Correction of scatter in CBCT with a new grid design.

Objective.This study aims at developing a simple and rapid Compton scatter correction approach for cone-beam CT (CBCT) imaging.Approach.In this work, a new Compton scatter estimation model is established based on two distinct CBCT scans: one measures the full primary and scatter signals without anti-scatter grid (ASG), and the other measures a portion of primary and scatter signals with ASG. To accelerate the entire data acquisition speed, a half anti-scatter grid (h-ASG) that covers half of the full detector surface is proposed. As a result, the distribution of scattered x-ray photons could be estimated from a single CBCT scan. Physical phantom experiments are conducted to validate the performance of the newly proposed scatter correction approach.Main results.Results demonstrate that the proposed half grid approach can quickly and precisely estimate the distribution of scattered x-ray photons from only one single CBCT scan, resulting in a significant reduction of shading artifacts. In addition, it is found that the h-ASG approach is less sensitive to the grid transmission fractions, grid ratio and object size, indicating a robust performance of the new method.Significance.In the future, the Compton scatter artifacts can be quickly corrected using a half grid in CBCT imaging.

A cone-beam optical CT based on a convergent light source - Characterization and optimization.

PURPOSE: Employing a Fresnel lens and a point-like light source to create a convergent light beam for the camera effectively minimizes stray light and enhances image quality in optical computed tomography (OCT), benefiting 3D dosimetry applications. This study outlines the development of an economical cone-beam optical computed scanner for 3D dosimetry. METHODS: Optical performance was assessed by calculating modulation transfer function (MTF) with pattern charts. Stray light was evaluated by imaging a cylinder flask and a square grid with 5 mm diameter holes to determine the stray-to-primary ratio. Reconstruction quality was determined using SIRT-TV and compared with spectrophotometry attenuation coefficients, with the best regularization parameter (λ = 0.01) chosen based on contrast-to-noise ratio (CNR). Dosimetry performance was assessed by determining percentage dose depth (PDD) for a 6MV beam with a 5 × 5 cm2 field using FXO-f gel dosimeter, compared with ionization chamber data. RESULTS: MTF evaluation yielded ≥ 50 % agreement with pattern charts. Stray-to-primary ratio was less than 0.1 or 10 % of the total signal. Reconstruction showed low noise and artifacts, with optimal CNR at λ = 0.01. Attenuation coefficients from optical CT aligned with spectrometer measurements within 1.2 %. PDD calculated with FXO-f gel dosimeter closely matched ionization chamber data (<1.2 % difference), achieving a dose resolution of 0.1 Gy. CONCLUSION: The built and optimization the de optical-CT based on a convergent beam is read to perform the 3D quality assurance in clinical applications.

Fully automatic online geometric calibration for non-circular cone-beam CT orbits using fiducials with unknown placement.

BACKGROUND: Cone-beam CT (CBCT) with non-circular scanning orbits can improve image quality for 3D intraoperative image guidance. However, geometric calibration of such scans can be challenging. Existing methods typically require a prior image, specialized phantoms, presumed repeatable orbits, or long computation time. PURPOSE: We propose a novel fully automatic online geometric calibration algorithm that does not require prior knowledge of fiducial configuration. The algorithm is fast, accurate, and can accommodate arbitrary scanning orbits and fiducial configurations. METHODS: The algorithm uses an automatic initialization process to eliminate human intervention in fiducial localization and an iterative refinement process to ensure robustness and accuracy. We provide a detailed explanation and implementation of the proposed algorithm. Physical experiments on a lab test bench and a clinical robotic C-arm scanner were conducted to evaluate spatial resolution performance and robustness under realistic constraints. RESULTS: Qualitative and quantitative results from the physical experiments demonstrate high accuracy, efficiency, and robustness of the proposed method. The spatial resolution performance matched that of our existing benchmark method, which used a 3D-2D registration-based geometric calibration algorithm. CONCLUSIONS: We have demonstrated an automatic online geometric calibration method that delivers high spatial resolution and robustness performance. This methodology enables arbitrary scan trajectories and should facilitate translation of such acquisition methods in a clinical setting.

Image quality evaluation of a new high-performance ring-gantry cone-beam computed tomography imager.

