Guided versus non-guided chin repositioning: a retrospective study on accuracy.

Genioplasty is a widely used surgical approach to address chin deformities by performing an osteotomy on the inferior border of the mandible to allow for comprehensive repositioning of the chin. This study aimed to compare the accuracy of freehand chin repositioning with a guided technique that employed specialised surgical guides. For this retrospective study, data from 30 adult patients who underwent orthognathic surgery to correct dentofacial deformities were analysed. All patients underwent virtual planning before surgery, with half of them treated using freehand chin repositioning and the other half using the guided technique. The surgical outcomes were measured and compared with the virtual plan to assess the positional and rotational accuracy of the techniques. In terms of translational assessment, noteworthy values that exceeded clinically acceptable limits were observed only in sagittal movement in the freehand group (0.97 mm, interquartile range (IQR) 0.73-2.29 mm). Regarding rotational accuracy, both groups exhibited an IQR that surpassed acceptable limits for pitch (3.26°, IQR 2.06-5.20 for the guided group and 2.57°, IQR 1.63-4.24° for the freehand group). The Mann-Whitney test indicated no statistical differences between the groups in any translational or rotational assessment. In conclusion, although there was no statistical difference, the guided technique proved effective in achieving clinically acceptable accuracy in all positions and almost all rotations, displaying superior results in sagittal positioning compared with the freehand technique. To fully harness the advantages of guides and to guarantee accuracy in all rotations, we recommend further research involving guides made of more rigid materials, and customised implants.

F-Chin/Feminizing the Chin: A Genioplasty Technique with Virtual Planning for Male-to-Female Transgender Patients.

The chin is an essential structure in facial harmony and an important gender marker. Advancing a receding chin is fundamental to improve the facial appearance, particularly in male-to-female transgender patients. However, in patients with microgenia and/or retrognathia, desiring a more feminine appearance, a chin advancement can result in a wider, square shape; an undesirable effect. Genioplasty is a versatile procedure used in facial feminization surgery that allows modifying the natural anatomy of the chin in all three spatial dimensions. The technique herein described proposes a simple genioplasty procedure for feminizing the chin (F-chin genioplasty) in transgender patients where anteroposterior advance is required. Virtual planning was used to establish the landmarks for an anteroposterior advancement with transverse reduction in the chin. A perpendicular line to the Frankfurt plane passing through the incisal edge of the upper central incisor was used to plan the anteroposterior movement, and two vertical lines on the outer wall of the nasal cavity  for the chin transverse measurement. The authors present three case reports with the F-chin genioplasty transgender technique with satisfactory results, ensuring a more feminine facial appearance.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Analysis of Sexual Dimorphic Features of the Jawline and Chin in White Celebrity Faces.

BACKGROUND: The jawline greatly influences facial shape and contributes to facial dimorphism. Analysis of lower facial shape and sexual dimorphic differences in contemporary attractive white faces can advance the goals of lower facial aesthetics and facial gender-affirming surgery (FGAS). METHODS: Full-face, front-view photos of 47 white female and 21 white male celebrities were included from a list generated using GQ magazine's Highest Paid Models issue, People Magazine's Beautiful issue (1991-2022), and celebrities featured on lifestyle websites. Facial landmarks were detected through a facial analysis program using Vision framework and MATLAB. After converting pixel distances to absolute distances, lower face measurements were compared between males and females. RESULTS: The mean lower facial height was 6.08 cm in females and 7.00 cm in males ( P value<0.001). The mean bigonial width was 11.21 cm in females and 12.30 cm in males ( P value<0.001). The ratio of facial height to lower facial height was 2.98 in females and 2.76 in males ( P value<0.001), signifying that symmetry in facial thirds is more prevalent in attractive female faces, while a longer lower face is more common in attractive male faces. The greatest differences in female and male facial contours were at gonial angles and chin. CONCLUSIONS: Analysis of contemporary white celebrity faces demonstrated significantly wider and longer lower facial measurements in males. The overall contour of the female lower face was more tapered at the gonial angles and chin compared to males. These results are important when planning lower facial rejuvenation or FGAS, as lower face size and proportions influence perceived gender and attractiveness.

Facial Analysis for Gender Affirmation/Gender-Related Facial Analysis.

There are anthropometric differences between the bony and integumentary facial features of male and female individuals. When compared to males, female faces in general are more heart-shaped, with a shorter and smoother forehead, a smaller more defined nose, and a tapered chin.

Clinical Anatomy of the Chin Evaluated by 3-Dimensional Tomography and Cadaveric Dissection: Implications for Safety and Optimal Injection Techniques in Chinese.

