The Impact of Orthognathic Surgery on Facial Expressions

Impact of the Orofacial Muscular Rehabilitation Exercise on Facial Expression Recovery Post-Orthognathic Surgery

OBJECTIVE

This study aimed to evaluate the impact of myofunctional rehabilitation of the orofacial muscles through specific exercises on the recovery of facial expression in patients following orthognathic surgery.

MATERIAL AND METHODS

The study included 62 patients who underwent Le Fort I and sagittal split ramus osteotomy (SSRO). Patients were divided into two groups: the first group started immediate post-operative myofunctional rehabilitation of the orofacial muscles through specific exercises. In contrast, patients in Group II did not undergo any myofunctional rehabilitation post-operative exercises. The recovery of facial expressions postoperatively was evaluated in both calm and smiling states by comparing the differences between 3D facial scanning data of chosen facial anatomical structures collected at five key time points: pre-surgery (D0), 2 days (D2), 14 days (D14), 1 month (D30), and 3 months (D90) postoperatively.

RESULTS

The analysis revealed that characteristic angles and lengths experienced significant changes post-surgery, with ∠chRnchL and ∠chRsnchL decreasing at D2 and normalizing by D30 in the experimental group, while the control group showed a slower recovery, normalizing by D90. The ChL-R length decreased at D2, returning to normal by D30 in the experimental group and D90 in the control group. The height Li-Ls increased at D2 and normalized by D30 in calm and smiling expressions across single and double jaw surgery patients. These findings underscore the more rapid recovery in the experimental group compared to the control group (P < 0.05; P < 0.005; P < 0.0001).

CONCLUSION

Initiating myofunctional rehabilitation immediately following orthognathic surgery enhances facial muscle function recovery, improves patient confidence, and expedites social reintegration. This approach is crucial for functional and psychological benefits.

New method for analysing spatial relationships of facial muscles on MRI: a pilot study

Dysfunction of the facial musculature can have significant physical, social, and psychological consequences. In surgeries such as cleft surgery or craniofacial bimaxillary osteotomies, the perioral facial muscles may be detached or severed, potentially altering their functional vectors and mimicry capabilities. Ensuring correct reconstruction and maintenance of anatomical sites and muscle vectors is crucial in these procedures. However, a standardized method for perioperative assessment of the facial musculature and function is currently lacking. The aim of this study was to develop a workflow to analyse the three-dimensional vectors of the facial musculature using magnetic resonance imaging (MRI) scans. A protocol for localizing the origins and insertions of these muscles was established. The protocol was implemented using the 3DMedX computer program and tested on 7 Tesla MRI scans obtained from 10 healthy volunteers. Inter- and intra-observer variability were assessed to validate the protocol. The absolute intra-observer variability was 2.6 mm (standard deviation 2.0 mm), and absolute inter-observer variability was 2.6 mm (standard deviation 1.5 mm). This study presents a reliable and reproducible method for analysing the spatial relationships and functional significance of the facial muscles. The workflow developed facilitates perioperative assessment of the facial musculature, potentially aiding clinicians in surgical planning and potentially enhancing the outcomes of midface surgery.

Addressing Acromegaly-Related Malocclusion With Surgery-First Orthognathic Surgery: A Clinical Case Report

Angle's class III malocclusions are characterized by the anterior positioning of the mandible in relation to the maxilla. The discrepancy can be caused by an anterior deficiency of the maxilla, excessive mandibular prognathism, or a combination of both. Acromegaly is a dysfunction caused by the excessive production of growth hormone (GH), which leads to systemic changes and orofacial manifestations. In acromegaly caused by a pituitary adenoma, which secretes an excessive amount of GH, disproportionate mandibular growth may occur, leading to skeletal class III malocclusion in adulthood. Excessive growth stops when the tumor is removed, but the skeletal deformity persists, requiring orthognathic surgery to reposition the mandible. This article reports the case of a 31-year-old man referred to the maxillofacial surgery consultation due to severe Angle's class III malocclusion, with prognathism, mandibular asymmetry, and maxillary retrusion. He had a history of disproportionate soft tissue growth (hands and feet) up to 18 years old, less evident after that age. Considering the possibility of acromegaly due to a pituitary adenoma, imaging studies (CT scan and magnetic resonance imaging (MRI)) and directed analytical studies were requested. When the diagnosis was confirmed, the patient was referred to endocrinology and neurosurgery consultations. After undergoing endoscopic resection of the pituitary adenoma, the patient underwent surgery-first orthognathic surgery to correct the dental malocclusion.

The Ability to Sustain Facial Expressions

To gain more insight into facial muscle function, imaging during action would be optimal. Magnetic resonance imaging is highly suitable for visualizing facial muscles. However, magnetic resonance imaging requires the individual to remain as still as possible for a while. Knowledge of the ability to sustain facial expressions is requisite before scanning individuals. This could help adapting the scanning protocol to obtain optimal quality of imaging the muscles in action. A study, including 10 healthy volunteers, was done to perceive the extent of movement while holding facial expressions of smiling and pouting. During 6 minutes, 3-dimensional photographs were taken every consecutive minute while the participants maintained their facial expressions as motionless as possible. The movement was objectified by creating distance maps between the 2 models and calculating the Root Mean Square using the software 3DMedX. The results showed that most movements occurred in the first minute, with a decrease of the intensity of the expression. After the first minute, the expression, although less intense, could be held stable. This implies that magnetic resonance imaging scanning during facial expression is possible, provided that the scanning starts after the first minute has elapsed. In addition, results demonstrated that more slackening of the muscles while smiling compared with pouting.

