Sex estimation from the hyoid bone measurements in an adult Eastern Turkish population using 3D CT images, discriminant function analysis, support vector machines, and artificial neural networks☆.

The hyoid bone is one of the bones in the human body that shows sexual dimorphism. The anthropological and anthropometric characteristics that determine sexual dimorphism are influenced by demographic differences. The aim of this study was to investigate the rate of sexual dimorphism of the hyoid bone in the adult Eastern Turkish population from the examination of the 3D computed tomography images of 240 patients, using discriminant function analysis (DFA), support vector machines (SVM), and artificial neural networks (ANN). These evaluations were based on eight hyoid measurements that have been frequently used in previous CT studies. The results showed that all eight measurements were higher in males than in females (p = 0.000). It was determined that sex could be estimated accurately at up to 93.3 % using DFA, 93.8 % using SVM and 95.4 % using ANN. The maximum accuracy rate achieved to 94.2 % in males using SVM, and 95.8 % in females using ANN. These high rates of sexual dimorphism found using DFA, SVM, and ANN in this study indicate that characteristics of the hyoid bone can be utilized to determine sex in the Eastern Turkish population.

Evaluation of the influence of hyoid bone position, volume, and types on pharyngeal airway volume and cephalometric measurements.

OBJECTIVES: We aimed to explore the position, morphological, and morphometric properties of the hyoid bone (HB) and to investigate the effect of HB on the pharyngeal airway (PA) volume and cephalometric measurements. METHODS: A total of 305 patients with CT images were included in the study. DICOM images were transferred to the InVivoDental three-dimensional imaging software. The position of the HB was determined based on the cervical vertebra level and in volume render tab, the bone was classified into six types after all structures around the HB were removed. Also, final bone volume was recorded. In the same tab, the pharyngeal airway volume was divided and measured in three groups (nasopharynx-oropharynx-hypopharynx). The linear and angular measurements were performed on the 3D cephalometric analysis tab. RESULTS: HB was most commonly located in C3 vertebra level (80.3%). While B-type was found to be the most frequent (34%), V-type was the least frequent (8%). The volume of the HB was found to be significantly higher in male (3205 mm3) than female (2606 mm3) patients. Also, it was significantly higher in the C4 vertebra group. The vertical height of the face was positively correlated with the HB volume, C4 level position, and increased oro-nasopharyngeal airway volume. CONCLUSION: The volume of the HB is found to differ significantly between genders and can potentially serve as a valuable diagnostic tool for understanding respiratory disorders. Its morphometric features are associated with increased face height and airway volume; however, are not related with the skeletal malocclusion classes.

Radiological morphometric study of the hyoid bone using three-dimensional computed tomography (3D-CT) scans / Estudio morfométrico radiológico del hueso hioides mediante tomografía computarizada tridimensional (3D-CT)

SUMMARY: Hyoid bone measurements have been proposed to vary between different genders and age groups. The aim of the study is to study hyoid morphometrics among Jordanian patients. 3D-CT scans of 637 patients were analyzed. Ten parameters of hyoid bone were measures, including the anteroposterior length, length of greater horns (right and left), height of greater horns (right and left), width of hyoid body, height of hyoid body, the distance between the midpoints of the posterior ends of the greater horns of the hyoid bone, the angle between right and left greater horns, and the distance of the hyoid bone to the vertebral column. Also, vertebral level, fusion rank, morphology of hyoid body lingula, and shape of hyoid bone were documented. All hyoid dimensions were longer in males, but greater horns angle was wider in females. In patients younger than 30 years, the parameters are the smallest with the widest angle. The distance from hyoid to vertebral column is higher in males (30-49) years of age. No fusion between hyoid body and greater horns was observed in patients younger than 10 years, but fusion (unilateral or bilateral) was found in only 73.2 % of patients ≥ 70 years. The hyoid was mostly at vertebra C3 level and "U" shaped. The lingula shape was mostly "Scar" in males (especially ≥ 50 years) and "Nothing" in females (especially < 50 years). The maximum growth of hyoid dimensions is before age of 30 years. Fusion between hyoid body and greater horns was not seen in patients younger than 10 years. Otherwise, the hyoid features failed to predict age or gender in our sample. Furthermore, 3D-CT scan is an excellent tool to assess the anatomy of head and neck region.