BACKGROUND: Soft tissue fillers have been widely used for the correction of chin volume loss because of congenital conditions and aging. OBJECTIVE: This study aimed to discuss anatomical concerns for chin filler injections, which may help to reduce the incidence of severe intravascular embolization complications and improve patient satisfaction. METHODS AND MATERIALS: We scanned 40 cadaveric heads with a contrast agent using a 64-row spiral computed tomography scanner. The scan was visualized by a Philips IntelliSpace workstation and analyzed by Materialise's interactive m image control system software to measure and quantify the arterial data. Twenty of 40 cadavers were dissected to define the layers of tissue. RESULTS: In total, 221 arteries passed through the sagittal plane of 40 specimens. The number of superficial arteries (163 of 221) was much greater than the number of deep arteries (58 of 221). The number of arteries gradually decreased with distance from the lower lip vermilion border plane, which formed the lower third of the face. CONCLUSION: This study introduces a safe and effective technique for administering chin filler injections that minimizes risks and improves patient satisfaction.

Genioplasty in Contemporary Orthognathic Surgery.

In contemporary orthognathic surgery planning, the genium/chin constitutes an important part that contributes to the maxillofacial profile. The aesthetics of the lower face is affected by the position of the genium which makes reestablishment of genial morphology an essential component. It is hence necessary to evaluate the genium objectively on its individual merit, and any discrepancy is addressed accordingly. This review presents an overview of contemporary genioplasty techniques, their applications, and considerations on stability, osteosynthesis, complications, and the future developments.

Assessment of soft-tissue vs hard-tissue changes after isolated functional genioplasty / Évaluation des modifications des tissus mous par rapport aux tissus durs après une génioplastie fonctionnelle isolée

Introduction: This study aimed to determine the vertical and horizontal soft-tissue vs hard-tissue changes after isolated functional genioplasty and to revisit hard-tissue remodeling at the symphysis. Methods: Seventy-five patients who underwent genioplasty as an isolated procedure at the end of their orthodontic treatment were divided into three groups on the basis of their age at surgery: < 15 years (group 1), 15-18 years (group 2) and ≥ 19 years (group 3). Patients were evaluated at three time points: immediately before surgery (T1), immediately after surgery (T2) and two years after surgery (T3). In addition, 25 patients who did not accept genioplasty, were age-matched with group 1, and had a follow-up radiograph two years after the end of their orthodontic treatment were used as a control group. Results: From T2 to T3, group 1 showed less forward horizontal hard-tissue and soft-tissue changes at pogonion (Pg) than the control group; however, no difference was noted for vertical changes at Me & Me'. From T1 to T3, the horizontal hard-tissue and soft-tissue changes at Pg were 6.39 mm and 6.72 mm, respectively, for surgical groups. Vertical hard-tissue change at menton (Me) showed a reduction of 1.63 mm (95% confidence interval [CI], -3.37 to 0.11) and 3.89 mm (95% CI, -5.83 to -1.95) in nongrowing female and male patients, respectively. The vertical soft-tissue change reduction was similar for nongrowing male and female patients (1.7 mm [95% CI, -2.96 to -0.45]). Soft-tissue thickness change at Pg (0.33 mm) was not significant. In contrast, a small but significant increase in soft-tissue thickness was noted at Me (0.54 mm). Linear regressions were calculated for all groups and allowed for predicting long-term soft-tissue changes (T3-T1) using the amount of surgical displacement (T2-T1). Conclusions: The horizontal hard-tissue change was stable for nongrowing patients, and the horizontal soft-tissue change was 92% of hard-tissue. Vertical soft-tissue change is less predictable. Variation of soft-tissue thickness after genioplasty can be explained by skeletal changes and the achievement of an unforced labial occlusion. These results support the functional and esthetic benefits of this surgery. Comparison with the control group showed that genioplasty does not change the growth pattern, and bone remodeling is likely to explain the difference noted at Pg.

