Cartesian three-dimensional method to quantify displacements between cone beam computed tomography models.

INTRODUCTION: Research in Orthodontics and Oral Surgery has been relying on three-dimensional (3D) models to evaluate treatment results with displacement color map techniques, even though it has important limitations. OBJECTIVES: This study proposed a method of tracking translational movements of 3D objects to evaluate displacements in surfaces with no shape modification. METHODS: Cone Beam Computed Tomography (CBCT) data of ten patients were imported to the Dolphin software. A hypothetical virtual surgical plan (randomly defined) was developed in the software and afterwards verified using the proposed method. All the procedures were carried out by two evaluators, in two different time-points, with a 15-day interval. ITK-Snap software was used to generate high quality STL models. Centroid points were automatically generated and their coordinates were compared to confirm if they represented the known displacements simulated. The paired t-test and the Bland-Altman plots were used, as well as the intraclass correlation coefficient. RESULTS: Interexaminers and intra-examiner tests showed excellent reliability of the method, with mean displacement measurement error values under 0.1mm. The paired t-test did not show any statistically significant differences. CONCLUSION: The method showed excellent reliability to track the simulated translational displacements of bone segments.

Evaluation of two stereophotogrametry software for 3D reconstruction of virtual facial models.

OBJECTIVE: The present study aimed to evaluate the accuracy of 3D facial soft tissue virtual models produced by two photogrammetry softwares (AgiSoft Photoscan and 3DF Zephyr Free), when compared to those created by cone beam computed tomography (CBCT). METHODS: Ten patients were submitted to two sequences of photographs performed with a DSLR camera (with and without the aid of a ring flash) and CBCT scans. Each photo series for each patient was processed with the softwares, and at the end, five models of each patient were generated: 1) CBCT, 2) AAL (Agisoft Ambient Light), 3) AFL (Agisoft Flash Light), 4) ZAL (Zephyr Ambient Light), and 5) ZFL (Zephyr Flash Light). Color coded maps and root-mean-square (RMS) distances were used to compare the photogrammetry models to the CBCT ones. RESULTS: One sample t-test showed significant differences between all methods versus CBCT. The worst results were seen in the ZAL group (discrepancies up to 5.17mm), while the best results were produced by AAL group (discrepancies up to 2.11mm). CONCLUSIONS: It can be concluded that this type of virtual facial models are reasonably accurate, although not perfect, and considering its lower biological and financial cost, they may play an important role in specific situations.

Utilização de programa gratuito para visualização tridimensional de dente impactado a partir de TCFC / Usefulness of free software for three-dimensional visualization of impacted tooth extracted from CBCT

Resumo Há pouco tempo, imagens bidimensionais (2D) eram rotineiramente utilizadas para planejamento e diagnóstico ortodônticos. A utilização de tomografias computadorizadas de feixe cônico (TCFC) acrescentou maior nível de detalhamento das imagens e, assim, elevação da qualidade do diagnóstico das más oclusões. O diagnóstico através de imagens tridimensionais (3D) de caninos impactados apresenta vantagens em relação ao diagnóstico e planejamento embasados em imagens 2D de radiografias. É possível gerar modelos virtuais nos três planos do espaço através de imagens adquiridas por TCFC. Em casos de caninos impactados, essas imagens 3D são valiosas para o ortodontista avaliar a posição real do canino impactado e, principalmente avaliar se existe reabsorção de raízes adjacentes causadas pelo canino impactado. Assim, este presente trabalho tem como objetivo demonstrar o passo a passo da utilização de software de livre acesso para a aquisição de imagens tridimensionais, através da utilização de arquivos digitais gerados pelos exames de TCFC. (AU)

Abstract Not long ago, two-dimensional (2D) images were routinely used for orthodontic planning and diagnosis. The use of cone-beam computed tomography (CBCT) added a greater level of detail to the images and, thus, increased the quality of the diagnosis of malocclusions. Diagnosis of impacted canines with three-dimensional (3D) images has advantages over diagnosis and planning based on 2D radiographic images. It is possible to generate virtual models in the three planes of space through images acquired by CBCT. In cases of impacted canines, these 3D images are valuable for the orthodontist to assess the actual position of the impacted canine and, especially, to assess whether there is resorption of adjacent roots caused by the impacted canine. Thus, this present article aims to demonstrate the step-by-step the use of free software for the acquisition of three-dimensional images, using digital files generated by CBCT exams. (AU)

Cartesian three-dimensional method to quantify displacements between cone beam computed tomography models

