What is a trait? Lessons from the human chin.

The chin, a distinguishing feature of Homo sapiens, has sparked ongoing debates regarding its evolutionary origins and adaptive significance. We contend that these controversies stem from a fundamental disagreement about what constitutes a well-defined biological trait, a problem that has received insufficient attention despite its recognized importance in biology. In this paper, we leverage paleoanthropological research on the human chin to investigate the general issue of character or trait identification. First, we examine four accounts of the human chin from the existing literature: the mandibular differential growth byproduct, the bony prominence, the inverted T-relief, and the symphyseal angle. We then generalize from these accounts and propose a three-stage framework for the process of character identification: description, detection, and justification. We use this framework to reinterpret the four accounts, elucidating key points of contention surrounding the chin as well as other morphological characters. We show that debates over the chin carry broad and important biological implications that extend beyond this trait and that are not mere semantic issues of definition.

Short-term cortical activation changes associated with postural compensation in swallowing.

Compensatory strategies used to treat dysphagia, like the chin-down and chin-up positions, are often employed by speech-language pathologists to enhance swallowing safety. However, their effects on cortical neural responses remain unclear. This study aimed to investigate the cortical hemodynamic responses to swallowing across three head positions -chin-down, chin-neutral, and chin-up - using functional near-infrared spectroscopy (fNIRS) in the bilateral precentral and postcentral gyrus regions of interest. Twenty-six healthy adults completed 32 swallows of 5 ml water in each head position. Results revealed short-term cortical activation increases for chin-up swallows compared to both chin-neutral (mean difference = 1.2, SE = 0.18, p = .048) and chin-down swallows (mean difference = 0.76, SE = 0.18, p = .009). These findings suggest that postural changes during swallowing induce immediate neural adaptations in people without swallowing difficulty. These modifications likely reflect the necessary sensory and neuromuscular adaptations required for safe swallowing in different head positions, with less hyolaryngeal movement needed for a chin-down swallow and more movement needed for a chin-up swallow. While challenging swallow conditions, like the chin-up, may offer promising therapeutic potential, caution is warranted considering the associated safety risk, and further investigation is needed. This study provides insights into the immediate effects of head positions on cortical activity during swallowing and highlights avenues for future research in dysphagia rehabilitation.

Prediction of persistent occiput posterior position by sonographic assessment of fetal head attitude at start of second stage of labor: prospective study.

OBJECTIVES: To evaluate the relationship between the attitude of the fetal head quantified by means of the chin-to-chest angle (CCA) in fetuses in occiput posterior (OP) position at the beginning of the second stage of labor, and persistent OP position at birth. METHODS: This was a single-center, prospective observational study conducted at the University Hospital of Parma, Parma, Italy. We included singleton pregnancies at term with fetuses in the OP position at the beginning of the second stage of labor. The fetal head position, station by means of angle of progression and head-to-perineum distance, and attitude by means of CCA were assessed using transabdominal or transperineal ultrasound. The primary outcome was persistent OP position at birth. RESULTS: Between January and July 2022, 76 women were included in the study. There were 48 (63.2%) spontaneous rotations of the fetal head and spontaneous vaginal delivery occurred in all. Among the 28 (36.8%) fetuses that did not rotate spontaneously into an occiput anterior position, eight (28.6%) had a spontaneous vaginal delivery, while operative vaginal delivery and Cesarean delivery was performed in 11 (39.3%) and nine (32.1%) cases, respectively. Multivariable logistic regression analysis showed that the CCA (adjusted odds ratio (aOR), 2.15 (95% CI, 1.22-3.78); P = 0.008) and nulliparity (aOR, 0.20 (95% CI, 0.06-0.76); P = 0.02) were associated independently with persistent OP position at birth. Moreover, the CCA showed an area under the receiver-operating-characteristics curve of 0.69 (95% CI, 0.56-0.82); P = 0.005) for the prediction of persistent OP position. The optimal cut-off value of the CCA was 36.5°, and was associated with a sensitivity of 0.82 (95% CI, 0.63-0.94), specificity of 0.50 (95% CI, 0.35-0.65), positive predictive value of 0.49 (95% CI, 0.34-0.64), negative predictive value of 0.83 (95% CI, 0.64-0.94), positive likelihood ratio of 1.64 (95% CI, 1.18-2.29) and negative likelihood ratio of 0.36 (95% CI, 0.15-0.83). CONCLUSIONS: Our data show that, within a population of women with fetal OP position at the beginning of the second stage of labor, the sonographic fetal head attitude measured by means of the CCA might help in the identification of fetuses at risk of persistent OP position. Such findings can be useful for patient counseling when OP position is diagnosed at full cervical dilatation. Further studies should investigate if the CCA might select patients who may benefit from manual rotation of the fetal head. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Basic concepts in facial and neck thread lifting procedures.

