Accuracy of photogrammetric technologies for the scanning of dental models: A systematic review / Precisión de las tecnologías fotogramétricas para el escaneo de modelos dentales: Una revisión sistemática

Background:Traditional dental scanners require a heavy investment, representing a high barrier of entry into digital dentistry. Photogrammetric-based scanners may represent an affordable cost-effective alternative to traditional dental scanners used for the digitalization of plaster models. Photogrammetry is the science of extracting 3D information from photographs. The process involves taking overlapping photographs of an object or space and converting them into 2D or 3D digital models. Objective:This review aimedto identify and appraise the reported accuracy of photogrammetric-generated digital dental models.Materials and methods:A search strategy was applied in 3 databases (Medline, Web of Science and Scopus), from Feb 1 2021 to Dec 1 2021, the search was limited to articles in English published in the last 5 years about studies evaluating the dimensional accuracy of 3-dimensional digital models acquired by the scanning of plaster models with photogrammetric technologies.Results:Two independent reviewers screened 75 records on basis of titles and abstracts for assessment against the inclusion criteria for the review, 4 articles were deemed eligible, the risk of bias for the selected articles was measured, data extraction was performed by only one author.Conclusion:With today's technology, based on the four studies evaluated, we conclude that photogrammetric-generated digital models while lacking accuracy for incorporation into the treatment flow, in the future it could be used for diagnostic, planning, and achieving.

Antecedentes:Los escáneres dentales tradicionales requieren una gran inversión, lo que representa una gran barrera de entrada a la odontología digital. Los escáneres basados en fotogrametría pueden representar una alternativa asequible y rentable a los escáneres dentales tradicionales utilizados para la digitalización de modelos de yeso. La fotogrametría es la ciencia de extraer información 3D de fotografías. El proceso implica tomar fotografías superpuestas de un objeto o espacio y convertirlas en modelos digitales 2D o 3D.Objetivo:esta revisión tuvo como objetivo identificar y evaluar la precisión informada de los modelos dentales digitales generados fotogramétricamente.Materiales y métodos:Se aplicó una estrategia de búsqueda en 3 bases de datos (Medline, Web of Science y Scopus), del 1 de febrero de 2021 al 1 de diciembre de 2021, la búsqueda se limitó a artículos en inglés publicados en los últimos 5 años sobre estudios que evalúan la dimensión precisión de modelos digitales tridimensionales adquirida por el escaneo de modelos de yeso con tecnologías fotogramétricas.Resultados:dos revisores independientes examinaron 75 registros sobre la base de títulos y resúmenes para evaluarlos según los criterios de inclusión para la revisión, 4 artículos se consideraron elegibles, se midió el riesgo de sesgo de los artículos seleccionados, la extracción de datos fue realizada por un solo autor.Conclusión:con la tecnología actual, con base en los cuatro estudios evaluados, concluimos que los modelos digitales generados por fotogrametría si bien carecen de precisión para incorporarlos al flujo de tratamiento, en el futuro podrían usarse para el diagnóstico, la planificación y el logro.

3D printing ophthalmology related models for enhancing learning through the concept of puzzle assembly - A comprehensive self-learning tactile tool kit

Practical sessions facilitate teaching, critical thinking, and coping skills, especially among medical students and professionals. Currently, in ophthalmology, virtual and augmented reality are employed for surgical training by using three?dimensional (3D) eyeball models. These 3D models when printed can be used not only for surgical training but also in teaching ophthalmic residents and fellows for concept learning through tactile 3D puzzle assembly. 3D printing is perfectly suited for the creation of complex bespoke items in a cost?effective manner, making it ideal for rapid prototyping. Puzzle making, when combined with 3D printing can evolve into a different level of learning in the field of ophthalmology. Though various 3D eyeball models are currently available, complex structures such as the cerebral venous system and the circle of Willis have never been 3D printed and presented as 3D puzzles for assembling and learning. According to our knowledge, this concept of ophthalmic pedagogy has never been reported. In this manuscript, we discuss in detail the 3D models created by us (patent pending), for printing into multiple puzzle pieces for effective tactile learning by cognitive assembling

Tratamiento de deformidad severa de la columna vertebral con modelos de impresión 3D / Treatment of severe spinal deformity with 3D printing models

