O condicionamento de tecido peri-implantar na reabilitação estética de próteses unitárias sobre implantes: relato de caso clínico / Peri-implant tissue conditioning in the esthetic rehabilitation of unitary prostheses on implants: Clinical case report / Acondicionamiento del tejido periimplantario en la rehabilitación estética de prótesis unitarias sobre implantes: Informe de caso clínico

Introdução:A reabilitação protética implantosuportada de espaços edêntulos na região do sorriso é um desafio para o cirurgião-dentista. Para obtenção da estética em próteses unitárias sobre implante é necessário considerar aspectos como o correto posicionamento do implante e sua harmonia com os tecidos moles e duros. Objetivo:relatar o resultado estético e funcional de um tratamento com auxílio de coroa provisória associada ao condicionamento gengival na reabilitação final com coroa unitária implantossuportada. Relato de caso clínico: Paciente MJFA, 36 anos, sexo feminino, compareceu à clínica de Prótese Dentária do Departamento de Odontologia/UFRN queixando-se de trauma dentário com perda do elemento dentário 15 e necessidade de "ficar com sorriso mais bonito". Após instalação de implante com conexão cônica e período de osseointegração, foi realizada a confecção da coroa provisória sobre implante e iniciada sessões de condicionamento gengival por meio de acréscimos com resina acrílica, utilizando a técnica de pressão gradual sob a margem gengival. Observou-se uma melhora no tecido periimplantar e um perfil de emergência adequado. O caso possui proservação de 3 anos. Conclusões:a realização de condicionamento gengival previamente a prótese final é uma etapa importante para alcançar umareabilitação com característicasestéticas e funcionais semelhantes à de dentes naturais (AU).

Introduction:Implant-supported prosthetic rehabilitation of edentulous spaces in the smile areais a challenge for dental surgeons. To achieve pleasing esthetics in single implant prostheses it is necessary to consider aspects such as the correct positioning of the implant and its harmony with the soft and hard tissues.Objective:to report the esthetic and functional results of a treatment with the aid of a provisional crown associated with gingival conditioning in the final rehabilitation with a single implant-supported crown.Clinical case report:Patient MJFA, 36 years old, female, attended the Prosthodonticsclinic of the Department of Dentistry/UFRN complaining of dental trauma with loss of tooth 15 and the need to "havea more beautiful smile". Afterinstalling an implant with a conical connection and a period of osseointegration, a temporary crown was made on the implant and gingival conditioning sessions were initiatedby means of acrylic resin augmentations, using the gradual pressure technique under the gingival margin. An improvement in the peri-implant tissue and an adequate emergenceprofile were observed. The case has a 3-year follow-up period.Conclusions:performing gingival conditioning prior to the final prosthesis is an important step in achieving rehabilitation with esthetic and functional characteristics similar to those of natural teeth (AU).

Introducción: La rehabilitación protésica implantosoportada de espacios edéntulos en el áreade la sonrisa es un desafío para el cirujano dentista. Para conseguir una buena estética en las prótesis unitarias sobre implanteses necesario tener en cuentaaspectos como el posicionamiento correctodel implante y su armonía con los tejidos blandos y duros.Objetivo: informar losresultadosestéticosy funcionalesde un tratamiento con ayuda de coronas provisionales asociado al acondicionamiento gingival en la rehabilitación final con corona única implantosoportada.Relato de caso clínico: Lapaciente MJFA, 36 años, sexo femenino, se dirigióa la clínica de Prostodonciadel Departamento de Odontología/UFRN quejándose de un traumatismodental con pérdida del diente 15 y de la necesidad de "tener una sonrisa más bonita". Después de la colocación de un implante con conexión cónica y de un período de osteointegración, se realizó una corona provisional sobre el implante y se iniciaron sesiones de acondicionamiento gingival con aumentos de resina acrílica, utilizando la técnica de presión gradual bajo el margen gingival. Se observó una mejora del tejido periimplantario y un perfil de emergencia adecuado. El caso tiene un seguimiento de 3 años. Conclusiones: el acondicionamiento gingival previo a la prótesis definitiva es una etapaimportante para conseguiruna rehabilitación con características estéticas y funcionales similares a las de los dientes naturales (AU).

Comparison of subjective image analysis and effective dose between low-dose cone-beam computed tomography machines.

OBJECTIVES: To compare the cone-beam computed tomography (CBCT) image quality and effective dose between low-dose scanning and standard manufacturer-recommended protocols among different CBCT units. METHODS: Three human-equivalent phantoms were scanned using the ultra-low-dose (ULD), low dose (LD), and standard dose (STD) modes of ProMax 3D Mid (Planmeca Oy, Helsinki, Finland) and Orthophos SL (Sirona, Bensheim, German) for the CBCT images. The quality of the dental anatomical images was assessed by four experienced oral and maxillofacial radiologists using a 5-point Likert scale. OnDemand3D (Cybermed Co., Seoul, Korea) was used as the third-party software for viewing. The percentage of absolute agreement was calculated to determine intra- and interrater agreements among the observers. The effective doses for all CBCT scanning protocols were also calculated. RESULTS: The STD protocol yielded a higher image quality than did the ULD and LD protocols in both ProMax 3D Mid and Orthophos SL. The ULD and LD protocols demonstrated an "acceptable-to-good" sense of visual perception of the CBCT images. The visibility scores significantly differed between the ULD and LD and the STD protocols in ProMax 3D Mid and Orthophos SL, except for the 120-kVp setting in ProMax 3D Mid. The average intra- and interrater agreement scores ranged from 0.63 to 0.89 and from 0.44 to 0.76, respectively. The ULD and LD protocols reduced the radiation dose sixfold compared with the STD protocol. CONCLUSIONS: High-tube-voltage protocols could remarkably reduce the imaging dose without degrading the image quality. Specifically, ULD and LD CBCT protocols may be adopted as routine practice for diagnosis and treatment planning.

