Computer-aided surgery in distraction osteogenesis of the maxilla and mandible

Preliminary study of the accuracy and safety of robot-assisted mandibular distraction osteogenesis with electromagnetic navigation in hemifacial microsomia using rabbit models

This study aimed to investigate the accuracy and safety of mandibular osteotomy and distraction device positioning in distraction osteogenesis assisted by an electromagnetic navigation surgical robot. Twelve New Zealand white rabbits were randomly divided into two groups after computed tomography. The control group underwent a procedure based on the preoperative three-dimensional design and clinical experience. Animals in experimental group underwent a procedure with robotic assistance after registration. The accuracies of osteotomy and distraction device positioning were analysed based on distance and angular errors. The change in ramus length after a 1 cm-extension of the distraction device was for assessing distraction effect. The preparation, operative and osteotomy times, intraoperative bleeding, and teeth injury were used for safety assessment. In the experimental group, the distance (t = 2.591, p = 0.011) and angular (t = 4.276, p = 0.002) errors of osteotomy plane, and the errors in distraction device position (t = 3.222, p = 0.009) and direction (t = 4.697, p = 0.001) were lower; the distraction effect was better (t = 4.096, p = 0.002). There was no significant difference in the osteotomy time and bleeding; however, the overall operative and preparation times were increased in the experimental group, with a reduced rate of teeth damage. Robot-assisted mandibular distraction osteogenesis with electromagnetic navigation in craniofacial microsomia is feasible, safe, significantly improves surgical precision.

Navigation-assisted maxillofacial reconstruction: accuracy and predictability

The aim of this study was to evaluate the accuracy of navigation-assisted maxillofacial reconstruction and to identify the predictors of the clinical outcomes. A total of 112 patients who underwent navigation-assisted maxillofacial reconstruction with free flaps between 2014 and 2019, performed by a single surgical team, were assessed. Accuracy was evaluated by superimposing the postoperative computed tomography data with the preoperative virtual surgical plan. Predictors of the clinical outcomes affecting the accuracy were identified and analysed. The mean deviation and root mean square (RMS) estimate of the orbital, maxillary, and mandibular reconstructions were 0.88 ± 3.25 mm and 3.38 ± 0.73 mm, 0.77 ± 3.44 mm and 3.69 ± 0.82 mm, and 1.07 ± 4.16 mm and 4.67 ± 3.95 mm, respectively (P < 0.05). There was no significant difference in orbital volume or projection between the preoperative, postoperative, and healthy orbits (P = 0.093 and P = 0.225, respectively). Multivariate linear regression analysis confirmed significant associations between the accuracy of navigation-assisted mandibular reconstruction and preservation of the condyle, type of reconstruction, type of osteosynthesis plate, and number of bony segments. Navigation-assisted midface reconstruction yielded a higher level of accuracy in the final surgical outcome when compared to mandibular reconstruction. Computer-assisted techniques and intraoperative navigation can be an alternative or adjunct to current surgical techniques to improve the final surgical outcome, especially in more complex maxillofacial reconstructions.

Cephalometric studies of the mandible, its masticatory muscles and vasculature of growing Göttingen Minipigs-A comparative anatomical study to refine experimental mandibular surgery

Over many decades, the Göttingen Minipig has been used as a large animal model in experimental surgical research of the mandible. Recently several authors have raised concerns over the use of the Göttingen Minipig in this research area, observing problems with post-operative wound healing and loosening implants. To reduce these complications during and after surgery and to improve animal welfare in mandibular surgery research, the present study elucidated how comparable the mandible of minipigs is to that of humans and whether these complications could be caused by specific anatomical characteristics of the minipigs' mandible, its masticatory muscles and associated vasculature. Twenty-two mandibular cephalometric parameters were measured on CT scans of Göttingen Minipigs aged between 12 and 21 months. Ultimately, we compared this data with human data reported in the scientific literature. In addition, image segmentation was used to determine the masticatory muscle morphology and the configuration of the mandibular blood vessels. Compared to data of humans, significant differences in the mandibular anatomy of minipigs were found. Of the 22 parameters measured only four were found to be highly comparable, whilst the others were not. The 3D examinations of the minipigs vasculature showed a very prominent deep facial vein directly medial to the mandibular ramus and potentially interfering with the sectional plane of mandibular distraction osteogenesis. Damage to this vessel could result in inaccessible bleeding. The findings of this study suggest that Göttingen Minipigs are not ideal animal models for experimental mandibular surgery research. Nevertheless if these minipigs are used the authors recommend that radiographic techniques, such as computed tomography, be used in the specific planning procedures for the mandibular surgical experiments. In addition, it is advisable to choose suitable age groups and customize implants based on the mandibular dimensions reported in this study.