In this review article, our objective is to elucidate fundamental principles and offer practical illustrations concerning the procedures involved in facial and neck thread lifting. Moreover, we aim to explore associated concepts such as the fixing point, hanging point, and anchoring point terminologies, along with the elucidation of vectors. Additionally, we will provide anatomically oriented explanations of the lifting process required for each facial region using thread lifting methods like V, U, and I techniques using floating type threads (Secrete line, Hyundai Meditech., Inc., Wonjusi, Republic of Korea). Furthermore, our intention is to delve deeply into the concepts of tensile strength, anchoring strength, and holding strength, contextualizing their practical applications within this specific field.

Variation of chin morphology and mandibular incisor length in different facial divergence patterns: New insights from CBCT records.

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.

Chin Dysmorphology in the Primary Rhinoplasty Population: Prevalence, Objective Analysis, and Implications.

BACKGROUND: Chin flaws are far more common than recognized. Denial of genioplasty by parents or adult patients can present a surgical planning enigma, especially in patients with microgenia and chin deviation. This study aims to investigate the frequency of chin imperfections on patients seeking rhinoplasty, review the conundrum they generate, and offer management suggestions based on over 40 years of the senior author's experience. METHODS: This review included 108 consecutive patients presenting for primary rhinoplasty. Demographics, soft tissue cephalometrics, and surgical details were obtained. Exclusion criteria included prior orthognathic or isolated chin surgery, mandiblular trauma, or congenital craniofacial deformities. RESULTS: Of the 108 patients, 92 (85.2%) were female. Mean age was 30.8 years (SD±13, range 14-72). Ninety-seven (89.8%) patients exhibited some degree of objective chin dysmorphology. Fifteen (13.9%) had Class I deformities (macrogenia), 63 (58.3%) Class II (microgenia), and 14 (12.9%) Class III (combined macro and microgenia in the horizontal or vertical vectors). Forty-one (38%) patients had Class IV deformities (asymmetry). While all patients were offered the opportunity to correct chin flaws, only 11 (10.1%) underwent such procedures. Five (4.6%) patients had simultaneous osseous genioplasty (mean advancement 7.8mm, range 5-9mm); 7 (6.5%) received fat grafting to the chin (mean volume 4.4cc, range 1-9cc). CONCLUSIONS: A considerable proportion of primary rhinoplasty patients possess quantifiable chin dysmorphology on circumspect examination, high-resolution photographs and cephalometric analysis. Only a small number agree to surgical interventions that pursue full facial harmony. Potential reasons for these findings, patient aversion, and mitigation strategies will be discussed. LEVEL OF EVIDENCE III: 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 .

Nonsurgical Chin Augmentation Using Hyaluronic Acid: A Systematic Review of Technique, Satisfaction, and Complications.