Se ha propuesto que las medidas del hueso hioides varían entre los diferentes sexos y grupos de edad. El objetivo del estudio fur estudiar la morfometría del hueso hioides en pacientes jordanos. Se analizaron tomografías computarizadas en 3D de 637 pacientes. Se midieron diez parámetros del hueso hioides, incluyendo la longitud anteroposterior, la longitud de los cuernos mayores (derecho e izquierdo), la altura de los cuernos mayores (derecho e izquierdo), el ancho del cuerpo hioides, la altura del cuerpo hioides, la distancia entre los puntos medios de los extremos posteriores de los cuernos mayores del hueso hioides, el ángulo entre los cuernos mayores derecho e izquierdo, y la distancia del hueso hioides a la columna vertebral. Además, se documentaron el nivel vertebral, el rango de fusión, la morfología de la língula del cuerpo hioides y la forma del hueso hioides. Todas las dimensiones del hioides fueron más largas en los hombres, pero el mayor ángulo de los cuernos fue más ancho en las mujeres. En pacientes menores de 30 años, los parámetros son los más pequeños con el ángulo más amplio. La distancia del hioides a la columna vertebral es mayor en el sexo masculino (30-49) años. No se observó fusión entre el cuerpo hioides y los cuernos mayores en pacientes menores de 10 años, pero se encontró fusión (unilateral o bilateral) en solo el 73,2 % de los pacientes ≥ 70 años. El hioides estaba mayormente al nivel de la vértebra C3 y en forma de "U". La forma de la língula era mayoritariamente "Cicatriz" en los hombres (especialmente ≥ 50 años) y "Nada" en las mujeres (especialmente < 50 años). El máximo crecimiento de las dimensiones del hioides es antes de los 30 años. La fusión entre el cuerpo hioides y los cuernos mayores no se observó en pacientes menores de 10 años. No obstante, las características del hueso hioides no pudieron predecir la edad o el sexo en nuestra muestra. Además, la tomografía computarizada 3D es una herramienta excelente para evaluar la anatomía de la región de la cabeza y el cuello.

More than two - A cadaveric study on the morphometry and classification of the digastric muscle in a selected kenyan population.

BACKGROUND: This study aims to elucidate anatomical variations of the digastric muscle in the Kenyan population. METHODS: A total of 41 bilateral neck dissections were performed whereby morphologic observations and morphometric measurements were carried out to characterize and classify the various presentations of the muscle. RESULTS: All cadavers presented with bilateral anterior (ABDM) and posterior (PBDM) bellies of the digastric muscle. Accessory ABDM was observed in 68.3% of cadavers with De-Ary-Pires et al.'s Type II (one accessory belly; 48.8%) and Type III (two accessory bellies; 34.1%) being the most common variations. Unilateral accessory ABDM (43.9%) was more common than bilateral accessory ABDM (24.4%). Two cadavers presented with a mentohyoid muscle. In addition, variations that have not been previously reported, namely fusion of ABDM to the midline and insertion of accessory ABDM into the hyoid bone were observed in one case each. Variation of the PBDM was less prominent, observed at 12.2% of sides dissected. Duplication of PBDM was observed on 4 sides with origin at the mastoid process. The PBDM was longer than the ABDM, but narrower in width. The mean length and width of the ABDM were 4.29±0.72cm and 1.52±1.07cm. The mean length and width of the PBDM were 5.64±1.31cm and 1.07±0.28cm, with the right side being statistically larger than the contralateral side. CONCLUSION: Variations of the digastric muscle are a common finding, with a high incidence at the ABDM. Two new variants were discovered.

Surgical landmarks for identification and preservation of the internal branch of the superior laryngeal nerve.

