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Aim: Evaluate constitutional differences in chin morphology and volume, and mandibular tooth size, between different facial divergence patterns., Materials and Methods: The sample consisted of 284 pretreatment cone beam computed tomography (CBCT) images of growing and non-growing patients who were stratified into 4 groups based on mandibular plane inclination to cranial base (SN) angle. Linear and angular measurements were made on the lateral CBCT images: mandibular lateral incisor crown (I-C) total (I-A) lengths, the distances between point D (centre of symphysis) and both incisor apex (D-A) and menton (D-Me) and between cemento-enamel junction and menton (CEJ-Me); chin width at the level of the central incisor apex (CWA) and point D (CWD); and the angles of the anterior and posterior symphyseal slopes. The volume of the symphysis was measured using a specialized 3D imaging software. Group differences and associations between parameters were gauged through the three-way ANOVA analysis., Results: I-C, I-A, D-A, D-Me and CEJ-Me were greater in the hyperdivergent group (p < .001). CWA and CWD were wider in the hypodivergent group (p = .003). Volume of the chin and inter-slope angles were similar in all groups (p > .05). The anterior slope angle decreased with hyperdivegence (p < .005) in opposite pattern to the posterior slope angle (p < .005)., Conclusions: Shape differences in mandibular symphysis were observed between opposite divergence patterns. Mandibular incisors were longer with hyperdivergence and shorter with hypodivergence. However, chin volumes were similar across divergence groups. These findings underline the role of genetic and environmental factors that impact facial growth., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Introduction: This study aimed to explore the distribution of deformational plagiocephaly in subjects with Class I skeletal pattern and the relationships of cranial vault asymmetry with menton deviation, condylar anteroposterior (AP) position and condylar angulation using cone-beam computed tomography images., Methods: Approximately 135 pretreatment records of patients with skeletal Class I growth patterns from the University of Detroit Mercy were examined using Anatomage Invivo6 software. The midsagittal plane constructed by nasion, incisive foramen, and basion was used to evaluate the asymmetry of the cranium vault, condyles, and menton deviation. For each patient, the radiographic cranial vault asymmetry (RCVA) was calculated and compared against condylar and chin measurements: the horizontal condylar angle, AP positions of the condyles, and menton deviation., Results: The Pearson correlation showed no direct correlation between RCVA and the mandibular variables (menton deviation and condylar measurements). The only mandibular variable that showed interaction with RCVA was the AP position discrepancy between the right and left condyles., Conclusions: The severity of cranial vault asymmetry did not correlate to the asymmetry of the horizontal condylar angle, AP condylar position, and chin deviation. A tendency toward a relation between cranial asymmetry and AP positions of right and left condyles was observed., (Copyright © 2024 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The early diagnosis of mandibular asymmetry (MA) in patients with unilateral cleft lip and palate (UCLP) can contribute to its treatment., Objective: The aim of this study was to evaluate the occurrence and the extent of MA in UCLP patients at different growth stages., Methods: Cone-beam computed tomography (CBCT) of 47 UCLP patients were included, and divided into two groups (prepubertal stage and pubertal stage). The mandibular ramus height (Co-Go), mandibular body length (Go-Me), total mandibular length (Co-Me), gonial angle (CoGoMe), the volume of the mandibular condyles, and lateral chin deviation were evaluated. The cleft side (CS) and noncleft side (NCS) were compared using the paired t-test for dependent samples. Chin deviation and its possible association with specific sides were evaluated using the Mann-Whitney and Fisher's Exact tests, respectively. The significance level was set at 5%., Results: Comparison of CS and NCS revealed that in prepubertal stage, Co-Me was shorter (105.5 ± 5.7 mm; p = 0.036) in the CS, and that in pubertal stage, Co-Go was lower (46 ± 6 mm; p= 0.004) and Go-Me was greater (78.5 ± 5.8 mm; p = 0.026) in the CS. In both growth stages, a significant association (p< 0.05) was observed between the side to which the chin has deviated and the CS., Conclusions: Although patients with UCLP in the prepubertal and pubertal stages presented significant measurements revealing MA, only Co-Go in the pubertal stage showed a clinically relevant difference. This specific result indicates that MA must be monitored during patients' growth.

Introduction: This study aimed to assess the bony and soft tissue parameters at mandibular symphysis among skeletal Class III patients with different vertical growth patterns, using cone-beam computed tomography (CBCT)., Materials and Methods: CBCT images of 60 skeletal Class III non-growing patients were evaluated (mean age 24.9 ± 8.4 years). Study samples were classified into three facial types based on the mandibular plane angle (SN-MP angle): low, normal, and high angle. The bony and soft tissue parameters at the mandibular symphysis were evaluated., Results: Among hard tissue variables, symphysis and pogonion width were significantly narrower in the high-angle group (P < .05). The thickness of the buccal cortex at pogonion was also significantly thinner in subjects with high angles (P < .01). Symphysis height showed an increasing tendency from the low-angle to the high-angle group. However, no significant differences were found in chin width and height according to vertical patterns. Across all soft tissue measurements, the low-angle group exhibited the highest thickness, which gradually decreased in the high-angle group. Statistically significant differences in soft tissue thickness were observed at Menton (Me) and Gnathion (Gn) (P < .05). A significant negative correlation was observed between the SN-MP angle and the thickness of both hard and soft tissues., Conclusions: In skeletal Class III subjects, significant differences existed in both hard and soft tissues at the mandibular symphysis, depending on the vertical patterns. These results provide a comprehensive evaluation of symphyseal area, which can aid clinicians in identifying appropriate treatment approaches, especially for combined orthognathic and orthodontic treatment., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: The determining effect of facial hard tissues on soft tissue morphology in orthodontic patients has yet to be explained. The aim of this study was to clarify the hard-soft tissue relationships of the lower 1/3 of the face in skeletal Class II-hyperdivergent patients compared with those in Class I-normodivergent patients using network analysis., Methods: Fifty-two adult patients (42 females, 10 males; age, 26.58 ± 5.80 years) were divided into two groups: Group 1, 25 subjects, skeletal Class I normodivergent pattern with straight profile; Group 2, 27 subjects, skeletal Class II hyperdivergent pattern with convex profile. Pretreatment cone-beam computed tomography and three-dimensional facial scans were taken and superimposed, on which landmarks were identified manually, and their coordinate values were used for network analysis., Results: (1) In sagittal direction, Group 2 correlations were generally weaker than Group 1. In both the vertical and sagittal directions of Group 1, the most influential hard tissue landmarks to soft tissues were located between the level of cemento-enamel junction of upper teeth and root apex of lower teeth. In Group 2, the hard tissue landmarks with the greatest influence in vertical direction were distributed more forward and downward than in Group 1. (2) In Group 1, all the correlations for vertical-hard tissue to sagittal-soft tissue position and sagittal-hard tissue to vertical-soft tissue position were positive. However, Group 2 correlations between vertical-hard tissue and sagittal-soft tissue positions were mostly negative. Between sagittal-hard tissue and vertical-soft tissue positions, Group 2 correlations were negative for mandible, and were positive for maxilla and teeth., Conclusion: Compared with Class I normodivergent patients with straight profile, Class II hyperdivergent patients with convex profile had more variations in soft tissue morphology in sagittal direction. In vertical direction, the most relevant hard tissue landmarks on which soft tissue predictions should be based were distributed more forward and downward in Class II hyperdivergent patients with convex profile. Class II hyperdivergent pattern with convex profile was an imbalanced phenotype concerning sagittal and vertical positions of maxillofacial hard and soft tissues., (© 2024. The Author(s).)