Resumen: Introducción: La escoliosis es una deformidad compleja que afecta los tres planos del eje de la columna vertebral. La asociación entre patología neuromuscular y la alineación vertebral fue descrita inicialmente en 1960. La patología neuromuscular es progresiva y resulta en anormalidades posturales. Las metas quirúrgicas en pacientes con deformidad neuromuscular engloban la corrección anatómica para la sedestación y deambulación, así como mejoría funcional. El estándar de oro de tratamiento es por vía posterior con tornillos transpediculares. La técnica de «manos libres¼ ahorra tiempo quirúrgico, disminuye la radiación al reducir el uso de fluoroscopía. El advenimiento de la tecnología de impresión 3D permite estudio preciso del área anatómica y detalle de la deformidad en sus tres planos. Este modelo puede ser esterilizado para guía transoperatoria. Paciente femenino de 13 años de edad que desarrolla escoliosis neuromuscular toracolumbar secundario a parálisis cerebral infantil (PCI) espástica, con instrumentación previa T11-L3 de la cual desarrolla curva severa proximal. Finalizada la segmentación del modelo tridimensional se detectó violación pedicular mayor a 2 mm hacia canal medular bilateral en los pedículos de L1 y L2 de instrumentación previa, displasia pedicular y se observaron las características morfológicas de los pedículos. La planeación tridimensional y el uso de guías quirúrgicas representan una herramienta para la planeación quirúrgica, sobre todo en casos severos y con displasia pedicular. Ayuda como guía quirúrgica para la colocación de tornillos transpediculares a manos libres con posible reducción de radiación y tiempo anestésico.

Abstract: Introduction: Scoliosis is a complex deformity that affects all three planes of the axis of the spine. The association between neuromuscular pathology and vertebral alignment was initially described in 1960. Neuromuscular pathology is progressive and results in postural abnormalities. Surgical goals in patients with neuromuscular deformity include anatomical correction for sedation and ambulation, as well as functional improvement. The gold standard of treatment is by posterior approach with transpedicular screws. The «hands-free¼ technique saves surgical time, decreases radiation by reducing the use of fluoroscopy. The advent of 3D printing technology allows precise study of the anatomical area and detail of the deformity in its three planes. This model can be sterilized for transoperative guidance. A 13-year-old female patient who develops thoracolumbar neuromuscular scoliosis secondary to spastic cerebral palsy (CP), with previous instrumentation T11-L3 of which he develops severe proximal curve. After the segmentation of the three-dimensional model, pedicle violation greater than 2 mm towards bilateral medullary canal was detected in the pedicles of L1 and L2 of previous instrumentation, pedicle dysplasia and the morphological characteristics of the pedicles were observed. Three-dimensional planning and the use of surgical guides represent a tool for surgical planning, especially in severe cases and with pedicle dysplasia. It helps as a surgical guide for the placement of hands-free transpedicular screws with possible reduction of radiation and anesthetic time.

Three-dimensional digitalized and printed tongue models of the cow, dog, pig, and horse for undergraduate veterinary educationh / Modelos tridimensionales digitalizados e impresos de lengua de vaca, perro, cerdo y caballo para la educación veterinaria de pregrado

SUMMARY: This study aimed to construct three-dimensional (3D) anatomical models of the tongue of domestic mammals of veterinary interest. The tongues were obtained from the didactic collection of the Laboratory of Veterinary Macroscopic Anatomy in the Surgery Department of the School of Veterinary Medicine and Animal Science, University of Sao Paulo. Tongues from a cow, dog, horse, and pig were selected for scanning and creation of the 3D-printed models. The printer used a filamentous thermoplastic material, acrylonitrile-butadiene-styrene (ABS), which was deposited together with a support resin. In addition to the printing of models, an interactive 3D PDF was generated, creating a didactic collection for students. The anatomical characteristics and peculiarity of the tongues were easily identified in the scanned and printed images. The 3D scanning and printing offered an innovative method of visualizing different anatomical structures and, together with the existing methods, can optimize anatomy teaching in an educational context.

