Randomized Clinical Trial of the Accuracy of Patient-Specific Implants versus CAD/CAM Splints in Orthognathic Surgery.

BACKGROUND: The maxilla position is essential for the aesthetic and functional outcomes of orthognathic surgery. Previous studies demonstrated the advantages of patient-specific implants in orthognathic surgery. However, more data are needed to confirm the superiority of patient-specific implants over surgical splints created with computer-aided design/computer-aided manufacturing (CAD/CAM). This randomized controlled trial aimed to compare the accuracy of patient-specific implants and CAD/CAM splints for maxilla repositioning in orthognathic surgery. METHODS: Patients (n = 64) who required orthognathic surgery were randomly assigned to use either patient-specific implants (patient-specific implant group) or CAD/CAM surgical splints (splint group) to reposition the maxilla. The outcome evaluation was completed by comparing virtual plans with actual results. The primary outcome was the discrepancies of the centroid position of the maxilla. Other translation and orientation discrepancies of the maxilla were also assessed. RESULTS: The authors analyzed 27 patients in the patient-specific implant group and 31 in the splint group. The maxilla position discrepancy was 1.41 ± 0.58 mm in the patient-specific implant group and 2.20 ± 0.94 mm in the splint group; the between-group difference was significant (p < 0.001). For the patient-specific implant group, the largest translation discrepancy was 1.02 ± 0.66 mm in the anteroposterior direction, and the largest orientation discrepancy was 1.85 ± 1.42 degrees in pitch. For the splint group, the largest translation discrepancy was 1.23 ± 0.93 mm in the mediolateral direction, and the largest orientation discrepancy was 1.72 ± 1.56 degrees in pitch. CONCLUSION: The result showed that using patient-specific implants in orthognathic surgery resulted in a more accurate maxilla position than CAD/CAM surgical splints. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, I.

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

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

Craniofacial Distraction: Orthodontic Considerations.

A combined surgical and orthodontic approach to midface and mandibular distraction optimizes stability and outcomes. Orthodontic considerations include proper planning of the distraction vector, appropriate device use, and thorough follow-up through the consolidation and postoperative period. The dental occlusion must be managed throughout treatment in order to achieve ideal results.

Orthognathic surgery: a randomized study comparing Piezosurgery and Saw techniques.

INTRODUCTION: The purpose of this study was to evaluate specific parameters: intra-operative time, facial swelling, degree of pain (VAS scale), recovery time and neurosensory disturbance in patients who underwent orthognathic surgery either using piezo or saw devices. MATERIAL AND METHODS: We designed a retrospective study, which included 100 patients who underwent bilateral sagittal split osteotomy (BSSO) surgery combined with maxillary Le Fort I. They were separated into 2 groups of 50 patients each. The surgeries were performed between September 2015 and April 2017 by the same surgeon. RESULTS: Intra-op time is unchanged but patients operated with the Piezo devices requested fewer painkilling medication and were dismissed on the second day after the surgery. Neurosensory recovery was statistically significant in the Piezo group. CONCLUSION: Far less post-op swelling and the reduction in the use of painkillers lead to a speedier recovery in patients who underwent orthognathic surgery using Piezosurgery. These patients also recovered more sensitivity in the lower lip area. KEY WORDS: Orthognatic surgery, Piezosurgery, Saw.

Accuracy of Mandible-First versus Maxilla-First Approach and of Thick versus Thin Splints for Skeletal Position after Two-Jaw Orthognathic Surgery.