The mandibular interforaminal region has been considered safe for surgical procedures; nevertheless, the risk of injury to neurovascular structures, such as the mental foramen (MF) and its related structures (anterior loop [AL] and lingual foramina [LF]) should not be overlooked. The study aimed to evaluate the relative risk of injury to these structures during surgical procedures in the anterior region of the mandible based on cone-beam computed tomography (CBCT) scans. A retrospective cross-sectional and observational study was performed on 250 CBCTs from adults (18-69 years) with dentate jaws. Linear measurements of the MF, AL, and LF were evaluated to estimate the risk of injury to these structures during chin-related surgical procedures. The most frequent distance between the base of the mandible (BM) and MF was 8 mm (30.2%). In addition, 20.4% of the CTs had 6 mm from the vestibular cortical bone to the LF. The commonly found measurement from LF to the apex of the nearest tooth was 7 mm (24.0%); 64.2% of the CTs showed a 2-mm distance between the most distal point of the dental implant site to the most anterior point of the AL. Safety distances for genioplasty techniques (MF to mandible base > 6 mm, 96.6% [CI 95%, 95.0%-98.2%]) were observed. Considering the 5-mm cut-off point between the lower limit of a hypothetical bone graft and the chin, 65.4% (CI 95%, 58.9%-71.9%) of CTs were within this distance. Regarding the safety margin of 8 mm, 85.6% (CI 95%, 80.8%-90.4%) were up to this value. This study found safety margins for genioplasty and chin bone grafting surgical techniques that adopt a 5-mm cut-off point. Further similar studies assessing other surgical methods and employing larger samples from different geographical origins may contribute to this field of investigation.

Background: Although maxillomandibular advancement is the treatment of choice for obstructive sleep apnea syndrome (OSAS) in the presence of underlying maxillomandibular complex hypoplasia, there is still a gap in the literature regarding the impact of genioplasty upon upper airway volume (UAV)., Objectives: The aim of this study was to evaluate the impact of isolated osseous genioplasty upon UAV., Methods: A retrospective analysis of all patients subjected to isolated osseous genioplasty between July 2015 and July 2022 was conducted. Cone-beam computed tomography was performed preoperatively and postoperatively to assess the chin and hyoid 3-dimensional (3D) spatial position and UAV changes after surgery., Results: A total of 44 patients were included in the study. Regarding surgical movements of the chin, almost all patients received a sagittal movement (n = 42; 39 forward and 3 backward), while in 8 patients a vertical movement (5 upward and 3 downward) was applied, and in 6 patients the chin was centered. Statistically significant increases in total UAV (P = .014) and at the level of the oropharynx (P = .004) were observed. Specifically, chin centering, upward and forward movements enlarged the oropharynx volume (P = .006, .043 and .065, respectively). Chin advancement enlarged the hypopharynx volume (P = .032), as did upward movement of the hyoid bone (P < .001)., Conclusions: Results of the study suggest that aesthetic osseous genioplasty impacts the UAV: each 3D spatial chin movement differently impacts the upper airway by enlarging or narrowing it. However, further studies addressing the apnea-hypopnea index are required to assess its effectiveness in treating OSAS., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Aesthetic Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: To assess soft tissue differences between monozygotic twins (MZ) for the total face and between facial regions using three-dimensional (3D) stereophotogrammetry and quantitative surface-based 3D deviation analyses., Materials and Methods: The study sample consisted of 14 untreated MZ twins (6 males, 8 females, mean age: 14.75 years) from the archive of Marmara University, Department of Orthodontics. The images were taken by the 3dMDface system, and 3dMDvultus software was used for removal of undesired areas and approximation of the images. Then, stereolithography (.stl) format images were superimposed using the best-fit algorithm using 3-matic software. The face was divided into facial thirds, and upper lip and lower lip + chin regions were created. For the comparison, 3D deviation analyses were performed, and a color map and histogram were created. The data were presented as mean deviation, root mean square (RMS), median, and interquartile range., Results: Between the facial thirds, there was no significant difference in soft tissue differences for mean deviation. A statistically significant difference was found between the upper and lower face for the RMS value. For the comparison of upper lip and lower lip + chin region, the only significant difference was for the RMS. When the data were presented as median and interquartile range, there were no statistically significant differences between any facial regions., Conclusions: Lower facial third and lower lip + chin regions had the greatest differences within MZ twin pairs. The genetic and environmental influences might not be the same for different parts of the face., (© 2023 by The EH Angle Education and Research Foundation, Inc.)

Introduction: Facial aesthetics have become one of the most important objectives of orthodontic treatment. The correction of dental arches should be performed in accordance with the face. This study explored the association between occlusal and facial asymmetries in adolescents, particularly emphasizing a Class II subdivision., Methods: Eighty-one adolescents (43 males, 38 females) with a median age of 15.9 (interquartile range, 15.17-16.33) years were enrolled. Of these patients, 30 had a Class II subdivision (right side, n = 12; left side, n = 18). Three-dimensional facial scans were analyzed using surface- and landmark-based methods. Chin asymmetry was determined using the chin volume asymmetry score. Three-dimensional intraoral scans were analyzed to assess occlusal asymmetry., Results: The surface matching scores were 59.0% ± 11.3% for the whole face and 39.0% ± 19.2% for the chin. Chin volume was larger on the right side than on the left side in most patients (n = 51, 63%), and it was associated with a dental midline shift to the corresponding subdivision side. A correlation between dental and facial asymmetries was noted. In addition, the dental midline shifted to the left in patients with a Class II subdivision, regardless of the side, and to the right in those with a symmetrical Class II subdivision. However, several patients did not possess asymmetrical occlusal traits sufficient for statistical analysis., Conclusions: Dental asymmetry was weak but significantly correlated with facial asymmetry., (Copyright © 2023 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Background: Facial symmetry severely affects appearance and function. Large numbers of patients seek orthodontic treatment to improve facial symmetry. However, the correlation between hard- and soft-tissue symmetry is still unclear. Our aim was to investigate the hard- and soft-tissue symmetry in subjects with different levels of menton deviation and sagittal skeletal classes with 3D digital analysis and to investigate the relationship between the entire and individual hard- and soft-tissues., Methods: A total of 270 adults (135 males and 135 females) consisting of 45 subjects of each sex in each sagittal skeletal classification group. All subjects were further classified into relative symmetry (RS), moderate asymmetry (MA) and severe asymmetry (SA) groups based on the degree of menton deviation from the mid-sagittal plane (MSP). The 3D images were segmented into anatomical structures and mirrored across the MSP after establishing a coordinate system. Original and mirrored images were registered by a best-fit algorithm, and the corresponding root mean square (RMS) values and colormap were obtained. The Mann‒Whitney U test and Spearman correlation were conducted for statistical analysis., Results: The RMS increased with greater deviations with regard to the deviation of the menton in most of anatomical structures. Asymmetry was represented in the same way regardless of sagittal skeletal pattern. The soft-tissue asymmetry had a significant correlation with dentition in the RS group (0.409), while in the SA group, it was related to the ramus (0.526) and corpus (0.417) in males and was related to the ramus in the MA (0.332) and SA (0.359) groups in females., Conclusions: The mirroring method combining CBCT and 3dMD provides a new approach for symmetry analysis. Asymmetry might not be influenced by sagittal skeletal patterns. Soft-tissue asymmetry might be reduced by improving the dentition in individuals with RS group, while among those with MA or SA, whose menton deviation was larger than 2 mm, orthognathic treatment should be considered., (© 2023. The Author(s).)