The impact of orthodontic-surgical treatment on facial expressions-a four-dimensional clinical trial

OBJECTIVE

The objective of this clinical trial was to compare facial expressions (magnitude, shape change, time, and symmetry) before (T0) and after (T1) orthognathic surgery by implementing a novel method of four-dimensional (4D) motion capture analysis, known as videostereophotogrammetry, in orthodontics.

METHODS

This prospective, single-centre, single-arm trial included a total of 26 adult patients (mean age 28.4 years; skeletal class II: n = 13, skeletal class III: n = 13) with indication for orthodontic-surgical treatment. Two reproducible facial expressions (maximum smile, lip purse) were captured at T0 and T1 by videostereophotogrammetry as 4D face scan. The magnitude, shape change, symmetry, and time of the facial movements were analysed. The motion changes were analysed in dependence of skeletal class and surgical movements.

RESULTS

4D motion capture analysis was feasible in all cases. The magnitude of the expression maximum smile increased from 15.24 to 17.27 mm (p = 0.002), while that of the expression lip purse decreased from 9.34 to 8.31 mm (p = 0.01). Shape change, symmetry, and time of the facial movements did not differ significantly pre- and postsurgical. The changes in facial movements following orthodontic-surgical treatment were observed independently of skeletal class and surgical movements.

CONCLUSIONS

Orthodontic-surgical treatment not only affects static soft tissue but also soft tissue dynamics while smiling or lip pursing.

CLINICAL RELEVANCE

To achieve comprehensive orthodontic treatment plans, the integration of facial dynamics via videostereophotogrammetry provides a promising approach in diagnostics.

TRIAL REGISTRATION NUMBER

DRKS00017206.

Novel Baseline Facial Muscle Database Using Statistical Shape Modeling and In Silico Trials toward Decision Support for Facial Rehabilitation

Backgrounds and Objective: Facial palsy is a complex pathophysiological condition affecting the personal and professional lives of the involved patients. Sudden muscle weakness or paralysis needs to be rehabilitated to recover a symmetric and expressive face. Computer-aided decision support systems for facial rehabilitation have been developed. However, there is a lack of facial muscle baseline data to evaluate the patient states and guide as well as optimize the rehabilitation strategy. In this present study, we aimed to develop a novel baseline facial muscle database (static and dynamic behaviors) using the coupling between statistical shape modeling and in-silico trial approaches. Methods: 10,000 virtual subjects (5000 males and 5000 females) were generated from a statistical shape modeling (SSM) head model. Skull and muscle networks were defined so that they statistically fit with the head shapes. Two standard mimics: smiling and kissing were generated. The muscle strains of the lengths in neutral and mimic positions were computed and recorded thanks to the muscle insertion and attachment points on the animated head and skull meshes. For validation, five head and skull meshes were reconstructed from the five computed tomography (CT) image sets. Skull and muscle networks were then predicted from the reconstructed head meshes. The predicted skull meshes were compared with the reconstructed skull meshes based on the mesh-to-mesh distance metrics. The predicted muscle lengths were also compared with those manually defined on the reconstructed head and skull meshes. Moreover, the computed muscle lengths and strains were compared with those in our previous studies and the literature. Results: The skull prediction's median deviations from the CT-based models were 2.2236 mm, 2.1371 mm, and 2.1277 mm for the skull shape, skull mesh, and muscle attachment point regions, respectively. The median deviation of the muscle lengths was 4.8940 mm. The computed muscle strains were compatible with the reported values in our previous Kinect-based method and the literature. Conclusions: The development of our novel facial muscle database opens new avenues to accurately evaluate the facial muscle states of facial palsy patients. Based on the evaluated results, specific types of facial mimic rehabilitation exercises can also be selected optimally to train the target muscles. In perspective, the database of the computed muscle lengths and strains will be integrated into our available clinical decision support system for automatically detecting malfunctioning muscles and proposing patient-specific rehabilitation serious games.

Causes of Reoperation Consultation and Clinical Review of Actual Reoperation After Previous Orthognathic Surgery

OBJECTIVE

To investigate the causes of reoperation consultation, and the actual percentage and procedures of reoperation after previous orthognathic surgery.

METHODS

The samples consisted of 30 patients who visited our clinic for reoperation consultation from October 2015 to September 2021 (6 males and 24 females; mean age at reoperation consultation, 28.4 y). Patient's causes of reoperation consultation were divided into "esthetic dissatisfaction," "airway changes," "temporomandibular disorders," "uncomfortable occlusion," and "other complications". In terms of esthetic dissatisfaction, the more detailed esthetic problem was evaluated by the clinical chart, facial photographs, and radiographs. In patients who actually underwent reoperation, the actual percentage and procedures of reoperation were investigated.

RESULTS

The most prevalent causes for reoperation consultation were "esthetic dissatisfaction" (n = 21, 70.0%), followed by "airway changes" (n = 11, 36.7%), "uncomfortable occlusion" (n = 8, 26.7%), "other complications" (n = 5, 16.7%), and "temporomandibular disorder" (n = 4, 13.3%). Less than half of patients actually underwent reoperation (n = 13, 43.3%). Actual reoperation procedures included minor revision surgery, reconstruction surgery, or complete reoperation according to the patient's need. In case of complete reoperation, more accurate and predictable results were obtained by using virtual surgical planning, customized surgical guides, titanium surgical plates made with computer-aided design and computer-aided manufacturing technique, and a 3-dimensional printing method.

CONCLUSION

It is important to communicate with patients about expectations for facial esthetic improvement by orthognathic surgery for obtaining the patient's postoperative satisfaction.