Objective. Newer cone-beam computed tomography (CBCT) imaging systems offer reconstruction algorithms including metal artifact reduction (MAR) and extended field-of-view (eFoV) techniques to improve image quality. In this study a new CBCT imager, the new Varian HyperSight CBCT, is compared to fan-beam CT and two CBCT imagers installed in a ring-gantry and C-arm linear accelerator, respectively.Approach. The image quality was assessed for HyperSight CBCT which uses new hardware, including a large-size flat panel detector, and improved image reconstruction algorithms. The decrease of metal artifacts was quantified (structural similarity index measure (SSIM) and root-mean-squared error (RMSE)) when applying MAR reconstruction and iterative reconstruction for a dental and spine region using a head-and-neck phantom. The geometry and CT number accuracy of the eFoV reconstruction was evaluated outside the standard field-of-view (sFoV) on a large 3D-printed chest phantom. Phantom size dependency of CT numbers was evaluated on three cylindrical phantoms of increasing diameter. Signal-to-noise and contrast-to-noise were quantified on an abdominal phantom.Main results. In phantoms with streak artifacts, MAR showed comparable results for HyperSight CBCT and CT, with MAR increasing the SSIM (0.97-0.99) and decreasing the RMSE (62-55 HU) compared to iterative reconstruction without MAR. In addition, HyperSight CBCT showed better geometrical accuracy in the eFoV than CT (Jaccard Conformity Index increase of 0.02-0.03). However, the CT number accuracy outside the sFoV was lower than for CT. The maximum CT number variation between different phantom sizes was lower for the HyperSight CBCT imager (∼100 HU) compared to the two other CBCT imagers (∼200 HU), but not fully comparable to CT (∼50 HU).Significance. This study demonstrated the imaging performance of the new HyperSight CBCT imager and the potential of applying this CBCT system in more advanced scenarios by comparing the quality against fan-beam CT.

First implementation of an innovative infra-red camera system integrated into a mobile CBCT scanner for applicator tracking in brachytherapy-Initial performance characterization.

PURPOSE: To enable a real-time applicator guidance for brachytherapy, we used for the first time infra-red tracking cameras (OptiTrack, USA) integrated into a mobile cone-beam computed tomography (CBCT) scanner (medPhoton, Austria). We provide the first description of this prototype and its performance evaluation. METHODS: We performed assessments of camera calibration and camera-CBCT registration using a geometric calibration phantom. For this purpose, we first evaluated the effects of intrinsic parameters such as camera temperature or gantry rotations on the tracked marker positions. Afterward, calibrations with various settings (sample number, field of view coverage, calibration directions, calibration distances, and lighting conditions) were performed to identify the requirements for achieving maximum tracking accuracy based on an in-house phantom. The corresponding effects on camera-CBCT registration were determined as well by comparing tracked marker positions to the positions determined via CBCT. Long-term stability was assessed by comparing tracking and a ground-truth on a weekly basis for 6 weeks. RESULTS: Robust tracking with positional drifts of 0.02 ± 0.01 mm was feasible using the system after a warm-up period of 90 min. However, gantry rotations affected the tracking and led to inaccuracies of up to 0.70 mm. We identified that 4000 samples and full coverage were required to ensure a robust determination of marker positions and camera-CBCT registration with geometric deviations of 0.18 ± 0.03 mm and 0.42 ± 0.07 mm, respectively. Long-term stability showed deviations of more than two standard deviations from the initial calibration after 3 weeks. CONCLUSION: We implemented for the first time a standalone combined camera-CBCT system for tracking in brachytherapy. The system showed high potential for establishing corresponding workflows.

Fast kV-switching and dual-layer flat-panel detector enabled cone-beam CT joint spectral imaging.

