Assessment of Efficiency of Bioactive Glass, Self-Assembling Peptide, and Ozone Remineralising Agents on Artificial Carious Lesion

ABSTRACT Objective: To assess the efficacy of bioactive glass, self-assembling peptide, and ozone-remineralizing agents on the artificial carious lesion. Material and Methods: On the extracted 60 premolar teeth, an artificial carious lesion/demineralization was created. Later, the remineralization of demineralized teeth was done with respective remineralizing agents (Group A: Calcium sodium phosphosilicate (bioactive glass), Group B: Self-assembling peptide, Group C: Ozone remineralizing agents and Group D (Control): De ionized water. The degree of demineralization and remineralization were evaluated using the Vickers Hardness Number. Results: There was a decrease in microhardness from baseline to demineralization in all the groups, and this reduction was found to be statistically considerable. After the remineralization of demineralized samples with respective remineralizing agents, there was an increase in microhardness of 312.38, 276.67, and 254.42 in groups A, B, and C, respectively. In contrast, in Group D, there were no changes. Conclusion: Bioactive glass and self-assembling peptides had higher remineralizing capacities, which can be used to treat early carious lesions.

Comportamiento Mecánico de un Premolar Humano Sano Sometido a Fuerzas Funcionales y Disfuncionales en un MEF / Mechanical Behavior of a Healthy Human Premolar Subjected to Functional and Dysfunctional Forces in a FEM

El propósito de este estudio fue analizar el comportamiento mecánico de la estructura dental sana de un primer premolar inferior humano sometido a fuerzas funcionales y disfuncionales en diferentes direcciones. Se buscó comprender, bajo las variables contempladas, las zonas de concentración de esfuerzos que conllevan al daño estructural de sus constituyentes y tejidos adyacentes. Se realizó el modelo 3D de la reconstrucción de un archivo TAC de un primer premolar inferior, que incluyó esmalte, dentina, ligamento periodontal y hueso alveolar considerando tres variables: dirección, magnitud y área de la fuerza aplicada. La dirección fue dirigida en tres vectores (vertical, tangencial y horizontal) bajo cuatro magnitudes, una funcional de 35 N y tres disfuncionales de 170, 310 y 445 N, aplicadas sobre un área de la cara oclusal y/o vestibular del premolar que involucró tres contactos estabilizadores (A, B y C) y dos paradores de cierre. Los resultados obtenidos explican el fenómeno de combinar tres vectores, cuatro magnitudes y un área de aplicación de la fuerza, donde los valores de esfuerzo efectivo equivalente Von Mises muestran valores máximos a partir de los 60 MPa. Los valores de tensión máximos se localizan, bajo la carga horizontal a 170 N y en el proceso masticatorio en la zona cervical, cuando la fuerza pasa del 60 %. Sobre la base de los hallazgos de este estudio, se puede concluir que la reacción de los tejidos a fuerzas funcionales y disfuncionales varía de acuerdo con la magnitud, dirección y área de aplicación de la fuerza. Los valores de tensión resultan ser más altos bajo la aplicación de fuerzas disfuncionales tanto en magnitud como en dirección, produciendo esfuerzos tensiles significativos para la estructura dental y periodontal cervical, mientras que, bajo las cargas funcionales aplicadas en cualquier dirección, no se generan esfuerzos lesivos. Esto supone el reconocimiento del poder de detrimento estructural del diente y periodonto frente al bruxismo céntrico y excéntrico.

SUMMARY: The purpose of this study was to analyze the mechanical behavior of the healthy dental structure of a human mandibular first premolar subjected to functional and dysfunctional forces in different directions. It was sought to understand, under the contemplated variables, the areas of stress concentration that lead to structural damage of its constituents and adjacent tissues. The 3D model of the reconstruction of a CT file of a lower first premolar was made, which included enamel, dentin, periodontal ligament and alveolar bone considering three variables: direction, magnitude and area of the applied force. The direction was directed in three vectors (vertical, tangential and horizontal) under four magnitudes, one functional of 35 N and three dysfunctional of 170, 310 and 445 N, applied to an area of the occlusal and/or buccal face of the premolar that involved three stabilizing contacts (A, B and C) and two closing stops. The results obtained explain the phenomenon of combining three vectors, four magnitudes and an area of force application, where the values of effective equivalent Von Mises stress show maximum values from 60 MPa. The maximum tension values are located under the horizontal load at 170 N and in the masticatory process in the cervical area, when the force exceeds 60%. Based on the findings of this study, it can be concluded that the reaction of tissues to functional and dysfunctional forces varies according to the magnitude, direction, and area of application of the force. The stress values turn out to be higher under the application of dysfunctional forces both in magnitude and in direction, producing significant tensile stresses for the dental and cervical periodontal structure, while under functional loads applied in any direction, no damaging stresses are generated. This supposes the recognition of the power of structural detriment of the tooth and periodontium against centric and eccentric bruxism.

Influencia de la Morfología Externa de la Raíz de Primeros Premolares Superiores en la Sobreestimación del Espesor Radiográfico Radicular Durante la Preparación para Poste, Evaluados Mediante Tomografía Computarizada Cone Beam / Influence of the External Morphology of the Root of Upper First Premolars on the Overestimation of Radiographic Root Thickness During Post Preparation, Evaluated by Cone Beam Computed Tomography

La investigación tuvo como objetivo determinar la influencia de la morfología externa de la raíz de primeros premolares superiores en la existencia de sobreestimación radiográfica durante la preparación para poste. Con este fin se realizó un estudio transversal in vitro, donde 60 premolares superiores uniradiculares fueron instrumentadas con fresas Gates Glidden y Pesso de calibre 1, 2 y 3. Seguidamente se obtuvieron imágenes radiográficas digitales de cada pieza dentaria mediante un aparato posicionador a una distancia constante en sentido vestíbulo lingual, asimismo se realizaron imágenes tomográficas volumétricas de las muestras. En ambas técnicas imagenológicas se midió el espesor a mesial y distal de las piezas. La sobreestimación fue calculada mediante la diferencia de la medida tomográfica menos la radiográfica. Los resultados indicaron que en ambas paredes radiculares hubo diferencia significativa entre las medidas radiográficas y tomográficas (p<0,05), encontrándose en la pared distal diferencias altamente significativas (p<0,001); además se evidenció que la sobreestimación radiográfica fue mayor en la pared distal. El estudio concluyó que existe sobreestimación radiográfica en premolares superiores durante la preparación para poste de un 20,42 % en promedio, siendo la pared distal la estructura que presenta mayor sobreestimación.