The article titled "Nonsurgical Chin Augmentation Using Hyaluronic Acid: A Systematic Review of Technique, Satisfaction, and Complications" by Ou et al. in Aesthetic Plastic Surgery presents a systematic review focused on categorizing complications associated with hyaluronic acid (HA) dermal fillers. However, concerns arise regarding the methodologies employed in the reviewed studies. It is essential to have precise knowledge of the properties of the active substance for treatment standardization. Gaining a comprehensive understanding of the key characteristics of the HA used is paramount to determine if there is an association between these properties and the risk of complications.Understanding HA's rheological properties, including viscosity, elasticity, and cohesiveness, is crucial for selecting the most suitable facial filler. While we acknowledge the authors' contributions, we strongly believe that further analysis should incorporate these factors.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 .

The effectiveness of chin-down manoeuvre in patients with dysphagia: A systematic review and meta-analysis.

AIM: The chin-down posture is a widely used compensatory manoeuvre for patients with dysphagia. The aim of this study was designed to systematically measure the effectiveness of chin-down manoeuvre application. METHODOLOGY: We retrieved the PubMed, Web of Science, Embase, Cochrane Library, EBSCO, Medline, CNKI, WANFANG, VIP and SinoMed databases from inception to 30 August 2022. Raters independently screened literature according to inclusion and exclusion criteria. The quality of the included literature was evaluated, and data were extracted. The software Review Manager software 5.3 was used for statistical analysis. RESULTS: Fourteen studies with a total of 571 patients were included in this meta-analysis. The meta-analysis indicated that chin-down manoeuvre could significantly reduce the risk of aspiration (MD = -1.35, 95% CI [-2.25, -0.44], Z = 2.92, p < .01), decrease the chin angle (MD = -12.20, 95% CI [-14.61, -9.79], Z = 9.91, p < .001), shorten oral transit time (MD = -0.81, 95% CI [-1.20, -0.43], Z = 4.17, p < .001), reduce the maximum swallowing pressure at upper oesophageal sphincter (MD = -82.07, 95% CI [-112.77, -51.37], Z = 5.24, p < .001) and decrease pharyngeal residue. CONCLUSIONS: Existing evidence indicated that chin-down manoeuvre could reduce the risk of aspiration and pharyngeal residue, decrease the maximum swallowing pressure at UES. More large-sample, high-quality clinical trials are still needed in the future to further ascertain the results of this research.

Custom-Made Implant Fabrication for Chin Augmentation Using Piled-Up Expanded Polytetrafluoroethylene Sheets: An Innovative Surgical Technique and Literature Review.

BACKGROUND: Alloplastic chin augmentation is the most common esthetic surgical treatment to reshape the chin. However, factory-made chin implants are typically standardized rather than custom-made and have potential to cause complications. Although the fabrication of custom-made implants by using computer-assisted planning and 3D-printing technology has become widespread, the process has several disadvantages, including long preoperative prosthesis preparation times, high costs, and unsuitability for patients with asymmetric chins or those who undergo combined mandibuloplasty before implant placement. The present study developed an innovative chin augmentation technique involving stacked expanded polytetrafluoroethylene (e-PTFE) sheets that is suitable for most patients and has minimal side effects. MATERIALS AND METHODS: A retrospective review of a single surgeon's experience was performed over a 2 year period for patients who underwent a procedure involving piled-up e-PTFE sheets for alloplastic chin augmentation. This study analyzed the outcomes, complications (temporary nerve numbness, wound infection, hematoma formation, and implant displacement), and patient satisfaction during follow-up. RESULTS: Between January 2018 and December 2020, 38 patients underwent the procedure involving piled-up e-PTFE sheets for alloplastic chin augmentation. Six patients (15.8%) experienced nerve-related temporary numbness, and one (2.6%) experienced wound infection. None had developed major complications such as implant displacement or wound infection at follow-up. Moreover, the patients demonstrated a high level of satisfaction with the surgical results. CONCLUSION: Piled-up e-PTFE sheets can be used to produce custom-fit porous polyethylene chin implants that result in minimal complications and a very high satisfaction rate. 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 .