Introduction: Cette étude avait pour but de déterminer les modifications verticales et horizontales des tissus cutanés par rapport aux tissus osseux après une génioplastie fonctionnelle isolée et d'évaluer le remodelage des tissus osseux au niveau de la symphyse. Méthodes: Soixante-quinze patients qui ont subi une génioplastie comme procédure isolée à la fin de leur traitement orthodontique ont été divisés en trois groupes sur la base de leur âge au moment de la chirurgie : moins de 15 ans (groupe 1), de 15 à 18 ans (groupe 2) et de 19 ans et plus (groupe 3). Les patients ont été évalués à trois moments : immédiatement avant la chirurgie (T1), immédiatement après la chirurgie (T2) et deux ans après la chirurgie (T3). En outre, 25 patients qui n'ont pas accepté la génioplastie, dont l'âge correspondait à celui du groupe 1 et qui ont subi une téléradiographie de profil de contrôle deux ans après la fin de leur traitement orthodontique ont été utilisés comme groupe témoin. Résultats: De T2 à T3, le groupe 1 a montré moins de changements horizontaux des tissus durs et mous vers l'avant au niveau du pogonion (Pg) que le groupe témoin ; cependant, aucune différence n'a été notée pour les changements verticaux au niveau de Me & Me'. De T1 à T3, les changements horizontaux des tissus osseux et cutanés à Pg étaient respectivement de 6,39 mm et 6,72 mm pour les groupes chirurgicaux. La modification verticale des tissus osseux au niveau du menton (Me) a montré une réduction de 1,63 mm (IC 95 %, -3,37 à 0,11) et de 3,89 mm (IC95 %, -5,83 à -1,95) chez les patients féminins et masculins sans croissance, respectivement. La réduction verticale de la modification des tissus mous était similaire chez les patients homme et femme qui ne sont pas en croissance (1,7 mm [IC 95 %, -2,96 à -0,45]). La modification de l'épaisseur des tissus mous à Pg (0,33 mm) n'était pas significative. En revanche, une augmentation faible mais significative de l'épaisseur des tissus cutanés a été observée à Me (0,54 mm). Des régressions linéaires ont été calculées pour tous les groupes et permettent de prédire les changements à long terme des tissus cutanés (T3-T1) en utilisant la quantité de déplacement chirurgical (T2-T1). Conclusions: Le changement horizontal des tissus osseux est stable pour les patients qui ne grandissent pas et le changement horizontal des tissus mous représente 92 % des tissus durs. Le changement vertical des tissus cutanés est moins prévisible. La variation de l'épaisseur des tissus cutanés après une génioplastie peut s'expliquer par les changements squelettiques et l'obtention d'une occlusion labiale non forcée. Ces résultats confirment les avantages fonctionnels et esthétiques de cette chirurgie. La comparaison avec le groupe témoin a montré que la génioplastie ne modifie pas le schéma de croissance et le remodelage osseux est susceptible d'expliquer la différence constatée à Pg.

Correlation between vertical dimension of occlusion and different facial measurements among a sample of sudanese adults / Correlación entre la dimensión vertical de la oclusión y diferentes medidas faciales en una muestra de adultos sudaneses

Aim: This study aimed to evaluate the correlation between vertical dimension of occlusion (VDO) and various facial measurements in a sample of Sudanese adults. Material and Methods: A total of 113 dental students (33 males and 80 females) with a mean age of 21.7±1.26 years were enrolled in this study. Different facial measurements including (Eye-Mouth, Eye-Eye, Eye-Ear, and Ear Height) were compared with two different measurements of VDO: N-Gn (from the tip of the nose to the tip of the chin), and Sn-Me (from the base of the nose to the bottom of the chin). Pearson's correlation coefficient test was utilized for the correlation between the measured parameters. A p-value of less than 0.05 was considered significant for all analyses. Results: A significant positive correlation was shown between all measured facial distances and both measured VDO distances. Though, the strongest correlation was seen for the eye-mouth distance (r= 0.725, p<0.001), while the weakest was for ear height (r= 0.254, p= 0.007). A paired t-test revealed a significant longer N-Gn distance than Sn-Me distance. Also, it has been shown that there were no significant differences between right and left sides of the face. Conclusion: The distance measured from the outer canthus of the eye to the angle of the mouth can be used to predict Subnasale-Menton (Sn-Me) distance.

Objetivo: Este estudio tuvo como objetivo evaluar la correlación entre dimensión vertical oclusal (DVO) y varias medidas faciales en una muestra de adultos sudaneses. Material y Métodos: Un total de 113 estudiantes de odontología (33 hombres y 80 mujeres) con una edad media de 21,7 ± 1,26 años se inscribieron en este estudio. Se compararon diferentes medidas faciales que incluyen (ojo- boca, ojo-ojo, ojo-oído y altura de la oreja) con dos medidas diferentes de DVO: N-Gn (desde la punta de la nariz hasta la punta del mentón) y Sn -Yo (desde la base de la nariz hasta la parte inferior del mentón). Se utilizó la prueba del coeficiente de correlación de Pearson para la correlación entre los parámetros medidos. Un valor de p inferior a 0,05 se consideró significativo para todos los análisis. Resultados: Se mostró una correlación positiva significativa entre todas las distancias faciales medidas y ambas distancias DVO medidas. Sin embargo, la correlación más fuerte se observó para la distancia ojo-boca (r=0,725, p<0,001), mientras que la más débil fue para la altura de las orejas (r=0,254, p=0,007). Una prueba de t pareada reveló una distancia N-Gn significativamente más larga que la distancia subnasal-mentón. Además, se ha demostrado que no hubo diferencias significativas entre los lados derecho e izquierdo de la cara. Conclusión: La distancia medida desde el canto externo del ojo hasta el ángulo de la boca puede utilizarse para predecir la distancia subnasal-mentón.