RESUMEN: Este estudio tuvo como objetivo construir modelos anatómicos tridimensionales (3D) de la lengua de mamíferos domésticos de interés veterinario. Las lenguas se obtuvieron de la colección didáctica del Laboratorio de Anatomía Macroscópica Veterinaria del Departamento de Cirugía de la Facultad de Medicina Veterinaria y Zootecnia de la Universidad de São Paulo. Se seleccionaron lenguas de vaca, perro, caballo y cerdo para escanear y crear los modelos impresos en 3D. La impresora utilizó un material termoplástico filamentoso, acrilonitrilo-butadieno-estireno (ABS), que se depositó junto con una resina de soporte. Además de la impresión de modelos, se generó un PDF 3D interactivo, creando una colección didáctica para los estudiantes. Las características anatómicas y la peculiaridad de las lenguas se identificaron fácilmente en las imágenes escaneadas e impresas. El escaneo e impresión 3D ofrecieron un método innovador para visualizar diferentes estructuras anatómicas y, junto con los métodos existentes, puede optimizar la enseñanza de la anatomía en un contexto educativo.

Comparación estadística entre modelo de yeso, digitalizado e impreso en 3D / Statistic comparison of digitalized plaster models and printed in 3D

Se realizaron mediciones en los ejes x, y, z sobre modelos dentales de yeso, digitalizados e impresos con impresoras 3D, con fines comparativos, estadísticos y evaluativos, cuyo objetivo fue estimar el grado de coincidencia significativa entre los modelos, realizados por dos profesionales, en dos momentos diferentes. Los resultados arrojaron datos de gran precisión en forma y tamaño en los tres estudios, con mínima distorsión (no significativa, p =0,05), lo que determinó la importancia de implementación en forma institucional o privado el estudio digital de los mismos, para realizar comparaciones, mediciones, diagnósticos y acopio de modelos virtuales en un ordenador, siendo estos más precisos y de menor tiempo de trabajo (AU)

Measurements were made in the x, y, z axes on gypsum dental models, digitized and printed with 3D printers, for comparative, statistical and evaluative purposes, whose objective was estimate the degree of significant coincidence between models, that were made by two professionals, at two different times.The results were the achieve of data with a great shape´s and size´s precisionat the three studies, with minimal distortion (not significant, p = 0.05), which determined the importance of the institutional or private way of an implementation of the model´s digital studies, with the aim of doing comparisons, measurements, diagnostics, and collection of virtual models in a computer, to being more precise and with less work time (AU)

Percepción de los estudiantes de anatomía humana frente a un método de enseñanza y aprendizaje basado en la construcción de un modelo de pelvis / Perception of human anatomy students facing a learning and teaching methodology based on the construction of a pelvis model

RESUMEN: Este estudio describe la percepción de estudiantes de anatomía humana frente a la actividad de construcción de modelos tridimensionales (3-D) a escala de pelvis. Pocos estudios evalúan la percepción de los estudiantes frente a una actividad de enseñanza y aprendizaje con modelos 3-D. La actividad se aplicó a un curso de anatomía humana de la carrera de obstetricia y puericultura a los cuales se les entregó modelos de estructuras óseas de la zona pélvica a escala real para que incorporaran las estructuras anatómicas (ligamentos, músculos, vascularización e inervación), finalizando la actividad se les entregó un cuestionario de percepción. 60 estudiantes realizaron la actividad de construcción de modelo anatómico 3-D y además completaron el cuestionario. Se reportaron niveles mayores al 93 % de estudiantes que sintieron motivación, creen que fue un facilitador del aprendizaje y que la actividad fue bien planificada. Entre los aspectos negativos se registraron: el tiempo de trabajo y los costos involucrados. Dada la positiva percepción de los estudiantes frente a las actividades de construcción de modelos anatómicos, se considera que es una metodología adecuada dentro de los procesos de enseñanza y aprendizaje de la anatomía humana.

SUMMARY: In this study, the perception of human anatomy students faced with constructing a three-dimensional (3-D) pelvis model (to scale) was studied. Few studies evaluate the perception of students facing learning and teaching methodologies with 3-D models. The activity was performed with students from a human anatomy course as part of the obstetrics degree, in which models of pelvic zone bone structures (to scale) were supplied in order to incorporate the anatomic structures (ligaments, muscles, vascularization and innervation). Once the activity was finished, a perception questionnaire was taken. 60 students participated in the activity of constructing the 3-D anatomical model and also completed the questionnaire. It was found that over 93 % of the students felt motivated, believed the activity facilitated learning and also that the activity was well planned. Some of the negative factors that were reported included time taken and the associated costs. Due to the positive perception of the students involved in the activity of constructing anatomical models, this is considered to be a suitable methodology for use during the process of teaching and learning about human anatomy.