Jawline Sharp Contouring With Hybrid Filler.

BACKGROUND: Having a well-defined jawline is a sign of youth and attractiveness among both men and women. Soft tissue fillers, such as calcium hydroxylapatite (CaHA) and hyaluronic acid (HA) fillers, offer nonsurgical alternatives for rejuvenating the lower face and enhancing the jawline. The aim of this study was to investigate the use of a premixed combination of HA with cohesive polydensified matrix technology (CPM, Belotero Intense, CPM-I) and CaHA to create a sharply defined jawline. METHODS: A total of 126 patients were enrolled in the study and treated with a premixed combination of CPM-I and CaHA using a retrograde fanning injection technique with cannulas. The injection volumes and product ratios were customized according to the patients' needs. RESULTS: The cohort consisted of 75 females and 51 males. The average injected volume of premixed CaHA:CPM-I was 5.83 mL. In the majority of patients, a 1:1 syringe ratio of CaHA:CPM-I was applied (n = 81, 64.2%). No adverse events were reported during the 6-month follow-up period. CONCLUSION: The hybrid filler approach investigated in this study shows promise for achieving well-defined, long-lasting jawline contours. 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 .

Hybrid Chin Advancement: Combining Fat and Sliced Cartilage Grafts for Chin Augmentation During Rhinoplasty.

BACKGROUND: Facial balance significantly impacts aesthetics, particularly in the middle and lower thirds. Patients with chin retrusion often benefit from sagittal plane chin advancement in rhinoplasty, enhancing surgical outcomes and satisfaction. OBJECTIVES: This article presents a method for analyzing chin deformities and discusses a hybrid treatment approach to harmonize facial features, complementing rhinoplasty. METHODS: The chin positions of patients treated by the senior author were assessed. A retrospective analysis included 49 patients with chin retrusion of 2.5-6 mm. Among them, 22 patients initially offered chin implants declined, leading to planned chin augmentation. Fat grafting was exclusively performed for 20 patients lacking sufficient cartilage. The "Hybrid Chin Advancement" technique involved supporting tissues beneath muscles with nasal septum cartilage and fat injections and tissues above muscles with fat injection alone. RESULTS: Pre- and postoperative Legan angle measurements and chin advancements were compared across three groups. While preoperative Legan angles were statistically similar, postoperative Legan angles and advancement changes were significantly higher in the implant group (p < 0.0001). Comparing hybrid chin advancement and fat grafting groups, postoperative Legan angles and advancement changes were significantly higher in the hybrid chin group (p < 0.0001). CONCLUSIONS: Fat grafting suffices for mild advancements (~ 2 mm), while the hybrid chin method is effective for moderate advancements (~ 4 mm). For advancements exceeding 6 mm, implants or osseous genioplasty are optimal. Our study's hybrid approach offers an easy, safe, and reliable method for achieving facial harmony in the lower two-thirds without compromising patient expectations. 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 .

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 .

Chin Augmentation and Treatment of Chin Retrusion with a Flexible Hyaluronic Acid Filler in Asian Subjects: A Randomized, Controlled, Evaluator-Blinded Study.

