A new way of analyzing tooth movement using universal coordinate system geometry single point superposition in a 3D model

ABSTRACT Introduction: Superposing 3D models is an imminent need. However, current methods rely on marking multiple points on the maxilla and mandible, which could increase point marking and overlapping errors. Objective: This study aimed at developing a method for superimposing 3D models of the maxillary and mandibular arches with Autodesk Inventor® engineering software, using a single universal coordinate system (UCS) point superposition. Methods: A total of 104 STL (stereolithography) models of the maxillary and mandibular arches exported from My iTero® platform were retrospectively selected, in which T0 and T1 were the initial and refinement periods, respectively (n=26 per group). The X, Y, and Z coordinates associated with a single point in each arch were inserted into the models with SlicerCMF® software for model orientation. The arch models with UCS registration were transferred to Autodesk Inventor® for superimposition and to measure tooth movements performed during Invisalign® treatment. Arch expansion, intrusion and rotation were analyzed by two examiners. The statistics were performed using intraclass correlation coefficients (ICC), Dahlberg's formula, and t-test (p<0.05). Results: A reliable method of superimposing 3D digital models using a single UCS point in the maxilla and mandible was developed. ICC showed excellent intra- and inter-examiner correlation (ICC>0.90). A systematic error was not found concerning linear and angular measurements (<1mm and <1.5°, respectively). Digital dental movements could be analyzed, including arch expansion, dental intrusion, and tooth rotation. Conclusions: The developed method was proven reliable and reproducible for superimposing 3D models of the maxillary and mandibular arches by using UCS system.

RESUMO Introdução: A sobreposição de modelos 3D é uma necessidade iminente. No entanto, os métodos atuais dependem da marcação de múltiplos pontos na maxila e na mandíbula, o que pode aumentar a incorporação de erros no processo de sobreposição. Objetivo: O objetivo desse estudo foi desenvolver um método para sobrepor modelos 3D das arcadas superior e inferior utilizando o software de engenharia Autodesk Inventor®, por meio da marcação de um único ponto em cada arcada, usando o sistema de coordenadas universal (UCS). Métodos: No total, 104 modelos STL das arcadas superior e inferior exportados da plataforma My iTero® foram selecionados retrospectivamente, onde T0 foi o período inicial e T1, o de refinamento (n=26 por grupo). As coordenadas X, Y e Z associadas a um único ponto em cada arcada foram inseridas nos modelos usando o software SlicerCMF®. Os modelos com os pontos UCS demarcados foram transferidos para o software Autodesk Inventor® para realizar a sobreposição e medir os movimentos dentários realizados durante o tratamento com Invisalign®. Os movimentos de expansão, intrusão e rotação foram analisados por dois examinadores. A análise estatística foi realizada usando os coeficientes de correlação intra-classe (ICC), fórmula de Dahlberg e teste t (p<0,05). Resultados: Foi desenvolvido um método confiável de sobreposição de modelos digitais 3D usando um único ponto UCS na maxila e mandíbula. O ICC apresentou excelente correlação intra e inter-avaliadores (ICC>0,90). Não foi encontrado erro sistemático nas medidas lineares e angulares (<1mm e <1,5°, respectivamente). Os movimentos dentários puderam ser analisados por meio do método proposto, incluindo expansão da arcada, intrusão e rotação dentária. Conclusão: O método desenvolvido provou ser confiável e reprodutível para sobreposição de modelos 3D das arcadas superior e inferior usando o sistema UCS com marcação de ponto único.

Dentoalveolar effects of skeletally anchored extrusion arch in anterior open bite patients: A prospective clinical trial

ABSTRACT Objective: The purpose of this prospective clinical trial was to explore the dental and soft tissue changes accompanying the use of skeletally anchored nickel-titanium (NiTi) extrusion arch in the correction of anterior open bite (AOB). Material and Methods: Twenty female patients with a mean age of 16.5 ± 1.5 years and a mean dentoalveolar AOB of 2.38±0.7 mm participated in this study. All patients were treated with an maxillary 0.017×0.025-in NiTi extrusion arch, with the aid of miniscrews inserted between the maxillary second premolars and first molars bilaterally, to act as indirect anchorage. Three-dimensional digital models and lateral cephalometric radiographs were taken just before the insertion of the extrusion arch (T0) and after 10 months (T1). Paired-sample t-tests were used in analyzing the data, to evaluate the changes after treatment (T1-T0). A significance level of p < 0.05 was used. Results: AOB was successfully closed in all patients, with a 4.35 ± 0.61 mm increase in the overbite. Maxillary incisors significantly extruded (2.52 ± 1.02 mm) and significantly reclined (5.78 ± 0.77°), with a resultant decrease in the overjet of 1.58 ± 0.5mm. A significant intrusion of maxillary first molars with no change in their inclination was observed. The upper lip showed a significant retraction tendency to the E-plane, and a significant increase in the nasolabial angle was observed. Conclusion: The skeletally anchored NiTi extrusion arch was an effective technique in treating AOB, with no adverse effects on the molars.