The aim of this study was to evaluate the prevalence and length of the anterior loop (AL) of the inferior alveolar nerve, nerve emergence from the mental foramen, and prevalence of sensory disorders after implant placement in the interforaminal region. Four hundred and fifty hemimandibles (225 patients) were evaluated using cone beam computed tomography and panoramic radiographs. Information on the presence of sensory disorders was obtained from the medical records. AL prevalence was 13.6% and mean AL length was 1.25 mm. The false-negative rate for the identification of the AL using panoramic radiography was 58.6%. Straight nerve emergence from the mental foramen was the most prevalent (62.7%), followed by anterior (21.8%) and posterior (15.6%) emergence. The incidence of sensory disorders was 4.4%, and 1.1% were related to the presence of the AL. When implants were placed within the planned distance of the mental foramen or further, 1.2% had sensory problems associated with the presence of the mandibular incisive canal. In cases of distances smaller than planned, 12.9% had sensory alterations. Only five (1.1%) had the AL, with a length between 0 and 4.5 mm. However, in four cases, the planned distance was respected and, even so, there was a sensory disorder. Posterior nerve emergence from the mental foramen was associated with a higher prevalence of AL., (Copyright © 2021 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Background: The aims of this study were to evaluate the association between mandibular divergence and facial soft tissue thickness (FSTT) measured at different profile levels, and the gender difference in FSTT., Materials and Methods: Lateral cephalograms were used to examine nine linear distances: the glabella area (G-G1), nasal (N-N1) and subnasal area (A-Sn), upper (Sd-Ls) and lower lip thickness (Id-Li), mentolabial sulcus (B-Sm), chin area (Pg-Pg1), gnathion area (Gn-Gn1) and menton area (Me-Me1) in 155 adult Caucasian subjects (79 males, 76 females) from the central Balkan area. Subjects were divided into three groups according to the ANB angle, Wit's appraisal and SN/GoGn angle into normodivergent (28 male, 27 female subjects), hypodivergent (26 males, 25 females) and hyperdivergent (25 males, 24 females)., Results: Progressive decreasing in the soft tissue thickness from hypo- towards hyperdivergent group was established in N-N1, A-Sn, Gn-Gn1, Me-Me1. There are significant differences in Gn-Gn1 and Me-Me1 (p < 0.02). Progressive increasing of FSTT happens only at the level of mentolabial sulcus and these differences are significant. Significant gender differences were established for the following distances: N-N1 in hyperdivergent, A-Sn in all three examined groups, the upper lip thickness in normo- and hyperdivergent, the lower lip thickness in hypodivergent, the thickness of mentolabial sulcus in hypo- and normodivergent, Pg-Pg1 in hyperdivergent and Me-Me1 in normodivergent subjects (p < 0.05)., Conclusions: Facial soft tissue thickness showed a various degree of dependence on vertical developmental pattern at different levels of measurement. The areas whose thickness is significantly conditioned by this pattern were established: the chin area at level Gn-Gn1, Me-Me1 and the region of the mentolabial sulcus (B-Sm). At most levels, male subjects have thicker soft tissues and these differences are significant for all three groups in the subnasal area.

The effectiveness of the chin tuck maneuver is still controversial, despite being widely used in clinical practice. The chin tuck maneuver has been shown to be able to reduce or eliminate aspiration in a group of patients with a number of favorable conditions, but its effectiveness in preventing or managing penetration remains unclear. This study was designed to investigate whether the chin tuck maneuver is effective in reducing penetration. Images from a videofluoroscopic swallowing study (VFSS) taken from 76 patients with penetration were collected and reviewed retrospectively. The severity of penetration was assessed by the penetration ratio (ratio of the penetration depth to the length of the epiglottis) measured and calculated from the images in which the deepest penetration was observed. The penetration ratio was significantly decreased in the chin tuck posture compared with the ratio in the neutral position (p = 0.001). Significant reducing effect was observed in 26 (34.2%) out of 76 patients. When comparing other parameters of VFSS, residues in the vallecular and pyriformis sinuses were less severe in the effective group. Chin tuck significantly decreased residues in both effective and ineffective group. The results demonstrate that the chin tuck maneuver can reduce penetration, but its effectiveness is limited., (© 2021. The Author(s).)

Accumulation of cervical and chin subcutaneous adipose tissues (SAT) represent known phenotypes of obesity. We aimed to evaluate the sensitivity of these fat storages to long-term weight-loss directed lifestyle-intervention and to assess their relations to bodily-adiposity, insulin-resistance, and cardiometabolic risk; We randomly assigned 278 participants with abdominal-obesity/dyslipidemia to low-fat or Mediterranean/low-carbohydrate diets +/- physical-activity. All participants underwent an 18 month whole-body magnetic resonance imaging follow-up, from which we assessed cervical and chin SAT-areas; Participants (age = 48 years; 90% men; body-mass-index = 30.9 kg/m 2 ) had an 18-month adherence-rate of 86%. Cervical-SAT and chin-SAT decreased after 6-months (-13.1% and -5.3%, respectively, p < 0.001). After 18-months only cervical-SAT remained decreased compared to baseline (-5%, p < 0.001). Cervical and chin-SAT 18-month changes were associated with changes in weight (r = 0.70, r = 0.66 respectively; <0.001 for both) and visceral-adipose-tissue (VAT; r = 0.35, r = 0.42 respectively; <0.001 for both). After adjustment to VAT, waist-circumference, or weight-changes, chin-SAT 18-month reduction was associated with favorable changes in fasting-glucose (β = 0.10; p = 0.05), HbA1c (β = 0.12; p = 0.03), and homeostasis-model-assessment-of-insulin-resistance (β = 0.12; p = 0.03). Cervical-SAT 18-month reduction was associated with decreased triglycerides (β = 0.16; p = 0.02) and leptin (β = 0.19; p = 0.01) independent of VAT; Cervical and chin-SATs are dynamic fat depots that correspond with weight-loss and are associated with changes in cardiometabolic profile. In long-term, chin-SAT displays a larger rebound compared with cervical-SAT. Chin-SAT accumulation is associated with in insulin-resistance, independent of central obesity. (ClinicalTrials identifier NCT01530724).

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.

Introduction: This study aimed to analyze adults with mandibular characteristics of skeletal Class II malocclusion with chin deviation., Methods: Seventy-five adult patients aged from 18 to 35 years were included and divided into 3 groups on the basis of sagittal skeletal pattern and chin deviation: skeletal Class I symmetry group, skeletal Class II symmetry group, and skeletal Class II asymmetry group (25 patients per group). Mandibular measurements on cone-beam computed tomography images were performed, and the differences between 2 sides in each group and the differences among the 3 groups were investigated., Results: Compared with the contralateral side, the deviated side of patients in the Class II asymmetry group showed significantly smaller condyle angle to midsagittal plane, condylar height, ramal length, and length of the mandibular body, whereas it showed a significantly larger distance from condylion to the midsagittal plane, ramus angle to the horizontal plane, and distance from gonion to the midsagittal plane. Most linear measurements in the Class II symmetry group were significantly smaller than those in the Class I symmetry group. These linear measurements on the contralateral side of the Class II asymmetry group showed no significant difference with the Class I symmetry group, and these measurements on the deviated side of the Class II asymmetry group showed no significant difference with the Class II symmetry group., Conclusions: Length of the mandible, rotation of condyle, the inclination of the ramus, and position of gonion should be considered in subjects with skeletal Class II asymmetry when making diagnosis and treatment planning., (Copyright © 2021. Published by Elsevier Inc.)

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., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Desire for improved aesthetic contour of the lower third of the face has resulted in an increase in chin augmentation. Although many fillers, including hyaluronic acid (HA), autologous fat and stromal vascular fraction gel (SVF-gel), have been used to improve facial morphology, chin augmentation requires fillers that provide greater support., Methods: The elastic and viscous moduli of SVF-gel and Coleman fat were assessed in vitro by rheological testing, whereas their elasticity were evaluated in vivo by ultrasonic elastography. Results in vitro were compared with those of highly elastic HA (HE-HA) and highly viscous HA (HV-HA), whereas results in vivo were compared with HE-HA. Changes in chin volume, SVF-gel retention rate and absorptivity for at least 12 months were measured by 3D white light scanning. Questionnaires were administered to assess patient satisfaction., Results: The elastic and viscous modulus of SVF-gel was, respectively, slightly lower than HE-HA and HV-HA but higher than the other two in vitro, with the elasticity of the three layers of SVF-gel lower than HE-HA but slightly higher than normal control in vivo. The average retention rate was 62.34±3.34% at 12 months. The absorptivity of 90% of the samples was <3% from 6 to 12 months, which was considered stable. Patients expressed satisfaction with their results., Conclusion: SVF-gel has ideal rheologic characteristics in vitro, which has slightly higher elasticity than normal fat tissue of chin in vivo, and could keep well retention rate for chin augmentation in clinic., Level of Evidence Iv: 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 ., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature and International Society of Aesthetic Plastic Surgery.)