An objective, quantitative, dynamic assessment of facial movement symmetry changes after orthognathic surgery

The aim of this study was to generate a quantitative dynamic assessment of facial movement symmetry changes after orthognathic surgery. Twenty-five patients diagnosed with skeletal class III malocclusion with facial asymmetry who underwent bimaxillary surgery were recruited. The patients were asked to perform a maximum smile that was recorded using a three-dimensional facial motion capture system preoperatively (T0), 6 months postoperatively (T1), and 12 months postoperatively (T2). Eleven facial landmarks were selected to analyse the cumulative distance and average speed during smiling. The absolute differences for the paired landmarks between the sides were analysed to reflect the symmetry changes. The results showed that the asymmetry index of the cheilions at T2 was significantly lower than that at T0 (P = 0.004), as was the index of the mid-lateral lower lips (P = 0.006). The mean difference in cheilions was 2.13 ± 1.41 mm at T0, 1.33 ± 1.09 mm at T1, and 1.00 ± 0.98 mm at T2. The facial total mobility at T1 was significantly lower than that at T0 (P < 0.001), while the total mobility at T2 was significantly higher than that at T1 (P = 0.012). The orthognathic surgical correction of facial asymmetry was able to improve the associated asymmetry of facial movements.

Effectiveness of Physical Therapy in Orthognathic Surgery Patients: A Systematic Review of Randomized Controlled Trials

Orthognathic surgery (OS) can present many complications that affect patients' rehabilitation. However, there have been no systematic reviews that assessed the effectiveness of physiotherapy interventions in the postsurgical rehabilitation of OS patients. The aim of this systematic review was to analyze the effectiveness of physiotherapy after OS. The inclusion criteria were randomized clinical trials (RCTs) of patients who underwent OS and who received therapeutic interventions that included any physiotherapy modality. Temporomandibular joint disorders were excluded. After the filtering process, five RCTs were selected from the 1152 initially obtained (two had acceptable methodological quality; three had insufficient methodological quality). The results obtained showed that the effects of the physiotherapy interventions studied in this systematic review on the variables of range of motion, pain, edema and masticatory muscle strength were limited. Only laser therapy and LED showed a moderate level of evidence in the postoperative neurosensory rehabilitation of the inferior alveolar nerve compared with a placebo LED intervention.

The Average Facial Expressions: A Range of Motion Analysis for Different Sex and Age Groups

Facial expressions are ubiquitous in communication. Therefore, assessment of mimic function is essential in facial surgery, but no reference standards are currently available. This prospective study aims to create reference values of three-dimensional landmark displacement for different sex and age groups.

Methods

Three-dimensional photographs were taken from healthy subjects in rest, maximum closed smile, and pouting. Displacement for both exercises of perioral landmarks was analyzed with MATLAB as absolute displacement and as the ratio of mouth width. Additionally, displacement in three planes was analyzed for each landmark. Averages were calculated for both genders in four age groups: 4-8, 8-12, 12-16, and >16 years.

Results

In total, 328 subjects were included. Oral landmarks predominantly moved forward and backward for both exercises. Nasal landmarks predominantly moved vertically. Growing up, oral landmark displacement decreased for smiling, whereas nasal landmark displacement increased. For pouting, oral landmark displacement increased while growing up, whereas nasal landmark displacement decreased.

Conclusions

The present study creates reference values for movement of perioral structures for different sex and age groups, for two facial expressions. These data are of great value for the assessment of mimic function and give insight into the development of facial animation over time.

Creating Three-Dimensional Templates of Smiling and Pouting Faces for Different Sex- and Age Groups

Smile appearance has a major psychological impact. Orthognathic surgery, which has harmonizing results on skeletal structures, can negatively influence the smile appearance due to soft tissue effects. To enhance the aesthetic effects of orthognathic surgery on soft tissues, reference models for large parts of the hospital’s adherent area are called for. This study aims to create average facial models for different sex and age groups in two facial exercises: maximum closed smile, and pouting. These models were created using coherent point drift and Procrustes algorithms in MATLAB. Principal component analysis was performed, and of 20 surgical landmarks, the in-group variation using standard deviation was calculated. Three distances were analyzed: nasal width, philtral width, and mouth width. To correct for facial size, these distances were analyzed as a ratio of intercanthal width. In total, 328 healthy subjects were included in the study. Subjects were grouped by sex, and in age categories spanning four years each, with an adult group with all ages >16 years. For both smiling and pouting faces, all ratios increased with ageing. These templates and data can benefit facial surgeons, to obtain an expected outcome according to the age of the patient.

Smile Reanimation with Masseteric-to-Facial Nerve Transfer plus Cross-Face Nerve Grafting in Patients with Segmental Midface Paresis: 3D Retrospective Quantitative Evaluation

Facial paresis involves functional and aesthetic problems with altered and asymmetric movement patterns. Surgical procedures and physical therapy can effectively reanimate the muscles. From our database, 10 patients (18–50 years) suffering from unilateral segmental midface paresis and rehabilitated by a masseteric-to-facial nerve transfer combined with a cross-face facial nerve graft, followed by physical therapy, were retrospectively analyzed. Standardized labial movements were measured using an optoelectronic motion capture system. Maximum teeth clenching, spontaneous smiles, and lip protrusion (kiss movement) were detected before and after surgery (21 ± 13 months). Preoperatively, during the maximum smile, the paretic side moved less than the healthy one (23.2 vs. 28.7 mm; activation ratio 69%, asymmetry index 18%). Postoperatively, no differences in total mobility were found. The activity ratio and the asymmetry index differed significantly (without/with teeth clenching: ratio 65% vs. 92%, p = 0.016; asymmetry index 21% vs. 5%, p = 0.016). Postoperatively, the mobility of the spontaneous smiles significantly reduced (healthy side, 25.1 vs. 17.2 mm, p = 0.043; paretic side 16.8 vs. 12.2 mm, p = 0.043), without modifications of the activity ratio and asymmetry index. Postoperatively, the paretic side kiss movement was significantly reduced (27 vs. 19.9 mm, p = 0.028). Overall, the treatment contributed to balancing the displacements between the two sides of the face with more symmetric movements.