OBJECTIVE: To determine the topographical anatomic features of the internal branch of the superior laryngeal nerve (ibSLN) at the thyrohyoid membrane entrance area in relation to certain consistent anatomical structures. MATERIALS: METHODS: Twenty-two fresh adult head cadavers (9 male, 13 female; age range 52-95 years) with no signs of abnormality in the neck were dissected to determine the anatomic relationship of ibSLN and superior border of thyroid cartilage, thyroid notch, carotid bifurcation, hyoid corpus, and hyoid greater cornu. RESULTS: The topographical relationship between ibSLN and superior border of thyroid cartilage, thyroid notch, carotid bifurcation, hyoid corpus, and hyoid greater cornu was identified bilaterally in all cadavers. According to the measures, danger zone and safe zone areas for surgical could be predicted and for surgical manipulations as well. CONCLUSION: We provided the surgical anatomy and important landmarks for determining the internal branch of superior laryngeal nerve in the thyrohyoid membrane entrance region to avoid surgical damage during surgeries of this region.

[Study on the thickness and morphology of lingual bone of impacted mandibular third molar based on CBCT and Simplant 3D reconstruction].

PURPOSE: The potential relationship between impacted mandibular third molar and lingual bone thickness was investigated by quantitative measurement of lingual bone thickness, and a three-dimensional visualization model of lingual bone was established. METHODS: Image data of 200 cases of mandibular impacted third molar were collected from the database of Hefei Stomatological Hospital. Thickness measurement and three-dimensional reconstruction of lingual bone at different measurement sites were performed by Simplant Pro software. Statistical analysis was performed using SPSS 22.0 software package, and the comparison of lingual thickness at different measurement sites was performed using rank sum test. Whether the thickness of bone plate was "high-risk type" was taken as the result variable, different related factors were analyzed by logistic regression. RESULTS: The lingual bone at the middle point of the root of the third molar was the thinnest. Multiple teeth, mesio-inclined and dial-inclined teeth, and Class Ⅱ and Ⅲ impacted teeth had thin lingual bone(P＜0.05). The mesial and distal inclines were observed, and the lingual bone was thin in the root apical region of the teeth in Class Ⅱ and Class Ⅲ(P＜0.05). In the lower impacted teeth, the thin lingual bone at the central crown site was more likely to be found in Class Ⅲ teeth(P＜0.05). CONCLUSIONS: The thickness of lingual bone was related to the number of impacted tooth roots, tilt direction and impacted type. In the extraction of impacted teeth, the above factors should be considered, and the injury of lingual nerve, lingual bone and surrounding soft tissue should be vigilant.

The Hyoid Bone - the Anatomy of a Small Bone of the Neck in Hellenic and Greco-Roman Medical Literature.

OBJECTIVES: To understand the nomenclature of the hyoid bone. MATERIALS AND METHODS: Hyoid, a small bone of the neck, is a bony part that is rather difficult to unearth and discover among skeletal remains. RESULTS: The named was coined by the ancient Greeks, along with its anatomic description. Galen (2nd - 3rd c. AD) and Theophilus Protospatharius (7th century AD), facing religious and social barriers, succeeded in presenting its anatomy and suggesting its probable function in speech and swallowing, regarding the bone as a muscle pillar of the neck area. CONCLUSION: Authorities of Hellenic antiquity surprise us with their accuracy and the resilience of their anatomical descriptions.

Effect of premolar extraction on upper airway volume and hyoid position in hyperdivergent adults with different mandibular length.

INTRODUCTION: The objective of this study was to investigate the morphological changes of the upper airway and the position of the hyoid bone in hyperdivergent adults with different mandibular lengths after premolar extraction. MATERIALS: The data of 57 hyperdivergent adults, aged 20-35 years, who had 4 premolar extractions were included for the study. Mandibular length (CoGn) was used for grouping (A: long CoGn, B: short CoGn). Pretreatment and posttreatment lateral cephalograms and cone-beam computed tomography images were used to assess the position of mandible, hyoid bone, and upper airway using paired t test. An independent sample t test was used to detect changes of the airway and hyoid position between groups A and B. Pearson correlation analysis was applied to estimate the correlation between pharyngeal spaces and dentoskeletal morphology at P <0.05. RESULTS: In all subjects, we observed retraction of the upper incisors, mesial movement of the lower molars, and reduction of the mandibular planes. In group A, differences were found in anterior and posterior movements of the hyoid bone, increase of airway volume, minimum cross-sectional area (MCA) and anteroposterior linear distance (APL) (P <0.05). There were notable differences in the change of hyoid position, airway volume, MCA, and APL between group A and group B. Glossopharyngeal and hypopharyngeal volumes, MCA, and APL were correlated with articular angle, mandibular plane, and hyoid bone position (P <0.05). CONCLUSIONS: With a comprehensive diagnosis and treatment, premolar extraction in hyperdivergent adults with favorable CoGn can facilitate improvement of esthetics, hyoid bone position, and the increase in glossopharyngeal and hypopharyngeal volumes and MCA.