The goal of this study was to determine the utility of submental ultrasound parameters in distinguishing difficult airway management from easy airway management. Forty-one adult patients who underwent elective surgery under general anesthesia with endotracheal intubation from March to December 2018 were included. We used submental ultrasound to measure tongue base thickness (TBT) in the midsagittal plane and the distance between lingual arteries (DLA) in the transverse dimension. The primary outcome was difficult laryngoscopy, and the secondary outcome was difficult mask ventilation. Receiver operating characteristic curve analysis and logistic regression revealed no correlation between difficult laryngoscopy and SMUS measurements. Nevertheless, patients with difficult mask ventilation had significantly higher TBT (p = 0.009) and longer DLA (p = 0.010). After adjustment of confounding factors, increased TBT (>69.6 mm) was the sole independent predictor of difficult mask ventilation. The results indicated that SMUS is effective in predicting difficult mask ventilation but not difficult laryngoscopy., Competing Interests: Conflict of interest disclosure The authors declare no conflicts of interest., (Copyright © 2021 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Abstract: Conventional operations correcting chin deviations mainly rely on the observation and experience of the surgeons during the operation. We have created a new surgical method, one-half wedge osteotomy genioplasty (1/2WOG), that combines three-dimensional computed tomography measurements and simulation. This study evaluated the clinical effect of chin deviation correction with the 1/2WOG method. A total of 38 patients (15 men and 23 women) who underwent 1/2WOG between October 2019 and October 2014 were evaluated. The chin deviation angle and distance, and partial chin deformity were measured preoperatively using three-dimensional computed tomography data. Precise calculations and osteotomy lines were achieved by preoperative simulation. All patients underwent the same surgery by the same surgical team. The clinical effect of 1/2WOG was evaluated according to the preoperative and postoperative data and patient satisfaction. All 38 patients achieved satisfactory aesthetic results without major complications such as chin nerve injury or bone nonunion. Eight patients occured numbness of the lower lip after surgery; at 6-month follow-up, the numbness was reduced in 2 patients and disappeared in 6 patients. Compared with preoperative data, the chin deviation angle, chin deviation distance, and gonion-menton difference were significantly reduced postoperatively. During the 12-month follow-up, the patient satisfaction rate reached 90%. We conclude that chin deviation can be improved by 1/2WOG. The combination of digital technology measurements and simulation can increase the accuracy of the osteotomy line design, thus reducing surgical trauma and increasing patient satisfaction, which is worthy of clinical promotion., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by Mutaz B. Habal, MD.)

Introduction: Facial soft tissue thickness is important not only for plastic surgeons but also for orthodontists to plan the treatment procedure. Genioplasty, an orthognathic surgery in combination with orthodontic treatment is indicated to restore adequate shape and projection of the chin in the face. It has been performed to enhance soft tissue contours related to disproportion between soft and hard tissue. These treatments require the critical information regarding the relation between soft and hard tissues for proper treatment plan-ning. However, there is very minimal documentation on comparison of soft tissue characteristics particularly in Class II malocclusion., Aim: To evaluate and compare soft tissue chin thickness in class II subjects with various growth patterns. To evaluate soft tissue chin thickness difference in males and females and compare the results with previous studies., Materials and Methods: The study comprised 150 adults aged between 18 and 26 years (mean age 21 years). Based on FH/MP angle the study sample was allocated into three groups: group I - low (hypodivergent), group II - average, and group III - high (hyper-divergent). Radiographs were traced manually. Angular measurements were computed to determine the vertical position of the maxilla and mandible in relation to anterior cranial base, to true horizontal and to each other. Soft tissue chin thickness was measured at three different levels., Results: Hyperdivergent group showed greater soft tissue chin thickness at Pog-Pog' than the hypodivergent and average angle groups. Hypodivergent group showed greater soft tissue chin thickness at Me-Me' and Gn-Gn' as compared to average and hyperdivergent groups. Males showed greater soft tissue chin thickness at hypodivergent, average and hyperdivergent group than females., Conclusions: Soft tissue thickness measurements were smaller in adult patients of hyperdivergent group compared to adult patients in clinically average and hypodivergent groups. All STC measurements were greater in men than in women. The findings suggested that STC thickness in hyperdivergent pattern should be considered differently at its most anterior point (Pog) relative to its inferior landmarks (Gn and Me)., (This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Retrognathia (recessed chin) and prognathism (prominent chin) often present as signs of an underlying condition. Accurate clinical definitions are important. Yet their definitions were according to "clinical impression", or to seldom used X-ray criteria. We propose a statistical and anthropometric definition of retrognathia and prognathism based upon the ratio between the goniomaxillar length (distance between the gonion at the mandible angle and the subnasale and the goniomandibular length (distance between the mandible angle and the most anterior point of the bony chin). We assumed that an increase in the ratio indicates retrognathia and a decrease reflects prognathism. We conducted a prospective, observational, anthropometric study in 204 consecutive healthy term infants. Measurements took place on the second day of life, using sliding calipers. Mean ± SD of goniomandibular length (5.1 ± 0.3 cm), goniomaxillar length (5.4 ± 0.3 cm), were calculated. All measurements correlated significantly with gestational age, and with infant birthweight. The mean ± SD goniomaxillar length/goniomandibular length ratio was 1.06 ± 0.05. We defined a normal ratio as being within 2 SD of the mean, that is, between 0.96 and and 1.16. This ratio correlated with neither gestational age nor with birthweight. We conclude that the goniomaxillar length/goniomandibular length ratio can be calculated whenever retro - or prognathism is suspected. A ratio outside of the 95% confidence interval should help in making this diagnosis. An increase in this ratio beyond 2 SD above the mean (1.16) could be interpreted as retrognathia and a decrease beyond 2 SD below the mean (0.96) as prognathism., (© 2020 Wiley Periodicals LLC.)

Background: To analyze the sagittal positions of the mandibular prominence and maxillary central incisors in adult Chinese Han men to establish their aesthetic profile characteristics., Methods: Seventy-four Chinese Han men aged 18 to 40 years underwent cone beam computed tomography for detecting the distances between Glabella and Subnasale, Subnasale and Menthon of soft tissue, Condyle and Gonion, Pogonion and Pogonion's Anterior Limit Line, Facial Axis point of maxillary central incisor and the Goal Anterior Limit Line as well as the angle of the Occlusal Plane. Dolphin Imaging and Photoshop software packages were used to generate silhouette profiles. Thirteen orthodontists assessed the silhouette profiles and assigned visual analog scale scores. Scores >70 were assigned to the aesthetic (group 1), scores of 60to 70 to the general (group 2), scores of 50 to 60 to the acceptable (group 3), and scores of <50 to the unaesthetic profile (group 4)., Results: A total of 15 men were assigned to group 1, 35 to group 2, 14 to group 3, and 10 to group 4. There were no significant differences in the variables examined between groups 1, 2, and 3, but comparing group 1 with group 4, Pogonion and Pogonion's Anterior Limit Line (1.16 ± 2.61 mm vs -1.44 ± 2.92 mm, P = .046) and Facial Axis-Goal Anterior Limit Line (-0.61 ± 2.54 mm vs 1.70 ± 2.62 mm, P = .038) there were significant differences., Conclusion: Compared with the unaesthetic profile group, the sagittal positions of the maxillary central incisors were slightly posterior, and the chin was slightly anterior in adult Chinese Han men with an aesthetic profile.