Using digitized 3Dmodel for assessing characteristics of pelvic and abdominal vessel imaging of CTA and MRA / 重庆医学

Objective To construct the digitalized 3 dimensional(3D)model by using the CTA and MRA original images and to assess the differences in the pelvic and abdominal vessel display between CTA and MRA.Methods The original data set in 25 healthy youth female cases of CTA and MRA were collected.The datasets,reconstructed the 3D models of arteries and venous on 3D reconstruction software Mimics10.0 was used to construct the 3D model of pevic and abdominal vessels.The reconstruction situation of abdominal aorta,inferior vena cava,common iliac artery and common iliac venous,internal and external iliac artery and iliac venous,uterine artery,obturator artery and obturator venous,hip artery and its branches,internal pudendal artery,middle sacral artery and venous,ovarian artery and venous and sacral venous plexus were observed.Moreover the chi-square test was used to analyze whether the above vessel display rate having differences between the two kinds of model.Results The abdominal aorta,inferior vena cava,common iliac artery and common iliac venous,internal and external iliac artery and iliac venous and uterine artery almost reached 100 ％ display.The display rates of CTA model for right and left obturator artery and venous were 92 ％,80 ％,44 ％ and 32 ％ respectively,while which of MRA model were 84 ％,72 ％,36 ％ and 4％ respectively,the difference was not statistically significant(P =0.382,P=0.508,P =0.564,P =0.382).The sacral venous plexus,including S1,2,3,4 transverse vein,the display rates in 25 cases of CTA 3D models were 4％,8％,0％and 4％respective,while which of MRA models were 76％,92％,96％and 44％respectively,the differences between them were statistically significant(P＜0.01,P＜0.01,P＜0.01,P=0.01).Conclusion Based on the observation of 3D models,the displaying rate of grade 4 pelvic and abdominal vessels has no statistical difference between MRA imaging technology and currently widely used CTA technology,moreover the MRA technology is superior to the CTA technology in presacral vessel net display.

EFECTO DEL REMODELADO ELÉCTRICO AURICULAR EN UN MODELO TRIDIMENSIONAL DE AURÍCULA HUMANA

Las arritmias cardíacas más frecuentes en humanos tienen origen auricular. El modelado de la actividad auricular se ha convertido en una importante herramienta en el análisis de arritmias como la fibrilación auricular. Estudios experimentales han demostrado que la fibrilación auricular tiende a perpetuarse, generando cambios electrofisiológicos denominados remodelado auricular. En este trabajo se presenta un modelo tridimensional geométricamente realista de la aurícula humana, al cual se le incorporan: anisotropía, dirección de las fibras y heterogeneidad en la conductividad. En un modelo del potencial de acción acoplado al modelo tridimensional, se estudió el efecto del remodelado auricular sobre el potencial de acción y su propagación teniendo en cuenta sus efectos sobre las corrientes iónicas. El modelo reprodujo el comportamiento de la actividad eléctrica en toda la superficie auricular. El remodelado redujo la duración del potencial de acción, el periodo refractario efectivo y la velocidad de conducción. Los resultados sugieren que en el modelo tridimensional desarrollado, es posible simular la actividad eléctrica auricular en condiciones fisiológicas y con remodelado eléctrico auricular.

The most common cardiac arrhythmias in humans originate in the atrium. Modelling of the atrial activity has become an important tool to analyze arrhythmias such as atrial fibrillation. Experimental studies have shown that atrial fibrillation tends to be perpetual, generating electrophysiological changes called atrial remodeling. In this study we present a geometrically realistic three-dimensional (3D) model of human atrium, which incorporates anisotropy, direction of the fibers and conductive heterogeneity. The effects of remodeling on the ionic currents were applied to an action potential model coupled to the 3D model. The effects of remodeling on the action potential and its propagation were studied the model reproduced the electrical activity behavior across the atrial surface. Remodelling induced a reduction in the action potential duration, the effective refractory period and the conduction velocity. Our results suggest that in the developed 3D model of human atrium is possible to simulate the atrial electrical activity under physiological conditions and with atrial electrical remodeling.