RESUMO Objetivo: O objetivo deste ensaio clínico prospectivo foi avaliar as alterações dentárias e em tecidos moles que acompanham o uso de arco de extrusão de níquel-titânio (NiTi) com ancoragem esquelético na correção da mordida aberta anterior (MAA). Material e Métodos: Participaram deste estudo 20 pacientes do sexo feminino com idade média de 16,5 ± 1,5 anos e MAA dentoalveolar (média de 2,38 ± 0,7 mm). Todos os pacientes foram tratados com arco de extrusão de NiTi 0,017×0,025" superior, com auxílio de mini-implantes inseridos entre os segundos pré-molares e primeiros molares superiores bilateralmente, para atuar como ancoragem indireta. Modelos digitais tridimensionais e radiografias cefalométricas laterais foram realizados imediatamente antes da inserção do arco de extrusão (T0) e após 10 meses (T1). Testes t para amostras pareadas foram utilizados na análise dos dados, para avaliar as alterações após o tratamento (T1-T0). Um nível de significância de p< 0,05 foi usado. Resultados: A MAA foi fechada com sucesso em todos os pacientes, com aumento de 4,35 ± 0,61 mm na sobremordida. Os incisivos superiores foram significativamente extruídos (2,52 ± 1,02 mm) e significativamente reclinados (5,78 ± 0,77°), com uma consequente diminuição na sobressaliência de 1,58 ± 0,5 mm. Foi observada intrusão significativa dos primeiros molares superiores, sem alteração na sua inclinação. O lábio superior apresentou tendência significativa de retração em relação ao plano E, e foi observado aumento significativo do ângulo nasolabial. Conclusão: O arco de extrusão de NiTi esquelético foi uma técnica eficaz no tratamento da MAA, sem efeitos adversos nos molares.

Closure of maxillary lateral incisor agenesis space in unilateral cleft lip and palate: a digital model assessment

ABSTRACT Objective: To compare dental positional and gingival parameters of maxillary anterior teeth in unilateral cleft lip and palate (UCLP) after orthodontic treatment with canine substitution due to lateral incisor agenesis. Methods: This split-mouth study comprised 57 subjects with UCLP (31 male, 26 female) and agenesis of maxillary lateral incisor at the cleft side, from a single center. Canine substitution was completed after the secondary alveolar bone graft. Dental models were taken between 2 to 6 months after debonding (mean age: 20.4 years). The following variables were measured in the maxillary anterior teeth: crown height, width, proportion, and symmetry, as well as steps between incisal edges, gingival margins, tooth mesiodistal angulation and labiolingual inclination. Paired t-tests with Bonferroni post-hoc correction was used for comparisons between cleft and non-cleft sides (p<0.05). Results: At the cleft side, canines replacing missing lateral incisors had a higher crown height (0.77mm) and an increased width (0.67mm), and first premolars showed a shorter crown height (1.39mm). Asymmetries were observed in the gingival level of central and lateral incisors, with a greater clinical crown at the cleft side (0.61 and 0.81mm, respectively). Cleft side central incisors were more upright than their contralaterals (2.12º). Conclusions: Maxillary anterior teeth demonstrated positional, size and gingival height differences between cleft and non-cleft side after space closure of maxillary lateral incisor agenesis. Slight asymmetries in tooth position and gingival margin in the maxillary anterior teeth should be expected after orthodontic treatment in UCLP patients.