BACKGROUND: The aim of this study was to investigate the accuracy of bimaxillary orthognathic surgery regarding different sequencing (maxilla-first or mandible-first surgery) and different thicknesses of intermediate splints. METHODS: This retrospective cohort study evaluated the accuracy of postoperative outcome in accordance with virtual planning in 57 patients requiring bimaxillary osteotomies with different operation sequence: maxilla-first (n = 31) or mandible-first (n = 26) surgery. The effect of different splint thicknesses (i.e., thick, n = 22; and thin, n = 35) was also evaluated. The 1-week postoperative cone-beam computed tomographic craniofacial images were superimposed onto preoperative simulated images to measure the discrepancy of the three-dimensional cephalometric landmarks. RESULTS: Neither sequencing approach differed in overall accuracy (1-week postoperative to preoperative simulated image discrepancy): maxilla-first, 1.69 ± 0.53 mm; versus mandible-first, 1.44 ± 0.52 mm. In detailed comparison, mandible-first surgery resulted in more accuracy in the vertical dimension. Thick intermediate splints provided better control (less error) of upper central incisors in the sagittal position (thick splint, 1.38 ± 1.17 mm; thin splint, 2.13 ± 1.38 mm). However, overall accuracy was not affected by splint thickness. Conditions affecting sequencing predilection included skeletal class III with vertical excess, maxillary down-grafting, counterclockwise rotation of the maxillomandibular complex, and simulated mandibular opening for splint fabrication clearance. CONCLUSIONS: Despite both means of sequencing being performed similarly, mandible-first surgery was more precise in the vertical dimension. Thick intermediate splints seemed to yield better control of central incisors in the sagittal position. However, under appropriate selection of intermediate splints to maintain interim condylar position, splint thickness has no effect on overall accuracy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Quantitative Augmented Reality-Assisted Free-Hand Orthognathic Surgery Using Electromagnetic Tracking and Skin-Attached Dynamic Reference.

The purpose of this study was to develop a quantitative AR-assisted free-hand orthognathic surgery method using electromagnetic (EM) tracking and skin-attached dynamic reference. The authors proposed a novel, simplified, and convenient workflow for augmented reality (AR)-assisted orthognathic surgery based on optical marker-less tracking, a comfortable display, and a non-invasive, skin-attached dynamic reference frame. The 2 registrations between the physical (EM tracking) and CT image spaces and between the physical and AR camera spaces, essential processes in AR-assisted surgery, were pre-operatively performed using the registration body complex and 3D depth camera. The intraoperative model of the maxillary bone segment (MBS) was superimposed on the real patient image with the simulated goal model on a flat-panel display, and the MBS was freely handled for repositioning with respect to the skin-attached dynamic reference tool (SRT) with quantitative visualization of landmarks of interest using only EM tracking. To evaluate the accuracy of AR-assisted Le Fort I surgery, the MBS of the phantom was simulated and repositioned by 6 translational and three rotational movements. The mean absolute deviations (MADs) between the simulation and post-operative positions of MBS landmarks by the SRT were 0.20, 0.34, 0.29, and 0.55 mm in x- (left lateral, right lateral), y- (setback, advance), and z- (impaction, elongation) directions, and RMS, respectively, while those by the BRT were 0.23, 0.37, 0.30, and 0.60 mm. There were no significant differences between the translation and rotation surgeries or among surgeries in the x-, y-, and z-axes for the SRT. The MADs in the x-, y-, and z-axes exhibited no significant differences between the SRT and BRT. The developed method showed high accuracy and reliability in free-hand orthognathic surgery using EM tracking and skin-attached dynamic reference.

Endoscopic Support and Virtual Surgical Planning as an Alternative to Repair Orbital Wall Fractures.

The reconstruction of the orbit has been carried out throughout history using different techniques. However, the persistence of high rates of complications mainly associated with the position of the eyeball and the migration of reconstruction implants have generated the need and importance of continuing to study new techniques, including with the help of technology. Virtual planning combined with endoscopic access and 3D models could decrease the number of complications associated with the aforementioned problems. For this, the aim of this observational retrospective study is to show the authors' experience of 19 cases in different orbital fractures using endoscopic support and virtual planning as great alternative in orbital reconstruction.

Recent advances in orthognathic surgery.

PURPOSE OF REVIEW: The aim of this article is to review the recent literature on orthognathic surgery for treatment of malocclusion and obstructive sleep apnea (OSA). The discussion outlines the refinements of the procedure and advances in technology. RECENT FINDINGS: Maxillomandibular advancement (MMA) may be performed for complex malocclusion and OSA. Although orthodontic management followed by MMA has been the gold standard in managing complex cases, the surgery first approach for treatment of malocclusion has increased in popularity because of decreased treatment time and improved patient quality of life. MMA continues to be the gold-standard for treatment of refractory sleep apnea. Technological advancements, including 3D printing and virtual surgical planning, have enhanced the patient experience and provided more efficiency to this surgery. SUMMARY: First introduced in the 19th century, orthognathic surgery has continuously been refined. Over the last few decades, there has been increasing support for a surgery first approach in the treatment of malocclusion. MMA has revolutionized the surgical treatment of OSA and provides the best opportunity for success or cure in patients with complex obstructive patterns. Technology has enhanced the surgical process and created more efficiency for the surgeon and patient. VIDEO ABSTRACT: http://links.lww.com/COOH/A40.