Oral Healthcare Services Delivered During COVID-19 Lockdown: A Report from Eastern Mediterranean Region

ABSTRACT Objective: To describe oral healthcare services administered during the lockdown in the Eastern Mediterranean region and to investigate the role of socio-professional characteristics of dental practitioners or their self-reported COVID-19 infection. Material and Methods: A questionnaire was distributed to dental practitioners in all healthcare sectors in Jordan, Egypt, and Saudi Arabia. Results: There was a total of 335 participants, with the majority being females (N=225, 67.2%) and general practitioners (N=202, 60.3%). Cellulitis was the most common emergency encountered (N=108). The most common urgent procedures were for pulpitis, abscesses, and pericoronitis (N=191, 130, and 95, respectively). Country-specific significant associations were pulpitis in Egypt and Jordan, broken symptomatic teeth in Jordan, and biopsy in Egypt (p<0.05). The Ministry of Health was significantly associated with the management of dental infections, avulsion, and orthodontic emergencies, while university hospitals were significantly associated with advanced restorative procedures (p<0.05). Male practitioners performed significantly more procedures, particularly surgical emergencies (p<0.05). Conclusion: Dental infections were the most common complaints among dental patients during lockdown. Countryand sector-specific dental procedures are detected. Male gender seems to play a determinant role in performing a higher number of procedures, particularly for surgical emergencies (AU).

Correlação entre os estágios de maturação da sutura palatina mediana e das vértebras cervicais / Correlation between the maturation stages of the median palatal suture and cervical vertebrae

Introdução: Atualmente, a avaliação da maturação da sutura palatina mediana (MSPM) em pacientes que precisam ser submetidos à expansão rápida da maxila é realizada por meio de tomografias computadorizadas de feixe cônico (TCFC). No entanto, doses adicionais de radiação são induzidas ao paciente para a aquisição desse exame. Objetivo: Correlacionar os estágios de MSPM com os estágios de maturação das vértebras cervicais (MVC). Material e métodos: Um total de 268 TCFC da região da cabeça e do pescoço de indivíduos de ambos os sexos e com idades variando entre 5 e 76 anos foram analisadas de forma cega por uma única examinadora. O estágio de MSPM foi avaliado por meio da observação da maxila no corte axial e foi classificado como A, B, C, D ou E. Por outro lado, o estágio de MVC foi avaliado por meio do corte sagital das vértebras cervicais e foi classificado como CS1, CS2, CS3, CS4, CS5 ou CS6. A concordância intraexaminador foi avaliada por meio do Coeficiente Kappa. O teste de Correlação de Spearman foi utilizado para avaliar a correlação entre os estágios de MSPM e os estágios de MVC. Resultados: Uma correlação positiva forte foi encontrada entre os estágios de MSPM e MVC. Os estágios A e B mostraram correlação com os estágios CS1, CS2 e CS3. Diferentemente, o estágio C se correlacionou com maior frequência com os estágios CS4 e CS5. Por fim, os estágios D e E, se mostraram mais frequentes em indivíduos nos estágios CS5 e CS6 de forma similar. Conclusão: A predição da MSPM por meio da MVC em telerradiografias laterais pode ser uma alternativa viável à avaliação sutural na TCFC em pacientes nos estágios CS1, CS2 e CS3. A partir do estágio CS4, uma TCFC é recomendável para avaliar com maior segurança o estágio de MSPM e definir a melhor modalidade de expansão (AU).

Introduction: Currently, the assessment of maturation of the midpalatal suture (MPSM) in patients who need to undergo rapid maxillary expansion is performed using cone-beam computed tomography (CBCT). However, additional doses of radiation are induced to the patient for the acquisition of this exam. Objective: To correlate the stages of MPSM with the stages of maturation of the cervical vertebrae (CVM). Material and methods: A total of 268 CBCT of the head and neck of individuals of both sexes and aged between 5 and 76 years were analyzed blindly by a single examiner. The MPSM stage was assessed by observing the maxilla in the axial view and was classified as A, B, C, D or E. On the other hand, the CVM stage was assessed in the sagittal view of the cervical vertebrae and was classified as CS1, CS2, CS3, CS4, CS5 or CS6. Intraexaminer agreement was analyzed using the Kappa coefficient. Spearman's Correlation test was used to assess the correlation between MPSM and CVM stages Results: A strong positive correlation was found between MPSM and CVM stages. Stages A and B showed correlation with stages CS1, CS2 and CS3. Differently, stage C correlated more frequently with stages CS4 and CS5. Finally, stages D and E were more frequent in individuals in stages CS5 and CS6, similarly. Conclusion: The prediction of MPSM by assessing CVM in lateral cephalograms seems to be a viable alternative to the sutural evaluation in CBCT in patients in stages CS1, CS2 and CS3. From the CS4 stage onwards, a CBCT is recommended to assess the MPSM stage and define the most adequate expansion modality for patients (AU).