BACKGROUND: Aesthetic improvement of the chin is increasingly requested by patients, including those of Chinese origin. METHODS: A randomized, evaluator-blinded, no-treatment controlled study evaluated the effectiveness and safety of a flexible hyaluronic acid (HA) filler, Restylane® DefyneTM (HADEF), in the correction of chin retrusion in a Chinese adult population over 12 months after treatment. On Day 1, subjects were randomized 3:1 into two groups, HADEF or delayed-treatment controls, and those in the HADEF group were administered treatment. An optional touch-up treatment was administered 1 month after treatment to obtain optimal chin augmentation. The initially untreated control group was offered delayed-treatment after 6 months (including 1-month touch-up). RESULTS: HADEF was superior to no-treatment in improving chin retrusion according to the blinded evaluator at 6 months [Galderma Chin Retrusion Scale (GCRS) responder rate (≥ 1-point improvement from baseline) of 81% vs. 5% for untreated controls; p < 0.001, meeting the primary effectiveness objective. A majority of subjects maintained improvement at 12 months (61% in the HADEF group). All subjects reported satisfaction with results at 6 months after treatment with HADEF and aesthetic improvement rates per the global aesthetic improvement scale (GAIS) were high for 12 months following treatment, with an acceptable safety profile. CONCLUSIONS: These results demonstrated HADEF to be effective and safe for the correction of mild-to-moderate chin retrusion in Chinese subjects, confirming findings previously observed in a western population. LEVEL OF EVIDENCE I: 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 .

Quantitative and qualitative condylar changes following stabilization splint therapy in patients with temporomandibular joint disorders with and without skeletal lateral mandibular asymmetry: a cone beam computed tomographic study.

BACKGROUND: Temporomandibular disorders (TMDs) encompass pain and dysfunction in the jaw, muscles, and adjacent structures. This study aimed to explore the quantitative (condylar position, morphology) and qualitative (bone mineral density (BMD)) therapeutic outcomes following a stabilization splint (S.S.) therapy in adult patients diagnosed with TMD (Arthralgia) with/without lateral mandibular asymmetry (MA) using cone beam computed tomography (CBCT). METHODS: In this retrospective clinical study, 60 adult TMD patients who received S.S. therapy were enrolled and allocated into the TMD group (TMDG) and TMD with MA group (TMD + MAG). The diagnosis was made according to the Diagnostic Criteria for TMD (DC/TMD) AXIS I. MA was measured from the mid-sagittal plane to the Menton point. CBCT was used to scan the temporomandibular joints pre- (T0) and post- (T1)-treatment for three-dimensional analysis. Intra- and intergroup statistical comparisons were performed using the Wilcoxon signed ranks and the Kruskal‒Wallis test. RESULTS: For quantitative comparisons, there was a statistically significant difference between T0 and T1 in the joint spaces of TMD + MAG (anterior, superior, posterior, and coronal lateral on the deviated side as well as in the superior, coronal medial joint space of the contralateral side). Morphologically, the deviated side had a narrower condylar width, reduced condylar height, and a steeper eminence angle. In contrast, the contralateral side tended to have a greater condylar length. For qualitative measurements, BMD also showed statistical significance between T0 and T1 in the majority of the condyle slopes (AS, SS, PS, and LS on the deviated side and in AS and MS on the contralateral side) of TMD + MAG. Additionally, only the AS and PS showed significance in TMDG. CONCLUSION: Multiple joint space widening (AJS and CMS) and narrowing (SJS, PJS, and CLS) could characterize the deviated side in TMD + MA. Factors like narrower condylar width, reduced condylar height, and steeper eminence angle on the deviated side can worsen TMD + MA. Proper alignment of the condyle-disc position is essential for optimal function and load distribution, potentially affecting bone mineral density (BMD). MA plays a prominent role in disturbing bone densities. S.S. therapy shows more evident outcomes in TMD + MAG (on the deviated side compared to the contralateral side) than the TMDG.

[Preliminary evaluation of chin symmetry with three dimentional soft tissue spatial angle wireframe template].