Computer-Aided Design and Manufacturing Cutting and Drilling Guides with Prebent Titanium Plates Improve Surgical Accuracy of Skeletal Class III Malocclusion.

BACKGROUND: The aim of this study was to evaluate the effects of the use of computer-aided design and manufacturing cutting and drilling guides with prebent titanium plates for the correction of skeletal class III malocclusion. METHODS: In this prospective, randomized, controlled clinical trial, 46 patients with skeletal class III malocclusion were randomly assigned into two groups. The patients underwent bimaxillary surgery with computer-aided design and manufacturing cutting and drilling guides with prebent titanium plates (experimental group) or computer-aided design and manufacturing splints (control group). Preoperative and postoperative imaging data were collected and then analyzed using Mimics Research 19.0, Geomagic Studio, and IBM SPSS Version 21.0. RESULTS: Deformity evaluation and posttreatment assessment were performed for all patients. The experimental group had fewer postoperative complications. Comparison of the linear and angular differences to facial reference planes revealed more accurate repositioning of the mandible and condyles in the experimental group, although the position of several landmarks still requires small adjustments. CONCLUSION: Computer-aided design and manufacturing cutting and drilling guides with prebent titanium plates effectively corrected skeletal class III malocclusion, providing positional control of segments with reasonable surgical accuracy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

The incidental finding of a retained 'throat pack'.

A postoperative radiograph demonstrated a folded radio-opaque structure in the nasopharynx, resembling a retained throat pack, despite her not having any respiratory symptoms. Retention of a throat pack is a never event.

The Medial Subcoronoid Process Region as a Novel Source of Bone Grafts in Orthognathic Surgery and Genioplasty.

BACKGROUND: Since 2012, the authors have adopted the medial subcoronoid process bone interpositional grafting in OGS and genioplasty procedures. The purpose of this study was to present the technical details and clinical outcomes of this alternative bone interpositional grafting for LeFort I and chin osteotomies. METHODS: Consecutive patients (n = 50) who underwent single-splint bimaxillary OGS with or without genioplasty and received medial subcoronoid bone interpositional grafting were included. Standardized facial and intraoral photographs at early and late postoperative periods (12.2 ±â€Š3.3 and 44.8 ±â€Š8.4 months postsurgery, respectively) were blindly rated to assess facial symmetry, chin, and occlusion status based on qualitative rating scales. Complication and reoperation rates were also reviewed. RESULTS: The medial subcoronoid bone interpositional grafts were adopted to stabilize different LeFort I maxillary movement types or lengthening/advancing genioplasty (36 and 14 patients, respectively). Overall, the early facial symmetry, chin, and occlusion status were maintained at late evolutions. None of the patients had donor-site or bone graft-related complications (i.e., bad split, undesired mandible fracture, infection, fibrous union, nonunion, and/or permanent neurosensory deficit) or revisionary surgery during follow-up. CONCLUSION: The medial subcoronoid process bone grafting was a feasible alternative for bone interpositional defects of LeFort I and chin osteotomies with no significant morbidity and avoiding secondary donor sites.

Stability of bioresorbable plates following reduction of mandibular body fracture: Three-dimensional analysis.

PURPOSE: The recent development of bioresorbable bone plates and screws allows plates to be applied to the load-bearing regions of the mandible and to remain in place over time without the need for removal. We hypothesized that the stability of composite plates and screws forged from unsintered hydroxyapatite particles and poly-l-lactide (u-HA/PLLA) is comparable to that of standard titanium fixation systems for the reduction of fractures of load-bearing regions of the mandibular body. MATERIALS AND METHODS: 40 patients underwent open reduction and internal fixation of the fractured mandibular body with either a titanium or u-HA/PLLA bone plate. Cone-beam CT images were obtained immediately postoperatively and at 6-month follow-up, and were analyzed for positional changes of the affected mandible. RESULTS: There were no significant differences in the postoperative positional changes of reference points between the titanium and u-HA/PLLA miniplates, except for that for the coronoid process (p-value = 0.03). Multivariate regression analysis revealed no significant differences in spatial changes between the immediate postoperative and 6-month follow-up images, after adjusting for age and sex. CONCLUSION: The stability of bioresorbable u-HA/PLLA miniplates and screws was comparable to that of titanium miniplates and screws immediately postoperatively and at 6-month follow-up, following surgical reduction of fractures of load-bearing regions of the mandibular body. Bioresorbable osteosynthesis can be considered a viable alternative to titanium osteosynthesis.

