 8) according to the root canal instrumentation system used (PTN, PTG, or WOG). Then, the root canals were prepared up to PTN X2, PTG F2, and WOG Primary instruments in the PTN, PTG, and WOG groups, respectively. After canal preparation, each specimen was scanned again. Pre-and post-operative cross-sectional images of the roots (N 5 35,304) were analyzed to identify the presence of dentinal microcracks. Results: Overall, 26% of the images presented dentinal defects (n 5 9188). Dentinal microcracks were observed in 24.6%, 26%, and 27.4% of the postinstrumentation images from the PTN, PTG, and WOG groups, respectively. However, all of these dentinal microcracks were already present in the corresponding preoperative images. No new microcracks were generated after the preparation of curved root canals of mandibular molars using the aforementioned systems. Conclusions: Root canal instrumentation with PTN, PTG, and WOG systems did not induce the formation of new dentinal microcracks. (J Endod 2020;-:1-6.)

Introduction: This study aimed to compare the ProTaper Universal (PTU) system with 6 replicalike instruments regarding instrument design, mechanical performance and alloy characteristics. Methods: New rotary instruments (size 20/.07v) of PTU and 6 replicalike systems (EdgeTaper, U-Files, Go-Taper Universal, Super Files, Multitaper, Pluri Taper) (n=329) were selected and evaluated regarding their design, mechanical performance, and metallurgical characteristics. Results were compared by using nonparametric Mood's median test and one-way ANOVA with significance level set at 0.05. Results: Overall, replicalike instruments were similar to the PTU regarding design, maximum torque to fracture (P>.05), and ratio of nickel and titanium elements. Scanning electron microscopy revealed differences in the geometry of the tip and finishing surfaces. Time to fracture of Go-Taper Universal (50.0s) was similar to the PTU (44.0s) (P>.05), but U-File (63.5s), Edge Taper (87.5s) and Super Files (130s) showed significantly higher values (P<.05). The highest maximum torque was observed in the Super Files instrument (P<.05), but no statistical difference was noted amongst the other instruments (P>.05). The angle of rotation before rupture of Multitaper (574º) and Pluri Taper (481º) were higher than the PTU (354º) (P<.05). Differential scanning calorimetric analysis showed clear differences on the transformation temperatures among the tested instruments. R-phase start and finish of PTU were 11.0ºC and -18.0ºC, respectively. Conclusions: Overall, replicalike instruments were similar to the PTU regarding the torsional resistance, the geometric design and the near equiatomic proportions of nickel and titanium elements. In 3 out of 4 mechanical tests the EdgeTaper (torque, angle of rotation and bending load) and Go-Taper Universal (time to fracture, torque and angle of rotation) were similar to PTU.