OBJECTIVE: To develop an efficient and robust method based on three dimensional facial landmarks for evaluating chin region asymmetry at the soft tissue level and to compare it with the traditional mirror-overlap analysis method in order to test its availability. METHODS: Standard symmetrical face was used for mental tubercle coordinate transformation so as to filter soft tissue three dimensional spatial angle and construct corresponding three dimensional spatial angle wireframe template. Ten patients aged 12-32 years with clinical chin region asymmetry diagnosis at the Department of Orthodontics of Peking University Hospital of Stomatology from November 2020 to November 2021 were randomly selected. Three dimensional soft tissue face scan data of the patients were collected by three dimensional face scanner and the landmark points were automatically determined by the Meshmonk non-rigid registration algorithm program, and in this way, the asymmetric three dimensional spatial angle wireframe template and corresponding spatial angle parameters were generated. Mirror-overlap analysis of face scan data was also performed in Geomagic Studio 2015 software and deviation color maps were generated. This study took mirror-overlap analysis as the gold standard method, the response rate of chin region asymmetry was eva-luated by the outcomes of the mirror-overlap analysis and three dimensional spatial angle wireframe template analysis. RESULTS: Nine three dimensional spatial angle indicators were selected through coordinate transformation, and the response rate was calculated using mirror-overlap analysis as the gold standard method. Among these ten selected patients, the response rate of the total chin region asymmetry was 90% (9/10). Using the deviation value of mirror-overlap analysis as a reference, the response rate of chin region asymmetry in the X dimension was 86%, the response rate of chin region asymmetry in the Y dimension was 89%, and the response rate of chin region asymmetry in the Z dimension was 100%. CONCLUSION: The three dimensional soft tissue spatial angle wireframe template proposed in this study has some feasibility in evaluating chin region asymmetry at the soft tissue level, and its ability to recognize asymmetry separately in the three dimensional direction is better than the mirror-overlap analysis method, and the indicators recognition rate still needs to be further improved.

Hair reconstruction of the burned chin region using a pre-expanded free temporo-parietal skin flap. About a case.

Reconstruction of the chin region represents a technical challenge due to its three-dimensional configuration and its location close to the mouth. It requires both a functional approach by restoring mobility and an aesthetic approach by restoring the perioral furrows. For men who want to wear a beard, it becomes more difficult to choose the donor site for hairy skin. In that case, strategies of full thickness skin graft or pre-expanded loco-regional flaps are unusable. We propose here a functional, aesthetic and hairy reconstruction by performing a pre-expanded temporal free flap which allowed to resolve the problem of adjacent cervical contractures and to restore an integrated the bearded chin subunit.

Vertical ridge augmentation of atrophic posterior mandible with corticocancellous onlay symphysis graft versus sandwich technique: clinical and radiographic analysis.

Alveolar ridge augmentation of atrophic posterior mandibular ridge represents a challenge in oral and maxillofacial surgery to restore aesthetic and function. The aim of the study was to compare the clinical and radiographic outcomes of bone formation in atrophic posterior mandibles augmented using onlay symphysis cortico-cancellous bone block with that augmented using sandwich bone augmentation technique (Inlay). Twelve patients were selected with missing mandibular posterior teeth. CBCT were done for all patients preoperatively to assess the residual bone height, ranged between 5 and 7 mm from the inferior alveolar nerve with adequate sufficient alveolar ridge width more than 4 mm. Patients required bone augmentation procedure with autologous onlay chin graft (group I) versus those used as inlay sandwich technique (group II). Clinical and radiographic analysis were done to analyses the newly formed bone and bone height. Percent of change in bone height was also calculated and revealed that group I was higher than group II, however, statistically insignificant differences between the two groups were found regarding the percentage of newly formed bone. Vertical ridge augmentation procedures using onlay chin graft took lesser time than the interpositional grafting with fixation technique, however, both techniques are promising for vertical ridge augmentation.

Correcting the Broad, Flat and Short Chin Using Modified M-genioplasty.