SUMMARY: he investigation´s objective was to determine the influence of external morphology of the root of upper first premolars in the existence of radiographic overestimation during preparation for post. An in vitro cross-sectional study was carried out, where 60 single-rooted upper premolars were instrumented with burs. Gates Glidden and Pesso of caliber 1, 2 and 3, then, digital radiographic images of each dental piece were obtained by means of a positioning device at a constant distance in the buccolingual direction; volumetric tomographic images of the samples were also performed. In both imaging techniques, the mesial and distal thickness of the pieces was measured. The overestimation was calculated by the difference of the tomographic measurement minus the radiographic one. The results indicated that in both root walls there was a significant difference between the radiographic and tomographic measurements (p<0.05), with highly significant differences being found in the distal wall (p<0.001); In addition, it was evidenced that the radiographic overestimation was greater in the distal wall. The study concluded that there is radiographic overestimation in upper premolars during post preparation of 20.42% on average, with the distal wall being the structure that presents the greatest overestimation.

Avaliação da profundidade da cárie proximal nos exames radiográfico convencional e digitalizado / Evaluation of the size of proximal caries in radiography and digitized

Introdução: A cárie dentária é uma doença multifatorial que compreende vários fatores biológicos e sociais. A superfície proximal dos dentes é uma região de difícil visualização que pode esconder pequenas lesões cariosas no esmalte dentário, impossibilitando o diagnóstico através de inspeções visuais e táteis. Objetivo: O objetivo deste trabalho foi avaliar a profundidade da cárie proximal nos exames radiográficos convencionais e digitais, comparando as profundidades das lesões consideradas nestes exames às do exame histológico. Método: Foram utilizados exames radiográficos interproximais de 40 dentes humanos, 20 pré-molares e 20 molares, com alterações clínicas em uma das superfícies proximais, como lesões de mancha branca ou acastanhada e pequenas cavitações. Três profissionais especializados em radiologia odontológica com mais de cinco anos de experiência clínica mediram a profundidade das lesões pelos exames radiográfico e digital das amostras. Para obter os resultados, utilizou-se a técnica de análise de variância (ANOVA). Resultados: Constatou-se um nível de significância de 5% nas mensurações dos exames radiográficos convencionais e digitalizados, mostrando a fidelidade das imagens radiográficas em relação a real profundidade da lesão. Conclusão: Conclui-se que os exames de imagem avaliados foram eficientes na determinação da profundidade das lesões de cárie proximal.

Introduction: Dental caries is a multifactorial disease that comprises several biological and social factors. The proximal surface of the teeth is a region of difficult visualization that can hide small carious lesions in the dental enamel, making diagnosis through visual and tactile inspection infeasible. Objective: The objective of this study was to evaluate the depth of proximal caries in the conventional and digitized radiographic examinations, comparing the depths of the lesions considered in these examinations to those of the histological examination. Method: Interproximal radiographic examinations of 40 human teeth, 20 premolars and 20 molars, with clinical alterations on one of the proximal surfaces, such as white or brown spot lesions and small cavitations, were used. Three professionals specialized in dental radiology with more than five years of clinical experience measured the depth of the lesions by radiographic examination of the samples. To obtain the results, we used the technique of analysis of variance (ANOVA). Results: A level of significance of 5% was found in conventional and digitized radiographic measurements, showing the fidelity of the radiographic images in relation to the actual depth of the lesion. Conclusion: It was concluded that the imaging tests evaluated were efficient in determining the depth of proximal caries lesions.

Benefícios do planejamento digital para cirurgias periodontais estéticas: relato de caso / Benefits of digital planning for esthetic periodontal surgeries: case report

Sorriso gengival é comumente conhecido pela exposição excessiva das gengivas ao sorrir, acarretando assim na diminuição das coroas dos elementos. No que tange a etiologia dessa condição, ela se apresenta de maneiras diversas e sua identificação é fundamental para o desenvolvimento de um plano de tratamento eficaz. O planejamento clínico pode ser feito usando uma abordagem dinâmica e digital do sorriso, como softwares, exames de imagem, modelos virtuais 3D e guias cirúrgicos, melhorando a qualidade e precisão do tratamento, oferecendo diversos benefícios aos pacientes. Sendo assim esse estudo teve como objetivo demonstrar a importância dos processos digitais no planejamento e correção do sorriso gengival. Paciente queixou-se da desproporção do sorriso, caracterizado por coroas curtas nas regiões de pré-molares e incisivos ligadamente com a exposição excessiva da gengiva ao sorrir. Após estudos clínicos e de imagem, a etiologia foi diagnosticada como erupção passiva alterada, tipo I (fenótipo espesso). O tratamento de escolha foi o remodelamento gengival associado à osteotomia e osteoplastia obtendo assim uma maior precisão no tratamento, sendo confeccionado um guia cirúrgico duplo. Sendo assim, é possível contemplar que o planejamento digital permite uma maior previsibilidade da execução, compatibilidade em relação a expectativa do paciente e profissional, além da total individualização do caso, tornando os resultados mais favoráveis e exatos e minimizando as chances de iatrogenias(AU)

Gummy smile is commonly known for exposing the gums to the smile, thereby increasing the crowns elevation of the elements. Regarding a condition, it presents itself in different ways and its identification is fundamental for the development of a treatment plan. The clinician can be done using a dynamic and digital approach to image treatment, such as software, imaging exams, various 3D virtual models and elaborate guides, improving the quality and precision of treatment, offering benefits to patients. Therefore, this study aimed to demonstrate the importance of digital processes in planning and correcting the gummy smile. Patient complained of disproportion of the smile, facing the regions of premolar crowns and incisors of the smile, facing the exposure of the gingiva when smiling. After clinical and imaging exams, the diagnostic studies were diagnosed as passive eruption, type I (phenotype and specific). The choice of choice was remodeling associated with surgery treatment and surgery treatment, thus providing a greater precision in the treatment, being a double guide elaborated. Therefore, it is possible that the digital is possible a predictability of execution, compatibility in relation to patient and professional care, in addition to the greater possibility of individualization planning than it allows, making the results more planned as possibilities and exactly the iatrogenic(AU)