Morphological disparity and evolutionary transformations in the primate hyoid apparatus.

The hyoid apparatus plays an integral role in swallowing, respiration, and vocalization in mammals. Most placental mammals have a rod-shaped basihyal connected to the basicranium via both soft tissues and a mobile bony chain-the anterior cornu-whereas anthropoid primates have broad, shield-like or even cup-shaped basihyals suspended from the basicranium by soft tissues only. How the unique anthropoid hyoid morphology evolved is unknown, and hyoid morphology of nonanthropoid primates is poorly documented. Here we use phylogenetic comparative methods and linear morphometrics to address knowledge gaps in hyoid evolution among primates and their euarchontan outgroups. We find that dermopterans have variable reduction of cornu elements. Cynocephalus volans are sexually dimorphic in hyoid morphology. Tupaia and all lemuroids except Daubentonia have a fully ossified anterior cornu connecting a rod-shaped basihyal to the basicranium; this is the ancestral mammalian pattern that is also characteristic of the last common ancestor of Primates. Haplorhines exhibit a reduced anterior cornu, and anthropoids underwent further increase in basihyal aspect ratio values and in relative basihyal volume. Convergent with haplorhines, lorisoid strepsirrhines independently evolved a broad basihyal and reduced anterior cornua. While a reduced anterior cornu is hypothesized to facilitate vocal tract lengthening and lower formant frequencies in some mammals, our results suggest vocalization adaptations alone are unlikely to drive the iterative reduction of anterior cornua within Primates. Our new data on euarchontan hyoid evolution provide an anatomical basis for further exploring the form-function relationships of the hyoid across different behaviors, including vocalization, chewing, and swallowing.

The use of hyoid bone dimensions in age and sex estimation in a Turkish population: a cone-beam computed tomography study.

BACKGROUND: The aim of the study was to determine sex and age from hyoid bone morphology on cone-beam computed tomography (CBCT). MATERIALS AND METHODS: The study sample comprised 130 CBCT images. Eight different measurements were performed for each hyoid bone. Fusion conditions were assigned to each side of the hyoid bone separately as; unfused, partially fused, and totally fused. RESULTS: The hyoid length, width of the left proximal end and stature variables showed sexual dimorphism in all hyoid fusion types (p < 0.05). In young adult age group, a significant difference was found between sex and fusion types (p = 0.025). The body length (81.35%) and stature measurements (76.25%) contributed most significantly to sex estimation. CONCLUSIONS: Patient's CBCT scans which enable reproducible and reliable measurements for bone tissues can be used for forensic procedures. Hyoid bone measurements with CBCT are useful methodology for age and sex estimation in forensic sciences with high predictive accuracy.

Age-related changes in the hyoid bone: An autopsy-based radiological analysis.

