ABSTRACT
INTRODUCTION: The increasing use of three-dimensional (3D) imaging in orthodontics has led to the development of 3D superimposition techniques. These techniques use stable anatomic structures as references in order to compare Cone Beam CT (CBCT) scans of the same subject at different time-points. Three methods have been described in the literature: landmark-based, surface-based and voxel-based 3D superimpositions. OBJECTIVE: This article focuses on the voxel-based approach, which is the most described and the only one that can be fully automatized. The aim of this paper is to offer clinicians a practical tutorial on craniofacial voxel-based 3D superimposition. MATERIAL AND METHODS: We provide an updated overview of the available implementation methods, describing their methodology, validations, main steps, advantages and drawbacks. The historical open-source method is the most widespread for research purposes, but takes around three hours to achieve for an experienced operator. Several commercially-available software perform superimpositions in a few minutes. RESULTS: We used two of the available methods to conduct the superimposition process with three representative clinical cases in order to illustrate the different types of results that can be obtained. CONCLUSIONS: Commercially-available software provide user-friendly and fully automatized superimposition methods, allowing clinicians to perform it easily and helping to reduce human error in image analysis. Still, quantitative evaluation of the results remains the main challenge of this technique.
Subject(s)
Cone-Beam Computed Tomography/methods , Imaging, Three-Dimensional/methods , Orthodontics/methods , Adolescent , Algorithms , Anatomic Landmarks , Child , Humans , Image Processing, Computer-Assisted , Orthognathic Surgery , Skull/diagnostic imaging , Skull Base/anatomy & histology , Skull Base/diagnostic imaging , Software , Young AdultABSTRACT
Resumen Introducción: numerosos estúdios mencionan que las variaciones del crecimiento y orientation del ángulo de la base craneal pueden alterar la posición de ambos maxilares en relación con la base craneal. En este estudio se busca relacionar el ángulo de la base craneal con las clases esqueletales, en telerradiografías laterales de pacientes adultos que acudieron a la Clínica Odontológica del Instituto Latinoamericano de Estudios Superiores, de la ciudad de Asuncion, Paraguay, entre los anos 2010 y 2018. Materiales y métodos: estudio transversal retrospectivo. Para clasificar la clase esqueletal, se utilizo el ángulo ANB de Steiner, y para determinar el ángulo de la base craneal posterior, el NSBA de Varjanne y Koski. Luego, se aplico la prueba chi-cuadrado para relacionar el ángulo de la base craneal y las clases esqueletales, con un nivel de confianza del 95 %. Resultados: formaron parte del estudio 185 telerradiografías laterales de cráneo de pacientes que acudieron a la clínica. La media del ángulo NSBa fue 128.4 ° ± 5.17 °; la clase I fue de 128.27 ° ± 5.27 °; la clase II, de 129.1 ° ± 4.7 °; y la clase III, de 127.84 ° ± 5 °. El 65.95 % posee valores del ángulo NSBa fuera de la norma, de los cuales el 87.7 % presentan un ángulo cerrado. Conclusión: el promedio del ángulo de la base craneal estaba fuera de la norma en todas las clases esqueletales, siendo más frecuente la flexion craneal, en orden decreciente para las clases III, I y II.
Abstract Introduction: Many studies mention that variations in growth and orientation of the cranial base angle can alter the position of both jaws in relation to the cranial base. This study seeks to relate the cranial base angle according to skeletal classes in adult patients who attended the Dental Clinic of the Instituto Latinoamericano de Estudios Superiores in Asuncion city in Paraguay, between 2010 and 2018, using lateral cephalometric radiographs. Materials and methods: Retrospective cross-sectional study. Skeletal classes were classified using the ANB angle and the NSBa angle of Varjanne and Koski to determine the cranial base angle. Chi-square tests were applied to associate the cranial base angle according to skeletal classes, with a confidence level of 95 %. Results: In this study, 185 lateral cephalometric radiographs were included in the study of people who attended the clinic. The mean values of NSBa angle were 128.84° ±5.17° for all classes; 128.27° ± 5.27° for class I, 129.1° ± 4.7° for class II and 127.84° ± 5° for class III. The 65.95 % of participants had NSBa angle values out of the norm, from which 87.7 % reported a small cranial base angle. Conclusion: The average cranial base angle was found to be out of the norm in every skeletal class in decreasing order for classes III, I, and II, cranial flexure being more frequent than others.
Resumo Introdução: Numerosos estudos mencionam que as variações do crescimento e orientação do ângulo da base craniana podem alterar a posição de ambos os maxilares em relação com a base craniana. Este estudo busca relacionar o ângulo da base craniana com as classes esqueléticas, em telerradiografias laterais de pacientes adultos que acudiram à Clínica Odontologica do Instituto Latino-Americano de Estudos Superiores, da cidade de Asuncion, Paraguai, nos años 2010-2018. Materiais e métodos: estudo transversal retrospectivo. Para classificar a classe esquelética utilizou-se o ângulo ANB de Steiner e para determinar o ângulo da base craniana posterior o NSBa de Varjanne e Koski. Se aplicou a prova Qhi quadrado para relacionar o ângulo da base craniana e as classes esqueléticas, com um nível de confiança do 95 %. Resultados: Formaram parte do estudo 185 telerradiografias laterais de crâneo de pacientes que acudiram à clínica. A média do ângulo NSBa foi 128.4° ± 5.17°; a classe I foi de 128.27° ± 5.27°, a classe II 129.1° ± 4.7° e classe III 127.84° ± 5°. O 65.95 % possui valores do ângulo NSBa fora da norma, dos quais o 87.7 % apresentam um ângulo fechado. Conclusão: A média do ângulo da base craniana estava fora da norma em todas as classes esqueléticas, sendo mais frequente a flexão craniana, em ordem decrescente para as classes III, I e II.
