The Skeletal Stability of Combined Surgery First Approach and Clear Aligners in Skeletal Class III Malocclusion Correction: A Randomized Controlled Trial.

The surgery first approach (SFA) and clear aligners technique can address traditional treatment defects, such as prolonged waiting times for surgery and a less desirable facial appearance due to wire aligners. However, the curative effect of the combination remains uncertain. The randomized controlled study aimed to evaluate the skeletal stability of the SFA compared to the conventional orthodontic first approach (OFA), both of which were applied with clear aligners. A total of 74 participants were randomly allocated to two groups: the SFA group (experimental) and the OFA group (control). The skeletal deviation was calculated using reconstruction models from computed tomography scans taken immediately and 6 months after surgery. The largest median deviations were detected in the y-axis of the mandible for both two groups, separately 1.36 mm in the experimental group and 1.19 mm in the control group. Apart from the maxillary yaw dimension (p = 0.005), there were no significant differences between the two groups in terms of linear and angular deviation. The experimental group had an overall treatment time of 18.05 ± 2.53 months, while the control group took 22.83 ± 3.60 months (p < 0.05). Therefore, the combined surgery-first and clear aligners treatment can achieve comparable skeletal stability to the conventional approach, while also saving significant time.

Three-dimensional printed titanium mesh combined with iliac cancellous bone in the reconstruction of mandibular defects secondary to ameloblastoma resection.

BACKGROUND: The reconstruction of large mandibular defects is a challenge, and free vascularized bone flaps are most commonly used. However, the precision and symmetry of this repair are deficient, and patients have a risk of vascular embolism, flap necrosis, and donor site complications. Therefore, to explore an ideal alternative in mandibular reconstruction with high surgical accuracy and low complications is indispensable. METHODS: Seven patients with recurrent or large-scope ameloblastoma were enrolled in this study. All patients were provided with a fully digital treatment plan, including the design of osteotomy lines, surgical guides, and three-dimensional printed titanium mesh for implantation. With the assistance of surgical guide, ameloblastomas were resected, and custom 3D printed titanium mesh combined with posterior iliac bone harvest was used in mandibular reconstruction. A comparison was made between the discrepant surgical outcomes and the intended surgical plan, as well as the average three-dimensional deviation of the mandible before and after the surgery. At the same time, the resorption rate of the implanted bone was evaluated. RESULTS: All patients completed the fully digital treatment process successfully without severe complications. Image fusion showed that the postoperative contour of the mandible was basically consistent with surgical planning, except for a slight increase in the inferior border of the affected side. The mean three-dimensional deviation of the mandible between the preoperative and postoperative periods was 0.78 ± 0.41 mm. The mean error between the intraoperative bone volume and the digital planning bone volume was 2.44%±2.10%. Furthermore, the bone resorption rates of the harvested graft 6 months later were 32.15%±6.95%. CONCLUSIONS: The use of digital surgical planning and 3D-printed templates can assist surgeons in performing surgery precisely, and the 3D-printed titanium mesh implant can improve the patient's facial symmetry. 3D printed titanium mesh combined with posterior iliac cancellous bone graft can be regarded as an ideal alternative in extensive mandibular reconstruction.

The application of a fully digital approach in the treatment of skeletal class III malocclusion: a preliminary study.