RESUMO Objetivo: O presente trabalho teve como objetivo comparar parâmetros dentários posicionais e gengivais de dentes anteriores superiores em pacientes com fissura labiopalatina transforame unilateral (FLPTU) após tratamento ortodôntico com substituição de incisivo lateral ausente por canino, devido a agenesia. Métodos: Esse estudo de boca dividida reuniu uma amostra, de um mesmo centro especializado de tratamento, de 57 indivíduos com FLPTU (31 homens, 26 mulheres) e agenesia do incisivo lateral superior no lado da fissura. A substituição do incisivo lateral por um canino foi concluída após o enxerto ósseo alveolar secundário. Os modelos dentários foram obtidos entre dois e seis meses após a remoção do aparelho (idade média: 20,4 anos). Foram mensuradas nos dentes anteriores as variáveis: altura, largura, proporção e simetria da coroa, bem como as distâncias entre as bordas incisais, margens gengivais, angulação mesiodistal e inclinação vestibulolingual. O teste t pareado com correção post-hoc de Bonferroni foi usado para comparações entre os lados fissurados e não fissurados (p<0,05). Resultados: No lado fissurado, os caninos que substituíram os incisivos laterais ausentes apresentaram uma altura de coroa maior (0,77 mm) e uma largura aumentada (0,67 mm). Os primeiros pré-molares apresentaram uma altura de coroa menor (1,39 mm). Assimetrias foram observadas no nível gengival dos incisivos centrais e laterais, com maior coroa clínica no lado fissurado (0,61 e 0,81mm, respectivamente). Os incisivos centrais do lado fissurado estavam mais intruídos do que os contralaterais (2,12 mm). Conclusão: Os dentes anteriores superiores demonstraram diferenças de posição, tamanho e altura gengival entre os lados fissurado e não fissurado, após o fechamento do espaço da agenesia dos incisivos laterais superiores. Leves assimetrias na posição do dente e margem gengival nos dentes anteriores superiores devem ser esperadas após o tratamento ortodôntico em pacientes com fissura labiopalatina transforame unilateral.

Three-dimensional virtual models of 3D-scanned real cadaveric samples used as a complementary educational resource for the study of human anatomy: undergraduate students perception of this new technology / Modelos virtuales tridimensionales de muestras cadavéricas reales obtenidas con escáner 3D, utilizados como recurso educativo complementario para el estudio de la anatomía humana: percepción de los estudiantes universitarios enfrentados a esta nueva tecnología

SUMMARY: The emergence of the digital society in the 21st century due to great advances in information and communication technologies (ICT) has allowed the development of research, communication, and collaboration activities related to knowledge and information. ICTs have influenced many aspects of society, especially educational work, and many educational establishments have adopted these technologies in a bid to enhance their teaching methods. One of the most representative cases is the global expansion of e-learning platforms. Until now, the traditional method of study of human anatomy, a key component of any study plan in the health education area, has been mainly based on classic texts. However, different types of software made an appearance in this century such as the three-dimensional (3D) atlases consisting of digital illustrations of the human body. However, there might be a high cost of investment involved when purchasing these kind of software. This research aimed to study the perception of human anatomy students regarding the use of models of 3D-scanned real cadaveric samples available at http://anatomiahumana3d.com, as a complementary educational resource to conventional study. A satisfaction survey was designed which consisted of four items. The survey was answered by 134 students. The format of the models, functionality of the resource, content and teaching of the resource, and finally the general evaluation, reached 96.8%, 84.05%, 81.14%, and 89.4% of perception of satisfaction, respectively. The results show that the new generations of students are immersed in a technological environment, therefore, both general and anatomy teaching could benefit from the use of new technologies.

RESUMEN: El comienzo de la sociedad digital en el siglo XXI debido a los grandes avances en las tecnologías de la información y comunicación (TIC) ha permitido el desarrollo de actividades de investigación, comunicación y colaboración relacionadas con el conocimiento y la información. Las TIC han influido en muchos aspectos de la sociedad, especialmente en el trabajo educativo, y muchos establecimientos educativos han adoptado estas tecnologías en un intento por mejorar sus métodos de enseñanza. Uno de los casos más representativos es la expansión global de las plataformas de e-learning. Hasta ahora, el método tradicional de estudio de la anatomía humana, componente clave de cualquier plan de estudios en el área de educación para la salud, se ha basado principalmente en textos clásicos. Sin embargo, en este siglo aparecieron diferentes tipos de software, como los atlas tridimensionales (3D) que consisten en ilustraciones digitales del cuerpo humano. Sin embargo, puede haber un alto costo de inversión involucrado al adquirir este tipo de software. Esta investigación tuvo como objetivo estudiar la percepción de los estudiantes de anatomía humana sobre el uso de modelos de muestras de cadáveres reales escaneados en 3D disponibles en http://anatomiahumana3d.com, como recurso educativo complementario al estudio convencional. Se diseñó una encuesta de satisfacción que constaba de cuatro ítems. La encuesta fue respondida por 134 estudiantes. El formato de los modelos, funcionalidad del recurso, contenido y didáctica del recurso, y finalmente la evaluación general, alcanzaron el 96,8%, 84,05%, 81,14% y 89,4% de percepción de satisfacción, respectivamente. Los resultados muestran que las nuevas generaciones de estudiantes se encuentran inmersas en un entorno tecnológico, por lo que tanto la enseñanza general como la de anatomía podrían beneficiarse del uso de las nuevas tecnologías.