Study of anatomical variations in premolars by cone beam computerized tomography in a radiologic clinic in Piauí / Estudo de variações anatômicas em pré-molares por tomografia computadoriza de cone beam em uma clínica radiológica no Piauí

Introduction: Root canal cleaning is the main objective of endodontic treatment and requires knowledge of the internal anatomy. The premolars are evidenced in the literature with great anatomical variations. In view of this, studies indicate that the use of Cone Beam Computed Tomography helps in the visualization of highly complex anatomy. Objective: to describe the anatomical variations in maxillary and mandibular premolars using cone beam computed tomography in a radiologic clinic in Piaui. Methods: 54 cone beam computed tomography scans with 160 premolars were used, produced using the Orthopantomograph OP300 equipment and analyzed by multiplanar reconstructions: axial, coronal and sagittal. Data regarding sex, number of roots and canals were recorded to compare and classify according to Vertucci. Results: the maxillary first pre-molars had 63.5% two roots,83.7% with one root and the mandibular pre-molars mostly with one root. Regarding the number of channels, 92.3% of the first premolars had two channels, most of them maxillary second premolars and mandibular premolars only one channel. Vertucci variations of types I, II, III and IV were verified in single-rooted elements, observing a great variation in superior elements. As for the prevalence of sex, only the first superiors showed greater variation in males. Conclusions: the upper first premolars prevailed with a great anatomical variation in relation to the other premolars with prevalence of Vertucci Type I and in males.

Introdução: a limpeza do canal radicular é o principal objetivo do tratamento endodôntico e requer conhecimento da anatomia interna. Os pré-molares são evidenciados na literatura com grandes variações anatômicas. Diante disso, estudos indicam que o uso da Tomografia Computadorizada Cone Beam auxilia na visualização de anatomias de alta complexidade. Metodologia: foram utilizadas 54 tomografias computadorizadas de feixe cônico com 160 pré-molares, produzidas no equipamento Orthopantomograph OP300 e analisadas por reconstruções multiplanares: axial, coronal e sagital. Os dados referentes ao sexo, número de raízes e canais foram registrados para comparação e classificação segundo Vertucci. Resultados: os primeiros pré-molares superiores apresentavam 63,5% de duas raízes, 83,7% dos segundos pré-molares superiores tinham uma raiz e a maioria dos pré-molares inferiores tinha uma raiz. Em relação ao número de canais, 92,3% dos primeiros pré-molares possuíam dois canais, sendo a maioria segundos pré-molares superiores e pré-molares inferiores apenas um canal. Vertucci variações dos tipos I, II, III e IV foram verificadas nos elementos uniradiculares, observando-se a grande variação nos elementos superiores. Quanto à prevalência do sexo, apenas os primeiros superiores apresentaram maior variação no sexo masculino. Conclusão: os primeiros pré-molares superiores prevaleceram com grande variação anatômica em relação aos demais pré-molares com prevalência de Vertucci Tipo I e no sexo masculino.

Diversity of root canal morphology in mandibular first premolars and its clinical strategies / 中华口腔医学杂志

It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.

Mechanical behavior of different machinable ceramic crowns using vertical and horizontal preparations: an in-vitro study / Comportamento mecânico de diferentes coroas cerâmicas usináveis usando preparos verticais e horizontais: um estudo in vitro

Objective: the aim of this study was to compare the mechanical behavior of different ceramics when used in thin vertical preparations versus traditional horizontal preparation. Material and Methods: two stainless-steel dies were milled to simulate a minimally invasive vertical preparation (VP) and a traditional horizontal preparation (HP) for an all-ceramic crown of a maxillary first premolar. The stainless-steel dies were duplicated using epoxy resin. Eighty monolithic crowns were milled and divided into 2 groups according to preparation design. Each design group was subdivided into 4 sub-groups according to material (n=10): IPS e.max CAD (lithium disilicate), Bruxzir shaded zirconia (full contour zirconia), CeraSmart (resin nanoceramic) and CEREC Tessera (advanced lithium disilicate). The crowns were cemented on their relevant epoxy resin dies using self-adhesive resin cement. All specimens were subjected to 15,000 thermocycles and then loaded to fracture in a universal testing machine. Data were analyzed using two-way ANOVA and Tukey pair wise comparison test. Results: the fracture resistance mean values of the VP (1344 + 118 N) was significantly lower than the HP design (1646 + 191 N). Ceramic crowns made of full contour zirconia had higher fracture resistance mean values (2842 + 380 N) than advanced lithium disilicate (1272 + 125 N) followed by lithium disilicate crowns (983 + 52 N) and resin nanoceramic (882 + 61 N). Conclusion: both vertical and horizontal preparations, regardless the different ceramic materials, showed clinically acceptable fracture resistance values. (AU)