Purpose: We used 3-dimensinonal (3D) images to assess the influence of chin asymmetry on perceived facial esthetics, investigate the cognitive boundaries of chin asymmetry among orthodontists, general dentists, and laypersons, and provide quantitative reference for clinical treatment., Materials and Methods: A 3D facial image was obtained using the 3dMD imaging system (3dMD, Atlanta, GA). The chin was altered in 2-mm increments from 0 to 12 mm and to the left and right using the software program. These images were rated by 66 orthodontists, 89 general dentists, and 66 laypersons as 1) chin symmetry; 2) slight chin asymmetry but acceptable; and 3) serious asymmetry and treatment needed. Multivariate mixed linear regression and multivariate mixed logistic regression analyses were used for statistical data analysis. Descriptive and bivariate statistics were calculated, and statistical significance was considered present at P = .05., Results: The observers progressively increased the grade ratings and the desire for surgery for greater asymmetries (P < .001). Orthodontists and general dentists could perceive a chin deviation of 4 mm to the right and 2 mm to the left, with 8-mm deviation considered to require treatment. Laypersons had a clear perception of a 4-mm chin deviation, with 8 mm to the right and 10 mm to the left considered to require treatment. The right chin deflection was more easily perceived than was the left (P < .05)., Conclusions: Chin asymmetry has a great influence on facial esthetics. We found a statistically significant difference between clinicians (orthodontists and general dentists) and laypersons in the cognition of chin asymmetry and the recommendations for treatment., (Copyright © 2020 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Background: As one of the most commonly used soft-tissue fillers, hyaluronic acid is generally considered safe and efficacious. However, evident bone resorption in mentum was observed. In this study, the authors analyzed the impact of hyaluronic acid on bone resorption in mentum and the influencing factors., Methods: The authors retrospectively compared the computed tomographic scans of patients with or without mentum augmentation using hyaluronic acid. The body mass index- and sex-matched control group was selected randomly. Semimandibular bone resorption index was calculated as the ratio of bone thickness in the incisive fossa to that in the mandibular symphysis. Injection volume, injection interval, the number of injections, product, complication were also recorded., Results: From January of 2014 to June of 2019, 80 patients (160 cases) and 80 controls were recruited. The bone resorption index in the hyaluronic acid injection cohort was significantly lower than in the controls (75.25 ± 10.02 versus 82.86 ± 6.38; p = 0.000). Patients injected with greater than or equal to 1 ml per time were more susceptible to bone erosion compared with patients injected with less (68.89 ± 10.84 versus 76.49 ± 9.42; p = 0.000). There was no significant difference between one- versus multiple-injection groups and short-injection-interval versus long-injection-interval (≥6 months) groups. Furthermore, no reduced aesthetics were realized., Conclusions: Hyaluronic acid injection could induce bone resorption in the mentum; nevertheless, the aesthetics were not impaired. The severity of the bone loss was positively correlated with the injection volume per time; therefore, large-volume injection of hyaluronic acid should be performed with caution. The patients should be fully informed about this complication preoperatively., Clinical Question/level of Evidence: Therapeutic, III.

Purpose: Degenerative joint changes commonly affect the temporomandibular joint (TMJ) and can result in chin deviation. However, the extent of degenerative TMJ changes and chin deviation has not been well-characterized. The present study sought to correlate degenerative TMJ changes with condylar volume, grayscale measures, and chin deviation., Materials and Methods: The present cross-sectional study had enrolled women with skeletal Class III malocclusion. Cone-beam computed tomography scans were acquired preoperatively. For each condyle, degenerative TMJ signs were analyzed and the condylar volume and grayscale were measured. The predictor variable was the presence of degenerative TMJ signs, classified as categorical data: 0, if none; 1, only present in 1 joint; and 2, present in both joints. The primary outcome variable was a chin deviation of 3 mm or more. Other associated variables were grouped by age, cephalometric data, and 3-dimensional condylar measurements. Descriptive bivariate statistics were computed, and univariate and multiple logistic regression analyses were conducted to identify any associations between degenerative TMJ disease and chin deviation., Results: We included 85 patients, who were classified into 2 groups: less than 3 mm of chin deviation (n = 43) and 3 mm or more of chin deviation (n = 42). The presence of more than 10 degenerative TMJ signs was significantly associated with the presence of 3 mm or more of chin deviation (P < .001). In multiple regression models, the presence of subcortical sclerosis in 1 joint and in both joints (adjusted odds ratio [OR], 3.698; 95% confidence interval [CI], 1.051 to 13.012; adjusted OR, 5.001; 95% CI, 1.461-17.119, respectively) correlated significantly with the presence of 3 mm or more of chin deviation (P < .05). The volume difference between the 2 condyles was significantly greater in the group with more than 10 degenerative TMJ signs and 3 mm or more of chin deviation than in the group with 10 or fewer degenerative TMJ signs and less than 3 mm of chin deviation (P = .016 and P < .001, respectively)., Conclusions: In women with skeletal Class III malocclusion, the presence of more than 10 degenerative TMJ signs increased the prevalence of 3 mm or more of chin deviation. The presence of subcortical sclerosis in either 1 or both joints and volume differences between the 2 condyles were associated with greater chin deviation., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Craniofacial asymmetry, mandibular condylar modeling and temporomandibular joint disorders are common comorbidities of skeletally disproportionate malocclusions, but etiology of occurrence together is poorly understood. We compared asymmetry, condyle modeling stability and temporomandibular health in a cohort of 128 patients having orthodontics and orthognathic surgery to correct dentofacial deformity malocclusions. We also compared ACTN3 and ENPP1 genotypes for association to clinical conditions. Pre-surgical posterior-anterior cephalometric and panometric radiographic analyses; jaw pain and function questionnaire and clinical examination of TMD; and SNP-genotype analysis from saliva samples were compared to assess interrelationships. Almost half had asymmetries in need of surgical correction, which could be subdivided into four distinct morphological patterns. Asymmetric condyle modeling between sides was significantly greater in craniofacial asymmetry, but most commonly had an unanticipated pattern. Often, longer or larger condyles occurred on the shorter mandibular ramus side. Subjects with longer ramus but dimensionally smaller condyles were more likely to have self-reported TMD symptoms (p = 0.023) and significantly greater clinical diagnosis of TMD (p = 0 .000001), with masticatory myalgia most prominent. Genotyping found two significant genotype associations for ACTN3 rs1671064 (Q523R missense) p = 0.02; rs678397 (intronic SNP) p = 0.04 and one significant allele association rs1815739 (R577X nonsense) p = 0.00. Skeletal asymmetry, unusual condyle modeling and TMD are common and interrelated components of many dentofacial deformities. Imbalanced musculoskeletal functional adaptations and genetic or epigenetic influences contribute to the etiology, and require further investigation., Competing Interests: The authors have declared that no competing interests exist.

The purpose of this study was to compare the efficacy of botulinum toxin (BoNT) in masseter muscle reduction depending on the amount of chin deviation. Exploring distinctive effects of BoNT relative to the characteristics of facial asymmetry will aid in planning and predicting treatment outcomes. Sixteen adult volunteers were classified into two groups according to the degree of menton deviation observed in posteroanterior cephalograms. Eight had a menton deviation of 3 mm or more and the other eight had less than 3 mm. A total of 25 Units of BoNT was injected into the unilateral masseter muscle of the prominent side for each participant. Changes in the volume and bulkiest height of the lower face on each side were measured with a 3D laser scan at four time points: before and 4, 8, and 12 weeks after the injection. Two-way mixed ANOVA was employed for analyses. The volume and bulkiest height of the injected side decreased over time in both types of asymmetry, with significant differences at each time point. The reductions in the volume and bulkiest height were significantly greater in subjects without chin deviation. The reductions in the volume and bulkiest height of the lower face using BoNT are more effective for subjects without chin deviation.

Background: A chin that is of right size, shape, and contour plays a crucial role in overall facial balance and esthetically harmonious appearance. Dermal fillers have been widely used for correcting mild to moderate chin retrusion and resorption., Aims: The aim of this study was to share our preferential technique for chin augmentation and to evaluate our results in 50 patients., Methods: A total of 50 patients consisting of females who received hyaluronic acid injection for chin augmentation and rejuvenation were enrolled in the study. We have described chin augmentation technique with the use of cannula from a single, midline entry point., Results: The study included 50 female patients, and the mean age was 37.56 ± 8.84 years. The median injected filler volume for augmentation of the mental area was 2.25 mL (minimum = 1, maximum = 4 mL). Four (8%) patients had ecchymosis related to the procedure., Conclusion: Chin has a profound effect on the perception of attractiveness and is an area of concern for rejuvenation of the lower third of the face. Our preferential technique allows the practitioners to increase the likelihood of a satisfactory esthetic outcomes and minimize the risks of the procedure., (© 2020 Wiley Periodicals, Inc.)