Modelos digitales 3D en el proceso de enseñanza-aprendizaje de las ciencias médicas / Digital models 3D in the teaching-learning process of the medical sciences

En la actualidad, las universidades de ciencias médicas deben adaptarse a los cambios que imponen los adelantos tecnológicos. Los modelos digitales 3D facilitan la impartición de los contenidos relativos a objetos anatómicos, morfológicos y fenómenos médicos que, ocasionalmente, pueden resultar complejos y/o abstractos para los estudiantes. Con este trabajo se pretende analizar las ventajas asociadas al empleo de dichos modelos en el proceso de enseñanza - aprendizaje de las carreras de las ciencias médicas, puesto que existe una insuficiente cultura tecnológica en los profesores de estas carreras en relación con las amplias posibilidades que pueden ofrecer los modelos digitales 3D para apoyar los contenidos específicos de las asignaturas, lo cual limita el desarrollo del proceso de enseñanza-aprendizaje. Dichos modelos pueden ser incorporados como importantes medios didácticos de última generación tendientes a lograr mejores niveles de motivación y comprensión de los contenidos por parte de los estudiantes.

Medical Sciences universities should adapt to the changes imposed by the technological advances at the present time. Digital models 3D facilitate the delivering of contents related to anatomical, morphological objects and medical phenomena that occasionally, can be complicated and/or abstract for the students. With this work it is intended to analyze the advantages associated with the use of such models in the teaching - learning process of the Medical Sciences careers, since an insufficient technological culture exists in professors of these careers taking into account the wide possibilities that digital models 3D can offer to support the specific contents of subjects, which limits the development of the teaching-learning process. Such models can be incorporate as important didactic means of last generation, which tend to achieve better motivation and understanding levels of the contents on the students.

Superimposition of 3D maxillary digital models using open-source software

Abstract Historically, whether for research purposes or clinical monitoring, orthodontic evaluation of dental movements has been done using plaster study models and two dimensional (2D) radiographs. However, new frontiers for the diagnosis, planning and outcome assessment of orthodontic treatments have arisen, due to the revolutionary digital tools which enable a three dimensional (3D) computerized analysis of dental movements by means of digital models. However, the software for 3D analysis are often costly, resulting in limited access to orthodontists. The present study aims to describe, through a clinical case presented to the Brazilian Board of Orthodontics and Dentofacial Orthopedics, a method for the superimposition of maxillary digital models using an open-source software to evaluate dental movements.

Resumo Historicamente, a avaliação ortodôntica da movimentação dentária, seja com finalidade de pesquisa, seja para monitoramento clínico, tem sido feita por meio de modelos de estudo em gesso e radiografias em duas dimensões (2D). Entretanto, com o desenvolvimento da Ortodontia digital, novas fronteiras para o diagnóstico, planejamento e avaliação dos resultados dos tratamentos ortodônticos têm surgido. Os modelos digitais possibilitam uma análise computadorizada da movimentação dentária nas três dimensões (3D); porém, os softwares usados para as análises 3D geralmente são onerosos e de limitado acesso aos clínicos. O presente artigo visa descrever um método de sobreposição de modelos 3D da arcada dentária superior utilizando um software de livre acesso para avaliar a movimentação dentária, ilustrado por um caso clínico apresentado ao Board Brasileiro de Ortodontia e Ortopedia Facial.

Average interradicular sites for miniscrew insertion: should dental crowding be considered?