BACKGROUND: Skeletal malocclusion patients have facial malformations and occlusal dysfunctions that require orthodontic-orthognathic joint treatment, while the combination treatment takes time and requires close communication between surgeons and orthodontists. Thus, improving the efficiency and effectiveness of the combination treatment is necessary, and it is still a challenge. Now, digital technology provides us with an excellent alternative. Despite the widespread use of digital technology in orthognathic surgery simulation and clear aligner orthodontic therapy, it has not been fully integrated into the combined orthognathic and orthodontic treatment process, and the components remain independent. METHODS: A fully digital approach to seamlessly integrating various parts of the combined treatment through digital technology was investigated in this study in order to achieve an efficient transition. Five patients with skeletal Class III malocclusion were enrolled, and all made fully digital treatment plans at the beginning of actual implementation, which included the design of pre-surgical orthodontic, orthognathic surgery, and post-surgical orthodontic. Then, every aspect of the clinical operation was carried out in accordance with the fully digital routine. After the entire treatment process was completed, the skeleton and dentition discrepancy between virtual planning and the actual result was evaluated. RESULTS: All participants completed the fully digital treatment process, and no complication was observed. The linear deviation of the skeletal anatomy was less than 1 mm, and the angular deviation was less than 1 degree. Except in one case in the lower dentition, the deviation of the virtual dental design from the real alignment was less than 2 mm. Furthermore, with one exception of maxillary anterior-posterior dimension, the linear deviations of the skeleton were not statistically significant. Therefore, the simulation accuracy of the fully digital approach was clinically acceptable. CONCLUSIONS: The digital treatment approach is clinically feasible and has achieved satisfactory results. The discrepancy between virtual design of the entire digital process and actual post-treatment situation was acceptable in clinic. A fully digital approach was proved effective in the treatment of skeletal Class III malocclusion, with which the efficient transition of treatment procedures was realized.

Reconstruction of Dentomaxillofacial Deformity Secondary to Mandibular Defect Using Concomitant Orthognathic Surgery and Fibula Free Flap.

SUMMARY: The reconstruction of mandibular defects may be delayed or compromised for many reasons, especially in pediatric patients. With the growth of the remaining mandible and the maxilla in the malocclusion status, secondary dentomaxillofacial deformity is plausible. To treat the concomitant mandibular defect and secondary dentomaxillofacial deformity, a hierarchical algorithm using orthodontics, orthognathic surgery, and fibula free flap was developed. This retrospective case series included six patients with long-term mandibular defects caused by tumor resection without repair or with compromised costochondral reconstruction. All patients were treated using the same staged protocol, but with minor changes: (1) presurgical orthodontics, (2) virtual surgical planning, (3) fabrication of the guides and splints, (4) sequenced operations, and (5) postoperative care. The sequence of surgery included the Le Fort I osteotomy, mandibular sagittal split ramus osteotomy of the remaining ramus, final occlusion registration, repositioning of the distal segment of the mandible, segmented fibula reconstruction, and finally, the fixation of mandibular sagittal split ramus osteotomy. The operations and wound healing were uneventful in all patients, and no flap failure or severe complications were detected. Also, the patients exhibited no signs of temporomandibular joint ankylosis during the follow-up. The subspinale-nasion-supramental angle was significantly reduced after surgery. A significant improvement was detected in the facial contour symmetry measurements postoperatively. This proposed workflow of concomitant orthognathic surgery and the fibula free flap is effective and reliable for the reconstruction of dentomaxillofacial deformity secondary to the long-term mandibular defect.

Implant-supported provisional prosthesis facilitated the minor revision of occlusion and incisor exposure after orthognathic surgery of extended oligodontia in maxilla.

BACKGROUND: The congenital oligodontia in maxilla could result in a significant skeletal jaw malformation such as atrophic maxilla and severe skeletal class III malocclusion. Since there is no referable dentition in anterior maxilla, the orthognathic surgery and oral rehabilitation for those patients becomes more challenging and less predictable. MATERIALS AND METHODS: We hereby present a new sequencing of interdisciplinary treatments, including calvarial bone grafting, installation of implant-supported provisional prosthesis, bimaxillary orthognathic surgery, and the final installation of dental implants and the fixed prosthesis. RESULTS: The facial esthetics and function of the permanent prosthesis were satisfactory, with a remarkable improvement in the maxillomandibular relation, adequate horizontal and vertical repositioning of the maxilla, and appropriate incisor exposure. CONCLUSION: Although more surgeries and longer treatment period may be required due to the interdisciplinary treatment plan, better aesthetic and functional outcomes may be acquired by this reported procedure in the long-term for young patients.

Evaluation of Mandibular Symmetry in Patients With Condylar Osteochondroma Who Underwent Intro-Oral Condylar Resection and Simultaneous Bimaxillary Orthognathic Surgery.