Assessment of soft-tissue vs hard-tissue changes after isolated functional genioplasty.

INTRODUCTION: This study aimed to determine the vertical and horizontal soft-tissue vs hard-tissue changes after isolated functional genioplasty and to revisit hard-tissue remodeling at the symphysis. METHODS: Seventy-five patients who underwent genioplasty as an isolated procedure at the end of their orthodontic treatment were divided into 3 groups on the basis of their age at surgery: <15 years (group 1), 15-18 years (group 2), and ≥19 years (group 3). Patients were evaluated at 3 time points: immediately before surgery (T1), immediately after surgery (T2), and 2 years after surgery (T3). In addition, 25 patients who did not accept genioplasty, were age-matched with group 1, and had a follow-up radiograph 2 years after the end of their orthodontic treatment were used as a control group. RESULTS: From T2 to T3, group 1 showed less forward horizontal hard-tissue and soft-tissue changes at pogonion (Pg) than the control group; however, no difference was noted for vertical changes at Me & Me'. From T1 to T3, the horizontal hard-tissue and soft-tissue changes at Pg were 6.39 mm and 6.72 mm, respectively, for surgical groups. Vertical hard-tissue change at menton (Me) showed a reduction of 1.63 mm (95% confidence interval [CI], -3.37 to 0.11) and 3.89 mm (95% CI, -5.83 to -1.95) in nongrowing female and male patients, respectively. The vertical soft-tissue change reduction was similar for nongrowing male and female patients (1.7 mm [95% CI, -2.96 to -0.45]). Soft-tissue thickness change at Pg (0.33 mm) was not significant. In contrast, a small but significant increase in soft-tissue thickness was noted at Me (0.54 mm). Linear regressions were calculated for all groups and allowed for predicting long-term soft-tissue changes (T3-T1) using the amount of surgical displacement (T2-T1). CONCLUSIONS: The horizontal hard-tissue change was stable for nongrowing patients, and the horizontal soft-tissue change was 92% of hard-tissue. Vertical soft-tissue change is less predictable. Variation of soft-tissue thickness after genioplasty can be explained by skeletal changes and the achievement of an unforced labial occlusion. These results support the functional and esthetic benefits of this surgery. Comparison with the control group showed that genioplasty does not change the growth pattern, and bone remodeling is likely to explain the difference noted at Pg.

Long-term hard and soft tissue response following isolated genioplasty: a systematic review.

PURPOSE: Genioplasty facilitates alteration of the chin position and contour which contributes to aesthetics and function. The response of the hard and soft tissues following genioplasty has not been assessed after a year or more of the surgery being performed. Hence, the aim of this systematic review was to assess the response of the hard and soft tissues occurring at least 1 year after the procedure. MATERIAL AND METHODS: A literature search was conducted in the following electronic databases: PubMed, Ovid, LILACS, and Cochrane Library. Potential articles were identified wherein only studies with genioplasty performed as an isolated procedure and with data at least 12 months after the procedure were included. RESULTS: Five studies were included in this systematic review. Two of the articles included were considered to be of good quality while three were considered to be of moderate quality using a modified Downs and Black tool. The ROBINS-I tool showed a moderate risk of bias for most domains. The study characteristics revealed varying degrees of relapse for the hard and soft tissues. CONCLUSIONS: In the anteroposterior plane, the soft tissue relapsed more than the hard tissues 3 years post genioplasty. However, relapse in the vertical plane showed a wide variation for both the hard and soft tissues. In the anteroposterior plane, the hard tissue to soft tissue response 2 years or more following genioplasty ranged from 1:0.77 to 1:0.91 while in the vertical plane the hard tissue to soft tissue response ranged from 1:0.67 to 1:1.16.