BACKGROUND: Several genioplasty techniques can narrow the width of the chin. Nevertheless, patients with a broad and short chin who received these methods were unsatisfied with the outcomes. The goal of this study was to analyze the clinical outcomes of modified M-shaped genioplasty for broad, flat and short chin deformity. METHODS: Thirty-eight patients with broad, flat and short chins were included in this study from January 2019 to December 2021. The preoperative design was performed individually according to the data of the chin and the patient's desire of final chin shape. Narrowing and vertical elongating genioplasty was performed for all the patients with modified M-shaped genioplasty under general anesthesia according to the preoperative designs. All patients have completed the FACE-Q preoperatively and 3 months postoperatively. The results were evaluated by clinical appearances and FACE-Q scores. RESULTS: The vertical lengthening of the chin was 2-5 mm, with an average of 3.02 mm. The horizontal narrowing width was 3-6 mm, with an average of 5.6 mm. FACE-Q scores in satisfaction with the chin increased significantly from 35.34 ± 9.57 to 72.95 ± 6.81. There were no severe complications took place during the time frame of 3-24 months postoperatively. CONCLUSIONS: The modified M-shaped genioplasty preserved the bone structure in the midsymphyseal area and suprahyoid muscular attachments as far as possible, and the bone segments may be repositioned quickly. This technique produced reliable and esthetically satisfying results in correcting a short, flat and broad chin, with altered vertical length, slope, width and protrusion three-dimensionally. 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 .

Nonsurgical Chin Augmentation Using Hyaluronic Acid: A Systematic Review of Technique, Satisfaction, and Complications.

BACKGROUND: Nonsurgical chin augmentation using hyaluronic acid (HA) has become a common procedure in cosmetic practices. This is offered to patients that prefer a nonsurgical, temporary method to correcting underdeveloped or retruded chin and restoring the volume loss. This systematic review highlights the main HA injection technique and associated patient satisfaction and complications of chin augmentation to further guide practitioners. METHODS: A systematic review was performed according to PRISMA guidelines. PubMed, Embase, and Web of Science were searched using the appropriate keywords. Data collected from each study included patient satisfaction and complications, in addition to injection protocol and technique. RESULTS: A total of 1305 studies were found based on search criteria. After full-text screening for inclusion and exclusion criteria, 8 studies were included. A total of 917 patients underwent HA chin augmentation, with different injection protocols. Most patients were satisfied with the results, and there were only 2 relatively major complications reported. The most common adverse events were local responses at the injection sites (swelling, bruising, pain, redness, and itching). There were no reports of vascular complications. CONCLUSIONS: HA filler is an effective temporary method to correct chin retraction and absorption for chin augmentation, with a high degree of patient satisfaction and a low risk of severe complications. LEVEL OF EVIDENCE III: 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 .

The Versatile Role of Fat Injection During Various Genioplasties.

BACKGROUND: Fat injection has become increasingly popular in aesthetic surgery, but there is a sparsity of literature regarding its role during genioplasty. In this study, we present the largest series of patients receiving fat injections to the chin for various indications. METHODS: Data were collected from January 2016 to December 2021 for patients who underwent chin fat injection for a variety of chin refinements. Patients with chin fat injection were divided into isolated genioplasty with fat injection (CF), combined facial and chin fat injection (CFC) and combined chin fat injection and osseous genioplasty (CFG). Complication rates and reoperations were compared using Fischer's exact test between each cohort. RESULTS: 181 patients were included in final analysis, with 14 patients in CF cohort, 130 patients in CFC cohort, 24 patients in CFG cohort, and 13 patients who underwent genioplasty alone. Repeat fat injections were required in 17 (9.4%) patients overall, which included 14 patients (10.8%) of CFC subcohort and three patients (12.5%) of CFG subcohort (p > 0.05). No patients who underwent genioplasty alone or CF required reoperation. There were no significant differences in complications between genioplasty alone group (0%) in comparison to CF (7.1%; p = 1.00), CFC (6.2%; p = .53), or CFG cohorts (7.7%; p = 1.00). CONCLUSION: Fat injection can safely correct minor chin deficiency or asymmetry, as either an isolated procedure or in combination with osteotomies. Additionally, fat injection enables advancement of the caudal segment to achieve superior outcomes by preventing unaesthetic deepening of labiomental groove which will not be advanced during sliding osteotomy. 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 .