Changes in facial width according to the ostectomy level of the proximal bone segment in intraoral vertical ramus osteotomy for mandibular prognathism

Background

This study aimed to investigate the changes in facial width according to the ostectomy level of the proximal segment after orthognathic surgery using intraoral vertical ramus osteotomy (IVRO) in patients with mandibular prognathism.

Methods

The participants included 32 individuals who were diagnosed with class III malocclusion prior to surgery. All participants underwent orthognathic surgery using either version of IVRO. The surgery patients were categorized into two groups depending on the type of proximal bone-segment ostectomy technique used: patients whose osteotomy height was at the level of the mandibular tooth occlusal surface (the mandibular tooth surface–level group) and patients whose osteotomy height was at the level of the mandibular inferior border (the mandibular inferior border–level group). The distances between the mandibular width and soft tissue width at the height of the sigmoid notch, mandibular foramen, and alveolar bone and at the anterior-posterior location of the mandibular condyle, mandibular foramen, and coronoid process were compared between the groups. All data were compared to identify differences between preoperative and postoperative measurements.

Results

The postoperative change in facial soft tissue width at the intersection of the coronal plane with the coronoid process and the horizontal plane at the height of the mandibular alveolar bone in the group with osteotomy at the level of the mandibular occlusal surface differed significantly from that in the group with osteotomy at the level of the mandibular inferior border, with respective increases (mean ± SD) of 1.3 ± 3.5% and 4.7 ± 5.6%, compared to preoperative measurements (p = 0.050).

Conclusions

Proximal segment ostectomy at the level of the mandibular occlusal surface must be considered with regard to postoperative facial soft tissue width in vertical ramus osteotomy. Additionally, it is necessary to study the visual effect of the width of the mandible appearing small because of the posterior position of the mandible, even when the mandibular facial width is maintained.

Identification of the Peri-oral Mimic Muscles on Cadaver Slices and 3 and 7 Tesla MRI Scans

Decreased smile dynamics is reported as an unwanted side effect after Le Fort I osteotomies. It is assumed that this negative sequela might be caused by postoperative changes in the anatomy of peri-oral mimic muscles. Due to a lack of specific anatomical knowledge, the exact mechanism is not yet clarified. This makes prevention of the undesired changes in smile dynamics difficult. The first aim of this study is to increase basic anatomical and radiological MRI knowledge of the peri-oral mimic muscles. The second aim is to investigate if 7 Tesla MRI scans are better suited to identify these muscles than 3 Tesla MRI scans.

Facial Contour Refining after Surgery-First SSRO with Computer-Assisted Design in East Asians

BACKGROUND

Surgery-first sagittal split ramus osteotomies (SF-SSRO) are an effective treatment for patients with dental malocclusion. However, some patients with mandibular prognathism usually have facial deficiencies which cannot be corrected completely after orthognathic surgery. These are not accepted because the remaining facial contours are in disharmony.

METHODS

Twenty-five patients, who were unsatisfied with their appearances after SF-SSRO and orthodontics, were included. The preoperative CTs were used to investigate patients for facial deformity. To achieve a harmonious facial contour, mandible long-curve osteotomy/mandible U-shaped osteotomy, genioplasty or facial autologous fat grafting was selected depending on patients' contour deformities with the assistance of CAD.

RESULTS

Among the patients who underwent osteotomy, the gonial angle was improved from 111.16° ± 9 to 111.58° ± 9.06 after SF-SSRO because of distal fragment setback and rotation. After facial refine surgery, the gonial angle was significantly increased to 121.69°±2.41 (p < 0.05). And the mandibular width was decreased from 11.29 cm ± 0.44 to 10.45 cm ± 0.39 (p < 0.05) after mandibular outer plate griding. All patients were shown no signs of infection, massive bleeding, and osteonecrosis in the early stage. After follow-up time, they were all satisfied with their results and most of them recovered from lip numbness.

CONCLUSIONS

This study indicated the clinical feasibility of two-stage orthognathic and facial bone contouring surgery for the treatment of dentofacial deformities. Two-stage facial contouring surgery can provide esthetic improvement for more accuracy in refining the facial contour.

LEVEL OF EVIDENCE IV

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Association of masseter muscles thickness and facial morphology with facial expressions in children

OBJECTIVE

To evaluate the potential influence of muscular capacity and facial morphology on facial expressions in children.

MATERIALS AND METHODS

A cross-sectional study was carried out on 40 healthy children (ages 9-13), without previous orthodontic treatment. Masseter muscle thickness and anthropometric facial proportions were measured using ultrasound and digital calipers respectively. A three-dimensional infrared face-tracking system was used to register facial expressions. The maximal amplitude of smile and lip pucker (representing maximal lateral and medial commissure movement) were used for analysis. Stepwise regression was used to investigate whether muscle thickness or anthropometric facial proportions were associated with the quantity of commissure movement.