Forensic age estimation is a crucial aspect of the biological profile of unidentified cadavers. The utility of age-related changes of hyoid bone fusion in forensic age estimation has not been explored much in the past. These age-related changes can be visualised in both the living and the dead using conventional radiography. These changes can assist medico-legal professionals and forensic anthropologists in the identification of unknown deceased, especially when the cadaver is mutilated or charred or when the other well-established indicators of skeletal and dental maturity are absent. The aims of this study were to evaluate age-related changes in the hyoid bone and to ascertain whether these changes may be utilised for age estimation in forensic examinations. The hyoid bone was carefully dissected using a standard procedure from 75 cadavers during post-mortem examination. The hyoid bone was radiographed, and the bone was replaced in the body cavity before the post-mortem examination was completed. Hyoid bone fusion was studied by using a standard grading method. Spearman's correlation coefficient was calculated between the fusion scores and chronological age to assess their relationship. Box and whisker plots of fusion stage-wise age distribution were constructed to demonstrate the gradual linear relationship between hyoid bone fusion and the chronological age of the study participants. The present study concludes that hyoid bone fusion is an indicator of the chronological age of an individual and can be used in conjunction with other methods of age estimation such as the skeletal and dental age.

Cranial anatomy of the Galápagos marine iguana Amblyrhynchus cristatus (Squamata: Iguanidae).

Amblyrhynchus cristatus, the marine iguana, is unique among the ~7,000 species of living limbed lizards as it has successfully evolved adaptations that allow it to live in both terrestrial and marine environments. This species is endemic to the Galápagos Archipelago and has evolved a specialized feeding behavior, consuming primarily the algae that grow on the rocky seafloor. The intriguing questions arising around the evolution of the marine iguana concerns the use of exaptations of terrestrial features for aquatic and specifically marine adaptations. However, the lack of fundamental information about its anatomy currently prevents us from understanding how it became adapted to such a peculiar lifestyle in comparison to all other iguanids. The goal of this study is to provide the first ever description of the skull, mandible, and hyoid of Amblyrhynchus. We examined several specimens of marine iguana, including skeletal, wet, and ct-scanned material, and individuals at different ontogenetic stages. We also analyzed specimens of all other modern iguanid genera (Conolophus, Iguana, Ctenosaura, Cyclura, Dipsosaurus, Brachylophus, Sauromalus) in order to make comparisons between Amblyrhynchus and its closest relatives. We were able to identify several autapomorphic features that distinguish the marine iguana from all other iguanids. These unique morphologies are mostly associated with the modified configuration of the snout (nasal chamber), increased muscle attachments in the temporal-postorbital region of the skull, and dentition. Since Amblyrhynchus is the only nonophidian squamate currently able to exploit the ocean at least for some vital functions (i.e., feeding), we used comparisons to fossil marine lizards (e.g., mosasaurids) to discuss some of these unique traits. The new cranial features described for Amblyrhynchus may represent a source of novel morphological characters for use in future phylogenetic analyses of iguanian (or squamate) relationships, which will then serve as the foundation for the exploration of evolutionary patterns and processes that led to the development of such unique adaptations.

Cambios en la vía aérea después de cirugía ortognática bimaxilar / Airway change after bimaxillary orthognathic surgery

RESUMEN: La cirugía ortognática se realiza en sujetos con algún tipo de alteración esqueletal. Los movimientos maxilo mandibulares tienen impacto en la vía aérea (VA) y este aspecto se debe incorporar en la planificación quirúrgica. El objetivo de esta investigación fue determinar los cambios generados en la VA después de realizada la cirugía ortognática. Se realizó un estudio piloto incluyendo 51 sujetos con deformidad facial de clase II y clase III; se incluyeron en base al estudio del ángulo ANB y el tipo de oclusión dentaria. Se realizaron estudios con tomografía de haz cónico identificando el volumen máximo en la vía área y las áreas mínimas y máximas; además se incluyó la posición del hueso hioide y la inclinación del plano mandibular para relacionar con la morfología de la VA; para definir significancia estadística se estableció un valor de p<0,05 incluyendo las pruebas T de student y T test. Los resultados indicaron que los sujetos clase II aumentaron significativamente el volumen y áreas máximas y mínimas de la VA; los sujetos de clase III esqueletal no presentaron diferencias significativas entre la etapa pre y post quirúrgica; el hueso hioides se presentó significativamente más anterior en ambos en casos de clase II y clase III. Es posible concluir que la VA mejora sustancialmente en sujetos con clase esqueletal facial tipo II y que se mantiene sin cambios en sujetos con clase facial tipo III.