Changes in the airway after mentoplasty (genioplasty): systematic review / Cambios en la vía aérea después de una mentoplastia (genioplastia): una revisión sistemática

SUMMARY: The aim of this research was to evaluate the changes obtained with the mentoplasty technique in the increase of the airway imaging. A systemic review was performed using the parameters of the prism matrix, in the PubMed, Science Direct, Redalyc database, covering the years 1984 to 2019 with the use of defined inclusion criteria. The authors independently applied the selected parameter of data extraction, study selection and risk-to-bias assessment. A total of 1,251 articles were obtained among the 3 databases, of which 10 met the inclusion criteria. The variables studied were: type of research, sample size, sex, age, dento-skeletal diagnosis, airway classification, diagnosis of obstructive sleep apnea syndrome (OSAS), type of imaging evaluation, variables evaluated in the image, pre and post-operative values, surgical technique and type of fixation used, other surgical procedures applied, and complications. In the cases of linear evaluation with cephalometric analysis (9 articles) they used PAS (posterior airspace), MP-H (mandibular plane to the hyoid) and SNB (saddle-nasion-point B), and SCSA (section area as the most relevant points, smallest cross section) and VT (total volume) in the volumetric evaluations (2 articles). The average change in posterior airspace achieved by the cited authors is 4.2 mm with standard deviation of 1.4 mm with the use of advancement mentoplasty. The most widely used technique was mentoplasty with a horizontal osteotomy by 5 authors. Based on the research there is a positive relationship between the increase in the airway and the advancement mentoplasty procedure, however, more standardized studies associated with the way of measuring and evaluating the relationship between advancement and the airway are necessary.

RESUMEN: El objetivo de esta investigación fue evaluar los cambios obtenidos con la técnica de mentoplastia en el incremento de la via aérea. Una revisión sistemática fue realizada utilizando parámetros de la matriz prisma, en PubMed, Science Direct, Redalyc database, cubriendo los años 1984 a 2019 con criterios de inclusión definidos. Los autores aplicaron de forma independiente los parámetros de selección y extracción de datos, selección de estudios y riesgos de sesgo. Un total de 1251 artículos fueron obtenidos de las 3 bases de dato, donde 10 artículos cumplieron los criterios de inclusión. Las variables estudiadas fueron: tipo de investigación, tamaño de la muestra, genero, edad, diagnóstico dento esqueletal, clasificación de la vía aérea, diagnostico de síndrome de apnea del sueño (SAOS), tipo de evaluación de la imagen, variables evaluadas en la imagen en pre y postoperatorio, técnica quirúrgica y tipo de fijación utilizada, otros procedimientos quirúrgicos y complicaciones. En el caso de la evaluación linear con cefalometria (9 artículos), usaron PAS (posterior airspace), MP-H (plano mandibular hacia el hueso hioide) y SNB (silla turca-nasion- punto B) y SCSA (sección de puntos mas relevantes, menores transfversales) y el VT (volumen total) en las evaluaciones volumétricas (2 artículos). El promedio de cambio posterior de la vía aérea citado por autores fue de 4,2 mm con una desviación estándar de 1,4 mm con el uso de la mentoplastia de avance. La técnica mas habitual fue la mentoplastia con osteotomía horizontal (5 autores). Basados en esta investigación existe una relación positiva entre el incremento de la vía aérea y el avance con genioplastia; sin embargo, mas estudios estandarizados junto con medidas definidas y la evaluación correcta del avance y la vía área son necesarios.

Rellenos faciales con ácido hialurónico: Un nuevo desafío en la valoración y predicción de vía área dificultosa / Dermal fillers with hyaluronic acid: A new challenge in the assessment of difficult airway

Difficulties in airway management turn out to be the leading cause of cardiac arrest in anesthesia and they represent 50% of severe non-fatal anesthesiological complications. The main obstacle lies in the difficulties to predict it. Difficult intubation occurs in 1.5 to 8% of general anesthesia procedures and it can be defined as one requiring more than three attempts at laryngoscopy or more than 10 minutes of laryngoscopy. In order to identify and prevent an adverse event in patients at risk of presenting a difficult intubation, several parameters have been investigated. Anatomical factors that can predict difficult direct laryngoscopy require a complete pre-anesthetic evaluation and physical examination by the anesthesiologist. These include: the Mallampati scale, the thyromental distance (of Patil), the sternomental distance, the mandibular protrusion test and the atlanto- occipital extension; which combined have a high positive predictive value to anticipate difficult airway management.