Assessment of root canal anatomy of maxillary and mandibular canine teeth: a cone-beam computed tomography study / Evaluación de la anatomía del canal radicular de caninos maxilares y mandibulares: un estudio de tomografía computarizada de haz cónico

Abstract To investigate the root canal anatomy of permanent maxillary and mandibular canines in a Turkish subpopulation using cone beam computed tomography (CBCT). Retrospective CBCT data of 300 patients admitted to our clinic between 2016 and 2018 were screened and evaluated. A total of 235 patients, 100 males and 135 females, aged 14-76 years (mean age 37.27±13.40) were included in this study. A total of 191 (44,8%) maxillary canine teeth and 235 (55,2%) mandibular canine teeth were examined. The number of roots and root canal morphology according to Vertucci's classification, the presence of accessory canals, and the position of the apical foramen of the root were analyzed. The effect of gender and age on the incidence of root canal morphology was also investigated. The majority of the teeth had a Type I canal configuration in both maxillary canines (100%) and mandibular canines (92,8%). In the mandibular canines the other canal patterns found were Type III (6,8%), and Type II (0,4%). Apical foramen was centrally positioned in the majority of the teeth, 70,2% and 66,8% in maxillary and mandibular canines, respectively. The occurrence of two roots in mandibular canines was 3,8% and the root canal separation was found 53,8% and 46,2% in the middle and cervical third of the root, respectively. No significant statistical difference was observed effect of gender and age on the incidence of the root canal morphology and the position of the apical foramen. Due to the diverse morphology and the potential presence of a second canal for canine teeth among the Turkish subpopulation, dentists should perform endodontic treatments with greater care. CBCT is an accurate tool for the morphological assessment of the root canals.

Resumen Investigar la anatomía del conducto radicular de los caninos maxilares y mandibulares permanentes en una subpoblación turca utilizando la tomografía computarizada de haz cónico (CBCT). Se examinaron y evaluaron los datos CBCT retrospectivos de 300 pacientes ingresados en nuestra clínica entre 2016 y 2018. Un total de 235 pacientes, 100 hombres y 135 mujeres, de entre 14 y 76 años (edad media de 37,27±13,40) fueron incluidos en este estudio. Se examinaron un total de 191 (44,8%) dientes caninos maxilares y 235 (55,2%) dientes caninos mandibulares. Se analizó el número de raíces y la morfología del conducto radicular según la clasificación de Vertucci, la presencia de conductos accesorios y la posición del foramen apical de la raíz. También se investigó el efecto del sexo y la edad en la incidencia de la morfología del conducto radicular. La mayoría de los dientes tenían una configuración de conductos de tipo I tanto en los caninos maxilares (100%) como en los caninos mandibulares (92,8%). En los caninos mandibulares los otros patrones de conductos encontrados fueron el Tipo III (6,8%) y el Tipo II (0,4%). El foramen apical estaba situado en posición central en la mayoría de los dientes, 70,2% y 66,8% en los caninos maxilares y mandibulares, respectivamente. La ocurrencia de dos raíces en los caninos mandibulares es del 3,8% y la separación del conducto radicular se encontró en el tercio medio y cervical de la raíz en el 53,8% y el 46,2%, respectivamente. No se observó ninguna diferencia estadística significativa en el efecto del sexo y la edad sobre la incidencia de la morfología del conducto radicular y la posición del foramen apical. Debido a la diversa morfología y a la posible presencia de un segundo conducto en los dientes caninos entre la subpoblación turca, los odontólogos deberían realizar los tratamientos endodónticos con mayor cuidado. La CBCT es una herramienta precisa para la evaluación morfológica de los conductos radiculares.

Estudo comparativo de métodos de orientação da cabeça para o planejamento virtual de cirurgias ortognáticas / Comparative study of the head orientation methods for 3d virtual planning of orthognathic surgeries

INTRODUÇÃO A simulação computadorizada 3D foi uma quebra de paradigma no tratamento das deformidades dentofaciais, porém, a melhor maneira de alcançar a Posição Neutra da Cabeça (PNC) ainda é controversa. Há uma carência de estudos comparativos entre os protocolos disponíveis, para avaliação do grau de precisão dos métodos. Este trabalho objetiva avaliar o grau de discrepância entre métodos de PNC em ambiente virtual. MÉTODOS Dez pacientes selecionados de forma consecutiva com deformidades dentofaciais foram incluídos na análise. Cada paciente foi submetido a todos os seguintes protocolos de aquisição da posição neutra da cabeça: (A) O Método do Protocolo CASS; (B) O Método do Protocolo Charlotte; (C) O Método do Protocolo Universal. Tomografias computadorizadas cone-beam (TCCB) com registro de mordida em RC foram solicitadas e moldagens de ambas as arcadas dentárias foram realizadas para o escaneamento 3D. Em seguida, para o preparo e posicionamento dos crânioscompostos na PNC foi utilizado o software Anatomic Aligner (Houston Methodist Research Institute), gerando um total de 30 crânios-compostos, uma vez que cada paciente virtual foi submetido a 3 protocolos de transferência de PNC. As discrepâncias foram avaliadas pela sobreposição dos modelos 3D craniofaciais pela análise cefalométrica Gateno-Xia, seguida de mensurações das diferenças lineares e angulares RESULTADOS Nos casos analisados nesse estudo, quando comparando os métodos de aquisição de PNC entre si os valores lineares e angulares obtidos encontram-se dentro dos limites preconizados na literatura como sendo excelentes (diferenças angulares inferiores a 4°, e lineares inferiores a 2mm, e para a linha média da maxila inferiores igual ou inferiores a 1mm), sendo o maior desvio linear de 1,1mm, e de orientação de 2,3°, e um máximo de desvio de linha média da maxila de 1mm, considerando todos os crânio-compostos orientados. Ainda, análises comparativas pareadas entre os métodos de PNC foram realizadas, seguindo as seguintes confrontações: Grupo A contra Grupo B; Grupo A contra Grupo C; e Grupo B contra Grupo C. Os autores não observaram desvios dos valores preconizados na literatura em todas as duplas comparativas. Por fim, análise estatística de ANOVA não evidenciou nenhuma diferença estatisticamente significante. DISCUSSÃO Os autores confirmam a hipótese de que todos os métodos de orientação da cabeça avaliados neste estudo não apresentam diferenças estatisticamente significantes (P>0,05) e consideram que quando realizado o preparo e orientação do crânio-composto em ambiente controlado e por profissionais especializados e capacitados na área cirúrgica, todas as técnicas para orientação da cabeça poderão ser úteis, precisas e válidas para o resultado desejado. Isso devido ao fato da checagem da PNC ser sempre baseado na análise facial e dados clínicos coletados pelo cirurgião. CONCLUSÃO Esse estudo evidenciou que não houve diferença estatística em questão de precisão entre todos os protocolos elencados para comparação, e mostrou-se de suma importância para a proporcionar aos cirurgiões uma reflexão sobre qual técnica seria mais adequada para o tratamento dos pacientes com deformidades dento faciais em seu centro, considerando sempre os principais aspectos que facilitam o dia a dia clínico do cirurgião, a saber: Simplicidade de execução; menor gasto de tempo; e familiaridade com a técnica (AU).