ABSTRACT Objective: To define a map of interradicular spaces where miniscrew can be likely placed at a level covered by attached gingiva, and to assess if a correlation between crowding and availability of space exists. Methods: Panoramic radiographs and digital models of 40 patients were selected according to the inclusion criteria. Interradicular spaces were measured on panoramic radiographs, while tooth size-arch length discrepancy was assessed on digital models. Statistical analysis was performed to evaluate if interradicular spaces are influenced by the presence of crowding. Results: In the mandible, the most convenient sites for miniscrew insertion were in the spaces comprised between second molars and first premolars; in the maxilla, between first molars and second premolars as well as between canines and lateral incisors and between the two central incisors. The interradicular spaces between the maxillary canines and lateral incisors, and between mandibular first and second premolars revealed to be influenced by the presence of dental crowding. Conclusions: The average interradicular sites map hereby proposed can be used as a general guide for miniscrew insertion at the very beginning of orthodontic treatment planning. Then, the clinician should consider the amount of crowding: if this is large, the actual interradicular space in some areas might be significantly different from what reported on average. Individualized radiographs for every patient are still recommended.

RESUMO Objetivo: elaborar um mapa dos espaços inter-radiculares nos quais os mini-implantes podem ser inseridos, em um nível coberto por gengiva inserida; e avaliar se existe correlação entre o apinhamento dentário e a disponibilidade de espaços. Métodos: radiografias panorâmicas e modelos digitais de 40 pacientes foram selecionados seguindo critérios de inclusão. Os espaços inter-radiculares foram medidos nas radiografias panorâmicas, enquanto a discrepância de modelo foi avaliada nos modelos digitais. Realizou-se, então, uma análise estatística para avaliar se os espaços inter-radiculares foram influenciados pela presença do apinhamento dentário. Resultados: na mandíbula, os locais mais adequados para a inserção dos mini-implantes foram os espaços compreendidos entre os segundos molares e primeiros pré-molares; na maxila, entre os primeiros molares e segundos pré-molares, bem como entre caninos e incisivos laterais, e entre os dois incisivos centrais. Os espaços inter-radiculares entre os caninos e incisivos laterais superiores e entre o primeiro e o segundo pré-molares inferiores mostraram-se influenciados pela presença do apinhamento dentário. Conclusões: o mapa dos espaços inter-radiculares mais adequados aqui proposto pode ser adotado como um guia geral para a inserção de mini-implantes, e pode ser usado logo ao início do planejamento do tratamento ortodôntico. Em seguida, o clínico deve levar em consideração a quantidade de apinhamento: caso esse seja grande, o real espaço inter-radicular, em algumas áreas, poderá ser significativamente diferente da média aqui relatada. Assim, recomenda-se que sempre sejam feitas radiografias individualizadas para cada paciente.

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.

A comparison of the precision of three-dimensional images acquired by 2 digital intraoral scanners: effects of tooth irregularity and scanning direction / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare the precision of three-dimensional (3D) images acquired using iTero(R) (Align Technology Inc., San Jose, CA, USA) and Trios(R) (3Shape Dental Systems, Copenhagen, Denmark) digital intraoral scanners, and to evaluate the effects of the severity of tooth irregularities and scanning sequence on precision. METHODS: Dental arch models were fabricated with differing degrees of tooth irregularity and divided into 2 groups based on scanning sequence. To assess their precision, images were superimposed and an optimized superimposition algorithm was employed to measure any 3D deviation. The t-test, paired t-test, and one-way ANOVA were performed (p < 0.05) for statistical analysis. RESULTS: The iTero(R) and Trios(R) systems showed no statistically significant difference in precision among models with differing degrees of tooth irregularity. However, there were statistically significant differences in the precision of the 2 scanners when the starting points of scanning were different. The iTero(R) scanner (mean deviation, 29.84 +/- 12.08 microm) proved to be less precise than the Trios(R) scanner (22.17 +/- 4.47 microm). CONCLUSIONS: The precision of 3D images differed according to the degree of tooth irregularity, scanning sequence, and scanner type. However, from a clinical standpoint, both scanners were highly accurate regardless of the degree of tooth irregularity.

Accuracy of Bolton analysis measured in laser scanned digital models compared with plaster models (gold standard) and cone-beam computer tomography images / 대한치과교정학회지