SUMMARY: Orthognathic surgery is performed in subjects with some type of skeletal alteration. Maxillomandibular movements have an impact on the airway (AW) and this aspect must be included into surgical planning. The aim of this research is to determine the changes in the AW after orthognathic surgery. A pilot study was conducted including 51 subjects with class II and class III facial deformity; they were included using the ANB angle and the type of dental occlusion. Cone beam computed tomography were performed showing the maximum volume in the airway and the minimum and maximum areas; in addition, the position of the hyoid bone and the angle of the mandibular plane were included to relate it to the morphology of the AW; to define statistical significance, a value of p<0.05 was established, including the student's t-test and the t-test. The results showed that class II subjects significantly increased the volume and maximum and minimum areas of the AW; skeletal class III subjects did not presented significant differences between the pre- and post-surgical stage; the hyoid bone was in an anterior position in both class II and class III cases. It is possible to conclude that AW improves substantially in subjects with facial class II and remains unchanged in subjects with facial class III.

Correlation between the upper airway volume and the hyoid bone position, palatal depth, nasal septum deviation, and concha bullosa in different types of malocclusion: A retrospective cone-beam computed tomography study.

BACKGROUND: The upper airway volume is among the factors that affect orthodontic treatment plans. Cone-beam computed tomography (CBCT), as an accurate diagnostic modality, can help assess anatomical structures associated with the upper airway volume. OBJECTIVES: This study aimed to use CBCT to determine if there are differences in the upper airway volume between different sagittal and vertical skeletal patterns, considering the hyoid bone position, palatal depth, nasal septum deviation (NSD), and concha bullosa. MATERIAL AND METHODS: From among 105 initial CBCT samples retrieved from the archive of a private radiology clinic in Tehran, Iran, 90 CBCT scans of 27 males and 63 females aged 17-65 years were considered in the study according to the inclusion criteria. The upper airway volume was assessed with regard to Angle's classification (using the A point-nasion-B point angle (ANB)), the vertical skeletal dimension (using the sella-nasion plane to mandibular plane angle (SN-MP)), the hyoid bone position, palatal depth, NSD, and concha bullosa, using CBCT and the NNT ® software. The one-way analysis of variance (ANOVA), Levene's test and the t test were used to analyze the data with the SPSS Statistics for Windows software, v. 17.0. RESULTS: The upper airway volume was significantly smaller in long-face cases (p = 0.037). There was no significant correlation between the upper airway volume and Angle's classification, the hyoid bone position, palatal depth, NSD, and concha bullosa. CONCLUSIONS: The vertical skeletal dimension was the only parameter that was related to the upper airway volume. The results of this study can be considered while preparing orthodontic treatment plans.

Prognosis of sexual dimorphism with unfused hyoid bone: Artificial intelligence informed decision making with discriminant analysis.

Depending on the metric and non-metric skeletal features of various bones, forensic experts proposed diverse sex identification methods. The main focus of the present study is to calculate sexual dimorphism in human unfused or disarticulated hyoid bone and compared it with studies conducted by different researchers. For this study, 293 unfused hyoid bones were accumulated and investigated from 173 male and 120 female cadavers of the northwest Indian population from the age of 15 to 80 years. Initially, discriminant analysis was performed on the dataset to predict sex and to get an idea for the crucial variables for sexual dimorphism. Later, significant variables predicted by the discriminant analysis were used for machine learning approaches to improve accuracy for sex determination. The standard scaler method is used for pre-processing of the data before machine learning analysis and to prevent overfitting and underfitting, 70 % of the whole dataset was utilized in the training of the model and the remaining data were used for testing the model. According to the discriminant analysis, body length (BL) and body height (BH) were found to be highly significant for the sex determination and predicted sex with 75.1 % accuracy. However, implementation of machine learning approaches such as the XG Boost classifier increased the accuracy to 83 % with sensitivity, and specificity scores of 0.81 and 0.84, respectively. Moreover, the ROC-AUC score achieved by the XG Boost classifier is 0.89; indicating machine learning investigation can improve the sex determination accuracy up to the appropriate standard.