Las dificultades en el abordaje de la vía aérea resultan ser la primera causa de paro cardíaco en anestesia y, a su vez, representan al 50% de las complicaciones severas no fatales de causa anestesiológica. El principal obstáculo a superar radica en las dificultades para predecirla[]. La intubación dificultosa se define como la necesidad de tres o más intentos o el empleo de más de 10 minutos para lograr la intubación traqueal, situación que ocurre en 1,5 a 8% de los procedimientos de anestesia gene- ral[]. Con el fin de identificar pacientes con riesgo de presentar una intubación dificultosa, se han investigado diversos parámetros capaces de anticipar un evento adverso. La caracterización de factores anatómicos que puedan dificultar la laringoscopia directa y la consecuente intubación orotraqueal, requieren de un examen e interrogatorio completo y minucioso por parte del anestesiólogo. Entre estos factores anatómicos encontramos la escala de Mallampati, la distancia tiromentoniana (de Patil)[],[], la distancia esternomentoniana, el test de protrusión mandibular y la extensión atlantooccipital; que combinados tienen un alto valor predictivo positivo para anticipar una vía aérea dificultosa

Osseous Genioplasty: Prevention of Witch's Chin Deformity with No-Degloving Technique.

BACKGROUND: Osseous genioplasty is a powerful procedure that can correct chin dysmorphology; however, traditional techniques may result in chin ptosis or a "witch's chin" deformity. Iatrogenic chin ptosis is thought to be caused by excessive degloving of soft tissue with a failure to reattach the mentalis muscle. In the authors' study, they compared the "no-degloving" technique (using a 90-degree plate with lag-screw fixation) to the "traditional" technique, for minimization of chin ptosis. METHODS: The authors compared genioplasty techniques for consecutive patients: group 1 (traditional) underwent degloving for fixation of a stair-step plate, whereas group 2 (no-degloving) underwent lag-screw fixation (n = 50; 25 patients per group). The authors compared operating room time, advancement, complications, preoperative-to-postoperative vertical height change of the pogonion and menton (obtained through cone beam computed tomographic scans), surgeons' assessment of witch's chin, and FACE-Q surveys. RESULTS: No-degloving versus traditional groups had similar age and sex distributions, horizontal/vertical change (5 mm/2 mm versus 6 mm/2 mm), length of surgery, and complication rate (5 percent). The traditional group had more deviation from expected position for both the pogonion (3.4 mm versus 1.2 mm; p ≤ 0.05) and menton (2.9 mm versus 0.8 mm; p ≤ 0.05), and more occurrences of witch's chin (six versus zero). No-degloving was superior for several FACE-Q scales, including Chin Appearance, Quality of Life, Satisfaction with Decision to Undergo Procedure, and Satisfaction with Outcome. CONCLUSION: No-degloving osseous genioplasty is a safe, reproducible technique that results in decreased soft-tissue ptosis and increased patient satisfaction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Morfología cefalométrica de la sínfisis del mentón en individuos jóvenes de la ciudad de Quito-Ecuador / Cephalometric morphology of chin symphysis in young individuals from the city of Quito-Ecuador

Resumen Introducción: La sínfisis del mentón aporta equilibrio, simetría y armonía al rostro. Por ser una estructura anatómica mandibular muy importante y altamente modificable en cirugía estética, se considera indispensable conocer su morfología y así obtener una correcta interacción en el diagnóstico, pronóstico y terapéutica médico-odontológica. Objetivo: Determinar la morfología sínfisis del mentón en jóvenes adultos de la ciudad de Quito- Ecuador, año 2019, mediante la identificación de las longitudes sagitales y coronales. Metodología: Este estudio tuvo un enfoque cuantitativo, tipo descriptivo-observacional, con temporalidad retrospectiva. Se calibraron, analizaron y trazaron 384 radiografías digitales laterales de adultos jóvenes de la ciudad de Quito-Ecuador, año 2019 en el software AutoCAD-2019. Resultados: Existió una elevada frecuencia de la forma geométrica cuadrada (60%) con respecto a la rectangular (40%), adicionalmente se identificó que la figura cuadrada es más frecuente en individuos de sexo femenino y sujetos clase I (56%) y II (70%), además de todos los patrones de crecimiento vertical hipodivergentes (58%), normodivergentes (64%) e hiperdivergentes (57%). Conclusiones: La forma cuadrada de la sínfisis del mentón es mayor que la forma rectangular. Por la originalidad de los resultados, se sugiere realizar nuevos estudios que correlacionen la morfología mentoniana con las diferentes estructuras cráneo-maxilofaciales.