Objetivo: o objetivo deste estudo foi comparar o comportamento mecânico de diferentes cerâmicas quando utilizadas em preparos verticais finos ou preparos horizontais tradicionais. Material e Métodos: dois modelos de aço inoxidável foram fresados para simular um preparo vertical minimamente invasivo (PV) e um preparo horizontal tradicional (PH) para uma coroa totalmente em cerâmica de um primeiro pré-molar superior. As matrizes de aço inoxidável foram duplicadas usando resina epóxi. Oitenta coroas monolíticas foram fresadas e divididas em 2 grupos de acordo com o desenho do preparo. Cada grupo foi subdividido em 4 subgrupos de acordo com o material (n=10): IPS e.max CAD (dissilicato de lítio), zircônia Bruxzir (zircônia de contorno total), CeraSmart (resina nanocerâmica) e CEREC Tessera (dissilicato de lítio avançado). As coroas foram cimentadas em suas respectivas matrizes de resina epóxi usando cimento resinoso autoadesivo. Todos os espécimes foram submetidos a 15.000 ciclos térmicos e então carregados até a fratura em uma máquina de teste universal. Os dados foram analisados usando ANOVA com dois fatores e teste de comparação por pares de Tukey. Resultados: os valores médios de resistência à fratura do PV (1344 + 118 N) foram significativamente menores do que PH (1646 + 191 N). As coroas de cerâmica feitas de zircônia de contorno total apresentaram maiores valores médios de resistência à fratura (2842 + 380 N) do que dissilicato de lítio avançado (1272 + 125 N), seguido por coroas de dissilicato de lítio (983 + 52 N) e resina nanocerâmica (882 + 61 N). Conclusão: preparos verticais e horizontais, independentemente dos diferentes materiais cerâmicos, apresentaram valores de resistência à fratura clinicamente aceitáveis. (AU)

Estudio de la morfología de los conductos radiculares de los primeros premolares superiores en tomografía computarizada de haz cónico / Study of the morphology of root canals of the first upper premolars in cone beam computed tomography

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))

Reproducibilidad y validez de criterio de dos técnicas radiográficas para variaciones de premolares mandibulares comparadas con CBCT / Reproducibility and criterion validity of two radiographic techniques for variations in mandibular premolar compared with CBCT technique

Introducción: La existencia de variaciones anatómicas ocasiona fracasos en tratamientos endodónticos, por lo que es importante diagnosticarlas. El objetivo fue determinar la reproducibilidad y la validez de criterio de las radiografías con placa de fósforo y la radiovisografía con sensor para identificar las variaciones anatómicas detectadas por tomografía computarizada de haz cónico (CBCT) en premolares inferiores. Métodos: En 140 premolares se obtuvieron imágenes por CBCT, radiografía y radiovisografía. Se realizó lectura independiente por dos endodocistas, evaluándose la clasificación de Vertucci y las ramificaciones. Se determinó la reproducibilidad intraobservador e interobservador. Se calcularon sensibilidad, especificidad y áreas bajo la curva operador-receptor (AUC) utilizando como estándar de oro la CBCT. Resultados: La reproducibilidad intraobservador e interobservador fue mayor para radiografía. Para la Clase I de Vertucci, la radiografía presentó mayor sensibilidad (94,7%), especificidad (64,9%) y AUC (0,795) que la radiovisiografía (89,3%, 62,2% y 0,757, respectivamente), al igual que para la Clase V (Radiografía 69,2%, 93% y 0,811; Radiovisiografía 50%, 84,2% y 0,671, respectivamente). Ninguna de las técnicas aportó al diagnóstico de la Clase III (AUC <0,5). Las ramificaciones fueron infrecuentes (2,9%) y su detección fue baja (Sensibilidad 25% para radiografía y 0% para radiovisiografía). Discusión: Este es el primer estudio que evalúa la reproducibilidad y validez de estas dos técnicas radiográficas comparadas con la CBCT para la detección de variaciones anatómicas en dientes. Conclusiones: La radiografía con placa de fósforo presentó mayor reproducibilidad y validez para el diagnóstico de las Clase I y V de Vertucci, que fueron las variaciones más frecuentes.

Introduction: Considering that the existence of anatomical variations causes endodontic treatment failures, therefore it is important to diagnose them. This study aimed to determine the reproducibility and criterion validity of phosphor plate radiographs and sensor-based radiovisiography to identify anatomical variations detected by cone-beam computed tomography (CBCT) in lower premolars. Materials and Methods: 140 premolars images were obtained by CBCT, radiographs and radiovisiography. Independent interpretation was performed by two endodontists to evaluate the Vertucci classification and ramifications. Intraobserver and interobserver reproducibility were determined. Sensitivity, specificity and areas under the receiver-operator curve (AUC) were calculated using CBCT as the gold standard. Results: Intraobserver and interobserver reproducibility was higher for radiography. For Vertucci type I, radiography showed higher sensitivity (94.7%), specificity (64.9%) and AUC (0.795) than radiovisiography (89.3%, 62.2% and 0.757, respectively), similarly for type V (radiography at 69.2%, 93% and 0.8111; radiovisiography at 50%, 84.2% and 0.671, respectively). None of the techniques contributed to the diagnosis of type III (AUC < 0.5). Ramifications were infrequent (2.9%) with a low level of detection (sensitivity at 25% for radiography and 0% for radiovisiography). Discussion: This is the first study to evaluate the reproducibility and validity of these two radiographic techniques compared with CBCT for the detection of anatomical variations in teeth. Conclusions: Phosphor plate radiography showed higher reproducibility and validity for the diagnosis of Vertucci types I and V, which were the most frequent premolar variations found. This is a dissertation for the Master's degree in Dentistry available in the repository of the Universidad Santo Tomas, Bucaramanga campus.

Introdução: A existência de variações anatômicas causa falhas no tratamento endodôntico, por isso é importante diagnosticá-las. O objetivo foi determinar a reprodutibilidade e validade dos critérios das radiografias em placas de fósforo e radiovisiografia sensorial para identificar variações anatômicas detectadas pela tomografia computadorizada de feixe cônico (TCFC) em pré-molares inferiores. Métodos: obtiveram-se TCFC, imagens radiográficas e radiovisográficas em 140 pré-molares. A leitura independente foi realizada por dois endodontistas, avaliando a classificação Vertucci e suas ramificações. Foi determinada a reprodutibilidade intra e interobservador. Sensibilidade, especificidade e áreas sob a curva operação do receptor (AUC) foram calculadas utilizando a TCFC como padrão-ouro. Resultados: A reprodutibilidade intra e inter-observador foi maior para a radiografia. Para a Classe I de Vertucci, a radiografia mostrou maior sensibilidade (94,7%), especificidade (64,9%) e AUC (0,795) do que a radiovisiografia (89,3%, 62,2% e 0,757, respectivamente), assim como para a Classe V (Radiografia 69,2%, 93% e 0,811; Radiovisiografia 50%, 84,2% e 0,671, respectivamente). Nenhuma das técnicas contribuiu para o diagnóstico da Classe III (AUC <0,5). A ramificação foi pouco frequente (2,9%) e a detecção foi baixa (Sensibilidade 25% para radiografia e 0% para radiovisiografia). Discussão: Este é o primeiro estudo para avaliar a reprodutibilidade e validade dessas duas técnicas radiográficas em comparação com a TCFC para a detecção de variações anatômicas nos dentes. Conclusões: A radiografia com placas de fósforo apresentou maior reprodutibilidade e validade para o diagnóstico da Classe I e V de Vertucci, que foram as variações mais frequentes. Este foi um trabalho de conclusão de durso para o título de Mestre em Odontologia e estará no repositório da Universidad Santo Tomas seccional Bucaramanga.