Purpose. Fast kV-switching (FKS) and dual-layer flat-panel detector (DL-FPD) technologies have been actively studied as promising dual-energy spectral imaging solutions for FPD-based cone-beam computed tomography (CT). However, cone-beam CT (CBCT) spectral imaging is known to face challenges in obtaining accurate and robust material discrimination performance. That is because the energy separation by either FKS or DL-FPD, alone, is still limited, along with apparently unpaired signal levels in the effective low- and high-energy projections in real applications, not to mention the x-ray scatter in cone-beam scan which will make the material decomposition almost impossible if no correction is applied. To further improve CBCT spectral imaging capability, this work aims to promote a source-detector joint multi-energy spectral imaging solution which takes advantages of both FKS and DL-FPD, and to conduct a feasibility study on the first tabletop CBCT system with the joint spectral imaging capability developed.Methods. For CBCT, development of multi-energy spectral imaging can be jointly realized by using an x-ray source with a generator whose kilo-voltages can alternate in tens of Hertz (i.e. FKS), and a DL-FPD whose top- and bottom-layer projections corresponds to different effective energy levels. Thanks to the complimentary characteristics inherent in FKS and DL-FPD, the overall energy separation will be significantly better when compared with FKS or DL-FPD alone, and the x-ray photon detection efficiency will be also improved when compared with FKS alone. In this work, a noise performance analysis using the Cramér-Rao lower bound (CRLB) method is conducted. The CRLB for basis material after a projection-domain material decomposition is derived, followed by a set of numerical calculations of CRLBs, for the FKS, the DL-FPD and the joint solution, respectively. To compensate for the slightly angular mismatch between low- and high- projections in FKS, a dual-domain projection completion scheme is implemented. Afterwards material decomposition from the complete projection data is carried out by using the maximum-likelihood method, followed by reconstruction of basis material and virtual monochromatic images (VMI). In this work, the first FKS and DL-FPD jointly enabled multi-energy tabletop CBCT system, to the best of our knowledge, has been developed in our laboratory. To evaluate its spectral imaging performance, a set of physics experiments are conducted, where the multi-energy and head phantoms are scanned using the 80/105/130 kVp switching pairs and projection data are collected using a prototype DL-FPD, whose both top and bottom layer of panels are composed of 550µm of cesium iodine (CsI) scintillators with no intermediate metal filter in-between.Results. The numerical simulations show that the joint spectral imaging solution can lead to a significant improvement in energy separation and lower noise levels in most of material decomposition cases. The physics experiments confirmed the feasibility and superiority of the joint spectral imaging, whose CNRs in the selected regions of interest of the multi-energy phantom were boosted by an average improvement of 21.9%, 20.4% for water basis images and 32.8%, 62.8% for iodine images when compared with that of the FKS and DL-FPD, respectively. For the head phantom case, the joint spectral imaging can effectively reduce the streaking artifacts as well, and the standard deviation in the selected regions of interest are reduced by an average decrement of 19.5% and 8.1% for VMI when compared with that of the FKS and DL-FPD, respectively.Conclusions. A feasibility study of the joint spectral imaging solution for CBCT by utilizing both the FKS and DL-FPD was conducted, with the first tabletop CBCT system having such a capability being developed, which exhibits improved CNR and is more effective in avoiding streaking artifacts as expected.

Image-Guided Transbronchial Pulmonary Cryoablation with a Flexible Cryoprobe in Swine: Performance and Radiology-Pathology Correlation.

PURPOSE: To evaluate the performance of a prototype flexible transbronchial cryoprobe compared with that of percutaneous transthoracic cryoablation and to define cone-beam computed tomography (CT) imaging and pathology cryolesion features in an in vivo swine model. MATERIALS AND METHODS: Transbronchial cryoablation was performed with a prototype flexible cryoprobe (3 central and 3 peripheral lung ablations in 3 swine) and compared with transthoracic cryoablation performed with a commercially available rigid cryoprobe (2 peripheral lung ablations in 1 swine). Procedural time and cryoablation success rates for endobronchial navigation and cryoneedle deployment were measured. Intraoperative cone-beam CT imaging features of cryolesions were characterized and correlated with gross pathology and hematoxylin and eosin-stained sections of the explanted cryolesions. RESULTS: The flexible cryoprobe was successfully navigated and delivered to each target through a steerable guiding sheath (6/6). At 4 minutes after ablation, 5 of 6 transbronchial and 2 of 2 transthoracic cryolesions were visible on cone-beam CT. The volumes on cone-beam CT images were 55.5 cm3 (SE ± 8.0) for central transbronchial ablations (n = 2), 72.5 cm3 (SE ± 8.1) for peripheral transbronchial ablations (n = 3), and 79.5 cm3 (SE ±11.6) for peripheral transthoracic ablations (n = 2). Pneumothorax developed in 1 animal after transbronchial ablation and during ablation in the transthoracic cryoablation. Images of cryoablation zones on cone-beam CT correlated well with the matched gross pathology and histopathology sections of the cryolesions. CONCLUSIONS: Transbronchial cryoablation with a flexible cryoprobe, delivered through a steerable guiding sheath, is feasible. Transbronchial cryoablation zones are imageable with cone-beam CT, with gross pathology and histopathology similar to those of transthoracic cryoablation.