INTRODUCTION The 3D computer simulation was a paradigm shift in treating dentofacial deformities. However, the best way to achieve the Neutral Head Position (NHP) is still controversial. There there are need to perform comparative studies between the available protocols to assess the degree of accuracy of the methods. This work aims to evaluate the degree of discrepancy between PNC methods in a virtual environment. METHODS Ten consecutively selected patients with dentofacial deformities were included in the analysis. Each patient underwent all the following neutral head position acquisition protocols: (A) The CASS Protocol Method; (B) The Charlotte Protocol Method; (C) The Universal Protocol Method. Cone-beam computed tomography (CBCT) with CR bite registration was requested, and impressions of both dental arches were taken for 3D scanning. Then, for preparing and positioning the composite skulls in the PNC, the Anatomic Aligner software (Houston Methodist Research Institute) was used, generating a total of 30 composite skulls since each virtual patient was submitted to 3 transfer protocols of PNC. The discrepancies were evaluated by superimposing the 3D craniofacial models using the Gateno-Xia cephalometric analysis, followed by linear and angular differences measurements. If within limits recommended in the literature as being excellent (angular differences less than 4°, and linear differences less than 2mm, and for the midline of the maxilla less than or equal to 1mm), the most significant linear deviation being 1.1mm, and orientation of 2.3°, and a maximum maxillary midline deviation of 1mm, considering all oriented cranial composites. Also, paired comparative analyzes between the PNC methods were carried out, following the following comparisons: Group A against Group B, Group A against Group C, and Group B against Group C. The authors did not observe deviations from the values recommended in the literature in all comparative pairs. Finally, ANOVA statistical analysis did not show any statistically significant difference. DISCUSSION The authors confirm the hypothesis that all the head orientation methods evaluated in this study do not present statistically significant differences (P>0.05) and consider that when the preparation and orientation of the skull-composite are carried out in a controlled environment and by specialized professionals and trained in the surgical area, all head orientation techniques can be helpful, accurate and valid for the desired result. This is because the PNC check is always based on facial analysis and clinical data collected by the surgeon. CONCLUSION This study showed no statistical difference in accuracy between all the protocols listed for comparison, and it proved to be of paramount importance to provide surgeons with a reflection on which technique would be most appropriate for the treatment of patients with dentofacial deformities. At its center, always consider the main aspects that facilitate the surgeon's day-to-day clinical: Simplicity of execution, less time spent, and familiarity with the technique (AU).

Universal orbit design for metal artifact elimination.

Objective.Metal artifacts are a persistent problem in CT and cone-beam CT. In this work, we propose to reduce or even eliminate metal artifacts by providing better sampling of data using non-circular orbits.Approach.We treat any measurements intersecting metal as missing data, and aim to design a universal orbit that can generally accommodate arbitrary metal shapes and locations. We adapted a local sampling completeness metric based on Tuy's condition to quantify the extent of sampling in the presence of metal. A maxi-min objective over all possible metal locations was used for orbit design. A simple class of sinusoidal orbits was evaluated as a function of frequencies, maximum tilt angles, and orbital extents. Experimental implementation of these orbits were performed on an imaging bench and evaluated on two phantoms, one containing metal balls and the other containing a pedicle screw assembly for spine fixation. Metal artifact reduction (MAR) performance was compared amongst three approaches: non-circular orbits only, algorithmic correction only, and a combined approach.Main results.Theoretical evaluations of the objective favor sinusoidal orbits with large tilt angles and large orbital extents. Furthermore, orbits that leverage redundant azimuthal angles to sample non-redundant data have better performance, e.g. even or non-integer frequency sinusoids for a 360° acquisition. Experimental data support the trends observed in theoretical evaluations. Reconstructions using even or non-integer frequency orbits present less streaking artifacts and background details with finer resolution, even when multiple metal objects are present and even in the absence of MAR algorithms. The combined approach of non-circular orbits and MAR algorithm yields the best performance. The observed trend in image quality is supported by quantitative measures of sampling and severity of streaking artifact.Significance.This work demonstrates that sinusoidal orbits are generally robust against metal artifacts and can provide an avenue for improved image quality in interventional imaging.