Morfología ósea facial en cirugía ortognática. ¿existe tendencia hacia el avance facial? / Facial morphology in orthognathic surgery: is there a facial advance trend?

RESUMEN: El objetivo de esta investigación fue determinar los movimientos preferidos en maxila y mandíbula para obtener normalidad en morfología facial utilizando técnicas de superimposición en análisis 3D. Se realizó un estudio descriptivo para evaluar el desplazamiento óseo bimaxilar y del hueso hioides en sujetos clase facial tipo II y clase facial tipo III sometidos a cirugía ortognática. Para la superimposición se utilizó como puntos fijos Nasion - Silla - Porion y la sutura cigomática-maxilar. Estos puntos se superpusieron en CBCT pre quirúrgico y postquirúrgico y se evaluó el desplazamiento de la espina nasal anterior, Punto A, Punto B, mentón y del hueso hioides. Para la evaluación y comparación de las variables continuas antes y después de la cirugía ortognática se utilizó la prueba T de Student. Para la correlación entre las variables, se utilizó el Test de Spearman considerando un valor p<0,05 como diferencia significativa. 44 sujetos de entre 18 y 40 años de ambos sexos, fueron incluidos en esta investigación. En el 90 % de los sujetos se realizó un movimiento sagital de avance de la maxila. El movimiento sagital de avance mandibular se realizó en el 100 % de los sujetos con clase facial tipo II, mientras que el 100 % de los sujetos con clase facial tipo III se realizó se le retroceso mandibular. El hueso hioides presentó un avance en 26 de los 27 sujetos con clase facial tipo III. Es posible concluir que existe una tendencia al avance maxilar independiente de la deformidad facial.

ABSTRACT: The objective of this research was to determine the preferred movements in the maxilla and mandible to obtain normality in facial morphology using superimposition techniques in 3D analysis. A descriptive study was carried out to evaluate bimaxillary bone displacement and hyoid bone in subjects facial class II and facial class III undergoing orthognathic surgery. were used as fixed points for superimposition: Nasion (N) - Silla (S) - Porion (Po) and the zygomatic-maxillary suture (Z). These points were superimposed in pre-surgical and post- surgical CBCT and was evaluated to displacement of the anterior nasal spine, Point A, Point B, Chin and the hyoid bone. For the evaluation and comparison of continuous variables before and after orthognathic surgery, was used the Student's t test. For the correlation between the variables, the Spearman test is used, considering a p value <0.05 as a significant difference. 44 subjects between 18 and 40 years old of both sexes were included in this research. A 90% of subjects a was performed a maxillay sagittal movement. The sagittal movement of mandibular advancement was performed in 100% with facial class type II, while 100 % of the subjects with with facial class type III had a mandibular recession. The hyoid bone advanced in 26 of the 27 subjects with facial class type II. It is possible to conclude that there is a tendency for maxillary advancement, independent of facial deformity.

The carotid axis revisited.

The aim was to determine the variations in the level of origin of carotid bifurcation and diameters of the common, internal, and external carotid arteries which is clinically important for several interventional procedures. Therefore, 165 human embalmed corpses were dissected. The data collected were analyzed using the Chi square-test and the Pearson correlation test. The results of previous studies have been reviewed. In relation to the level of the carotid bifurcation, taking as a reference point the hyoid bone, the values ranged from 4 cm below the hyoid body to 2.5 cm above the body of the hyoid, being the average height-0.33 cm, with a standard deviation of 1.19 cm. The right carotid bifurcation was established at a higher level (x = - 0.19 cm.) than the left one (x = - 0.48 cm.) (p = 0.046). On the contrary, no significant gender differences could be observed. The arterial calibres of the common and internal carotid arteries were higher in male than female. In the internal carotid artery (X = 0.76 cm.), the left was greater than the right (X = 0.72 cm.) (P = 0.047). However, no differences in the distribution of the calibre of the external carotid artery were found neither by side nor gender. Variations in the level of bifurcation and calibres of carotid arteries are relevant for interventional radiology procedures and head and neck surgeries. Knowledge of these anatomical references might help clinicians in the interpretation of the carotid system.