Three-dimensional evaluation of the root resorption of maxillary incisors after the orthodontic traction of bicortically impacted canines: case reports.

BACKGROUND: The root resorption of the maxillary incisors after the orthodontic traction of impacted canines is a concern for clinicians. The aim of this case series report was to evaluate the root resorption of the maxillary incisors after traction until the occlusal plane of the bicortically impacted canines (placed between the two cortical bones in the middle of the alveolar process) located in a complex position using three-dimensional superimposition. This case series report describes the root resorption of the maxillary incisors after orthodontic traction with NiTi closed coil springs and a heavy anchorage appliance in three cases of bilateral impacted canines located in a complex position (bicortically) near to midline. Cone-beam computed tomographies (CBCTs) were obtained before and after traction. Root resorption in all root surfaces of the maxillary incisors was evaluated with color-coded maps using the ITK-SNAP and the 3D Slicer software to indicate loss of the root surface (in red) or gain of the surface (in blue) and was quantified in millimeters by the superimposition method. RESULTS: The root changes mainly occurred in the apical third of the maxillary incisor root and did not exceed 2 mm. CONCLUSIONS: Root resorption of the maxillary incisors after the traction of bicortically impacted canines located in a complex position was observed mainly in the apex region, and the amount of root resorption was smaller than 2 mm in all root surfaces.

Maxillary transverse dimensions in subjects with and without impacted canines: A comparative cone-beam computed tomography study.

INTRODUCTION: The objective of this study was to compare the maxillary transverse dimensions between subjects with impacted maxillary canines and subjects without canine impactions, with similar vertical and sagittal features. METHODS: In this retrospective study, 86 cone-beam computed tomography images of subjects with impacted maxillary canines (45 unilateral, 41 bilateral) and 67 images of subjects without dental impactions (control group) matched by similar vertical (NSAr, SArGo, ArGoMe) and sagittal (ANB, SNA, APDI) skeletal characteristics, were analyzed. The maxillary width was measured at 4 levels: first molar basal width, first molar alveolar width, first premolar basal width, and first premolar alveolar width. Group comparisons were performed with analysis of variance and post-hoc Scheffé tests. The influence of group features on the transverse dimensions was evaluated by a multiple linear regression analysis. RESULTS: Groups with unilateral and bilateral impacted maxillary canines showed significantly smaller first molar basal widths, first molar alveolar widths, and first premolar alveolar widths compared with the control group (P = 0.030, P <0.001, and P <0.001, respectively). First premolar basal widths were not significantly different among the groups. CONCLUSIONS: Subjects with unilateral or bilateral impacted maxillary canines have smaller maxillary transverse dimensions than do subjects without impaction. Orthodontists should consider the relationship of maxillary width and canine impaction during diagnosis and treatment planning.

Three-dimensional characterization of root morphology for maxillary incisors.

The aim of this study was to test the reproducibility of three-dimensional (3D) surface models of maxillary incisors and to propose a characterization of root morphology. The sample was comprised of pre-treatment cone-beam computed tomography (CBCT) images of fifty-five patients. The CBCTs were used to construct 3D surface models of the maxillary incisors. The reproducibility of surface models was tested by repeated construction of them by two observers. A 3D surface model that corresponded to the average of all lateral and all central incisors was generated. 3D surface distances and vector differences were calculated for each individual tooth and the average of the teeth considered. The corresponding points on the 3D surface mesh for each subgroup were compared statistically to those of the neutral subgroup using shape analysis MANCOVA and Hotelling's t-statistic (p < 0.05). Repeated construction of surface models demonstrated adequate inter-rater reproducibility. The distribution of 3D models into root morphology subgroups was: blunt (11% and 26% of the central and lateral incisors, respectively), conical (15% of the central incisors), long (27% and 20% of the central and lateral incisors, respectively), and short (15% and 4% of the central and lateral incisors, respectively). Compared to the neutral average, statistically significant differences in root morphology were found for blunt, long, conical, and short central incisors and for blunt, long, and short lateral incisors. We can conclude that 3D surface models construction for upper incisors is reproducible. 3D shape analysis using CBCT images allows a phenotypic characterization of incisor root morphology.