ABSTRACT Introduction: Research in Orthodontics and Oral Surgery has been relying on three-dimensional (3D) models to evaluate treatment results with displacement color map techniques, even though it has important limitations. Objectives: This study proposed a method of tracking translational movements of 3D objects to evaluate displacements in surfaces with no shape modification. Methods: Cone Beam Computed Tomography (CBCT) data of ten patients were imported to the Dolphin software. A hypothetical virtual surgical plan (randomly defined) was developed in the software and afterwards verified using the proposed method. All the procedures were carried out by two evaluators, in two different time-points, with a 15-day interval. ITK-Snap software was used to generate high quality STL models. Centroid points were automatically generated and their coordinates were compared to confirm if they represented the known displacements simulated. The paired t-test and the Bland-Altman plots were used, as well as the intraclass correlation coefficient. Results: Interexaminers and intra-examiner tests showed excellent reliability of the method, with mean displacement measurement error values under 0.1mm. The paired t-test did not show any statistically significant differences. Conclusion: The method showed excellent reliability to track the simulated translational displacements of bone segments.

RESUMO Introdução: Grande parte das pesquisas em Ortodontia e Cirurgia Oral tem utilizado modelos tridimensionais e realizado avaliações por meio de mapa de cores de deslocamento, apesar das limitações existentes. Objetivo: O presente estudo teve como objetivo propor um método de rastreamento de movimentos translacionais de objetos 3D, para avaliar deslocamentos em superfícies sem modificação de forma. Métodos: Dez adultos que seriam submetidos à cirurgia ortognática tiveram suas tomografias computadorizadas de feixe cônico pré-cirúrgicas importadas para o software Dolphin. Um plano cirúrgico virtual hipotético com deslocamentos conhecidos foi desenvolvido e posteriormente verificado pelo método proposto. Todos os procedimentos foram realizados por dois avaliadores, em dois momentos diferentes, com intervalo de 15 dias. O software ITK-Snap foi usado para gerar modelos STL de alta qualidade dos ossos do paciente. Os pontos do centroide foram gerados automaticamente, e suas coordenadas foram comparadas, para confirmar se representavam os deslocamentos conhecidos simulados. Para análise estatística, foram usados teste t pareado, coeficiente de correlação intraclasse e os gráficos de Bland-Altman. Resultados: O teste inter e intraexaminadores mostrou boa confiabilidade do método, com valores médios abaixo de 0,1mm para os erros de medida de deslocamento. Conclusão: O método mostrou boa confiabilidade para avaliar o deslocamento de segmentos ósseos após cirurgia ortognática, devendo ser aplicado como uma ferramenta completa de avaliação verdadeiramente tridimensional.

Evaluation of two stereophotogrametry software for 3D reconstruction of virtual facial models

ABSTRACT Objective: The present study aimed to evaluate the accuracy of 3D facial soft tissue virtual models produced by two photogrammetry softwares (AgiSoft Photoscan and 3DF Zephyr Free), when compared to those created by cone beam computed tomography (CBCT). Methods: Ten patients were submitted to two sequences of photographs performed with a DSLR camera (with and without the aid of a ring flash) and CBCT scans. Each photo series for each patient was processed with the softwares, and at the end, five models of each patient were generated: 1) CBCT, 2) AAL (Agisoft Ambient Light), 3) AFL (Agisoft Flash Light), 4) ZAL (Zephyr Ambient Light), and 5) ZFL (Zephyr Flash Light). Color coded maps and root-mean-square (RMS) distances were used to compare the photogrammetry models to the CBCT ones. Results: One sample t-test showed significant differences between all methods versus CBCT. The worst results were seen in the ZAL group (discrepancies up to 5.17mm), while the best results were produced by AAL group (discrepancies up to 2.11mm). Conclusions: It can be concluded that this type of virtual facial models are reasonably accurate, although not perfect, and considering its lower biological and financial cost, they may play an important role in specific situations.

RESUMO Objetivo: O presente estudo teve como objetivo avaliar a acurácia de modelos virtuais 3D de tecidos moles faciais produzidos por dois softwares de fotogrametria (AgiSoft Photoscan e 3DF Zephyr Free), em comparação aos gerados por tomografia computadorizada de feixe cônico (TCFC). Métodos: Dez pacientes foram submetidos a duas sequências de fotografias realizadas com câmera DSLR (com e sem auxílio de ring flash) e a TCFC. Cada série de fotografias de cada paciente foi processada com os softwares e, ao fim, foram gerados cinco modelos de cada paciente: 1) TCFC; 2) AAL (Agisoft Ambient Lighting); 3) AFL (Agisoft Flash Light); 4) ZAL (Zephyr Ambient Lighting); e 5) ZFL (Zephyr Flash Light). Mapas codificados por cores e distâncias quadráticas médias (RMS) foram usados para comparar os modelos de fotogrametria com os de TCFC. Resultados: O teste t para uma amostra mostrou diferenças significativas entre todos os métodos versus a TCFC. Os piores resultados foram observados no grupo ZAL (discrepâncias de até 5,17 mm), enquanto os melhores resultados foram produzidos pelo grupo AAL (discrepâncias de até 2,11 mm). Conclusões: Pode-se concluir que esse tipo de modelos faciais virtuais é razoavelmente preciso, embora não sejam perfeitos; e, considerando-se seu menor custo biológico e financeiro, podem desempenhar um papel importante em situações específicas.