Optimization of the interface between radiology, surgery, radiotherapy, and pathology in head and neck tumor surgery: a navigation-assisted multidisciplinary network

A navigation-assisted multidisciplinary network to improve the interface between radiology, surgery, radiotherapy, and pathology in the field of head and neck cancer is described. All implicated fields are integrated by a common server platform and have remote data access in a ready-to-use format. The margins of resection and exact locations of biopsies are mapped intraoperatively. The pathologist uses the numerical coordinates of these samples to precisely trace each specimen in the anatomical field. Subsequently, map-guided radiotherapy is planned. In addition to the benefits of image-guided resection, this model enables radiotherapy planning according to the specific coordinates of the resection defect plus any residually affected sites identified by the pathologist. Irradiation of adjacent healthy structures is thereby minimized. In summary, the navigation-assisted network described grants timely multidisciplinary feedback between all fields involved, attains meticulous pathological definition, and permits optimized coordinate-directed radiotherapy.

A novel design of a computer-generated splint for vertical repositioning of the maxilla after Le Fort I osteotomy

OBJECTIVE

The objective of this study was to evaluate the efficacy of a novel tooth/bony-supported virtual splint design to control the maxillary vertical, rotational, and anteroposterior intraoperative movements.

STUDY DESIGN

A tooth/bone-borne splint was designed to position the osteotomized maxilla intraoperatively. Lateral cephalometric radiographs were obtained 1 week before the operation and 1 week after to compare the planned and actual movements of the maxilla.

RESULTS

The paired t test showed no significant difference between the planned and actual movements in both the vertical and horizontal measurements (P ≤ .05). The difference between the planned and actual horizontal movements in 4 (66.7%) of the 6 patients was 1 mm or less. For the vertical movements, 5 (83.3%) of the 6 patients showed a difference equal to or less than 1 mm.

CONCLUSIONS

The 2-piece surgical stent showed accurate control on the osteotomized maxilla and succeeded its repositioning to the preplanned positions.

Craniofacial distractor applicator

Craniofacial distraction can be planned using cephalograms, computed tomography, medical models, and other forms of anatomic data. However, it is often difficult to translate this plan to the patient. Specifically, it is difficult to obtain true parallel placement of bilateral midface and mandibular distractors. Intraoperative translation of preoperatively determined vectors is also troublesome. One method of application uses computed tomography data with radiofrequency triangulation technology in a specially equipped room. This helps with the issue of placement on the patient but does not establish parallelism. We have developed a simple-to-use craniofacial application stabilization device that allows equal placement of bilateral distractors and measurement of distraction vectors. The applicator measures 20 cm in length in its open configuration. The terminal portion of the device has a coupler that holds the distractor during placement. The device is hinged in 3 points so that it can be easily folded into a compact and autoclavable device (7 x 3 cm). The hinges allow equal placement of bilateral distractors. Each hinge can be calibrated to determine the vector of distraction and confirm equal application. Lastly, the stabilizer can be fixed to nasion with a Steinmann pin for reference, allowing intraoperative translation of distraction vectors. We demonstrated on skull models that the craniofacial distractor applicator can accurately allow parallel intraoperative placement of craniofacial distractors. We demonstrated simultaneous placement of the distractors allowing a more precise determination of end points.

Meta-analysis of mandibular distraction osteogenesis: clinical applications and functional outcomes

BACKGROUND

Mandibular distraction osteogenesis has been used effectively to treat syndromic craniofacial deformities. In recent years, its scope of application has widened to include treatment of airway obstruction in adults and children and nonsyndromic class II mandibular hypoplasia. So far, there has been no evidence-based review of mandibular distraction osteogenesis for mandibular lengthening.

METHODS

Two rounds of searches were performed by two independent assessors. The first-round PubMed search used the keywords "mandible" and "distraction osteogenesis." In the second-round search, the reference lists of the articles were retrieved. For both rounds, abstracts and then full articles were reviewed and selected on the basis of a set of inclusion and exclusion criteria.

RESULTS

The 178 retrieved articles yielded 1185 mandibular distraction osteogenesis patients: 539 received unilateral mandibular distraction osteogenesis and 646 received bilateral mandibular distraction osteogenesis. Mandibular distraction osteogenesis was reported to improve facial asymmetry and retrognathia (50.1 percent), correct the slanted lip commissure (24.7 percent), and improve or level the mandibular occlusal plane (11.1 percent) in unilateral asymmetry cases, whereas bilateral mandibular distraction osteogenesis was shown to be effective in preventing tracheostomies for 91.3 percent of neonates or infants with respiratory distress, and in relieving symptoms of obstructive sleep apnea for 97.0 percent of children and 100 percent of adult patients.