RESULTS

When performing maximal smile, children with thicker masseter muscles were found to have more limited displacement of the commissures (R = 0.39; p = 0.036). When performing lip pucker, children with thicker masseter muscles were found to have greater commissure movement (R = 0.40; p = 0.030). No significant associations were found between anthropometric facial proportions and facial expressions.

CONCLUSION

Masseter muscle thickness seems to be associated with facial expressions in children. Those with thicker muscles show more limited commissure movement when smiling, but greater movement with lip pucker. This indicates that masticatory muscles may serve as a surrogate for mimic muscle activity. Facial morphology of the subjects does not seem to be associated with facial expression.

Three-Dimensional Dynamic Analysis of the Reproducibility of Verbal and Nonverbal Facial Expressions

OBJECTIVE

The aim of this study is to compare the short- and long-term reproducibility of verbal and nonverbal facial expressions of normal people using dynamic 3-dimensional (3-D) imaging.

DESIGN

Prospective, cross-sectional, controlled study.

SETTING

Peking University School and Hospital of Stomatology, Beijing, China.

PATIENTS AND PARTICIPANTS

Twenty-seven participants, 12 males and 15 females, were recruited for this study.

METHODS

A 3-D dynamic system was applied to capture the process of 4 nonverbal facial expressions (smile lips closed, smile lips open, lip purse, cheek puff) and 2 verbal facial expressions (/i:/, /u:/) at an initial time point, 15 minutes later, and 1 week later. Key frames were selected from each expression recording sequence.

MAIN OUTCOME MEASURES

The root mean square (RMS) between each key frame and its corresponding frame at rest was calculated. ΔRMS reflected the difference of the same key frames between the different sessions of the same expression of the same participant. The reproducibility of different facial expressions at different time intervals were analyzed.

RESULTS

There was no significant difference in verbal and nonverbal expression repeatability during a 15-minute interval, except for cheek puff motion. Following a 1-week interval, verbal expression repeatability was superior to that of nonverbal expressions (P < .01). Compared with nonverbal expressions, the repeatability of verbal expressions did not obviously decrease with the increase in recording interval.

CONCLUSIONS

Dynamic 3-D imaging is a useful technique for facial expression analysis. Verbal expressions showed greater reproducibility than nonverbal expressions.

Kinect-driven Patient-specific Head, Skull, and Muscle Network Modelling for Facial Palsy Patients

BACKGROUND AND OBJECTIVE

Facial palsy negatively affects both professional and personal life qualities of involved patients. Classical facial rehabilitation strategies can recover facial mimics into their normal and symmetrical movements and appearances. However, there is a lack of objective, quantitative, and in-vivo facial texture and muscle activation bio-feedbacks for personalizing rehabilitation programs and diagnosing recovering progresses. Consequently, this study proposed a novel patient-specific modelling method for generating a full patient specific head model from a visual sensor and then computing the facial texture and muscle activation in real-time for further clinical decision making.

METHODS

The modeling workflow includes (1) Kinect-to-head, (2) head-to-skull, and (3) muscle network definition & generation processes. In the Kinect-to-head process, subject-specific data acquired from a new user in neutral mimic were used for generating his/her geometrical head model with facial texture. In particular, a template head model was deformed to optimally fit with high-definition facial points acquired by the Kinect sensor. Moreover, the facial texture was also merged from his/her facial images in left, right, and center points of view. In the head-to-skull process, a generic skull model was deformed so that its shape was statistically fitted with his/her geometrical head model. In the muscle network definition & generation process, a muscle network was defined from the head and skull models for computing muscle strains during facial movements. Muscle insertion points and muscle attachment points were defined as vertex positions on the head model and the skull model respectively based on the standard facial anatomy. Three healthy subjects and two facial palsy patients were selected for validating the proposed method. In neutral positions, magnetic resonance imaging (MRI)-based head and skull models were compared with Kinect-based head and skull models. In mimic positions, infrared depth-based head models in smiling and [u]-pronouncing mimics were compared with appropriate animated Kinect-driven head models. The Hausdorff distance metric was used for these comparisons. Moreover, computed muscle lengths and strains in the tested facial mimics were validated with reported values in literature.

RESULTS

With the current hardware configuration, the patient-specific head model with skull and muscle network could be fast generated within 17.16±0.37s and animated in real-time with the framerate of 40 fps. In neutral positions, the best mean error was 1.91 mm for the head models and 3.21 mm for the skull models. On facial regions, the best mean errors were 1.53 mm and 2.82 mm for head and skull models respectively. On muscle insertion/attachment point regions, the best mean errors were 1.09 mm and 2.16 mm for head and skull models respectively. In mimic positions, these errors were 2.02 mm in smiling mimics and 2.00 mm in [u]-pronouncing mimics for the head models on facial regions. All above error values were computed on a one-time validation procedure. Facial muscles exhibited muscle shortening and muscle elongating for smiling and pronunciation of sound [u] respectively. Extracted muscle features (i.e. muscle length and strain) are in agreement with experimental and literature data.

CONCLUSIONS

This study proposed a novel modeling method for fast generating and animating patient-specific biomechanical head model with facial texture and muscle activation bio-feedbacks. The Kinect-driven muscle strains could be applied for further real-time muscle-oriented facial paralysis grading and other facial analysis applications.