Planejamento virtual utilizando software de livre acesso / Use of open source software for virtual treatment planning

Resumo O setup ortodôntico é um método de diagnóstico utilizado para simular tridimensionalmente um plano de tratamento. E a partir de sua análise, planeja-se a mecânica a ser utilizada durante o tratamento ortodôntico. Para sua realização é necessário duplicar o modelo de estudo em gesso, recortar seus dentes e montar os mesmos sobre as bases remanescentes. Entretanto esse processo demanda tempo laboratorial para sua confecção e espaço físico para o armazenamento dos modelos. Nos últimos anos, os setups em modelos de gesso têm sido substituídos pela versão virtual tridimensional, uma vez que não demandam espaço físico para armazenamento. Apesar da curva de aprendizado, o seu tempo de realização é bem reduzido, quando comparado com o setup em modelos de gesso. A desvantagem está no elevado custo dos softwares utilizados para sua realização. Assim o objetivo deste trabalho é descrever um passo-a-passo de como realizar um setup ortodôntico virtual 3D, utilizando para isso um software de livre acesso. (AU)

Abstract The orthodontic setup is a tool used for tridimensional simulation for visual treatment planning. Its analysis allows to plan the mechanics to be used during the orthodontic treatment. For this purpose, it is necessary to duplicate the cast model, to cut the teeth and replace them in their respective cast bases. However, this process demands laboratory time and physical space for cast models storage. The traditional setup with cast models has been substituted by the 3D virtual version once it does not demand physical space for storage. Despite the learning curve, the 3D virtual computerized process has a reduced time when compared to the setup with cast models. But the software high cost is still the main point of disadvantage for its use. Thus, the aim of this study is to describe a step-by-step of 3D virtual orthodontic setup process, by using an open-source software.(AU)

Análise de modelo virtual em software gratuito / Analysis of a virtual model in using free software

Resumo Os modelos virtuais vêm sendo utilizados por cada vez mais profissionais. Dessa forma, há a necessidade de softwares que permitam a simples visualização destes modelos. Além disso, assim como em modelos de gesso, é necessário que os softwares permitam que medições lineares e as análises já consagradas em Ortodontia sejam realizadas de forma virtual. Uma das principais limitações dos softwares disponíveis é com relação ao seu alto custo. Além disso, observa-se que em alguns softwares suas funcionalidades não são intuitivas sendo pouco amigáveis para o uso odontológico. Assim, o presente estudo pretende demostrar de forma prática e didática como é possível realizar medições e análises simples, através do software, gratuito, 3D Viewer, auxiliando no diagnóstico e planejamento através de modelos virtuais. Para isso, descreve-se o caso clínico de uma paciente que utilizou aparelho ortodôntico fixo e que teve suas análises de modelo realizadas através do software 3D Viewer, descrevendo e exemplificando cada uma das 17 ferramentas presentes no mesmo. Pode-se observar que é possível realizar medições e análises simples, através do software, gratuito, 3D Viewer, auxiliando o ortodontista no diagnóstico e planejamento realizados através de modelos virtuais.(AU)

Abstract Virtual models have been increasingly used by clinicians. Thus, there is a need for softwares that allows the simple visualization of these models. In addition, as with plaster models, software must allow linear measurements and analyzes already established in Orthodontics to be performed virtually (linear, angular measurements, and calculation of tooth discrepancies). High cost is the main limitation for softwares acquisitions. In addition, it is observed that in some software its features are not intuitive, being unfriendly for dental use. Thus, this study intends to demonstrate in a clarifying and didactic way how to proceed measurements and simple analysis by the use of open-source software: 3D Viewer. For this purpose, a case report of an orthodontic patient as well as its virtual dental cast model analysis on 3D Viewer is presented. All the 17 tools of 3D Viewer are presented and described. It is possible to proceed measurements and simple analysis by the use of the 3D viewer to support the orthodontists during diagnosis and treatment planning on 3D cast models. (AU)

Orthodontic-surgical treatment for a patient with Class II malocclusion and inadequate maxillary incisor inclination.