ACR benchmark testing of a novel high-speed ring-gantry linac kV-CBCT system.

A new generation cone-beam computed tomography (CBCT) system with new hardware design and advanced image reconstruction algorithms is available for radiation treatment simulation or adaptive radiotherapy (HyperSight CBCT imaging solution, Varian Medical Systems-a Siemens Healthineers company). This study assesses the CBCT image quality metrics using the criteria routinely used for diagnostic CT scanner accreditation as a first step towards the future use of HyperSight CBCT images for treatment planning and target/organ delineations. Image performance was evaluated using American College of Radiology (ACR) Program accreditation phantom tests for diagnostic computed tomography systems (CTs) and compared HyperSight images with a standard treatment planning diagnostic CT scanner (Siemens SOMATOM Edge) and with existing CBCT systems (Varian TrueBeam version 2.7 and Varian Halcyon version 2.0).  Image quality performance for all Varian HyperSight CBCT vendor-provided imaging protocols were assessed using ACR head and body ring CT phantoms, then compared to existing imaging modalities. Image quality analysis metrics included contrast-to-noise (CNR), spatial resolution, Hounsfield number (HU) accuracy, image scaling, and uniformity. All image quality assessments were made following the recommendations and passing criteria provided by the ACR. The Varian HyperSight CBCT imaging system demonstrated excellent image quality, with the majority of vendor-provided imaging protocols capable of passing all ACR CT accreditation standards. Nearly all (8/11) vendor-provided protocols passed ACR criteria using the ACR head phantom, with the Abdomen Large, Pelvis Large, and H&N vendor-provided protocols produced HU uniformity values slightly exceeding passing criteria but remained within the allowable minor deviation levels (5-7 HU maximum differences). Compared to other existing CT and CBCT imaging modalities, both HyperSight Head and Pelvis imaging protocols matched the performance of the SOMATOM CT scanner, and both the HyperSight and SOMATOM CT substantially surpassed the performance of the Halcyon 2.0 and TrueBeam version 2.7 systems. Varian HyperSight CBCT imaging system could pass almost all tests for all vendor-provided protocols using ACR accreditation criteria, with image quality similar to those produced by diagnostic CT scanners and significantly better than existing linac-based CBCT imaging systems.

Accuracy of Working Length Determination - Electronic Apex Locator Versus Cone Beam Computed Tomography

ABSTRACT Objective: To compare the accuracy of working length determination between cone beam computed tomography (CBCT) and electronic apex locator by measuring the actual working length of teeth. Material and Methods: A total of 150 single-rooted tooth assessed by radiograph undergoing root canal therapy were selected. The process was repeated to obtain a buccolingual and mesiodistal section of all teeth. The measurement line was considered from the reference occlusal plane following the center of the canal to the terminus. All information regarding the accuracy of cone-beam computed tomography and apex locator was noted in a pre-designed proforma. Results: CBCT consistently demonstrated high accuracy across all tooth types in both jaws. The electronic apex locator exhibited varying precision, with greater accuracy observed in the mandible. Statistical analyses revealed significant differences in electronic apex locator accuracy among tooth types in the maxilla (p=0.042), emphasizing the importance of specific clinical considerations. Conclusion: Cone beam computed tomography emerges as a reliable diagnostic tool for accurate working length determination, especially in complex cases, while the electronic apex locator remains valuable with careful consideration of potential variations in accuracy. An individualized approach, considering tooth type, jaw location, and clinical context, is crucial for precise working length determination in endodontic practice.

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).

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).

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.

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).

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).

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.

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.