CONCLUSIONS

Mandibular distraction osteogenesis is effective in treating craniofacial deformities, but further clinical trials are required to assess the long-term stability and to compare the treatment with conventional treatment methods, especially in cases of obstructive sleep apnea or class II mandibular hypoplasia.

Comparison of two computerassisted surgery techniques to guide a mandibular distraction osteogenesis procedure Technical note

The accuracy of distracted facial bone displacement depends on the preoperative clinical assessment, surgical planning and technique. The aim of this study was to evaluate two different techniques to guide the mandibular distraction surgical procedure using an intraoral device. This study was performed on a fresh cadavre. 3D reconstructions from a computed tomographic (CT) acquisition were used for the two techniques. The first technique comprised a customised stereolithographic template and the second technique used a computer-assisted surgery (CAS) unit to guide the osteotomy and the positioning and screwing of the distractor device. Both methods were planned and compared with the same 3D software. The authors discuss the feasibility and reliability of the two techniques. The accuracy of the two techniques appears to be comparable for clinical applications, although the rapid prototyping template technique appears to be more satisfactory.

Reliability of Distraction Vector Transfer in Unilateral Vertical Distraction of the Mandibular Ramus

Mandibular distraction osteogenesis fails in correcting the skeletal deformities if the vector of distraction is incorrect. Lack of vector control is caused mainly by two factors: first, deficient vector planning and transfer, and, second, resistance of the masticatory muscles and the remaining soft tissue envelope toward elongation. To enhance predictable placement of intraoral distraction devices during surgery and thereby the treatment outcome, a method combining planning, simulation, and transfer was developed. The presurgical planning was based on frontal and lateral head films, and the planned position and orientation of the distraction device was applied on the stereolithographic model. This model was cut according to the planned osteotomy, and the distraction was simulated. The transfer procedure copied the planned and simulated position of the distraction device during surgery by use of an individual guiding splint. The guiding splint was fabricated on plaster models, and transferred to the stereolithographic model to reproduce the planned and simulated distraction treatment during surgery. The reliability of the vector-transfer method was evaluated cephalometrically in a homogenous group of 13 patients and their respective stereolithographic models in comparison with the planned, simulated, and transferred distraction vectors.

Basic research and 12 years of clinical experience in computer-assisted navigation technology: a review

Computer-aided surgical navigation technology is commonly used in craniomaxillofacial surgery. It offers substantial improvement regarding esthetic and functional aspects in a range of surgical procedures. Based on augmented reality principles, where the real operative site is merged with computer generated graphic information, computer-aided navigation systems were employed, among other procedures, in dental implantology, arthroscopy of the temporomandibular joint, osteotomies, distraction osteogenesis, image guided biopsies and removals of foreign bodies. The decision to perform a procedure with or without computer-aided intraoperative navigation depends on the expected benefit to the procedure as well as on the technical expenditure necessary to achieve that goal. This paper comprises the experience gained in 12 years of research, development and routine clinical application. One hundred and fifty-eight operations with successful application of surgical navigation technology--divided into five groups--are evaluated regarding the criteria "medical benefit" and "technical expenditure" necessary to perform these procedures. Our results indicate that the medical benefit is likely to outweight the expenditure of technology with few exceptions (calvaria transplant, resection of the temporal bone, reconstruction of the orbital floor). Especially in dental implantology, specialized software reduces time and additional costs necessary to plan and perform procedures with computer-aided surgical navigation.

Computer-aided navigation in dental implantology: 7 years of clinical experience

PURPOSE

This long-term study gives a review over 7 years of research, development, and routine clinical application of computer-aided navigation technology in dental implantology. Benefits and disadvantages of up-to-date technologies are discussed.

MATERIALS AND METHODS

In the course of the current advancement, various hardware and software configurations are used. In the initial phase, universally applicable navigation software is adapted for implantology. Since 2001, a special software module for dental implantology is available. Preoperative planning is performed on the basis of prosthetic aspects and requirements. In clinical routine use, patient and drill positions are intraoperatively registered by means of optoelectronic tracking systems; during preclinical tests, electromagnetic trackers are also used.

RESULTS

In 7 years (1995 to 2002), 55 patients with 327 dental implants were successfully positioned with computer-aided navigation technology. The mean number of implants per patient was 6 (minimum, 1; maximum, 11). No complications were observed; the preoperative planning could be exactly realized. The average expenditure of time for the preparation of a surgical intervention with navigation decreased from 2 to 3 days in the initial phase to one-half day in clinical routine use with software that is optimized for dental implantology.