Variaciones anatómicas en primer y segundo molar permanente mandibular con tratamiento endodóntico, evaluadas con tomografía computarizada de haz cónico. Revisión narrativa / Anatomical variations in the first and second permanent mandibular molar with endodontic treatment, evaluated with cone-beam computed tomography. Narrative review

Introducción: Una de las dificultades de los tratamientos endodónticos son las variaciones anatómicas de las raíces y sistema de canales radiculares. Existe poca información sobre prevalencia y distribución espacial de estas variaciones en casos reportados con CBCT (del inglés Cone-Beam Computed Tomography). El propósito de la presente revisión fue analizar las variaciones anatómicas en primer y segundo molar permanente mandibular con tratamiento endodóntico evaluadas con CBCT. Materiales y métodos: Se seleccionaron artículos con casos de tratamiento endodóntico en primer o segundo molar permanente mandibular. Se determinaron el número, distribución espacial de variaciones anatómicas radiculares y canales. Además, el número y tipo de alteraciones de forma. Resultados: La mayor prevalencia del número y distribución espacial de raíces en primer molar fue de tres raíces [1M (mesial), 2D (distal)] con un 76,5% y cuatro raíces (2M, 2D) con un 55,6% en segundo molar. La mayor prevalencia del número y distribución de canales radiculares para el primer y segundo molar fue de cuatro canales: 1mesiovestibular, 1mesiolingual, 1distovestibular y 1distolingual, con un 30% y 90,9% de los casos seleccionados respectivamente. La distribución de alteraciones de forma fue de 8,7% para geminación y de 2,1% para taurodontismo. Conclusiones: La variación anatómica de raíces del primer y segundo molar inferior permanente con más frecuencia fue de tres y cuatro respectivamente. La variación anatómica de canales con más frecuencia fue de cuatro: 2M y 2D. El número de alteraciones de forma fueron poco frecuentes, presentando geminaciones y taurodontismo, solo en segundos molares.

Introduction: One of the difficulties of endodontic treatments is the anatomical variations of the roots and the root canal system. There is little information on the prevalence and spatial distribution of these variations in cases reported with CBCT (Cone-Beam Computed Tomography). The purpose of this review was to analyze the anatomical variations in the mandibular first and second permanent molars with endodontic treatment evaluated with CBCT. Materials and methods: Articles with cases of endodontic treatment in the first or second permanent mandibular molar were selected. The number, spatial distribution of anatomical variations of roots and canals were determined. The number and type of shape alterations were also determined. Results: The highest prevalence regarding number and spatial distribution of root in the first molar was three roots (1M (mesial), 2D (distal)) with 76.5% and four roots (2M, 2D) with 55.6% in second molar. The highest prevalence regarding number and distribution of root canals for the first and second molars was four channels: 1 mesiobuccal, 1 mesiolingual, 1 distobuccal and 1 distolingual, with 30% and 90.9% of the cases selected, respectively. The distribution of shape alterations was 8.7% for gemination and 2.1% for taurodontism. Conclusions: The anatomical variation of roots of the first and second permanent lower molars with the most frequency was three and four respectively. The most frequent anatomic variation of channels was four: 2M and 2D. The number of shape alterations were less frequent, presenting geminations and taurodontism, only in second molars.

In Vivo Detection of External Apical Root Resorption Induced by Apical Periodontitis Using Periapical Radiography and Cone-Beam Computed Tomography

Abstract Objective: To compare the accuracy of periapical radiography (PR) and cone-beam computed tomography (CBCT) for the detection of external apical root resorption (EARR) due to root canal contamination. Material and Methods: Dog's teeth with experimentally induced root resorption due to root canal contamination underwent or not root canal treatment (n=62). True positives (TP), false positives (FP), true negatives (TN), and false negatives (FN) in PR and CBCT diagnoses were determined using histopathologic findings as the gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy (TP + TN) in the diagnosis of EARR were calculated. Data were compared using chi-squared test (α=0.05). Results: EARR was detected in 35% of roots by PR, in 47% by CBCT, and in 50% of the roots by microscopy (p=0.03 PR versus microscopy; p=0.67 CBCT versus microscopy). Overall, CBCT produced more accurate diagnoses than PR (p=0.008). PR and CBCT allowed the identification of large resorption in 100% of the cases and showed the same accuracy. However, for small resorptions, PR showed an accuracy of 0.83, whereas CBCT showed an accuracy of 0.96 (p=0.003). Conclusion: Cone-beam computed tomography showed higher accuracy in detecting external apical root resorption of endodontic origin.

Prevalencia y distribución de cálculos pulpares en un grupo de adultos peruanos: un estudio mediante tomografías de haz cónico / Prevalence and Distribution of Pulp Stones in a Group of Peruvian Adults: a Cone Beam Computed Tomography Study

Resumen: El objetivo de este estudio fue evaluar la prevalencia y distribución de cálculos pulpares en un grupo de adultos peruanos mediante tomografía de haz cónico (CBCT). Materiales y métodos: Se analizaron 67 tomografías de haz cónico seleccionadas aleatoriamente de un centro tomográfico en Lima, Perú. Fueron evaluadas 1263 imágenes de piezas dentarias mediante el tomógrafo Point 3D Combi 500 S. El análisis de las imágenes se realizó con el software Real Scan y todas las piezas dentarias fueron evaluadas en las vistas sagital, axial y coronal. Todas las medidas fueron sometidas a prueba de chi cuadrado. (p<0.05). Resultados: De un total de 67 pacientes, un 83,58% presentaron calcificaciones y de 1263 piezas dentarias, un 30.8% a través de la CBCT. La prevalencia de calcificaciones fue mayor en el sexo femenino que masculino. Los molares maxilares y mandibulares fueron los grupos de dientes con mayor frecuencia de cálculos pulpares. Se encontró significancia entre los cálculos pulpares y el género, rango de edad, tipo y estado de pieza dentaria. Conclusiones: La primera molar maxilar tuvo mayor prevalencia de calcificaciones pulpares que la mandibular. La presencia de caries aumentó la posibilidad de aparición de estas calcificaciones, específicamente en maxilar. La CBCT podría ser una herramienta sensible para detectar cálculos pulpares. El conocimiento de la distribución de cálculos pulpares puede ayudar a los dentistas en el tratamiento clínico de endodoncia.