OBJECTIVE: The aim of this study was to compare the accuracy of Bolton analysis obtained from digital models scanned with the Ortho Insight three-dimensional (3D) laser scanner system to those obtained from cone-beam computed tomography (CBCT) images and traditional plaster models. METHODS: CBCT scans and plaster models were obtained from 50 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner; Bolton ratios were calculated with its software. CBCT scans were imported and analyzed using AVIZO software. Plaster models were measured with a digital caliper. Data were analyzed with descriptive statistics and the intraclass correlation coefficient (ICC). RESULTS: Anterior and overall Bolton ratios obtained by the three different modalities exhibited excellent agreement (> 0.970). The mean differences between the scanned digital models and physical models and between the CBCT images and scanned digital models for overall Bolton ratios were 0.41 +/- 0.305% and 0.45 +/- 0.456%, respectively; for anterior Bolton ratios, 0.59 +/- 0.520% and 1.01 +/- 0.780%, respectively. ICC results showed that intraexaminer error reliability was generally excellent (> 0.858 for all three diagnostic modalities), with < 1.45% discrepancy in the Bolton analysis. CONCLUSIONS: Laser scanned digital models are highly accurate compared to physical models and CBCT scans for assessing the spatial relationships of dental arches for orthodontic diagnosis.

Reference points suitable for evaluation of the additional arch length required for leveling the curve of Spee / 대한치과교정학회지

OBJECTIVE: The additional arch length required for leveling (AALL) the curve of Spee (COS) can be estimated by subtracting the two-dimensional (2D) arch circumference, which is the projection of the three-dimensional (3D) arch circumference onto the occlusal plane, from the 3D arch circumference, which represents the arch length after leveling the COS. The purpose of this study was to determine whether the cusp tips or proximal maximum convexities are more appropriate reference points for estimating the AALL. METHODS: Sixteen model setups of the mandibular arch with COS depths ranging from 0 mm to 4.7 mm were constructed using digital simulation. Arch circumferences in 2D and 3D were measured from the cusp tips and proximal maximum convexities and used to calculate the AALL. The values obtained using the two reference points were compared with the paired t-test. RESULTS: Although the 3D arch circumference should be constant regardless of the COS depth, it decreased by 3.8 mm in cusp tip measurements and by 0.4 mm in proximal maximum convexity measurements as the COS deepened to 4.7 mm. AALL values calculated using the cusp tips as reference points were significantly smaller than those calculated using the proximal maximum convexities (p = 0.002). CONCLUSIONS: The AALL is underestimated when the cusp tips are used as measurement reference points; the AALL can be measured more accurately using the proximal maximum convexities.

Avaliação da acurácia e confiabilidade de modelos digitais por escaneamento do modelo de gesso / Evaluation of the accuracy and reliability of digital models by scanning the plaster cast

Introdução: o objetivo deste estudo foi avaliar a acurácia e a confiabilidade de medições feitas em modelos digitais obtidos com um scanner a laser de superfície (R700; 3Shape, Copenhagen, Dinamarca). Material e métodos: foram selecionados 30 modelos ortodônticos de gesso de dentições permanentes. As medições foram realizadas por três examinadores com um paquímetro digital, diretamente sobre os modelos de gesso, e digitalmente, através do programa Ortho Analyser (3Shape, Copenhagen, Dinamarca), nos modelos digitais. Foram determinadas 62 medidas, incluindo diâmetro e altura dentária, overjet, overbite, distâncias intercanino e intermolar, e relação sagital bilateral. Utilizou-se o teste t pareado para avaliar o erro intraexaminador e a acurácia das medições nos modelos digitais. Avaliou-se a reprodutibilidade entre os examinadores por meio do coeficiente de correlação intraclasse e a confiabilidade pelo teste de Bland e Altman. Resultados: apesar de existirem diferenças estatisticamente significantes entre as medições realizadas entre os modelos de gesso e os digitais, as discrepâncias foram consideradas clinicamente não significantes. Tanto os modelos de gesso quanto os modelos digitais apresentaram altos valores no coeficiente de correlação intraclasse entre os examinadores. Conclusão: os modelos digitais por escaneamento do modelo de gesso, utilizando o scanner R700 e o programa Ortho Analyser, podem ser utilizados com acurácia clinicamente aceitável e uma excelente confiabilidade e reprodutibilidade. Os modelos digitais podem substituir os modelos de gesso com segurança.

Introduction: the aim of this study was to evaluate the accuracy and reliability of measurements made on digital models obtained with a laser scanner surface (R700; 3Shape, Copenhagen, Denmark). Material and methods: thirty orthodontic plaster models of permanent dentition were selected. The measurements were performed by three examiners with a digital caliper directly on the plaster casts and digitally, through Ortho Analyser software (3Shape, Copenhagen, Denmark), in digital models. It was determined sixty two measures, including diameter and tooth height, overjet, overbite, intercanino and intermolar distances and bilateral sagittal relationship. It was used paired t test to assess intra-examiner error and the accuracy of measurements in digital models. It was evaluated the reproducibility between examiners using the intraclass correlation coefficient and reliability by Bland and Altman test. Results: although there were significant differences between the plaster casts and the digital models measurements, the discrepancies were considered clinically insignificant. Plaster casts and digital models showed high values of intraclass correlation coefficient among examiners. Conclusion: digital models by scanning plaster cast using the R700 scanner and Ortho Analyser software can be used with clinically acceptable accuracy and excellent reliability and reproducibility. Digital models can replace the plaster models safely.