Mandibular condylar osteochondroma (OC) can result in facial asymmetry, malocclusion, and temporomandibular joint dysfunction. The authors have previously demonstrated a novel method for conservative condylectomy and simultaneous orthognathic surgery for treatment of mandibular condylar OC. The purpose of this study was to evaluate the immediate improvement and long-term stability of mandibular symmetry in the treatment of condylar OC. Fifty-six patients with unilateral mandibular condylar OC combined with secondary facial asymmetry and malocclusion were enrolled in this retrospective study. The computerized tomography (CT) scans were acquired with the mandible in centric relation (CR) before surgery, 1 week and 12 to 18 months after surgery. The images were reconstructed and processed for the analysis with ProPlan CMF 2.1 software. After defining the skeletal landmarks and the reference planes, the chin deviation, chin rotation and mandibular asymmetry index were calculated. The operations and healing were uneventful and the patients showed no signs of recurrence or temporomandibular joint ankylosis during the follow-up. Facial symmetry was greatly improved right after the surgery in the chin deviation (from 9.2 to 1.7 mm, P < 0.01), chin rotation (from 11.2 to 2.3, P < 0.01) and the asymmetry index of three mandibular landmarks (Go, MF and Sg, all P < 0.01). It also showed a stable result after 12 to 18 months follow-up. We also established a novel measurement method, which showed that the combination of conservative condylectomy via the intraoral approach based on intraoperative navigation and simultaneous orthognathic surgery is effective for improving the facial symmetry when treat the mandibular condylar OC.

Modified Usage of Negative Pressure Wound Therapy for the Management of Severe Deep Fascial Space Infections in the Head and Neck.

PURPOSE: Although negative pressure wound therapy (NPWT) has been widely used in complicated wound care, there are still some obstacles regarding its use in the treatment of severe deep fascial space infections in the head and neck. The purpose of this study is to describe a new modified usage of NPWT and investigate the clinical efficacy of this system in a consecutive case series of severe deep fascial space infections. METHODS: The investigators implemented a new modification of NPWT for the management of severe deep fascial space infections. In this new system, the half-plugged bar-shaped foam material was arranged along with the through-and-through side-holed latex drainage tube, which could maintain negative pressure in the distal part of the spaces, and the tube was easy to remove 5-7 days after surgery. Twelve patients had severe deep fascial space infections in the head and neck with a direct threat to the airway. The median time of removal of the NPWT device, the median amount of drainage fluid and the median healing time were investigated. RESULTS: A total of 7 male and 5 female patients with an average age of 63.2 years old were included in this study. The median time of removal of the NPWT device was 6 days (ranging from 4 to 7 days). The median amount of drainage fluid within 3 days after surgery was 420 mL (ranging from 280-760 mL), and the median time for complete wound healing was 12 days (ranging from 10 to 21 days). CONCLUSION: The results of this study suggest that the modification of NPWT provides various advantages and leads to excellent clinical outcomes in the treatment of severe deep fascial space infections. Future studies will focus on the safety verification of portable usage and the cost effectiveness analysis of NPWT.

A Modified Method Using Double Computed Tomography Scan Procedure to Maintain Mandibular Width in Mandibular Reconstruction.

OBJECTIVE: The purpose of this study was to evaluate the use of a modified template system and double computed tomography scan procedure to maintain mandibular width in cases of mandibular reconstruction. STUDY DESIGN: Ten patients who underwent mandibular reconstruction with a fibular flap were enrolled. The surgeries were planned with a computer-aided surgical simulation (CASS) planning method. Following double computed tomography scan procedure, the template system was designed in a computer and was fabricated using a three-dimensional printing technique. The cutting guides were designed with the holes of the conventional reconstruction plate on the remnant mandibular segments. After surgery, the outcome evaluation was compared by first superimposing the post-operative computed tomography model onto the planned model and then measuring the differences between the planned and actual outcomes. RESULTS: All surgeries were completed successfully using the template system. With the use of the templates, the largest linear root-mean-square deviation (RMSD) between the planned and post-operative remnant segments was 1.01 mm, and the largest angular RMSD was 4.05°. CONCLUSIONS: The authors conclude that this template system and double computed tomography scan procedure provides a reliable method to maintain mandibular width in mandibular reconstruction using a fibular flap.