Torus mandibular e palatino predisponentes em um grupo familiar: fatores genéticos e ambientais, relato de uma série de casos / Mandibular and palatine torus predisposing in a family group: genetic and environmental factors, report of a series of cases / Torus mandibular y palatino predisponente en un grupo familiar: factores genéticos y ambientales, informe de una serie de casos

As exostoses mais conhecidas são o Torus palatino e mandibular, que se desenvolvem a partir do crescimento benigno da cortical óssea, localizadas respectivamente na linha média palatina e superfície lingual de caninos e pré-molares, podendo ser unilaterais ou bilaterais. Esse trabalho tem como objetivo o estudo de um grupo familiar que apresentaram o Torus como característica em comum, buscando confirmar a presença e prevalência das características clínicas multifatoriais listadas na literatura, possibilitando o diagnóstico da etiologia e assim traçando um plano de tratamento individual, se necessário. Como metodologia, foi realizada uma triagem com cada membro familiar na clínica Odontológica da Faculdade Sete Lagoas - FACSETE, descartando a participação no estudo os membros que não apresentaram o Torus. Os indivíduos que apresentaram indicação da remoção cirúrgica foram encaminhados para clínica de cirurgia da própria instituição. Concluímos, portanto, com este estudo que fatores genéticos e ambientais colaboram como fator etiológico mais predominantes para surgimento do Torus no grupo familiar estudado... (AU)

The best known exostosis are the palatine and mandibular Torus, which develop from the benign growth of the cortical bone, located respectively in the midpalatal line and lingual surface of canines and premolars, and maybe unilateral or bilateral. This work aims to study a family group that had Torus as a common feature, confirming the presence and prevalence of multifactorial clinical features listed in the literature, enabling the diagnosis of etiology and thus outlining an in dividual treatment plan, if necessary. As a methodology, a screening was performed by each family member at the Dental Clinic of Facul dade Sete Lagoas - FACSETE, discarding the participation in the study for members who did not present Torus. Individuals who indicated surgical removal were referred to the institution's own surgery clinic. Therefore, we conclude with this study that genetic and environmental factors collaborate as the most predominant etiological factor for the emergence of Torus in the studied family group... (AU)

Las exostosis más conocidas son el Torus palatino y el Torus mandibular, las cuales se desarrollan a partir del crecimiento benigno del hueso cortical y están ubicadas respectivamente en la línea medio palatina y en la cara lingual de los caninos y de los premolares que pueden ser unilaterales o bilaterales. Este proyecto tiene como objetivo el estudio de un grupo familiar que presentó en sus características comunes el Torus, buscando confirmar la presencia y el predominio de las características clínicas multifactoriales listadas en la literatura, lo que hizo posible el diagnóstico de la etiología y diseñar un plan de tratamiento individual, caso necesiten. Como la metodología fue hecho una selección con los miembros de la familia en la clínica odontologica de la Faculdade Sete Lagoas - FACSETE, quitando de los estudios las personas de la familia que no presentaron el Torus. Los individuos que presentaron indicación de extirpación quirúrgica fueron enviados a la clínica de cirugía de la escuela. Concluimos con este estudio que los factores genéticos y ambientales colaboraron como los factores etiológicos más predominantes para la aparición del Torus en la familia analizada... (AU)

In vitro assessment of interaction between lidocaine hydrochloride and irrigating solutions on root canal dentin: a scanning electron microscope study / Evaluación in vitro de la interacción entre el clorhidrato de lidocaína y las soluciones de irrigación en la dentina del conducto radicular: un estudio con microscopio electrónico de barrid

Aim: To investigate the precipitate formed from the interaction between 2% lidocaine hydrochloride with adrenaline (LA) with 2.5% sodium hypochlorite (NaOCl) and 0.2% chitosan nanoparticles on root canal dentin, using scanning electron microscopy (SEM). Material and Methods: Sixty mandibular premolars were decoronated, and the root length standardised. The specimens were randomly distributed into the following groups: Group 1 (control): 2% LA mixed with sterile water without root canal instrumentation, Group 2: 2% LA with 2.5% NaOCl in water without root canal instrumentation, and Group 3: 2% LA with 0.2% chitosan nanoparticles in water without root canal instrumentation. Teeth specimens were split and subjected to SEM analysis at cervical, middle, and apical root thirds. On observing precipitate formation in Group 2, 10 premolars were decoronated and treated with 2% LA and 2.5% NaOCl and subjected to root canal instrumentation. Results: Group 1 and Group 3 showed patent dentinal tubules and no precipitate formation. Group 2 showed precipitate blocking dentinal tubules in all the three sections, and the precipitate could not be removed completely after cleaning and shaping. Conclusion: NaOCl forms an insoluble precipitate on interaction with local anaesthetic solution that cannot be removed after chemo-mechanical preparation. Chitosan nanoparticles do not form any such precipitate and show patent dentinal tubules. Hence, chitosan can be used as a flushing irrigant.