The Drilling Guiding Templates and Pre-Bent Titanium Plates Improves the Operation Accuracy of Orthognathic Surgery With Computer-Aided Design and Computer-Aided Manufacturing Occlusal Splints for Patients With Facial Asymmetry.

Facial asymmetry is a common maxillofacial deformity which requires surgery to recover the 3-dimensional relationship of bones. The computer-aided design and computer-aided manufacturing (CAD/CAM) has been developed and applied to improve orthognathic analysis and surgery design. How to accurately realize the preoperative design of orthognathic surgery with CAD/CAM occlusal splints during operation remains a big problem. In this study, 24 consecutive patients with facial asymmetry were recruited and assigned to 2 groups. For Group A, CAD/CAM was applied to designing and producing not only the occlusal splints, but also the drilling guiding templates and pre-bent titanium plates, and for Group B CAD/CAM was applied for occlusal splints only. Postoperative clinical examinations, symmetry evaluation through 3D cephalometric analysis, accuracy comparison using color distance maps and quantitative accuracy analysis were performed. Symmetry evaluation showed that patients of both groups achieved improved facial symmetry after surgery. The color distance maps and quantitative accuracy analysis together demonstrated significantly less difference found between virtual simulated surgery and postoperative CT scan data in Group A than in Group B. In conclusion, by navigation with the drilling guiding templates and pre-bent titanium plates, the facial symmetry for patients with facial asymmetry was successfully restored after orthognathic surgery, same as applying CAD/CAM occlusal splints only. However, the drilling guiding templates and pre-bent titanium plates would provide a more accurate performance according to preoperative simulation, especially for proximal mandibular segments.

Intraoral Scanning and Setting Up the Digital Final Occlusion in Three-Dimensional Planning of Orthognathic Surgery: Its Comparison with the Dental Model Approach.

BACKGROUND: Three-dimensional surgical planning for orthognathic surgery is becoming prevalent, with improving outcomes. However, conventional dental casts are still used for evaluations, digital image conversion, surgical planning, and occlusal splint production. This study used intraoral scanning for the three-dimensional planning of the final digital occlusion and compared this method with the conventional dental cast approach. METHODS: Thirty consecutive patients who underwent two-jaw orthognathic surgery to treat mandibular prognathism and asymmetry were included. Dental casts (control group) and intraoral scans (study group) were collected simultaneously for designing the final dental occlusion. A step-by-step setup of the final digital occlusion was established for the study group. To validate results, the intraoral scanning-based virtual occlusion was superimposed over the dental model-based final digital occlusion for comparison. Intraobserver and interobserver variability were assessed for setting up the final digital occlusion. The fitness of splints fabricated using the conventional and virtual occlusion methods were compared. RESULTS: The steps for setting up the final digital occlusion were applicable in all cases. The average root-mean-square difference of final occlusion images between the two groups was 0.45 mm, indicating a comparable occlusal relationship. The intraobserver reproducibility and interobserver reliability for setting up the virtual occlusion were satisfactory. Moreover, no significant difference existed in the splint fitness test between the groups. CONCLUSIONS: The proposed intraoral scan and setup process of the final digital occlusion was reliable and accurate. Thus, the method can replace the dental model approach for the three-dimensional planning of orthognathic surgery. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Blood loss and operative time associated with orthognathic surgery utilizing a novel navigation system in cleft lip and palate patients.

PURPOSE: This retrospective study evaluated the volume of blood loss and operative time associated with management of nongrowing patients with cleft lip and palate (CLP) using bimaxillary orthognathic surgery (OGS) designed by a three-dimensional (3D) computer-assisted simulation and navigation for orthognathic surgery (CASNOS) system. METHODS: This study included 53 skeletal Class III nongrowing patients with unilateral CLP who underwent bimaxillary OGS using either the CASNOS protocol (n = 30) or the traditional two-dimensional (2D) method (n = 23). The skeletal parameters of jaw-bone components, the levels of hemoglobin (Hb) and hematocrit (Hct) were measured before and after surgery. The estimated blood loss and actual blood loss (ABL) were also calculated. RESULTS: The two groups did not differ significantly with regard to the demographic parameters (age, gender, and body mass index), the preoperative skeletal parameters and surgical changes of jaw-bone components. The mean ABL of the CASNOS group was significantly lower than that of the control group (915.6 ± 280.5 vs. 1204.9 ± 201.0 ml, p < 0.001), and the changes in Hb and Hct level also followed a similar pattern in both groups. The mean operative time was significantly shorter in the CASNOS group compared with the control group (384.2 ± 48.5 vs. 469.0 ± 94.9 min, p < 0.001). CONCLUSION: This study demonstrated that the application of the 3D CASNOS approach in OGS for the management of complicated Class III nongrowing patients with CLP significantly shortened the operative time and reduced ABL in comparison with the traditional 2D methods.