Evaluation of the postoperative stability of a counter-clockwise rotation technique for skeletal class II patients by using a novel three- dimensional position-posture method.

The aim of this study is to evaluate the postsurgical stability of skeletal class II patients after performing a counter-clockwise rotational (CCWR) procedure for the maxilla-mandibular complex (MMC) by using a novel Three-dimensional (3D) Position-Posture(P-P) measuring method. Twenty-five patients (5 males and 20 females) were included in this study. The postoperative CT scans of the skull were taken before surgery(T0), 3-7 days (T1), 3 months (T2), and 6 months (T3) after surgery. Specific anatomic landmarks were chosen to determine the position of the segments, while three equally perpendicular planes were created to describe their posture. The results show that the linear relapse of maxillary landmarks during the follow-up were acceptable (≤0.5 mm). The relapse of maxillary pitch plane at 6-months follow-up is 1.52°, which is acceptable. There was a significant pitch plane relapse of the mandibular-body segment with an average of 1.86° between T1 and T2 models, 3.28° between T1 and T3 models. There was no significant difference between roll and yaw planes during the follow-up. We therefore conclude that the P-P method could be used to accurately analyze the postsurgical stability of skeletal class II orthognathic surgery cases. For CCWR procedures, it was also shown that the there is a tendency for recurrence most specially on the body of the mandible.

A New Modified Method for Accurate Mandibular Reconstruction.

Mandible plays a pivotal role for both function (mastication, swallowing, and phonation) and aesthetic. Traumas, osteomyelitis, osteoradionecrosis, and benign or malignant neoplasm can cause mandibular defect. Several techniques have been proposed for mandibular reconstruction along the past decades. In this article, we present and discuss a new modified method for accurate mandibular reconstruction. This method is mainly indicated in patients with benign mandibular tumors, where the resection margins can be more often anticipated prior to surgery. However, it is less useful for patients with malignant mandibular tumors, in whom resection margins are often finalized intraoperatively.

An eFTD-VP framework for efficiently generating patient-specific anatomically detailed facial soft tissue FE mesh for craniomaxillofacial surgery simulation.

Accurate surgical planning and prediction of craniomaxillofacial surgery outcome requires simulation of soft tissue changes following osteotomy. This can only be achieved by using an anatomically detailed facial soft tissue model. The current state-of-the-art of model generation is not appropriate to clinical applications due to the time-intensive nature of manual segmentation and volumetric mesh generation. The conventional patient-specific finite element (FE) mesh generation methods are to deform a template FE mesh to match the shape of a patient based on registration. However, these methods commonly produce element distortion. Additionally, the mesh density for patients depends on that of the template model. It could not be adjusted to conduct mesh density sensitivity analysis. In this study, we propose a new framework of patient-specific facial soft tissue FE mesh generation. The goal of the developed method is to efficiently generate a high-quality patient-specific hexahedral FE mesh with adjustable mesh density while preserving the accuracy in anatomical structure correspondence. Our FE mesh is generated by eFace template deformation followed by volumetric parametrization. First, the patient-specific anatomically detailed facial soft tissue model (including skin, mucosa, and muscles) is generated by deforming an eFace template model. The adaptation of the eFace template model is achieved by using a hybrid landmark-based morphing and dense surface fitting approach followed by a thin-plate spline interpolation. Then, high-quality hexahedral mesh is constructed by using volumetric parameterization. The user can control the resolution of hexahedron mesh to best reflect clinicians' need. Our approach was validated using 30 patient models and 4 visible human datasets. The generated patient-specific FE mesh showed high surface matching accuracy, element quality, and internal structure matching accuracy. They can be directly and effectively used for clinical simulation of facial soft tissue change.

A clinically validated prediction method for facial soft-tissue changes following double-jaw surgery.