A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. METHODS: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. RESULTS: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. CONCLUSIONS: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. METHODS: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. RESULTS: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. CONCLUSIONS: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

Carrea` s method application to estimate stature in individuals using teeth measures in brazilian population

AIM: The purpose of the present study was to evaluate a methodology to estimate the stature in orthodontically treated individuals using odontometric data obtained from digitalized 3-dimensional image. MATERIAL AND METHODS: The sample consisted of 46 Brazilian people from the southern of the country, aged between 22 and 37 years and divided into two groups; group 1 (control) composed by 24 individuals with no orthodontic treatment and adequate alignment of the six anterior mandibular teeth and group 2 (experimental) composed by 22 individuals with crowding of the anterior mandibular teeth before the orthodontic treatment (Group 2A) and after orthodontic alignment (Group 2B). The odontometric data was obtained from their digitalized cast models. Mathematical formulas were used to obtain the stature range between the minimum and maximum estimated stature. RESULTS: The descriptive analysis of the percentage of people with real stature within the estimated stature range showed an average between the right and left hemiarchs of 44%, 75% and 52% for groups 1, 2A and 2B, respectively. CONCLUSION: It was concluded that this method can be used for the stature estimation in orthodontically treated patients but as an auxiliary tool together with other methodologies.

A utilização dos modelos digitais em ortodontia / The use of digital orthodontic models

O modelo digital pode se tornar em breve uma realidade na clínica ortodôntica, pois apresenta grandes vantagens e facilita o planejamento dos casos clínicos, com a possibilidade de inter-relação com outros arquivos digitais. Os trabalhos publicados na literatura demonstraram que os modelos digitais apresentam precisão e confiabilidade aceitáveis para serem aplicados como método de diagnóstico, além de auxiliar no planejamento ortodôntico. No entanto, este recurso ainda é pouco explorado no Brasil. Este trabalho objetiva apresentar o panorama atual da utilização dos modelos digitais em Ortodontia.

The digital model may soon become a reality in clinical orthodontics because it presents great advantages and facilitates treatment planning, with the possibility of interrelation with other digital files. The published papers have shown that digital models exhibit acceptable accuracy and reliability to be applied as a method to assist the diagnosis and orthodontic planning. However, this resource is still little explored in Brazil. This paper aims to present a current overview of the use of digital models in orthodontics.

Surgery-first approach using a three-dimensional virtual setup and surgical simulation for skeletal Class III correction / 대한치과교정학회지

A 19-year-old woman presented to our dental clinic with anterior crossbite and mandibular prognathism. She had a concave profile, long face, and Angle Class III molar relationship. She showed disharmony in the crowding of the maxillomandibular dentition and midline deviation. The diagnosis and treatment plan were established by a three-dimensional (3D) virtual setup and 3D surgical simulation, and a surgical wafer was produced using the stereolithography technique. No presurgical orthodontic treatment was performed. Using the surgery-first approach, Le Fort I maxillary osteotomy and mandibular bilateral intraoral vertical ramus osteotomy setback were carried out. Treatment was completed with postorthodontic treatment. Thus, symmetrical and balanced facial soft tissue and facial form as well as stabilized and well-balanced occlusion were achieved.

Evaluación de la confiabilidad del índice PAR en modelos de estudio físicos y digitales / Reliability assessment of PAR index plaster and digital study models