The purpose of this study was to document changes in social perceptions and facial esthetics, and document occlusion outcomes in a series of short face (SF) dentofacial deformity (DFD) subjects. The investigators hypothesized that subjects would achieve positive change in social perceptions and facial esthetics, and maintain a long-term corrected occlusion after undergoing bimaxillary and chin osteotomies.A retrospective cohort study was implemented. Photographic records and occlusion parameters were studied preoperatively and >2 years after surgery. The first outcome variable was social perceptions of SF subjects, judged by laypersons. The second outcome variable was facial esthetics, judged by professionals. The third outcome variable was occlusion maintained long-term.Fifteen subjects met inclusion criteria. Mean age at operation was 33 years. Consistent facial contour deformities at presentation included deficient maxillary dental show and downturned oral commissures. As a group, there was improvement (P < 0.05) in 11 of 12 social perceptions, judged by laypersons, all subjects achieved correction of the facial esthetic parameters studied by professionals, and all subjects maintained a favorable occlusion long-term.In SF DFD subjects, bimaxillary and chin surgery proved effective to improve social perceptions, to correct facial contour deformities, and in achieving a long-term corrected occlusion.

Background/purpose: The objective of this study was to create a normative database of 3D cephalometric measurements for adult Chinese in Taiwan to understand the specific features, as well as to provide information for 3-dimensional (3D) orthognathic surgery planning for patients with maxillofacial deformity., Methods: A cross-sectional study was conducted on 30 male and 30 female adults with normal and balanced facial appearance, skeletal Class I pattern, and proper interincisal relationship with normal occlusion. Cone-beam computed tomography was performed. After standard orientation of the 3D image models, 51 landmarks were digitized and 3D cephalometric measurements of overall facial features, midface, maxilla, mandible, dentoalveolus, and soft tissue were performed and analyzed., Results: Reliability and reproducibility of the 3D measurement were achieved. The data showed significant differences between males and females in facial height ratio, midface prominence, midface and maxilla width, mandible width and length for the skeleton, lower incisal inclination and interincisal angle for the dentoalveolus, and lip height, facial height and chin throat angle for the soft tissue. These dataset presented specific facial characteristics of the Chinese face as compared with other populations., Conclusion: The normative data helps to serve as a guide for maxillofacial treatment for globally ethnic Chinese, particularly useful for orthodontic treatment, 3D planning of orthognathic surgery and outcome assessment. Gender and ethnic differences need to be taken into consideration., (Copyright © 2019. Published by Elsevier B.V.)

Introduction: The 3 Noffel signs, "Ramal height", "Smiling chin", and "B-line space", often present in class II division 2, are called "danger signs" for aesthetics, when they are strongly marked and absolutely need to be taken into account in the therapeutic strategy. The main objective was to assess whether the three measurements associated with Noffel signs (Gonion/Articulare distance, Cutaneous Pogonion/Na-B, and B-line space) were pathognomonic of class II division 2. The secondary objective was to determine whether there was a correlation between the severity of Noffel signs and the sagittal and/or vertical skeletal severity of class II division 2., Materials and Methods: In this comparative, mono-centric study based on a retrospective cohort, lateral cephalograms of all the growing patients who were treated at the CSERD between 2012 and 2018 and had normodivergent and hypodivergent profiles, were analysed., Results: The logistic regression analysis showed that only "Total chin" and "B-line space" were significantly related to class II division 2 (P=0.00199; P=0.00778, respectively). The three signs were related to the severity of the hypodivergence, but not to the severity of skeletal class II., Conclusion: Only "Total chin" and "B-line space" are pathognomonic of class II division 2. The correlation between the severity of Noffel's three signs and skeletal severity exists only in the vertical dimension., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

A strong demand is expected for high-sensitivity, high-resolution and low-cost brain positron emission tomography (PET) imaging for early diagnosis of dementia, as well as for general neuroscience studies. Therefore, we have proposed novel geometries of a hemisphere detector arrangement for high-sensitivity brain imaging, in which an add-on detector at the chin position or neck position helps in sensitivity uniformity improvement. In this study, we developed the first prototype system for proof-of-concept using four-layer depth-of-interaction detectors, each of which consisted of 16  ×  16  ×  4 Zr-doped GSO crystals with dimensions of 2.8  ×  2.8  ×  7.5 mm 3 and a high-sensitivity 64-channel flat-panel photomultiplier tube. We used 47 detectors to form a hemisphere detector with a hemisphere shape of 25 cm inner diameter and 50 cm outer diameter, and we used seven detectors for each of the add-on detectors. The total detector number of 54 was about one-fourth that of a typical whole-body PET scanner. The hemisphere detector for the prototype system was realized by multiple rings having different numbers of detectors and a cross-shaped top detector unit covering the top. Performance evaluation showed uniform spatial resolutions of 3-4 mm by the filtered back-projection method. Imaging tests of a hot-rod phantom done with an iterative method were able to resolve 2.2 mm rods. Peak sensitivity was measured as more than 10% at a region near the top of the head, which was achieved with the help of the top detector unit. In addition, using the prototype system, we performed the first FDG clinical test with a healthy volunteer. The results showed that the proposed geometries had high potential for realizing high-sensitivity, high-resolution, and low-cost brain PET imaging. As for the add-on detector position, it was shown that the neck position resulted in higher sensitivity and wider field of view (FOV) than the chin position because the add-on detector at the neck position can be placed continuously to the hemisphere detector and close to the FOV.

The workflow digital to aid the treatment of dentofacial deformities is a reality. Associated with the virtual planning, the creation of surgical guides assists the performance of osteotomies and bone positioning, increasing the accuracy of surgical outcomes. This study aims to present a new method of surgical guide for genioplasty based on the selected osteosynthesis plate.

Background: To investigate the layered anatomy of the jawline and to provide anatomic background for the formation of the labiomandibular sulcus, the jowl deformity, and the "double-chin" for safe and effective minimally invasive procedures., Materials and Methods: Seventy-two fresh-frozen human cephalic cadavers (32 males, 40 females; mean age 75.2 ± 10.9 years, BMI 24.2 ± 6.6 kg/m 2 , 99% Caucasian ethnicity) were investigated by layer-by-layer anatomical dissection. Magnet resonance and computed tomographic imaging was additionally carried out to support the anatomical findings., Results: No major neuro-vascular structures were found to run in the subdermal plane or in the subcutaneous fat. The jowl deformity was identified to be caused by the loose adherence of the platysma to the mandible, which occurs posterior (but not anterior) to the mandibular ligament. The formation of the submental sulcus was identified to be caused by the submental septum, an osteo-cutaneous adhesion spanning all facial layers in the submental area. The formation of the labiomandibular sulcus was caused by the change in the subcutaneous fibro-connective arrangement rather than by an underlying adhesion or ligament., Conclusion: The layered arrangement of the jawline predisposes this region for subdermal and subcutaneous treatment options located superficial to the platysma. Subdermal subcision procedures might have a beneficial effect on the labiomandibular sulcus as the boundary between the different types of subcutaneous arrangement, which form the sulcus, is being smoothened., (© 2018 Wiley Periodicals, Inc.)