PURPOSE: It is clinically important to accurately predict facial soft-tissue changes prior to orthognathic surgery. However, the current simulation methods are problematic, especially in anatomic regions of clinical significance, e.g., the nose, lips, and chin. We developed a new 3-stage finite element method (FEM) approach that incorporates realistic tissue sliding to improve such prediction. METHODS: In Stage One, soft-tissue change was simulated, using FEM with patient-specific mesh models generated from our previously developed eFace template. Postoperative bone movement was applied on the patient mesh model with standard FEM boundary conditions. In Stage Two, the simulation was improved by implementing sliding effects between gum tissue and teeth using a nodal force constraint scheme. In Stage Three, the result of the tissue sliding effect was further enhanced by reassigning the soft-tissue-bone mapping and boundary conditions using nodal spatial constraint. Finally, our methods have been quantitatively and qualitatively validated using 40 retrospectively evaluated patient cases by comparing it to the traditional FEM method and the FEM with sliding effect, using a nodal force constraint method. RESULTS: The results showed that our method was better than the other two methods. Using our method, the quantitative distance errors between predicted and actual patient surfaces for the entire face and any subregions thereof were below 1.5 mm. The overall soft-tissue change prediction was accurate to within 1.1 ± 0.3 mm, with the accuracy around the upper and lower lip regions of 1.2 ± 0.7 mm and 1.5 ± 0.7 mm, respectively. The results of qualitative evaluation completed by clinical experts showed an improvement of 46% in acceptance rate compared to the traditional FEM simulation. More than 80% of the result of our approach was considered acceptable in comparison with 55% and 50% following the other two methods. CONCLUSION: The FEM simulation method with improved sliding effect showed significant accuracy improvement in the whole face and the clinically significant regions (i.e., nose and lips) in comparison with the other published FEM methods, with or without sliding effect using a nodal force constraint. The qualitative validation also proved the clinical feasibility of the developed approach.

[Analysis of three dimensional stability of the hypoplastic maxilla after orthognathic surgery in cleft lip and palate patients].

PURPOSE: To establish a three dimensional spacial measurement method to analyze the short-term stability of maxilla after orthognathic surgery in cleft lip and palate patients. METHODS: Twenty-five patients with maxillary hypoplasia secondary to cleft lip and palate seeking for orthognathic surgery were included in this study between January 2008 and September 2012. The spiral CT scan for the skull were taken 6 weeks preoperatively (T0), 4 days postoperatively (T1)，3 months postoperatively (T2), and 6 months postoperatively (T3) and collected. A three dimensional analytic method for measuring maxilla was set up in ProPlan CMF software, and good repeatability of identification of landmarks was confirmed. Twenty-two indicators to describe the maxillary position and three new angles to describe the maxillary orientation were measured and analyzed. Student's t test was used to analyze the difference between T2 and T3 using SPSS 16.0 software package. RESULTS: In 25 patients with cleft palate there was a translational relapse upwards along vertical axis and a pitch-up relapse of maxilla with an average of 7.46% at the anterior part of the cleft maxilla. The relapse rate was 30.95% in LUCLP, 8.01% in RUCLP, and 34.76% in BCLP, but with no significant difference. Along the horizontal axis, there was a maxillary translational relapse toward noncleft side in both LUCLP and RUCLP group, while a yaw relapse was confirmed with the anterior part of maxilla toward noncleft side and the posterior part toward cleft side. CONCLUSIONS: There is a three-dimensional relapse tendency for the maxilla in the cleft patient postoperatively. The established three-dimensional analytic method well describes the special position of cleft maxilla especially in the translational and rotational movement of maxilla in three different axes comparing with that from lateral cephalometry, thus providing references for accurate measurements in study of the three dimensional maxillary stability after orthognathic surgery.

Titanium Mesh Shaping and Fixation for the Treatment of Comminuted Mandibular Fractures.