Abstract Introduction: The chin symphysis contributes to the balance, symmetry and harmony of the face. Since it is an important anatomical jaw structure and highly modifiable in aesthetic surgery, it is considered crucial to know its morphology and, thus, obtain a correct interaction in the diagnosis, prognosis and medical-dental therapy. Objective: To determine the symphysis morphology of the chin in young adults in the city of Quito, Ecuador, in the year 2019, through the identification of sagittal and coronal lengths. Methodology: This study had a quantitative approach, descriptive-observational type, with retrospective temporality. We calibrated, analyzed and plotted 384 lateral digital radiographs of young adults from the city of Quito-Ecuador, year 2019 in the software AutoCAD-2019. Results: There was a high frequency of the square geometric shape (60%) in comparison to the rectangular one (40%). Additionally, it was identified that the square figure is more frequent in female individuals and class I (56%) and II (70%) subjects, in addition to all the hypodivergent (58%), normodivergent (64%) and hyperdivergent (57%) vertical growth patterns. Conclusions: The square shape of the chin symphysis is larger than the rectangular shape. Due to the originality of the results, it is suggested to carry out new studies that correlate chin morphology with the different cranio-maxillofacial structures.

Three-dimensional virtual planning in mandibular advancement surgery: Soft tissue prediction based on deep learning.

The study aimed at developing a deep-learning (DL)-based algorithm to predict the virtual soft tissue profile after mandibular advancement surgery, and to compare its accuracy with the mass tensor model (MTM). Subjects who underwent mandibular advancement surgery were enrolled and divided into a training group and a test group. The DL model was trained using 3D photographs and CBCT data based on surgically achieved mandibular displacements (training group). Soft tissue simulations generated by DL and MTM based on the actual surgical jaw movements (test group) were compared with soft-tissue profiles on postoperative 3D photographs using distance mapping in terms of mean absolute error in the lower face, lower lip, and chin regions. 133 subjects were included - 119 in the training group and 14 in the test group. The mean absolute error for DL-based simulations of the lower face region was 1.0 ± 0.6 mm and was significantly lower (p = 0.02) compared with MTM-based simulations (1.5 ± 0.5 mm). CONCLUSION: The DL-based algorithm can predict 3D soft tissue profiles following mandibular advancement surgery. With a clinically acceptable mean absolute error. Therefore, it seems to be a relevant option for soft tissue prediction in orthognathic surgery. Therefore, it seems to be a relevant options.

Are chin and symphysis morphology facial type-dependent? A computed tomography-based study.

INTRODUCTION: The chin is a major determinant of the facial profile; hence, it plays a major role in orthodontics and orthognathic surgery. It is thus essential to follow and better understand its expression in different facial types. The major objectives of the current study were to characterize morphometrically the chin and symphysis and reveal their association with different facial types. METHODS: Computed tomography scans of the head and neck of 311 adults (163 males, 148 females; age range, 18-95 years) were classified into 3 facial types: short, average, and long. Height, width, projection, inclination, thickness, and area were measured on the chin and symphysis. RESULTS: The majority of the population (70%) manifested an average facial type; the other 30% were almost equally distributed between short and long facial types. The long facial type was more common among females and the short facial type among males. Chin projection, area, and size were significantly greater in short-faced patients. Chin width in males was similar for all facial types, whereas, in females, chin width was the widest in the short facial type and the narrowest in the long facial type. Symphysis height was significantly greater in long-faced patients in both sexes. The mandibular incisors' inclination relative to the mandibular plane was not significantly associated with the chin or symphysis morphology. CONCLUSIONS: Chin and symphysis morphology is facial type-dependent. Orthodontists and maxillofacial surgeons should be aware of the complex relationship between facial types and chin/symphysis size and shape when planning treatment.

Factors associated with the morphology of the mandibular symphysis and soft tissue chin

ABSTRACT Objectives: This study aimed to (I) assess the morphology of the symphysis and soft tissue chin associated with sex, age and sagittal/vertical skeletal patterns, and (II) identify the individual and combined contributions of these variables to different portions of the symphysis. Methods: This cross-sectional study included 195 lateral cephalometric radiographs from untreated adults. Alveolar, basal, and soft tissue of the symphysis were measured by an X/Y cranial base coordinate system, and divided in accordance to four predictor variables: sex, age, and sagittal/vertical skeletal patterns. Parametric tests were conducted for comparison and correlation purposes, while multiple regression analysis was performed to explore combined interactions. Results: Alveolar inclination is related to sagittal and vertical patterns, and both explained 71.4% of the variations. Alveolar thickness is weakly predicted and poorly influenced by age. Symphysis height was 10% higher in males, and associated with a vertical skeletal pattern and sex, and both explained 43.6% of variations. Basal symphyseal shows an individual thickness, is larger in males, and vertically short-positioned with age. Soft tissue chin is not necessarily related to the size of the underling skeletal pattern, and enlarges with age, even in adulthood. Conclusions: The symphysis and surrounding tissues are influenced by sex, age, and sagittal and vertical patterns, acting differently on the alveolar, basal and soft tissue portions. Sagittal and vertical skeletal patterns are the strongest association on alveolar symphysis inclination, whereas sex and age acts on the vertical symphysis position and soft tissues thickness.