Abstract: The aim of this study was to evaluate the prevalence and distribution of pulp stones in a group of Peruvian adults using cone beam tomography (CBCT). Materials and methods: 60 randomly selected CBCT from a tomographic center in Lima, Peru were analyzed. A total of 1263 images of teeth using the Point 3D Combi 500 S tomograph were evaluated. Images analysis was performed with Real Scan software and all teeth were evaluated in sagittal, axial and coronal views. All measurements were subjected to a chi square test. (p<0.05). Results: Of the 1263 teeth, 30.8% presented pulp calcifications through the CBCT. The prevalence of calcifications was higher in women than in men. The maxillary and mandibular molars were the groups of teeth with the highest frequency of pulp stones. There was significance between the pulp stones and the gender, age range, type and state of the tooth. Conclusions: The maxillary first molars had a higher prevalence of pulp calcifications than the mandibular ones. The presence of caries increased the possibility of the appearance of these calcifications, specifically in the maxillary teeth. CBCT could be a sensitive tool to detect pulp stones. Knowledge of the distribution of pulp stones can help dentists in the clinical treatment of endodontics.

Effects of Exposure Parameters and Voxel Size for Cone-Beam Computed Tomography on the Image Matching Accuracy with an Optical Dental Scan Image: An In Vitro Study.

This study is aimed at assessing the effects of exposure parameters and voxel size for cone-beam computed tomography (CBCT) on the image matching accuracy with an optical dental scan image. CBCT and optical scan images of a dry human mandible were obtained. Different CBCT settings were used: tube voltage, 60, 80, and 100 kVp; tube current, 6 and 8 mA; and voxel size, 100, 200, and 300 µm. Image matching between the CBCT and optical scan images was performed using implant planning software by dental professionals (n = 18). The image matching accuracy in each combination of CBCT settings was evaluated by assessing the linear discrepancy between the three-dimensionally reconstructed radiological image and the registered optical scan image using an image analysis software program. The Kruskal-Wallis test and a post hoc Mann-Whitney U test with Bonferroni correction were used to compare the accuracy of image registration between the groups (α = 0.05). Overall, the image matching accuracy was not significantly different between tube voltage and current settings; however, significantly higher image registration errors were found at the combination of 100 kVp tube voltage/8 mA tube current (F = 8.44, P < 0.001). Changes in voxel sizes did not significantly interfere with the image registration results. No interaction was found among voltage, current, and voxel size in terms of image registration accuracy (F = 2.022, P = 0.091). Different exposure parameter settings in tube voltage and tube current did not significantly influence the image matching accuracy between CBCT and optical dental scan images; however, a high radiation dose could be inappropriate. The image matching accuracy was not significantly affected by changing the voxel sizes of CBCT.

StaticCodeCT: single coded aperture tensorial X-ray CT.

Coded aperture X-ray CT (CAXCT) is a new low-dose imaging technology that promises far-reaching benefits in industrial and clinical applications. It places various coded apertures (CA) at a time in front of the X-ray source to partially block the radiation. The ill-posed inverse reconstruction problem is then solved using l1-norm-based iterative reconstruction methods. Unfortunately, to attain high-quality reconstructions, the CA patterns must change in concert with the view-angles making the implementation impractical. This paper proposes a simple yet radically different approach to CAXCT, which is coined StaticCodeCT, that uses a single-static CA in the CT gantry, thus making the imaging system amenable for practical implementations. Rather than using conventional compressed sensing algorithms for recovery, we introduce a new reconstruction framework for StaticCodeCT. Namely, we synthesize the missing measurements using low-rank tensor completion principles that exploit the multi-dimensional data correlation and low-rank nature of a 3-way tensor formed by stacking the 2D coded CT projections. Then, we use the FDK algorithm to recover the 3D object. Computational experiments using experimental projection measurements exhibit up to 10% gains in the normalized root mean square distance of the reconstruction using the proposed method compared with those attained by alternative low-dose systems.

Toward on-the-fly trajectory optimization for C-arm CBCT under strong kinematic constraints.

Cone beam computed tomography (CBCT) has become a vital tool in interventional radiology. Usually, a circular source-detector trajectory is used to acquire a three-dimensional (3D) image. Kinematic constraints due to the patient size or additional medical equipment often cause collisions with the imager while performing a full circular rotation. In a previous study, we developed a framework to design collision-free, patient-specific trajectories for the cases in which circular CBCT is not feasible. Our proposed trajectories included enough information to appropriately reconstruct a particular volume of interest (VOI), but the constraints had to be defined before the intervention. As most collisions are unpredictable, performing an on-the-fly trajectory optimization is desirable. In this study, we propose a search strategy that explores a set of trajectories that cover the whole collision-free area and subsequently performs a search locally in the areas with the highest image quality. Selecting the best trajectories is performed using simulations on a prior diagnostic CT volume which serves as a digital phantom for simulations. In our simulations, the Feature SIMilarity Index (FSIM) is used as the objective function to evaluate the imaging quality provided by different trajectories. We investigated the performance of our methods using three different anatomical targets inside the Alderson-Rando phantom. We used FSIM and Universal Quality Image (UQI) to evaluate the final reconstruction results. Our experiments showed that our proposed trajectories could achieve a comparable image quality in the VOI compared to the standard C-arm circular CBCT. We achieved a relative deviation less than 10% for both FSIM and UQI metrics between the reconstructed images from the optimized trajectories and the standard C-arm CBCT for all three targets. The whole trajectory optimization took approximately three to four minutes.

A Preliminary Study on Animal Experiments of Robot-Assisted Craniotomy.