PURPOSE: Treating comminuted mandibular fractures remains a challenge. In this study, we used titanium mesh to treat comminuted mandibular fractures. MATERIALS AND METHODS: Nine patients with traumatically comminuted mandibular fractures who received open reduction and internal stable fixation with titanium mesh were retrospectively reviewed. Open reduction-internal stable fixation was performed 7 to 10 days after primary debridement of the facial trauma. After the fractured mandible and the displaced fragments were reduced, the titanium mesh was reshaped according to the morphology of the mandible, and the reduced bone fragments were fixed with the reshaped titanium mesh and screws. Then, the surgical effects were evaluated during routine follow-up. RESULTS: Most of the displaced fragments were preserved and exhibited a favorable shaping ability in restoring the morphology of the mandible during surgery. No intraoperative complications were encountered. In addition, all patients were infection free, with no obvious resorption in the fixed fragments after surgery. The mandible also exhibited favorable morphology and offered sufficient bone mass for dental implantation or a denture prosthesis. CONCLUSIONS: We conclude that titanium mesh shaping and fixation can effectively treat comminuted mandibular fractures with little bone fragment loss, little soft tissue exposure, a low infection rate, and favorable mandibular morphology.

An eFace-Template Method for Efficiently Generating Patient-Specific Anatomically-Detailed Facial Soft Tissue FE Models for Craniomaxillofacial Surgery Simulation.

Accurate surgical planning and prediction of craniomaxillofacial surgery outcome requires simulation of soft-tissue changes following osteotomy. This can only be accomplished on an anatomically-detailed facial soft tissue model. However, current anatomically-detailed facial soft tissue model generation is not appropriate for clinical applications due to the time intensive nature of manual segmentation and volumetric mesh generation. This paper presents a novel semi-automatic approach, named eFace-template method, for efficiently and accurately generating a patient-specific facial soft tissue model. Our novel approach is based on the volumetric deformation of an anatomically-detailed template to be fitted to the shape of each individual patient. The adaptation of the template is achieved by using a hybrid landmark-based morphing and dense surface fitting approach followed by a thin-plate spline interpolation. This methodology was validated using 4 visible human datasets (regarded as gold standards) and 30 patient models. The results indicated that our approach can accurately preserve the internal anatomical correspondence (i.e., muscles) for finite element modeling. Additionally, our hybrid approach was able to achieve an optimal balance among the patient shape fitting accuracy, anatomical correspondence and mesh quality. Furthermore, the statistical analysis showed that our hybrid approach was superior to two previously published methods: mesh-matching and landmark-based transformation. Ultimately, our eFace-template method can be directly and effectively used clinically to simulate the facial soft tissue changes in the clinical application.

Computer-Aided Design and Computer-Aided Manufacturing Hydroxyapatite/Epoxide Acrylate Maleic Compound Construction for Craniomaxillofacial Bone Defects.

The aim of this study was to investigate the use of computer-aided design and computer-aided manufacturing hydroxyapatite (HA)/epoxide acrylate maleic (EAM) compound construction artificial implants for craniomaxillofacial bone defects. Computed tomography, computer-aided design/computer-aided manufacturing and three-dimensional reconstruction, as well as rapid prototyping were performed in 12 patients between 2008 and 2013. The customized HA/EAM compound artificial implants were manufactured through selective laser sintering using a rapid prototyping machine into the exact geometric shapes of the defect. The HA/EAM compound artificial implants were then implanted during surgical reconstruction. Color-coded superimpositions demonstrated the discrepancy between the virtual plan and achieved results using Geomagic Studio. As a result, the HA/EAM compound artificial bone implants were perfectly matched with the facial areas that needed reconstruction. The postoperative aesthetic and functional results were satisfactory. The color-coded superimpositions demonstrated good consistency between the virtual plan and achieved results. The three-dimensional maximum deviation is 2.12 ±â€Š0.65  mm and the three-dimensional mean deviation is 0.27 ±â€Š0.07  mm. No facial nerve weakness or pain was observed at the follow-up examinations. Only 1 implant had to be removed 2 months after the surgery owing to severe local infection. No other complication was noted during the follow-up period. In conclusion, computer-aided, individually fabricated HA/EAM compound construction artificial implant was a good craniomaxillofacial surgical technique that yielded improved aesthetic results and functional recovery after reconstruction.