Both deep understanding and reliable prediction of postoperative soft tissue changes are crucial for planning orthognathic surgery. Instead of estimating soft tissue responses by measuring individual landmark changes, this study aimed to investigate the relationship (ratio) between soft and hard tissue movements in different facial regions through three-dimensional cone-beam computed tomography (CBCT). Preoperative and postoperative CBCT images were superimposed using the surface registration method on the basis of the cranial base, and 10 facial regions of interest were defined. Region-based volumetric subtractions between the preoperative and postoperative segments were performed. The volumetric differences and surface of each region were used to estimate the average movement. Correlation and regression analyses were performed to examine the relationships between the corresponding soft and hard tissue movements. An overall pattern of facial soft tissue movement was observed in patients with prognathism who underwent orthognathic surgery. The experiment results have shown that mean ratios for the average soft-to-hard tissue movements in the facial regions varied, which may not exactly be similar to the published reports because of the population biocharacteristics and study methods, but the trend is in agreement with the previous studies. Additionally, the prediction capability of the regression model was significantly high, ranging from 0.786 to 0.857, in upper lip, upper vermilion, and chin regions, thus demonstrating that the skin outline changes in these critical regions could be reliably predicted from the underlying bone movements. These results could likely be applied in future soft tissue simulation in orthognathic surgery., Competing Interests: The authors have declared that no competing interests exist.

Background: The introduction of CAD/CAM technology allowed clinicians to carry out complex procedures with a high level of precision and reproducibility and minimize the risk of injury during the procedure., Purpose: The aim of the present study is to evaluate the efficacy of the CAD/CAM surgical guide during chin harvesting procedures in reducing the risk of neurosensory damage and patient morbidity compared with the standard technique., Materials and Methods: About 20 cases of autogenous block chin harvest were randomly into two groups. The first group received computer-guided chin block harvest while the second group received autogenous block chin harvest using the standard approach., Results: In the guided group, out of the 10 subjects, 2 subjects presented with wound dehiscence which resolved within 1 month. No teeth showed any negative pulp sensitivity results. The pointed-Blunt test and 2 point discrimination tests showed a single case of neurodeficits at 1 week follow-up appointment which resolved within 1 month. In the nonguided group, out of the 10 subjects, 1 case presented with wound dehiscence that resolved completely within 1 month. Pulp vitality test showed negative results in 29.4% of the involved teeth at 1 week which decreased to 9.8% and 3.9% at 1 and 6 months follow-up, respectively. The pointed blunt test revealed 3 subjects with neurodeficits at 1 week, out of which 2 subjects showed persisting symptoms at 6 months follow-up. The 2 point discrimination test showed 3 subjects with neurodeficits, out of which two subjects showed persistent symptoms with no resolution at the 6 months follow-up., Conclusion: Within the limits of this study, computer-guided chin harvest shows promising results in the reduction of neurosensory complications following harvesting procedures and presents as a safe alternative to the standard technique., (© 2018 Wiley Periodicals, Inc.)

Objective: To evaluate the relationship between the hyoid-related cephalometric measurements and the apnea-hypopnea index (AHI) in patients diagnosed with obstructive sleep apnea (OSA)., Methods: A total of 56 subjects were evaluated by lateral cephalometric radiography and polysomnography (PSG). The OSA diagnosis was made according to the patients' AHI. Included were 13 primary snoring, 16 mild OSA, 10 moderate OSA, and 17 severe OSA. C3-hyoid distance and mentum-hyoid distance were measured on lateral cephalogram. Cephalometric measurements and PSG parameters were compared among the different OSA groups., Results: The distance between the mentum and hyoid was significantly longer in the severe OSA group than in the primary snoring, mild OSA, and moderate OSA groups (P = 0.029). There was a significant positive correlation between the AHI value and the distance of the mentum hyoid (r = 0.368, P = 0.005). The C3-hyoid distance among the groups was not statistically significant different (P = 0.889)., Conclusion: The mentum-hyoid distance of patients with severe OSA was longer compared to the other OSA groups. These patients might have more benefit from the surgeries that have an impact on the position of the hyoid bone compared to other patients with OSA.

Background: Recently, the mandibular body and chin shape are known to be important issue as well as the mandibular angle. The authors have performed the one-piece mandibuloplasty from the mandibular angle to the most anterior part of chin to achieve the change of the whole mandibular shape as a one-piece., Methods: All of 14 patients who complaint prominent mandibular angle and chin were randomly allocated into 2 groups. Group I (n = 7) was treated with conventional mandibuloplasty with narrowing genioplasty and Group II (n = 7) was treated with one-piece mandibuloplasty. Pre- and postoperative clinical photography, cephalometry, computed tomography scan, 3-dimensional photography were taken and occurrence of secondary angle, patient's satisfaction, and operative time were evaluated., Results: The mean volume reduction per side was 41.8 cc on one-piece mandibuloplasty and 36.5 cc on conventional mandibuloplasty with narrowing genioplasty. Furthermore, average lower facial decreased from 64.3 to 61.0 after 6 months postoperatively and was maintained until 3 years on average after the operation. In one-piece mandibuloplasty group shows a little higher satisfaction about mandible body, and it was estimated that the presence of secondary angle makes dissatisfaction. The authors' treatment approach resulted in a shorter total surgery time than conventional technique (70.57 versus 105.14 min, P = 0.002)., Conclusions: One-piece mandibuloplasty based on 3-dimensional printing model turned out to be very successful for the natural shaping of the lower jaw in the patients with the prominent mandible in terms of the technical efficiency and the aesthetic point of view.

Objective: This study aimed to investigate the frequency and characteristics of accessory mental foramina (AMFs) and their bony canals in a selected Chinese population using cone-beam computed tomography (CBCT)., Materials and Methods: Reconstructed CBCT images of the mandible in 784 Chinese patients (305 males and 479 females) were retrospectively analysed to identify the AMF. The presence, dimension and location of the AMF as well as the origin and course of the associated bony canal were evaluated and classified. Variations in these characteristics were analysed according to gender, side and age., Results: A total of 66 AMFs were found in 57 (7.3%) of the 784 patients. The frequency of AMFs was significantly influenced by gender and side of the mandible (p < .05). Most AMFs were located apically between apices of the first and second premolars. The high-position AMFs (above the mental foramen) accounted for 54.5% of the total. The mean horizontal and vertical diameters of the AMF were 1.38 ± 0.47 and 1.23 ± 0.37 mm, respectively. Two typical types of the bony canal leading to the AMF were identified according to their bifurcation site from the mandibular canal. Most bony canals originated from the anterior loop of the mental canal (56.1%) and coursed posterosuperiorly (36.3%). The mean length of the bony canals was 5.78 ± 2.31 mm., Conclusions: This study presents a considerable frequency of AMFs in a Chinese population. The high-position AMF and the associated bony canal coursing in the oblique upward direction appear frequently. Thus, clinicians should be alert to the presence of the AMF to avoid neurovascular complications especially when dental procedures require periosteum detachment and implant insertion in the mental region.

Background: Recent advancements in clinical dentistry have increased the possibilities of surgical procedures in the mental region. A detailed knowledge of mental foramen (MF) morphometry is significant to preserve integrity of the mental nerve trunk in surgical interventions such as orthognathic surgery, implant placement and anaesthetic block., Objective: The aim of this study was to determine the most accurate position of the mental foramen by using new assessment approach in a sample of dental patients presenting to the specialist dental clinic, College of Dentistry, Al Jouf University, Saudi Arabia., Study Design: A retrospective study was performed using cone beam computed tomography (CBCT) of 600 patients (40.1 ± 11.78 years old). Following inclusion and exclusion criteria, 395 CBCT were finally obtained and analyzed for the most accurate position of the mental foramen (MF) by OnDemand 3D software (Seoul, Korea). Prevalence of shape of MF and accessory MF were also assessed. Pearson chi-square test was employed to test significant differences between genders and races., Results: The most common horizontal and vertical position of the mental foramen was in line with the long axis of 2nd premolar (41.3%) and below the root apex level (93.2%), respectively. The most common shape of MF was round type (72.66%). The prevalence of accessory 2MF and 3MF was 2.28% and 0.25%, respectively., Conclusion: New information about MF presented in this article can help anatomists, prosthodontists, orthodontists, surgeons, forensic odontologists and paleoanthropologists to predict the position of the MF and perform safer surgeries.