BACKGROUND: Traditional craniotomy relies on the surgeon's experience and can be complicated owing to excessive skull bone removal, undesirable brain tissue penetration, or severe bleeding. For craniotomy, we developed a robot system based on intraoperative cone-beam computed tomography image guidance and human-robot cooperative interaction, aiming to improve the safety and accuracy of surgery and reduce the labor-intensiveness of the procedure. METHODS: Intraoperative cone-beam computed tomography image guidance was adopt to improve the accuracy in our experiment. Craniotomy was performed using an interactive method based on human-robot collaboration, which could achieve a natural interactive method in accordance with surgeons' operating habits. The frequency-based method of contact distinction and the method of torque estimation were used to improve the safety of the designed robot. RESULTS: An animal experiment was conducted to verify the effectiveness of the robot system. During the drilling process, the position error was 0.92 ± 0.17 mm (upper surface) and 0.97 ± 0.11 mm (lower surface), and the angle error was 3.37 ± 1.43°. During the milling process, the position error was 1.06 ± 0.13 mm (upper surface) and 1.09 ± 0.09 mm (lower surface). The results showed that the system had sufficient precision and could better complete craniotomy with human-robot collaboration. In addition, with the feedback of multisensor information, the robot system could achieve a sufficient level of safety. CONCLUSIONS: The robot system can achieve accurate positioning and safe user-friendly human-robot interaction, which solves problems encountered in the drilling and milling of craniotomy, meets clinical needs, and provides a new method for robot-assisted craniotomy.

Accuracy of cone-beam CT in detecting vertical root fractures in teeth with post-endodontic restorations: an in vitro study

The aim of this study was to evaluate the accuracy of cone-beam CT (CBCT) for the detection of artificially created vertical root fractures (VRF) in extracted teeth restored with metallic (MP) and fiberglass (FGP) posts. After root canal obturation, 60 extracted human premolars were scanned by using the highest-resolution settings of a CBCT unit. Theprepared roots were randomly divided into three groups: group C (control group): non-restored and non-endodontically treated teeth (n = 20); group MP (n = 20); group FGP (n = 20). In all groups, 10 teeth were artificially fractured. Two external and independent observers blindly recorded the presence or absence of VRF. Sensitivity, specificity, accuracy, intra-and interobserver agreement were calculated. Kappa value for inter-and intraobserver agreement was 0.82 and 0.84 respectively, demonstrating goodagreement. The highest values for sensitivity (0.80 -0.90), specificity (1.00) and accuracy (0.90 -0.95) were found in the control group. The teeth with FGP restoration presented the lowest sensitivity (0.30 -0.50) and accuracy (0.60 -0.65) values. Both examiners had a good performance in the diagnosis of fractures in teeth with MP, with accuracy ranging between 0.85 -0.90. The presence of MP did not influence accuracy; however, the presence of FGP reduced the diagnostic capacity of CBCT.

Relationship of Angulation of Maxillary Impacted Canines with Maxillary Lateral Incisor Root Resorption

ABSTRACT Objective: To assess the relationship of ɑ and ß angles of maxillary impacted canines with maxillary lateral incisor root resorption. Material and Methods: For this, 40 patients (between 11 and 45 years) with impacted maxillary canines presenting to a private orthodontic clinic were evaluated.20% of the cases were male and 80% were female. The ɑ and ß angles were measured on panoramic radiographs to determine the angulation of impacted canine. CBCT scans had been taken by ProMax 3D CBCT system were used to examine lateral root reorption. The relationship between the size of ɑ and ß angles of impacted maxillary canines and root resorption in the adjacent maxillary lateral incisor was analyzed using SPSS version 22. Results: The mean size of ɑ and ß angles had no significant correlation with the presence/absence, location, or severity of root resorption in the adjacent lateral incisor or the buccolingual position of impacted canine. The ɑ and ß angles in impacted maxillary canines cannot be used to determine the incidence or severity of root resorption in the adjacent lateral incisor. Conclusion: No significant association between ɑ and ß angles and incidence or severity of root resorption in the adjacent lateral incisor was found.

Dentin Thickness of Pulp Chamber Floor in Primary Molars: Evaluation by Cone-Beam Computed Tomography

ABSTRACT Objective: Use cone-beam computed tomography (CBCT) images to evaluate the dentin thickness of the pulp chamber floor in primary molars. Material and Methods: Cross-sectional study, conducted with CBCT images of teeth of children. Primary molars with preserved pulp chamber floor were included. The dentin thickness of the pulp chamber floor in the primary molars was measured linearly in CBCT cross-sections. Data were descriptively analyzed and the Mann-Whitney test was applied (p<0.05). Results: 27 CBCT exams and 123 primary molars of children aged 4 to 13 years were analyzed; the majority was female (52.0%). In maxillary molars, the median dentin thickness was 1.50 (0.6-2.2) mm in the first and 1.65 (0.6-2.3) mm in the second (p=0.049) molars. In mandibular molars, the median was 1.20 (0.3-1.7) mm in the first and 1.60 (1.0-2.2) mm in the second (p<0.001) molars. Children aged 4 to 8 years showed less dentin thickness (p<0.001). Conclusion: The median dentin thickness of the pulp chamber floor in primary molars was 1.50 mm, ranging from 0.3 to 2.3 mm. Less dentin thickness was associated with younger children, teeth in the mandibular arch, and first molars.