A Modified Method of Proximal Segment Alignment After Sagittal Split Ramus Osteotomy for Patients With Mandibular Asymmetry.

PURPOSE: The purpose of this study was to evaluate a modified method of aligning the proximal segment after bilateral sagittal split ramus osteotomy (BSSO) in the treatment of patients with facial asymmetry. PATIENTS AND METHODS: Eleven patients with mandibular excess and facial asymmetries were enrolled in this prospective study. The surgery was planned according to a computer-aided surgical simulation protocol. In addition, the proximal segment on the hypoplastic side was intentionally flared out after the distal segment was rotationally set back. If the gap between the proximal and distal segments was too wide, then bone grafts were used. The surgery was completed according to the computerized plan. The proximal segment on the hypoplastic side was fixed with bicortical lag screws, and the proximal segment on the hyperplastic side was fixed with a 4-hole titanium miniplate. Postoperative evaluation was performed 6 months after surgery. Statistical analyses were performed. RESULTS: All surgeries were completed uneventfully. Of the 11 patients, 4 also underwent genioplasty and 3 underwent bone grafting to fill in the gap and smooth the anterior step. The physicians and patients were satisfied with the surgical outcomes. Only 1 patient underwent a secondary revision using an onlay hydroxyapatite implant. Results of statistical analyses showed that the computerized surgical plan could be accurately transferred to the patients at the time of surgery and the surgical outcomes achieved with this modified method were better than with the routine method of aligning the proximal and distal segments in maximal contact. CONCLUSION: The present modified method of aligning the proximal segment for BSSO can effectively correct mandibular asymmetry and obviate a secondary revision surgery.

Bioinformatic analysis of Msx1 and Msx2 involved in craniofacial development.

Msx1 and Msx2 were revealed to be candidate genes for some craniofacial deformities, such as cleft lip with/without cleft palate (CL/P) and craniosynostosis. Many other genes were demonstrated to have a cross-talk with MSX genes in causing these defects. However, there is no systematic evaluation for these MSX gene-related factors. In this study, we performed systematic bioinformatic analysis for MSX genes by combining using GeneDecks, DAVID, and STRING database, and the results showed that there were numerous genes related to MSX genes, such as Irf6, TP63, Dlx2, Dlx5, Pax3, Pax9, Bmp4, Tgf-beta2, and Tgf-beta3 that have been demonstrated to be involved in CL/P, and Fgfr2, Fgfr1, Fgfr3, and Twist1 that were involved in craniosynostosis. Many of these genes could be enriched into different gene groups involved in different signaling ways, different craniofacial deformities, and different biological process. These findings could make us analyze the function of MSX gens in a gene network. In addition, our findings showed that Sumo, a novel gene whose polymorphisms were demonstrated to be associated with nonsyndromic CL/P by genome-wide association study, has protein-protein interaction with MSX1, which may offer us an alternative method to perform bioinformatic analysis for genes found by genome-wide association study and can make us predict the disrupted protein function due to the mutation in a gene DNA sequence. These findings may guide us to perform further functional studies in the future.

A novel method to determine the potential rotational axis of the mandible during virtual three-dimensional orthognathic surgery.

During virtual three-dimensional orthognathic surgery in cases where an overlap or penetrability occurs between the 2 jaws due to the repositioning of the maxillary segment, it is necessary to establish a vertical opening of the mandible to obtain a relatively good relationship with the maxillary segment for the fabrication of an intermediate occlusal splint. However, there are few reports that address the precise definition of the rotational axis of the mandible during virtual surgery. Here, we present the idea that the mandible's movement during virtual three-dimensional orthognathic surgery is similar to hinge movement in vivo and developed a method for locating the geometric center of the three-dimensional condyle using Hypermesh software combined with Mimics software. Subsequently, we defined the rotational axis of the mandible based on the located geometric centers of the bilateral condyles, and the mandible was then rotated around the defined axis from the retruded contact position to mimic the hinge movement. Preliminary results indicated that the presented method could approximately mimic the hinge movement of the mandible with a relatively high accuracy in a three-dimensional environment, which may improve the accuracy of virtual intermediate occlusal splint.