Introducción y objetivo: El índice PAR evalúa los resultados del tratamiento de ortodoncia en términos de mejora y la calidad técnica de la atención. Se puede utilizar para evaluar las normas de tratamiento de ortodoncia. Una buena oclusión tiene un récord nominal de menos de 5 puntos PAR. El objetivo de este estudio es evaluar la confiabilidad del índice PAR medido en los modelos dentales digitales y físicos para el diagnóstico de problemas oclusales. Materiales y métodos: Este estudio se realizó en 21 modelos de estudio correspondientes a individuos distribuidos equitativamente tanto del sexo femenino como masculino, con diferentes rangos de edades entre 6 y 17 años y en tres tipos de maloclusión (clase I, clase II y oclusiones ideales) escogidos al azar entre 480 modelos disponibles en el grupo de investigación del GIB. Para la medición digital a los modelos de estudio se les tomo un registro de mordida con cera para modelar; las mediciones manuales se realizaron con un calibrador digital y la regla correspondiente al índice PAR; se calibraron 2 investigadores en forma ciega en dos momentos diferentes para la realización de las mediciones. Resultados: Se encontró una excelente confiabilidad de las medidas del índice PAR entre los modelos físicos y los digitales con un coeficiente de correlación intra clase (CCI=0,99) y un intervalo de confianza de 95%. (0,98; 0,99) Conclusión: La medición del índice PAR es igualmente confiable cundo se mide en modelos de yeso que en modelos digitales.

Introduction and objective: The PAR index evaluates the results of orthodontic treatment in terms of improving the technical quality of care. It can be used to assess orthodontic treatment standards. A good occlusion has a nominal record of less than 5 PAR points. The aim of this study was to assess the reliability of the PAR index measured in physical and digital dental models for diagnosing occlusal problems. Materials and methods: This study was conducted in 21 study models of both female and male patients, with different age ranges between 6 and 17 years and three types of malocclusion (Class I, Class II and ideal occlusions) randomly selected from 480 models available in the IPF Research Group. In order to make digital measurements of study models bite registration with modeling wax were taken; manual measurements were made with a digital caliper and ruler for the PAR index; two researchers were blindly standardized at two different times in order to perform the measurements. Results: An excellent reliability of PAR index measurements was observed between physical and digital models with intraclass correlation coefficient (ICC = 0,99) and a confidence interval of 95%. (0,98; 0,99). Conclusions: PAR Index measurements are equally reliable when measured on plaster or digital models.

Comparison of mandibular arch forms of Korean and Vietnamese patients by using facial axis points on three-dimensional models / 대한치과교정학회지

OBJECTIVE: This study was aimed at comparing the mandibular arch forms of Korean and Vietnamese patients by using facial axis (FA) points on three-dimensional (3D) models. METHODS: Mandibular casts of 68 Korean (Class I malocclusion, 30; Class II malocclusion, 38) and 78 Vietnamese (Class I malocclusion, 41; Class II malocclusion, 37) patients were scanned in their occluded positions and grouped according to arch form (tapered, ovoid, and square). The FA point of each tooth was digitized on the 3D mandibular models. The measurements and frequency distributions of the arch forms were compared between the ethnic groups. RESULTS: The Vietnamese patients had significantly greater intercanine depth and intercanine and intermolar width-to-depth ratios than the Korean patients (p < 0.05). The frequency distributions of the arch forms were also significantly different (p = 0.038), but no sexual dimorphism was found. CONCLUSIONS: Vietnamese people tend to have deeper and wider arches than Korean people. The three arch forms are evenly distributed in Korean people, but Vietnamese people frequently have square arches. Clinicians should identify the correct arch form of an ethnic group before initiating orthodontic treatment.

Differences in molar relationships and occlusal contact areas evaluated from the buccal and lingual aspects using 3-dimensional digital models / 대한치과교정학회지

OBJECTIVE: The aims of this study were to use a 3-dimensional (3D) system to compare molar relationship assessments performed from the buccal and lingual aspects, and to measure differences in occlusal contact areas between Class II and Class I molar relationships. METHODS: Study casts (232 pairs from 232 subjects, yielding a total of 380 sides) were evaluated from both the buccal and lingual aspects, so that molar relationships could be classified according to the scheme devised by Liu and Melsen. Occlusal contact areas were quantified using 3D digital models, which were generated through surface scanning of the study casts. RESULTS: A cusp-to-central fossa relationship was observed from the lingual aspect in the majority of cases classified from the buccal aspect as Class I (89.6%) or mild Class II (86.7%). However, severe Class II cases had lingual cusp-to-mesial triangular fossa or marginal ridge relationships. Mean occlusal contact areas were similar in the Class I and mild Class II groups, while the severe Class II group had significantly lower values than either of the other 2 groups (p < 0.05). CONCLUSIONS: Buccal and lingual assessments of molar relationships were not always consistent. Occlusal contact areas were lowest for the Class II-severe group, which seems to have the worst molar relationships - especially as seen from the lingual aspect.