Objetivo: Investigar el precipitado formado a partir de la interacción entre el clorhidrato de lidocaína al 2% con adrenalina (LA), el hipoclorito de sodio al 2,5% (NaOCl) y nanopartículas de quitosano al 0,2% en la dentina del conducto radicular, mediante microscopía electrónica de barrido (SEM). Material y Métodos: Se decoraron 60 premolares mandibulares y se estandarizó la longitud de la raíz. Los especímenes se distribuyeron aleatoriamente en los siguientes grupos: Grupo 1 (control): 2% la que fue mezclado con agua estéril sin instrumentación del conducto radicular, Grupo 2: 2% LA con 2,5% de NaOCl sin instrumentación del conducto radicular y Grupo 3: 2 % LA con 0,2% de nanopartículas de quitosano sin instrumentación del conducto radicular. Las muestras de dientes se dividieron y se sometieron a análisis SEM en los tercios radiculares cervical, medio y apical. Al observar la formación de precipitado en el Grupo 2, 10 premolares fueron decorados y tratados con LA al 2% y NaOCl al 2,5% y sometidos a instrumentación de conductos radiculares. Resultado: El Grupo 1 y el Grupo 3 mostraron túbulos dentinarios permeables y sin formación de precipitados. El grupo 2 mostró precipitado que bloqueaba los túbulos dentinarios en las tres secciones, y el precipitado no se pudo eliminar por completo después de limpieza y conformación. Conclusión: el NaOCl forma un precipitado insoluble al interactuar con la solución anestésica local que no se puede eliminar después de la preparación quimiomecánica. Las nanopartículas de quitosano no forman ningún precipitado de este tipo y muestran túbulos dentinarios permeables. Por lo tanto, el quitosano se puede utilizar como irrigante para el lavado.

In vitro bacterial adherence on teeth submitted to whitening with musa paradisiaca / Adherencia bacteriana in vitro en dientes sometidos a blanqueamiento con musa paradisiaca

Objetive: To compare in vitro bacterial adherence on teeth submitted to whitening with 50% ethanolic extract of Musa paradisiaca and 35% hydrogen peroxide. Material and Methods: The study was experimental and used 18 premolars that were grouped into: G1 (control), G2 (50% ethanol extract of Musa paradisiaca) and G3 (35% hydrogen peroxide). The teeth were then exposed to a Streptococcus mutans culture for 24 hours, followed by centrifugation in thioglycolate broth. A culture on trypticase soy agar was done with a 1 in 100 dilution, and after 48 hours colony forming units (CFU) were counted. Statistical analysis was performed using the ANOVA test, complemented by the Bonferroni post-hoc. Results: Bacterial adherence was 77x105 CFU/ml in Group 3 using 35% hydrogen peroxide, 40x105 CFU/ml in Group 2 using 50% ethanol extract of Musa paradisiaca, and 89x104 CFU/ml in Group 1 (control). The difference between the three groups was significant (p=0.000). Conclusion: Both whitening methods cause bacterial adherence to the tooth surface, although to a lower degree with Musa paradisiaca.eses.

Objetivo: Comparar la adherencia bacteriana in vitro en dientes sometidos a blanqueamiento con extracto etanólico de Musa paradisiaca al 50% y con peróxido de hidrógeno al 35%. Material y Métodos: Comparar la adherencia bacteriana in vitro en dientes sometidos a blanqueamiento con extracto etanólico de Musa paradisiaca al 50% y con peróxido de hidrógeno al 35%.Resultados: La adherencia bacteriana fue de 77x105 UFC/ml con el peróxido de hidrógeno al 35%, de 40x105 UFC/ml con el extracto etanólico de Musa paradisiaca al 50% y de 89x104 UFC/ml con el control. La diferencia fue significativa entre los tres grupos (p=0.000). Conclusión: Ambos métodos de blanqueamiento causan adherencia bacteriana en la superficie dental, siendo menor con Musa paradisiaca.

Anatomical and morphological findings of the root canal of maxillary premolars and their prevalence: CBCT study in a Mexican population / Hallazgos anatómicos y morfológicos del conducto radicular de premolares maxilares y su prevalencia: estudio CBCT en una población mexicana

SUMMARY: An essential prerequisite to perform any dental procedure is a clear understanding and knowledge of dental anatomy and its possible variations. The root canal system is characterized for a complex morphology, which varies among populations, individuals in the same population and even in the same person. The aim of this study was to evaluate by CBCT the morphology, number, curvature, and length of roots of first and second maxillary premolars in a Mexican population. In this stud 1700 maxillary premolars were evaluated by CBCT scans of patients; the axial, sagittal and coronal sections were analyzed following the longitudinal axis of each tooth. As a result 51.60 % of the maxillary first premolars had a single root, 31.03 % had two roots, 16.29 % had root fusion, and 1.07 % had three roots. 22.3 % of the maxillary first premolars showed mesial curvature, 41.9 % had a distal curvature, and 35.7 % did not show any curvature; and the most prevalent configuration in maxillary first premolars was Type V. 88.9 % of the maxillary second premolars had a single root, 3.9 % had two roots, 6.9 % had root fusion, and 0.11 % had three roots; 37.59 % of the maxillary second premolars showed a mesial curvature and 62.40 % showed a distal curvature; and the most prevalent configuration in maxillary second premolars was Type I. The anatomy of the root canal system is extremely complex and has many anatomical configurations, these clinical situations must be considered previous to performing any endodontic treatment.

RESUMEN: Un requisito esencial previo a la realización de cualquier procedimiento dental es una clara comprensión y conocimiento de la anatomía dental y sus posibles variaciones. El sistema de canales radiculares se caracteriza por una morfología compleja, que varía entre poblaciones, individuos en una misma población e incluso en una misma persona. El objetivo de este estudio fue evaluar mediante CBCT la morfología, número, curvatura y longitud de raíces de primeros y segundos premolares maxilares en una población mexicana. En este estudio se evaluaron 1700 premolares maxilares mediante escaneos CBCT de pacientes; se analizaron los cortes axial, sagital y coronal siguiendo el eje longitudinal de cada diente. El 51,60 % de los primeros premolares maxilares tenían una sola raíz, el 31,03 % tenían dos raíces, el 16,29 % tenían fusión de raíces y el 1,07 % tenían tres raíces. El 22,3 % de los primeros premolares maxilares presentaban curvatura mesial, el 41,9 % presentaban curvatura distal y el 35,7 % no presentaban curvatura alguna; y la configuración más prevalente en primeros premolares maxilares fue el Tipo V. El 88,9 % de los segundos premolares maxilares tenían una sola raíz, el 3,9 % dos raíces, el 6,9 % fusión de raíces y el 0,11 % tres raíces; El 37,59 % de los segundos premolares maxilares presentaban curvatura mesial y el 62,40 % curvatura distal y la configuración más prevalente en segundos premolares maxilares fue el Tipo I. La anatomía del sistema de canales radiculares es extremadamente compleja y tiene muchas configuraciones anatómicas, estas situaciones clínicas deben ser consideradas antes de realizar cualquier tratamiento de endodoncia.