RESUMO Introdução: O presente estudo objetivou: 1) avaliar a morfologia da sínfise mandibular e dos tecidos tegumentares do mento, associada ao sexo, idade, padrões sagital e vertical; e 2) identificar as contribuições dessas variáveis, individualmente ou combinadas, às diferentes regiões da sínfise. Métodos: Este estudo transversal incluiu 195 radiografias cefalométricas laterais de adultos não tratados ortodonticamente. Os tecidos alveolar, basal e mole da sínfise foram medidos por um sistema de coordenadas x, y e z da base do crânio e divididos de acordo com quatro variáveis preditoras: sexo, idade e padrões esqueléticos sagitais e verticais. Testes paramétricos foram conduzidos para fins de comparação e correlação, enquanto a análise de regressão múltipla foi realizada para explorar as interações combinadas. Resultados: A inclinação alveolar está relacionada aos padrões sagitais e verticais, e ambos explicaram 71,4% das variações. A espessura alveolar é fracamente prevista e pouco influenciada pela idade. A altura da sínfise foi 10% maior no sexo masculino e esteve associada ao padrão esquelético vertical e ao sexo, sendo que ambos explicaram 43,6% das variações. A sínfise basal mostra espessura individual, é maior no sexo masculino e verticalmente curta com a idade. O tecido mole do mento não está necessariamente relacionado ao tamanho do padrão esquelético subjacente e aumenta com a idade, mesmo na idade adulta. Conclusões: A sínfise e os tecidos circundantes são influenciados pelo sexo, idade e padrões sagitais e verticais, que atuam de forma diferenciada nas porções alveolar, basal e de tecidos tegumentares. Os padrões esqueléticos sagitais e verticais são a associação mais forte na inclinação da sínfise alveolar, enquanto o sexo e a idade atuam na posição vertical da sínfise e na espessura dos tecidos tegumentares.

Attitudes Toward Submental Fat Among Adults in the United States.

BACKGROUND: Excess submental fat (SMF) can cause submental fullness resulting in negative perceptions of individuals. However, the impact of SMF on perceptions of social traits has not been well studied. OBJECTIVE: To characterize the impact of SMF on external value judgments in adults in the United States. METHODS: Respondents completed an online survey in which they reacted to statements about individuals with varying grades of SMF. Attributes were rated on a scale from 0 to 100 with higher scores for more positive attributes. RESULTS: Similar proportions of respondents (N = 1996) indicated that women and men with double chins were less attractive than those without (91% and 90%, respectively). A double chin was more likely to be noticed on a woman than on a man (78% of respondents). With increasing SMF, individuals were perceived as significantly less likeable, intelligent, happy, active, and easygoing. Those with greater amounts of SMF were rated as significantly less attractive than those with less SMF. For all attributes, male respondents rated all individuals lower than female respondents did. CONCLUSION: Results from this study provide further evidence of negative perceptions of individuals with SMF. Aesthetics of the submental area, especially SMF, likely impact the overall assessment of attractiveness and social attributes.

Branching Patterns of Mental Nerve in Newborns.

In classical textbooks of Anatomy, the mental nerve is considered to be the terminal or main branch of the inferior alveolar nerve, especially trifurcate with no designated names as soon as it emerges from the mental foramen. The textbooks define the innervation area of the mental nerve regionally without naming its terminal branches. Nomina Anatomica designates 3 terminal branches of mental nerve as "labial, gingival, and mental branch" but offers no description about their distribution on the mandible. In the present study, bilateral dissections were performed on the lower lip specimens of 20 newborns for 40 mental nerves to determine the branching types of mental nerve. Although anatomy textbooks indicate that mental nerve divides into 3 branches, the authors noted that mental nerve branched into 1, 2, or 3 branches at or right after its exit from the mental foramen. Branching patterns were typed in 13 different subclasses under 3 main groups (Form I-II-III). Moreover, the branching patterns that could not be included in one of these 3 main groups were defined as "Complex Form." The most common type of branching that the authors observed was Form II, which had 2 terminal branches with an incidence of 41.9% (16 specimens). The next frequently encountered type was Form III, having 3 terminal branches, and it was detected in 32.0% of patients (12 specimens). The least common form was Form I, which had 1 terminal branch with a frequency of 15.8% (6 specimens). The unclassified group, Complex Form, was found 10.5% (4 specimens).