Objectives: To determine the position of the mandibular medial lingual foramen with cone-beam CT (CBCT) 3D imaging modalities when implants are to be placed in the anterior symphysis of the mandible., Materials and Methods: A total of 111 CBCTs were considered acceptable and analyzed. The variables measured were as follows: (1) length of the outlet duct; (2) distance from the canal to the buccal cortex; (3) distance from the canal to the inferior cortex; (4) distance from the canal to the lingual cortex; (5) distance from the canal to the alveoli of the nearest tooth in dentate patients and distance from the canal to the marginal crest in edentulous patients; (6) angle of the duct to the horizontal Frankfurt plane; (7) diameter of the exit orifice; and (8) output level of the socket in relation to the teeth and the presence of bifurcations., Results: A single canal was observed in 64% of patients; 2 canals were observed in 33% of patients; and a triple foramen was observed in 3% of patients. Women showed slightly lower values than men for each of the analyzed variables, with statistically significant differences in the length of the canal in edentulous (P = 0.029) and dentate patients (P = 0.027)., Conclusion: The medial lingual foramen should be considered while performing presurgical planning. Careful attention is needed while setting the placement position of the dental implant to decrease the risk of complications.

Segmentation of characteristic facial regions has often been an initial step of thermographic analysis in face recognition and clinical diagnosis. Moreover, fast and accurate thermographic analysis on characteristic areas is highly reliant on segmentation approach. Usually, frontal and lateral projections are used to capture the facial thermograms. The significant role of lateral facial thermography to diagnose the various problems associated with orofacial regions has been remarkable in many studies. So far, no study has presented an automatic approach for the segmentation of characteristic areas in lateral facial thermograms. For this purpose, an automatic approach to segment the characteristic areas in lateral facial thermograms is proposed. The dataset of 140 facial thermograms with 1 left and 1 right lateral view per subject is created. Initially, image binarization is performed using optimal temperature thresholding for better visualization of facial geometry. Then, the automatic localization of characteristic points is performed at two levels, based on (a) geometrical features of the face, and (b) local thermal patterns. At last, the characteristic points and auxiliary points are used to segment the characteristic areas in the orofacial region of the face. To evaluate the segmentation performance of the proposed methodology, the automatically localized characteristic points are compared with manually marked using Euclidean distance based comparison criterion. With the localization error δ ch&#95;pt ≤0.05, the proposed automatic approach shows 92.04% of overall localization accuracy and 85% of overall segmentation accuracy. The key conclusion is that the proposed algorithm can potentially automate the process of thermographic analysis on characteristic areas to assist the diagnosis of problems in the orofacial region., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Purpose: The chin is a common donor site for alveolar cleft bone grafting. The amount of bone available at this site can be limited, because conservative harvesting with mixed dentition must consider the incisive nerve, the unerupted mandibular canine, and the integrity of the inferior mandibular border., Materials and Methods: Patients with nonsyndromic unilateral alveolar cleft in the mixed dentition stage were selected for this study. The volume of bone obtained from the mandibular symphysis (symphysis menti), degree of alteration in lower lip sensation, anterior tooth vitality, remaining bone in the alveolar cleft, and bone defects at the donor site 1 year after surgery were evaluated., Results: Eighteen patients were enrolled in this study. The mean volume of bone harvested from the symphysis was 2.1 mL (range, 1.6 to 2.3 mL). For all cases, the bone volume harvested from the symphysis was insufficient to fill the alveolar cleft defect, and allograft had to be added to completely fill the cleft. Allograft was admixed in the range of 0.5 to 1 mL with autogenous bone harvested from the mandible. Lower lip sensation and vitality of the anterior teeth of the mandible were within the normal range 1 year after surgery in all cases. Fourteen of 18 patients (77.8%) had normal bone height or bone height at least three fourths of the expected height in the grafted alveolar cleft after 1 year; only 10% of the defect remained in the mandible., Conclusion: The amount of bone yielded by conservative monocortical bone harvest from the mandibular symphysis during the mixed dentition stage for unilateral alveolar cleft bone grafting is not sufficient in volume and should be mixed with allograft. However, donor site morbidity is low with this approach., (Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: To demonstrate the interchangeable neck shape-specific (NSS) coil concept that supplements standard commercial spine and head/neck coils to provide simultaneous high-resolution (hi-res) head/neck imaging with high signal-to-noise ratio (SNR)., Methods: Two NSS coils were constructed on formers designed to fit two different neck shapes. A 7-channel (7ch) ladder array was constructed on a medium neck former, and a 9-channel (9ch) ladder array was constructed on large neck former. Both coils were interchangeable with the same preamp housing., Results: The 7ch and 9ch coils demonstrate SNR gains of approximately 4 times and 3 times over the Siemens 20-channel head/neck coil in the carotid arteries of our volunteers, respectively. Coupling between the Siemens 32-channel spine coil, Siemens 20-channel head/neck coil, and the NSS coils was negligible, allowing for simultaneous hi-res head/neck imaging with high SNR., Conclusions: This study demonstrates that supplementing existing commercial spine and head/neck coils with an NSS coil allows uniform simultaneous hi-res imaging with high SNR in the anterior neck, while maintaining SNR of the commercial coil in the head and posterior neck. Magn Reson Med 78:2460-2468, 2017. © 2017 International Society for Magnetic Resonance in Medicine., (© 2017 International Society for Magnetic Resonance in Medicine.)

Competing Interests: Competing interests: None declared.

Objective: To quantify the postoperative changes of the dental show and chin projection following SARME using 3D CBCT imaging., Material and Methods: 78 patients with transversal maxillary hypoplasia and mandibular hypoplasia who underwent SARME were enrolled into the study. A cone beam computed tomography (CBCT) scan was acquired preoperatively and at least 1 year postoperatively. 3D postoperative changes in the dental show and pogonion position were measured based on soft tissue and hard tissue landmarks., Results: 68 patients (87%) exhibited a postoperative increase in the dental show. The dental show was increased by a mean of 2.2 ± 2.0 mm (p < 0.01). The mean horizontal and vertical displacement of the chin (pogonion) following SARME was 1.6 ± 2.5 mm posteriorly and 1.6 ± 2.0 mm inferiorly (p < 0.01). An inferior displacement of the maxilla and maxillary tooth as well as a consequent clockwise pitch of the mandible seemed to play a role in inducing these postoperative changes., Conclusion: An increase in dental show and a posterior and inferior displacement of the chin should be considered prior to SARME to prevent undesirable postoperative changes of the facial esthetics., (Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Background: The overlapping bone flap genioplasty, described by Tessier, was developed to treat major retrognathia or long and retruded chins. For 15 years, we have used a modified version of this technique to avoid its drawbacks. The aim of this article is to describe our modification and evaluate the long-term morphologic and radiologic outcomes., Patients and Method: The authors included every split-overlapping genioplasty performed in our department between 2004 and 2014. Demographics, surgical data, and complications were recorded. Radiologic bone resorption was evaluated comparing preoperative, day-1 postoperative, and year-1 postoperative cephalometric x-rays. Morphologic outcomes were evaluated on standardized pre- and postoperative views using an analogic Likert scale., Surgical Technique: The main modification of the procedure consists in separating the posterior cortex of the transplant using a reciprocating saw. After overlapping the reduced transplant onto the mandible, the posterior cortex is used as an apposition graft to soften the labiomental crease., Results: Forty-seven patients were analyzed during this period. In 44 patients, the procedure was combined with mandibular and/or maxillary osteotomy. The average reduction of symphysis height was 5 mm, and the average pogonion advancement was 4.3 mm. After 1 year, we recorded 7% average bone resorption. No major complications (nerve injury, hematoma, among others) were reported. Morphologic outcomes were deemed satisfactory or very satisfactory in the vast majority of cases., Conclusion: Split-overlapping genioplasty is a safe and reliable procedure with stable, long-lasting outcomes. This versatile technique is particularly useful for the correction of a massive symphysis or high and retruded chins.