The Effects of Maxillary Movements on Nasal Aesthetics Following Orthognathic Surgery

Improvement of the harmony between facial subunits is the ultimate goal of orthognathic surgery and surgeons must accurately make soft tissue projections for planned bony movements. Yet, few studies have examined the effects' of orthognathic surgery on aesthetic parameters of nasolabial area on a thorough basis.This retrospective study included 61 patients that underwent orthognathic surgery. Demographic data, evaluation period, and surgical details were analyzed. Superficial topographical analysis of intercanthal distance, alar width, nasal height, nasal length, nasal tip protrusion, upper lip height, nasal bone angle, supratip break angle, nasal dorsum angle, nasal tip angle, columellar-lobular angle, columellar-labial angle, upper lip angle, and tip-to-midline angle was recorded before and after surgery. Postoperative changes in these parameters and their correlation to maxillary movements were analyzed.Alar width, upper lip height, columellar-labial angle, supratip break angle, nasal dorsum angle, and upper lip angle increased postsurgery, whereas tip-to-midline angle decreased. Upper lip height and columellar-labial angle were significantly correlated with clockwise/counter-clockwise rotation and anterior re-positioning. Columellar-labial angle increased 2° for each 1 mm of anterior movement and decreased 4° for each 1 mm of counter-clockwise rotation. Novel parameters, such as columellar-lobular angle and tip-to-midline angle, were not associated with any maxillary movement postsurgery.Orthognathic surgery primarily affected the lower third of the nose and changed alar width, upper lip height, supratip break angle, nasal dorsum angle, columellar-labial angle, upper lip angle, and tip-to-midline angle in this region; however, only columellar-labial angle and upper lip height were found to be correlated solely with maxillary movements.

An Innovative Assessment of the Dynamics of Facial Movements in Surgically Managed Unilateral Cleft Lip and Palate Using 4D Imaging

OBJECTIVE

Assess facial asymmetry during maximum smile in patients with surgically managed unilateral cleft lip and palate (UCLP), using a dynamic 3-dimensional (3D) imaging (4-dimensional) system.

DESIGN

Prospective 2 cohort comparative study.

METHODS

Twenty-five surgically managed UCLP cases and 75 controls at 8 to 10 years of age were recruited. Facial movements during maximum smile were recorded using video stereophotogrammetry at a rate of 60 3D facial images per second. Maximum smile took approximately 3 seconds and generated 180 3D facial images for the analysis. A generic facial mesh which consists of more than 7000 quasi landmarks was used for the assessment of facial asymmetry at 5 key 3D frames representing the pattern of maximum smile.

RESULTS

Statistically significant differences were seen regarding the magnitude of facial asymmetry between the UCLP group and the noncleft controls. Higher average asymmetry in the UCLP group was seen in the 3D frame midway between maximum smile and rest (frame 4) followed by the frame at peak expression of maximum smile (frame 3). The average magnitude of nasolabial asymmetry of the control group was within 0.5 mm in comparison with the UCLP cases which was about 1.8 mm.

CONCLUSION

This study provided for the first time, an objective tool for analysis of the dynamics of muscle movements which provided an unprecedented insight into the anatomical basis of the residual dysmorphology. The research demonstrates the limitations of the primary lip repair in achieving symmetrical results and underpins the required refinements to improve the quality of surgical repair of cleft lip.

The effect of facial expression on facial symmetry in surgically managed unilateral cleft lip and palate patients (UCLP)

AIM

To evaluate the symmetry of facial expression in surgically managed UCLP patients.

MATERIALS AND METHODS

The study was conducted on 13 four-year-old children. Facial images were captured at rest and at maximum smile using stereophotogrammetry. A generic mesh, which is a mathematical facial mask consisting of a fixed number of indexed vertices, was utilised for the assessment of facial asymmetry. This was quantified by measuring the disparity between the left- and right-hand sides of the face after superimposing the original 3D images on their mirror copies.

RESULTS

Residual asymmetries at rest were identified at the vermillion of the upper lip and at the nares with a deviation of the philtrum towards the scar tissue. Vertical and anteroposterior asymmetries were identified on the cleft side. At maximum smile, the asymmetry increased noticeably at the vermillion of the upper lip and at the alar base. In the mediolateral direction, the philtrum deviated towards the cleft side with a significant increase of the asymmetry scores.

DISCUSSION

Asymmetry of the upper lip has significantly increased at maximum smile as a result of the upward forces of all perioral lifting muscles, which affected the lip directly.

CONCLUSIONS

The innovation of this study is the measurement of facial asymmetry for the objective outcome measure of the surgical repair of UCLP. The philtrum was the main site of residual asymmetry, which indicates the need for refining the primary repair of the cleft lip. Further corrective surgery may be required.

Three-dimensional longitudinal evaluation of facial mimicry in orthognathic class III surgery

The effect of bimaxillary orthognathic surgery on facial mimicry was assessed longitudinally in 15 patients with dentoskeletal class III facial dysmorphism (seven men, eight women, mean age 28 years). The patients were analysed pre-surgery and at 6, 12, and 24 months post-surgery while performing verbal (five vowels) and non-verbal (open and closed mouth smile, lip purse) soft tissue facial movements. The three-dimensional motions of right and left nasogenian, crista philtri, cheilion, and lower lip landmarks were detected by an optoelectronic instrument, and a total mobility index was obtained. Differences between the sides were quantified by the symmetry index. Patient values were compared to those collected previously from healthy volunteers by computing z-scores. On average, no significant differences were found in the mobility of the buccal soft tissues at 24 months after surgery (ANOVA P-value, range 0.075-0.808), with positive median z-scores (pooled mean value close to 0.6). Symmetry indices ranged around the control reference values, showing no stage-related differences (Friedman test P-value, range 0.252-0.937), and exceeding 90% for all movements at 24 months after surgery. Bimaxillary osteotomy does not compromise facial mimicry in either verbal or non-verbal facial movements.