Dental health and patient satisfaction at the end of orthodontic treatment are needed if the treatment is to be considered successful. This case report highlights the importance of proper diagnosis for a patient initially treated with camouflage, despite the indications for surgery. A 16-year-old male patient sought treatment complaining about his appearance. He had been using an appliance for 6 years without improvement. He had a convex profile, an enlarged lower third of the face, reduced cervical-mandibular line, and Class II molar relationship. The maxillary incisors had excessive buccal root torque, throbbing pain, and dental mobility, with no visible bone coverage in the tomographic sections. The cephalometric analysis confirmed the skeletal Class II relationship (ANB, 11.6°; Wits appraisal, 14.2 mm) because of severe mandibular deficiency (SNB, 71.2°), aggravated by the vertical growth tendency (FMA, 27.3°). Changes in IMPA (108.1°) and U1-NA (0.9°; -2.9 mm) reflected the previous orthodontic attempt to compensate for the malocclusion. After periodontal and endodontic evaluation, a new treatment plan was developed. The incisors would be positioned in their bone bases, the mandibular first premolars would be extracted to create space for the second molars and increase the overjet, and the patient would be referred for orthognathic surgery. The patient was satisfied with the esthetic and functional results of this treatment.

Acurácia de modelos ortodônticos por escaneamento a laser, luz estruturada e tomografia computadorizada / Accuracy of orthodontic models scanned by laser, structured light, and computed tomography

Introdução: com a crescente utilização dos modelos digitais em Ortodontia, aumenta também a necessidade de se conhecer as opções disponíveis para sua obtenção. Atualmente, a alternativa mais utilizada é o escaneamento de modelos de gesso, que pode ser realizado em scanners a laser, por luz estruturada ou por tomografia computadorizada. O objetivo deste trabalho foi avaliar, através de uma análise por sobreposição de modelos digitais, a acurácia dos modelos digitais gerados por estes três métodos de escaneamento e a influência de dois diferentes níveis de resolução de escaneamento. Material e métodos: 30 pares de modelos de gesso foram escaneados utilizando as três tecnologias. O escaneamento por luz estruturada foi realizado com duas configurações do nível de resolução: máxima e padrão. Os modelos digitais gerados foram sobrepostos e as diferenças entre as superfícies foram calculadas. Mapas de cores foram utilizados para evidenciar as discrepâncias entre os modelos. Resultados: para todos os parâmetros avaliados, foram obtidas diferenças estatisticamente significantes. As diferenças entre os modelos escaneados a laser e por luz estruturada foram menores, o que sugere maior similaridade entre eles. Conclusão: as diferenças encontradas entre os modelos digitais obtidos pelas três tecnologias de escaneamento estudadas foram estatisticamente significantes. No entanto, por serem muito pequenas quantitativamente, não foram consideradas clinicamente significantes. Não houve diferença entre os dois níveis de resolução estudados, portanto, os três métodos de escaneamento avaliados possuem uma acurácia clinicamente aceitável para ser utilizado em Ortodontia.

Introduction: the increasing use of digital models in orthodontics demands knowledge of the available options for their acquisition. Currently, the most used option is the plaster model scanning, which can be made by laser, structured light and computed tomography scanners. The aim of this study was to evaluate, by a model superimposition analysis, the accuracy of digital models acquired by these three scanning methods and the influence of two different resolution levels of scanning. Methods: thirty pairs of plaster models were scanned using three different scanning technologies: laser, structured light and computed tomography. The structured light scanning was performed using two different resolution levels: maximum and standard. The respective digital models were superimposed and their mean differences were compared using color maps by Geomagic Qualify software. Results: for all parameters studied, statistically significant differences were found. Lower differences were presented between models scanned by laser and structured light techniques, which suggests a higher similarity between them. Conclusion: the differences found between digital models obtained by the three scanning technologies were statistically significant. However, they were quantitatively very small, which was considered clinically insignificant. There was no difference between the two resolution levels of scanning studied. Therefore the three scanning methods studied presented accuracy clinically acceptable to be used in orthodontics.

Effect of polyvinylsiloxane material and impression handling on the accuracy of digital models.

INTRODUCTION: The objective of this study was to evaluate the accuracy and reliability of measurements on digital models obtained by scanning impressions 5, 10, and 15 days after they were made from 2 soft putty polyvinylsiloxane (PVS) materials. METHODS: Thirty volunteers were selected for making impressions of their dentitions with alginate to create a plaster model and with PVS impression material to create a digital model by laser scanning. Three examiners made the plaster model measurements with digital calipers and repeated these measurements on the digital models made from the scanned PVS impressions. A total of 34 distances were evaluated. Paired t tests were used to evaluate intraexaminer error and the accuracy of the digital model measurements. Measurement reproducibility and reliability among examiners were tested. RESULTS: Although statistically significant differences between measurements on plaster and digital models were found, these discrepancies were not clinically significant except for overbite. Both plaster and digital models had high intraclass correlation coefficient values. CONCLUSIONS: Digital models acquired by laser scanning of 2 types of soft putty PVS material may be used with clinically acceptable accuracy, reliability, and reproducibility, even at a postscanning interval of 15 days.