A New Software Suite in Orthognathic Surgery : Patient Specific Modeling, Simulation and Navigation.

Orthognathic surgery belongs to the scope of maxillofacial surgery. It treats dentofacial deformities consisting in discrepancy between the facial bones (upper and lower jaws). Such impairment affects chewing, talking, and breathing and can ultimately result in the loss of teeth. Orthognathic surgery restores facial harmony and dental occlusion through bone cutting, repositioning, and fixation. However, in routine practice, we face the limitations of conventional tools and the lack of intraoperative assistance. These limitations occur at every step of the surgical workflow: preoperative planning, simulation, and intraoperative navigation. The aim of this research was to provide novel tools to improve simulation and navigation. We first developed a semiautomated segmentation pipeline allowing accurate and time-efficient patient-specific 3D modeling from computed tomography scans mandatory to achieve surgical planning. This step allowed an improvement of processing time by a factor of 6 compared with interactive segmentation, with a 1.5-mm distance error. Next, we developed a software to simulate the postoperative outcome on facial soft tissues. Volume meshes were processed from segmented DICOM images, and the Bullet open source mechanical engine was used together with a mass-spring model to reach a postoperative simulation accuracy <1 mm. Our toolset was completed by the development of a real-time navigation system using minimally invasive electromagnetic sensors. This navigation system featured a novel user-friendly interface based on augmented virtuality that improved surgical accuracy and operative time especially for trainee surgeons, therefore demonstrating its educational benefits. The resulting software suite could enhance operative accuracy and surgeon education for improved patient care.

Real-time augmented model guidance for mandibular proximal segment repositioning in orthognathic surgery, using electromagnetic tracking.

It is essential to reposition the mandibular proximal segment (MPS) as close to its original position as possible during orthognathic surgery. Conventional methods cannot pinpoint the exact position of the condyle in the fossa in real time during repositioning. In this study, based on an improved registration method and a separable electromagnetic tracking tool, we developed a real-time, augmented, model-guided method for MPS surgery to reposition the condyle into its original position more accurately. After virtual surgery planning, using a complex maxillomandibular model, the final position of the virtual MPS model was simulated via 3D rotations. The displacements resulting from the MPS simulation were applied to the MPS landmarks to indicate their final postoperative positions. We designed a new registration body with 24 fiducial points for registration, and determined the optimal point group on the registration body through a phantom study. The registration between the patient's CT image and physical spaces was performed preoperatively using the optimal points. We also developed a separable frame for installing the electromagnetic tracking tool on the patient's MPS. During MPS surgery, the electromagnetic tracking tool was repeatedly attached to, and separated from, the MPS using the separable frame. The MPS movement resulting from the surgeon's manipulation was tracked by the electromagnetic tracking system. The augmented condyle model and its landmarks were visualized continuously in real time with respect to the simulated model and landmarks. Our method also provides augmented 3D coronal and sagittal views of the fossa and condyle, to allow the surgeon to examine the 3D condyle-fossa positional relationship more accurately. The root mean square differences between the simulated and intraoperative MPS models, and between the simulated and postoperative CT models, were 1.71 ± 0.63 mm and 1.89 ± 0.22 mm respectively at three condylar landmarks. Thus, the surgeons could perform MPS repositioning conveniently and accurately based on real-time augmented model guidance on the 3D condyle positional relationship with respect to the glenoid fossa, using augmented and simulated models and landmarks.

Supplemental Internal Wire Suspension in Orthognathic Surgery Fixation.

Internal wire suspensions were previously used in the management of maxillary trauma and orthognathic surgery, but currently the gold standard is rigid internal fixation with bone plates and screws. The authors report a case of bimaxillary osteotomy in a skeletal class III patient where a supplemental circum-zygomatic-mandibular suspension was done to stabilize the maxilla because of the instability after rigid internal fixation due to poor bone thickness.