Primary Mandibular Deficiency Dentofacial Deformities: Occlusion and Facial Aesthetic Surgical Outcomes

PURPOSE

The purpose of the present study was to document the malocclusion and facial dysmorphology in primary mandibular deficiency (PMD) subjects with chronic obstructive nasal breathing before treatment and the outcomes after bimaxillary orthognathic, genioplasty, and intranasal surgery.

PATIENTS AND METHODS

A retrospective cohort study of PMD subjects undergoing bimaxillary, chin, and intranasal surgery was implemented. The predictor variables were grouped into demographic, anatomic, operative, and longitudinal categories. The primary outcome variables were the initial postoperative occlusion achieved at 5 weeks postoperatively (T₂) and that maintained long-term more than 2 years after surgery (T₄). Six occlusion parameters were assessed: overjet, overbite, coincidence of dental midlines, Angle classification, molar vertical, and transverse positions. A second outcome variable was the facial esthetic results. Photographs were analyzed to document 7 facial contour characteristics.

RESULTS

Forty subjects met the inclusion criteria. Their age at surgery averaged 32 years (range 13 to 63). The study included 25 females (63%). The findings confirmed that the occlusion after initial surgical healing (T₂) met the objectives for all parameters in 39 of the 40 patients (98%). Most patients (35 of 40; 88%) achieved and maintained a favorable occlusion for each parameter in the long-term (mean 5 years, 3 months). Subjects requiring counterclockwise rotation of the maxillomandibular complex were more likely to a have recurrent anterior open bite in the long-term. Facial contour deformities on presentation included weak chin (80%), deep labiomental fold (90%), everted lower lip (100%), short neck-to-chin length (88%), obtuse neck-to-chin angle (85%), weak mandible angles (93%), and "bunching" of the neck soft tissues (85%). Before surgery, 88% of the subjects exhibited a minimum of 5 of the 7 facial deformities. Correction of all 7 facial deformities was confirmed in 86% of the subjects in the long-term.

CONCLUSIONS

Most PMD subjects achieved and maintained a corrected occlusion in the long-term. In the untreated subjects, a "facial type" was identified. Orthognathic surgery proved effective in correcting the associated facial dysmorphology in most patients.

Upper Lip Asymmetry During Smiling: An Analysis Using Three-Dimensional Images

Objective

The aim of this study was to use three-dimensional images to determine the presence of upper lip asymmetry at rest and during smiling in a group of individuals with no history of orthodontics or facial cosmetic surgery.

Methods

Standardized three-dimensional frontal resting and smiling images of 54 volunteers were analyzed using the 3dMDvultus software (3dMD, Atlanta, GA). Measurements were made from the soft tissue nasion, ipsilateral ala, subnasale, and menton to the right and left commissures of the lip. A 2.5 mm or greater difference between the right and left sides was defined as an asymmetry. The agreement on the presence or absence of asymmetry between the subjects' states of rest and smiling was determined by the McNemar's chi-squared test. Statistical significance was defined as p<0.05.

Results

Menton was the most stable facial landmark to evaluate the upper lip symmetry at rest and during smiling (p=0.002). Using menton as a landmark, only one of the 54 subjects showed asymmetry while resting, but 12 (22%) showed asymmetry when smiling.

Conclusion

As part of treatment planning for orthodontics or orthognathic surgery, patients should be evaluated for the upper lip symmetry during resting and smiling. The presence of asymmetry during smiling is a significant clinical problem that needs to be recognized so that patients can be informed about the effect it can have on the final esthetic result.

Orthognathic surgery "again" to correct aesthetic failure of primary surgery: Report on outcomes and patient satisfaction in 70 consecutive cases

PURPOSE

An increasing number of patients complain about unsatisfactory aesthetic outcomes of orthognathic surgery, desiring reoperation to improve facial aesthetics. The aims of this article are to present a wide range of aesthetic reasons to justify a secondary orthognathic surgery and to report aesthetic outcomes and patient satisfaction after reoperation.

MATERIAL AND METHODS

This research covers 70 consecutive patients who underwent a secondary bimaxillary orthognathic surgery with simultaneous facial lipofilling procedures between January 2006 and December 2015. The screening criteria are described for patient selection, the diagnostic process, surgical procedures, and outcomes. Pre- and postoperative facial appearances are compared. Postoperatively, patients were asked to state the improvements perceived in their facial appearance and their satisfaction with the aesthetic outcomes.

RESULTS

After reoperation, all patients showed a full Class I occlusion. Major complications did not occur. According to the clinicians' evaluation, a postoperative evident aesthetic improvement was achieved in 65 patients (92.9%), and 64 patients (91.4%) were satisfied with the aesthetic outcomes achieved.

CONCLUSION

Secondary orthognathic surgery performed in conjunction with facial lipofilling procedures in most cases led to satisfactory aesthetic outcomes. A very accurate selection of patients, a meticulous three-dimensional diagnostic process and planning, and appropriate intra-operative maneuvers are required.

Three-Dimensional Accuracy of Facial Scan for Facial Deformities in Clinics: A New Evaluation Method for Facial Scanner Accuracy

In this study, the practical accuracy (PA) of optical facial scanners for facial deformity patients in oral clinic was evaluated. Ten patients with a variety of facial deformities from oral clinical were included in the study. For each patient, a three-dimensional (3D) face model was acquired, via a high-accuracy industrial “line-laser” scanner (Faro), as the reference model and two test models were obtained, via a “stereophotography” (3dMD) and a “structured light” facial scanner (FaceScan) separately. Registration based on the iterative closest point (ICP) algorithm was executed to overlap the test models to reference models, and “3D error” as a new measurement indicator calculated by reverse engineering software (Geomagic Studio) was used to evaluate the 3D global and partial (upper, middle, and lower parts of face) PA of each facial scanner. The respective 3D accuracy of stereophotography and structured light facial scanners obtained for facial deformities was 0.58±0.11 mm and 0.57±0.07 mm. The 3D accuracy of different facial partitions was inconsistent; the middle face had the best performance. Although the PA of two facial scanners was lower than their nominal accuracy (NA), they all met the requirement for oral clinic use.