Tooth Coronal Index: A Novel Tool For Age Estimation on Cone-Beam Computed Tomography

ABSTRACT Objective: To evaluate dental age assessment reliability through Tooth Coronal Index (TCI) method. Material and Methods: The cone-beam computed tomography (CBCT) scans of 160 individuals aged between 20-70 years were analyzed in the present study. The height of the crown, i.e., coronal height, and the height of the coronal pulp cavity, i.e., coronal pulp cavity height, of mandibular second premolars and first molars were calculated and then TCI was measured. The actual age of a subject was compared with TCI of tooth and the acquired data were subjected to Pearson's correlation and unpaired t-tests. Results: Negative correlation was observed between the real age and TCI of mandibular first molar (r = -0.094, p=0.382) and second premolar (r = -0.176, p=0.0961. Statistically significant difference was observed between actual age and TCI for mandibular second premolar and first molar (p<0.001). Conclusion: Tooth coronal index has the potential to estimate age of an individual on CBCT scans. It is simple, cost-effective than histological methods and can be applied to both living and unknown dead.

El uso de rayos X en odontología y la importancia de la justificación de exámenes radiográficos / Use of X rays in dentistry and the importance of justification of radiographic examinations

INTRODUCCIÓN: Los exámenes radiográficos odontológicos usan radiaciones ionizantes, las que pueden producir efectos adversos en la salud de pacientes y trabajadores ocupacionalmente expuestos a radiaciones. La protección radiológica busca que la justificación de la exposición a radiación ionizante sea adecuada, y produzca al paciente mayor beneficio que riesgo. El objetivo del presente artículo es revisar los efectos adversos de las radiaciones ionizantes en el ser humano, analizar el principio de justificación y entregar recomendaciones para su aplicación en la práctica diaria odontológica, presentando guías clínicas actuales. REVISIÓN: Para cumplir con el principio de justificación, la elección de cada examen radiográfico debe realizarse responsablemente, basándose en las necesidades individuales de cada paciente. Este proceso debe realizarse conjuntamente entre clínico y radiólogo maxilofacial. A pesar de que existen numerosas guías para distintas especialidades odontológicas, desarrolladas por instituciones de diversas partes del mundo, son pocas las guías basadas en evidencia. Las guías aportan recomendaciones, con distintos niveles de evidencia, para el uso de exámenes radiográficos, permitiendo al clínico seleccionar el examen adecuado para cada paciente, contribuyendo a la disminución de exposiciones innecesarias. CONCLUSIONES: La comunicación entre clínico y radiólogo maxilofacial es fundamental para lograr el proceso de justificación, y por lo tanto, una reducción en las dosis de radiación a los pacientes. Además, es necesario el uso de guías clínicas para correcta selección del examen radiográfico. Se requiere más investigación que justifique el uso de nuevas tecnologías imagenológicas en indicaciones específicas y permitan elaborar guías clínicas basadas en evidencia

INTRODUCTION: Dental radiographic examinations use ionizing radiation, which can have adverse health effects in patients and workers occupationally exposed to radiation. Radiological protection seeks to ensure that justification for exposure to ionizing radiation is adequate, so that the patient has a greater benefit than risk. The aim of this article is to review the adverse effects of radiation on humans, to analyze the principle of justification and to provide recommendations for its application in daily dental practice, presenting current clinical guidelines. REVIEW: In order to comply with the principle of justification, the choice of each radiographic examination must be made in a responsible manner, based on the individual needs of each patient. This process should be performed jointly between the clinician and the maxillofacial radiologist. Although there are numerous guidelines for different dental specialties, developed by institutions from different parts of the world, few of them are evidence-based guidelines. Guidelines provide recommendations, with different levels of evidence, for the use of radiographic examination, allowing the clinician to select the appropriate exam for each patient, contributing to the reduction of unnecessary exposures. CONCLUSIONS: Communication between clinician and maxillofacial radiologist is essential to achieve the justification process, and therefore a reduction in radiation doses to patients. In addition, the use of clinical guidelines is necessary for a correct choice of the radiographic examination. More research is needed to justify the use of new imaging technologies in specific indications, to develop clinical evidence-based guidelines

Endobronchial Navigation Guided by Cone-Beam CT-Based Augmented Fluoroscopy without a Bronchoscope: Feasibility Study in Phantom and Swine.

PURPOSE: To evaluate the accuracy of cone-beam computed tomography (CT)-based augmented fluoroscopy (AF) image guidance for endobronchial navigation to peripheral lung targets. METHODS: Prototypic endobronchial navigation AF software that superimposed segmented airways, targets, and pathways based on cone-beam CT onto fluoroscopy images was evaluated ex vivo in fixed swine lungs and in vivo in healthy swine (n = 4) without a bronchoscope. Ex vivo and in vivo (n = 3) phase 1 experiments used guide catheters and AF software version 1, whereas in vivo phase 2 (n = 1) experiments also used an endovascular steerable guiding sheath, upgraded AF software version 2, and lung-specific low-radiation-dose protocols. First-pass navigation success was defined as catheter delivery into a targeted airway segment solely using AF, with second-pass success defined as reaching the targeted segment by using updated AF image guidance based on confirmatory cone-beam CT. Secondary outcomes were navigation error, navigation time, radiation exposure, and preliminary safety. RESULTS: First-pass success was 100% (10/10) ex vivo and 19/24 (79%) and 11/15 (73%) for in vivo phases 1 and 2, respectively. Phase 2 second-pass success was 4/4 (100%). Navigation errors were 2.2 ± 1.2 mm ex vivo and 4.9 ± 3.2 mm and 4.0 ± 2.6 mm for in vivo phases 1 and 2, respectively. No major device-related complications were observed in the in vivo experiments. CONCLUSIONS: Endobronchial navigation is feasible and accurate with cone-beam CT-based AF image guidance. AF can guide endobronchial navigation with endovascular catheters and steerable guiding sheaths to peripheral lung targets, potentially overcoming limitations associated with bronchoscopy.