Evaluación radiográfica de 5000 tratamientos endodónticos realizados en premolares y molares mandibulares y maxilares en una población en Argentina / Radiographic evaluation of 5000 endodontic treatments performed on mandibular and maxillary premolars and molars in a population in Argentina

Objetivo: Evaluar radiográficamente tratamientos en- dodónticos del sector posterior de la cavidad bucal y com- parar la frecuencia de aceptabilidad en cada pieza dentaria involucrada. Materiales y métodos: Se evaluaron 5000 radiogra- fías de archivo de tratamientos endodónticos realizados apro- ximadamente entre 2005 y 2019 en premolares y molares mandibulares y maxilares en Argentina. Se consideraron tratamientos correctos e incorrectos de acuerdo con: 1) con- formación de la preparación quirúrgica; 2) límite apical de la obturación; 3) homogeneidad de la obturación. Se obtuvo la fre- cuencia absoluta y relativa de correctos e incorrectos. El aná- lisis entre frecuencias y pieza dentaria se realizó con la prueba de chi cuadrado y el cálculo del coeficiente V de Cramer. Para la comparación entre grupos de piezas dentarias se utilizó la partición del valor de chi cuadrado obtenido en los corres- pondientes grados de libertad. Nivel de significación P <0.05. Resultados: La partición del valor de chi cuadrado no mostró diferencias significativas entre primeros y segundos premolares mandibulares. Las otras comparaciones exhibie- ron diferencias significativas. Conclusiones: Un alto porcentaje de los tratamientos endodónticos de la población estudiada tiene por lo menos una condición que permite categorizarlos como incorrectos según el criterio establecido en este trabajo. Este porcentaje es más preponderante en anatomías complejas (AU)

Aim: To evaluate radiographically endodontic treat- ments performed in the posterior area of the oral cavity and compare the frequency of acceptability in each tooth involved. Materials and methods: 5,000 archival radiographs of endodontic treatments performed between 2005 and 2019 on mandibular and maxillary premolars and molars in Argentina were evaluated. The percentages of correct and incorrect treatments were considered according to 1) shaping of the preparation; 2) apical limit of the obturation; 3) homogeneity of the obturation. The absolute and relative frequencies of correct and incorrect treatments were calcu- lated. The association between these frequencies and tooth type was analyzed using the chi-square test and Cramer's V coefficient. For the comparison between groups of teeth, the partition of the chi-square value obtained in the corre- sponding degrees of freedom was used. Level of significance was P <0.05. Results: The partition of the chi-square value did not show a significant difference between the first and second lower premolars. The differences were significant in the other comparisons. Conclusions: A high percentage of the endodontic treat- ments in the study population have at least one condition war- ranting their classification as incorrect according to the crite- ria established in this study. This percentage is more prevalent in complex anatomies (AU)

Efficacy of vertical control by using mini-implant anchorage in maxillary posterior buccal area for Angle class Ⅱ extraction patients / 北京大学学报(医学版)

OBJECTIVE@#To investigate the efficacy of vertical control by using conventional mini-implant anchorage in maxillary posterior buccal area for Angle class Ⅱ extraction patients.@*METHODS@#Twenty-eight Angle class Ⅱ patients [9 males, 19 females, and age (22.6±2.8) years] were selected in this study. All of these patients were treated by using straight wire appliance with 4 premolars extraction and 2 mini-implant anchorage in maxillary posterior buccal area. In this study, the self-control method was used to measure and analyze the lateral radiographs taken before and after orthodontic treatment in each case, the main cephalometric analysis items were related to vertical changes. The digitized lateral radiographs were imported into Dolphin Imaging Software (version 11.5: Dolphin Imaging and Management Solutions, Chatsworth, California, USA), and marked points were traced. Each marked point was confirmed by two orthodontists. The same orthodontist performed measurement on the lateral radiographs over a period of time. All measurement items were required to be measured 3 times, and the average value was taken as the final measurement result.@*RESULTS@#Analysis of the cephalometric radiographs showed that, for vertical measurements after treatment, the differences of the following measurements were highly statistically significant (P < 0.001): SN-MP decreased by (1.40±1.45) degrees on average, FMA decreased by (1.58±1.32) degrees on average, the back-to-front height ratio (S-Go/N-Me) decreased by 1.42%±1.43% on average, Y-axis angle decreased by (1.03±0.99) degrees on average, face angle increases by (1.37±1.05) degree on average; The following measurements were statistically significant (P < 0.05): the average depression of the upper molars was (0.68±1.40) mm, and the average depression of the upper anterior teeth was (1.07±1.55) mm. The outcomes indicated that there was a certain degree of upper molar depression after the treatment, which produced a certain degree of counterclockwise rotation of the mandibular plane, resulting in a positive effect on the improvement of the profile.@*CONCLUSION@#The conventional micro-implant anchorage in maxillary posterior buccal area has a certain vertical control ability, and can give rise to a certain counterclockwise rotation of the mandible, which would improve the profile of Angle Class Ⅱ patients.