The effect of orthognathic surgery on the lip lines while smiling in skeletal class III patients with facial asymmetry

BACKGROUND

The aim of this study was to examine the relationship between improvements in lip asymmetry at rest and while smiling after orthognathic surgery in patients with skeletal class III malocclusion.

METHODS

This study included 21 patients with skeletal class III malocclusion and facial asymmetry. We used preoperative and postoperative CT data and photographs to measure the vertical distance of the lips when smiling. The photographs were calibrated based on these distances and the CT image. We compared preoperative and postoperative results with the t test and correlations between measurements at rest and when smiling by regression analyses.

RESULTS

There were significant correlations between the postoperative changes in canting of the mouth corners at rest, canting of the canines, canting of the first molars, the slope of the line connecting the canines, and the slope of the line connecting first molars. The magnitude of the postoperative lip line improvement while smiling was not significantly correlated with changes in the canting and slopes of the canines, molars, and lip lines at rest.

CONCLUSIONS

It remains difficult to predict lip line changes while smiling compared with at rest after orthognathic surgery in patients with mandibular prognathism, accompanied by facial asymmetry.

Dynamic facial asymmetry in patients with repaired cleft lip using 4D imaging (video stereophotogrammetry)

BACKGROUND

Unilateral cleft lip is a profoundly asymmetrical condition affecting all hard and soft tissue layers from the nose to the upper lip. Although the asymmetry is minimized through cleft lip repair, a degree of asymmetry inevitably persists. Studies investigating asymmetry in patients with cleft lip have used facial measurements, and static 2D and 3D photography. The nose/lip/mouth area, however, is rarely static in our day to day social interactions.

METHODS

Non-syndromic patients with cleft lip and palate, and a control group without orofacial clefts underwent 50 frames per second 4D imaging while generating facial expressions including smiling and pouting. Key landmarks were tracked throughout the expression, corrected for head movement and a motion path of each landmark was generated. Asymmetry was assessed for both extent of displacement, using Euclidean distances between frames, and the shape of the motion path using Procrustes analysis.

RESULTS

Twelve patients were compared in each group with an age range from 8 to 18. Comparing the motion path of key landmarks in the upper lip demonstrated statistically significant differences in both the magnitude and shape of motion during smiling and pouting between cleft and non-cleft groups.

CONCLUSION

Video stereophotogrammetry of the repaired cleft lip demonstrates asymmetry of both the magnitude of motion as well as asymmetry of the path of the motion itself. This may be due to the effect of the scar tissue from the repair, from the abnormal anatomy involved with cleft lip or a combination of the two.

Three-dimensional evaluation of social smile symmetry

OBJECTIVE

To evaluate the social smile symmetry using three-dimensional (3D) stereophotogrammetric images.

MATERIALS AND METHODS

The study was conducted with 3D facial images of 30 individuals (age range 13-25 years). The rest position was considered as the reference image and the social smile image was aligned on this image using the best-fit alignment method. The spatial differences between the same points established on both images using 3D analyses were determined for right and left points in X, Y, and Z planes.

RESULTS

The highest difference related to spatial distance in right and left points was -0.56 mm (95% confidence interval [CI], -1.19, 0.06 mm) between right and left commissure (Com) points. The difference was not significant, and the Bland-Altman upper and lower limits were -3.85 mm and 2.71 mm, respectively. The highest difference for the transversal plane was found in Com points, similarly to the spatial distance (mean: 0.50 mm, 95% CI, -2.62, 1.02 mm). The differences between the changes in the left and right points in the Y and Z plane were not significant (P > .05).

CONCLUSIONS

The social smile was observed to show asymmetry in varying amounts in the different directions. Asymmetry increases in some cases, specifically for the corners of the mouth.

Breast volumetric analysis for aesthetic planning in breast reconstruction: a literature review of techniques

BACKGROUND

Accurate volumetric analysis is an essential component of preoperative planning in both reconstructive and aesthetic breast procedures towards achieving symmetrization and patient-satisfactory outcome. Numerous comparative studies and reviews of individual techniques have been reported. However, a unifying review of all techniques comparing their accuracy, reliability, and practicality has been lacking.

METHODS

A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE, was undertaken.

RESULTS

Since Bouman's first description of water displacement method, a range of volumetric assessment techniques have been described: thermoplastic casting, direct anthropomorphic measurement, two-dimensional (2D) imaging, and computed tomography (CT)/magnetic resonance imaging (MRI) scans. However, most have been unreliable, difficult to execute and demonstrate limited practicability. Introduction of 3D surface imaging has revolutionized the field due to its ease of use, fast speed, accuracy, and reliability. However, its widespread use has been limited by its high cost and lack of high level of evidence. Recent developments have unveiled the first web-based 3D surface imaging program, 4D imaging, and 3D printing.

CONCLUSIONS

Despite its importance, an accurate, reliable, and simple breast volumetric analysis tool has been elusive until the introduction of 3D surface imaging technology. However, its high cost has limited its wide usage. Novel adjunct technologies, such as web-based 3D surface imaging program, 4D imaging, and 3D printing, appear promising.