Evaluación de los métodos de localización del punto pronasal para la reconstrucción facial forense / Evaluation of the pronasal point prediction methods for forensic facial reconstruction

La reconstrucción facial por escultura forense es un procedimiento que se utiliza en identificación Humana. Consiste en la colocación de un material modelable sobre el esqueleto óseo, respetando los grosores tisulares y la anatomía facial. Una de las principales dificultades de la técnica es la reproducción de estructuras de posición variable como los ojos, las orejas y la nariz. Se ha descrito que es posible reconstruir la nariz de manera confiable si se cuenta con el punto pronasal, es por esto que se han desarrollado diversas técnicas para la ubicación de este punto a partir de osamentas craneales. El propósito de este estudio es evaluar mediante radiografías laterales la exactitud de 4 métodos ampliamente utilizados para la ubicación del punto pronasal a partir de cráneos. Se utilizaron 34 radiografías tomadas en norma lateral con perfil blando visible, sobre los cuales se realizaron los trazados de perfil blando y duro (perfil de control). Se evaluaron los métodos de Gerásimov, krogman, Prokopec & Ubelaker y de George, determinándose las diferencias existentes en un eje de coordenadas (X, Y) con respecto al gold estándar (punto pronasal determinado en el perfil blando). Todos los métodos presentaron bajos niveles de exactitud, subestimando la proyección anterior de la nariz. De acuerdo a las medias el método de Prokopec & Ubelaker fue el más cercano al gold standard, con medias de 5,6 (DS 3,66) en X y 1,7 (DS 3,3) en Y, y mayores niveles de exactitud, los otros métodos evaluados fueron menos exactos y presentaron una alta dispersión. El uso de métodos de determinación del punto pronasal confiables y aplicables a nuestra población es fundamental para la correcta reconstrucción de la nariz.

Facial reconstruction for forensic sculpture is a procedure used in human identification. It consists of placing a mouldable material on the bone, respecting the soft tissue and facial anatomy. One of the main technical difficulties is the reproduction of structures of variable position as the eyes, ears and nose. It has been reported that the nose can be reconstructed reliably if you have pronasal point, that's why we have developed various techniques for the location of this point from the cranial bones. The purpose of this study is to evaluate by mean lateral cephalometric radiography the accuracy of four methods widely used for the location of the pronasal point from skulls. 34 lateral cephalometric radiography with soft-tissue facial profile taken under standardized conditions were used, on which tracings were made in hard and soft profile (control profile). Gerasimov, Krogman, Prokopec & Ubelaker and George methods were evaluated, determining the differences in a coordinate axis (X, Y) with respect to the gold standard (pronasal point given in the soft profile). All methods had low levels of accuracy, underestimating the anterior projection of the nose. According to the averages, the method of Prokopec & Ubelaker was the closest to the gold standard, with averages of 5.6 (SD 3.66) in X and 1.7 (SD 3.3) in Y, and higher levels of accuracy. The other methods tested were less accurate and had a high dispersion. The use of reliables and applicables methods for determining the pronasal point to our population are essential for the proper reconstruction of the nose.

Ponticulus posticus on the posterior arch of atlas, prevalence analysis in asymptomatic patients / Ponticulus posticus en el arco posterior del atlas, análisis de su prevalencia en pacientes asintomáticos

The Ponticulus posticus is a bony bridge located in the posterior arch of the atlas in relation to the passage of the vertebral artery. Its presence has been associated with development of cervical pain and cerebrovascular disorders. The purpose of this study was to assess its prevalence in asymptomatic patients. We examined 436 digital teleradiographs of patients aged from 5 to 70 years (mean of 18.44 years, SD. 9.59) of both sexes (173 men, 263 women). In 80.7 percent (n = 352) of cases, no radiographic evidence of ossification was found; 19.3 percent showed some degree of ossification, of which 10.1 percent had partial ossification and 9.2 percent complete ossification. The prevalence of complete ossification was slightly higher in women than in men and occurs in all the age groups analyzed. Our results suggest that the Ponticulus posticus is an anatomic condition with a protective function.

El Ponticulus posticus es un puente óseo ubicado en el arco posterior de atlas en relación al paso de la arteria vertebral. Su presencia se ha asociado al desarrollo de cervicalgias y trastornos vasculares encefálicos. El propósito de este estudio fue analizar su prevalencia en pacientes asintomáticos, para ello fueron examinadas 436 teleradiografías digitales de pacientes de entre 5 y 70 años (Media 18,44 años; DS 9,59), de ambos sexos (173 hombres; 263 mujeres). En el 80,7 por ciento (n=352) no se encontraron signos radiograficos de osificación, el 19,3 por ciento de los casos se pudo apreciar algún grado de osificación, de los cuales el 10,1 por ciento presento una osificación parcial y el 9,2 por ciento completa. La prevalencia de osificación completa fue levemente mayor en mujeres y se presentó en todos los grupos etáreos analizados. Nuestros resultados sugieren que el Ponticulus posticus es una condición anatómica destinada a proteger el paso de la arteria verebral y no debe considerarse una calcificación con significado patológico.