Clinical characteristics and comprehensive treatment of patients with cleidocranial dysplasia / 中华口腔医学杂志

Objective: To summarize the clinical characteristics of patients with cleidocranial dysplasia (CCD) and analyze their treatment methods. Methods: From January 2000 to December 2020, patients with CCD who completed comprehensive treatment in the Department of Orthodontics and the First Dental Clinic, School and Hospital of Stomatology, China Medical University were retrospectively analyzed. A total of 14 CCD patients [7 males and 7 females, aged (16.1±4.5) years] were collected. There were 153 impacted permanent teeth in this study. In addition to the teeth that needed to be extracted due to special conditions, 147 impacted teeth were pulled into the dentition using closed traction. Patients were divided into adolescent group (≥12 years and<18 years, 10 patients) and adult group (≥18 years, 4 patients). Failure rate of traction was compared between the two groups. Factors affecting the success rate of closed traction such as vertical position of teeth (high, middle and low) and horizontal position of the teeth (palatal, median and buccal) were analyzed. Results: The incidence of maxillary impacted teeth [69.3% (97/140)] was higher than that of mandibular impacted teeth [40% (56/140)]. The difference was statistically significant (χ2=24.22, P<0.001). The supernumerary teeth were mainly located in the premolar area 61.4% (21/44), and most of them were in the palatal region of the permanent teeth 95.5% (42/44). They were generally located at the same height or the occlusal side of the corresponding permanent teeth. The success rate of closed traction was 93.9% (138/147). The success rate in the adolescent group [98.2% (108/110)] was higher than that in the adult group [81.1% (30/37)], and the difference was significant (χ2=14.09, P<0.05). Failure after closed traction of 9 teeth was found totally, including 7 second premolars. The success rate of traction in impacted second premolars at different vertical (χ2=11.44, P<0.05) and horizontal (χ2=9.71, P<0.05) positions in alveolar bone was different significantlly. The success rates of the second premolars were high (15/16), middle (12/13), low (2/7), and lingual palatine (10/17), median (19/19), lip-buccal (0/0), respectively. Conclusions: The closed traction of impacted teeth in patients with CCD was effective, and the age was the main variable affecting the outcome. The success rate of traction in impacted second premolars located in low position vertically or in palatal position was low, which required close observation during treatment.

Effect of straight-line minimally invasive access cavity on the mechanical properties of maxillary first premolars: a finite element analysis / 中华口腔医学杂志

Objective: To investigate the effects of straight-line minimally invasive access cavity on the mechanical properties of endodontically treated maxillary first premolars using finite element analysis. Methods: Micro-CT data of twenty maxillary first premolars were collected for three-dimensional reconstruction. Three access cavities, including the conventional access cavity (ConvAC), the truss access cavity (TrussAC) and the straight-line minimally invasive access cavity (SMIAC), as well as the root canal treatment procedure, were simulated in all the 20 reconstruction samples of three-dimensional models, respectively. The peak von Mises stress on the cervical area of each model, as well as the stress distribution under vertical and oblique loading circumstances, were subsequently determined by using finite element analysis. Results: In comparison to the stresses of ConvAC [buccal cervical (BC): (188.7±13.4) MPa, palatal cervical (PC): (200.9±25.7) MPa], the stresses of TrussAC [BC: (146.0±12.9) MPa, PC: (167.6±15.9) MPa] (t=9.01, P<0.001; t=4.59, P<0.001) and SMIAC [BC: (142.6±13.7) MPa, PC: (168.1±17.4) MPa] (t=9.64, P<0.001; t=3.76, P=0.004) significantly reduced the peak von Mises stress on the cervical area of the maxillary first premolars after root canal treatment. Under vertical loading conditions, SMIAC also reduced the central tendency of stresses on the occlusal surface, cervical area and root. In the case of oblique loading conditions, similar results were observed. Under both loading conditions, there was no significant difference in the peak von Mises stress on the cervical area of the maxillary first premolar between TrussAC and SMIAC groups. Conclusions: The design of SMIAC could preserve the mechanical properties of the maxillary first premolar following root canal treatment, which might have certain clinical feasibility.

Cone Beam Computed Tomography Evaluation of Root Morphology of the Premolars in Saudi Arabian Subpopulation

Abstract Objective: To evaluate root canal configuration and morphology of premolar teeth among Saudi subpopulations using cone beam computed tomography (CBCT). Material and Methods: In this retrospective cross-sectional study, CBCT images of 314 patients comprising 346 maxillary and 412 mandibular first premolar (FPM) teeth, 298 maxillary and 387 mandibular second premolar (SPM) teeth were analyzed to evaluate the number of roots, root canal morphology, and configuration based on the Vertucci's classification. The average intra-class correlation coefficient value was 0.931. Results: In the maxillary first premolar, 52.6% were two separate rooted and single rooted teeth, with one canal in 81.2% of the maxillary second premolar. Among the mandibular FPM, 96.6% of the teeth had one root and canal, and 97.9% of mandibular SPM had one root and canal. Type 1 canal configuration was seen as most common in all premolars. The number of roots in mandibular premolars did not reveal the difference among gender. Conclusion: Wide variations in root canal morphology and canal configuration system exists among maxillary and mandibular premolar teeth (AU).

Effect of Light-Curing Unit Type and Bulk-Fill Composite Resins with Different Photoinitiators on Marginal Gaps of Class II Restorations

Abstract Objective: To evaluate the effect of two types of light-curing units (second and third generations) and two types of bulk-fill composite resins with different photoinitiators - Tetric N-Ceram Bulk Fill (TNCB) and Xtra Fil (XTF) on gap formation at the gingival margins of Cl II restorations. Material and Methods: Fifty-six standard Cl II cavities were prepared on the mesial and distal surfaces of premolar teeth, with the gingival margin of the cavities 1 mm apical to the CEJ. The samples were randomly assigned to two groups based on the composite resin type and two subgroups based on the light-curing unit type and restored. After 5000 rounds of thermocycling, gingival margin gap in each sample was measured in µm under an electron microscope at ×2000 magnification. Data were analyzed by two-way ANOVA and Tukey tests (α=0.05). Results: Marginal gaps of TNCB composite resin were significantly smaller than those of XTF composite resin (p<0.001). There were no significant differences between the two light-curing units in each group (p=0.887 with XTF and p=0.999 with TNCB). Conclusion: The gaps at gingival margins of Cl II cavities with TNCB bulk-fill composite were smaller than XTF composite resin. Both composite resins can be cured with both the second- and third-generation LEDs (AU).