CONCLUSIONS

The use of computer-aided navigation technology can contribute to considerable quality improvement. Preoperative planning is exactly realized and intraoperative safety is increased, because damage to nerves or neighboring teeth can be avoided.

Do position and soft tissue affect distraction vector? An in vitro investigation

OBJECTIVES

The purpose of this investigation was to provide an in vitro evaluation of the effects of soft tissue and position on vector during distraction.

MATERIALS AND METHODS

A polyurethane skull and mandible replica (Synbone, Landquart, Switzerland) was used in this study along with an internal distraction device (Synthes Maxillofacial, Paoli, PA). The first portion of the investigation evaluated the effects of distractor position (inferior body, midbody, and superior body) on distraction vector. The second portion of the investigation used polyethylene straps to simulate the suprahyoid muscles and muscles of mastication, and polysulfide to simulate periosteum and mucosa. A laser light source attached to the synthetic mandible was projected on a grid 7.1 m from the construct to measure deflection from the starting point. The distractor was advanced 8.0 mm for each trial. Five trials each for inferior, middle, and superior, with and without simulated soft tissues (N = 30) were performed. Vertical and horizontal deflection along with absolute distance were measured and recorded. Means and standard deviations were derived for groups, and compared for statistical significance (P <.05) with a 1-way analysis of variance for the effects of position with and without simulated soft tissue, and with a paired t-test for the effects of simulated soft tissue within groups of similar distractor position.

RESULTS

Statistically significant differences (P <.05) for distractors without simulated soft tissues were only noted for vertical deflection between the inferior and superior distractor groups. Statistically significant differences were noted for all measures, for all distractor positions with simulated soft tissues. Statistically significant differences were noted for all measures between similar distractor positions with and without simulated soft tissues. Distractors without simulated soft tissues were deflected lateral to the y-axis and above the x-axis. Distractors with simulated soft tissues were deflected lateral to the y-axis, but below the x-axis. For distractors with simulated soft tissues, the closer to the inferior border, the less the deflection from the x-axis.

CONCLUSION

Position alone had minimal effects on distraction vector. Simulated soft tissues affected the vector of distraction. The combination of position and simulated soft tissues affected distraction vector.

Biomedical technology revolution: opportunities and challenges for oral and maxillofacial surgeons

During this 45-minute presentation, I have tried to describe my vision of the exciting future that awaits us. I have tried to impart my enthusiasm for the opportunities provided to us as surgeons by the advances in molecular biology and genetics, imaging, surgical technology and bioinformatics. Most of all, I hope I have transmitted my optimism for the future to our younger members. I think the following statement or observation by the great educator Margaret Mead accurately summarizes our current situation regarding the application of all this new knowledge that will become available to us as surgeons: 'We are now at the point where we must educate people (surgeons) in what nobody knew yesterday, and prepare in our schools (training programs) for what no one knows yet but what some people must know tomorrow.'

Hemifacial microsomia. Etiology, diagnosis and treatment

BACKGROUND

Three percent of all newborns have significant structural anomalies. Hemifacial microsomia, or HFM, is the second most common facial anomaly, second only to cleft lip and palate. New therapeutic and clinical management techniques offer promising interventions that can allow many patients to have more normal childhoods at earlier ages.

DESCRIPTION

Due to a unilateral deficiency of the mandible and lower face, patients who have HFM have specific dental needs that require restorative, orthodontic and surgical correction.

CLINICAL IMPLICATIONS

Oral and maxillofacial malformations present diagnostic and treatment challenges unique to the dental profession. The etiology, diagnosis and treatment modalities discussed in this article can be used to help effectively rehabilitate patients who have HFM.

The role of three-dimensional information in health care and medical education: the implications for anatomy and dissection

The purposes of medical education can be summarized as learning how to take an effective history, perform a physical examination, and perform diagnostic and therapeutic procedures with minimal risk and maximal benefit to patients. Because patients are three-dimensional (3-D) objects, health care and medical education involve learning and applying 3-D information. The foundation begins in anatomy where students form and confirm or reform their own 3-D ideas and images of the development and structure of the human body at all levels of organization. Students go on to understand the interdependence of structure and function in health and disease. The basic questions for those teaching anatomy are "How do we learn and use 3-D information?" and "How is it taught most effectively?" These are not easy questions for teachers and are rarely asked by those who currently defend or reframe curricula. Unfortunately, there is little information on how we learn 3-D information and no evidence-based literature on the relative long-term vocational effectiveness of methods for teaching it. It is clear that we learn in several distinct modalities and that our students represent a spectrum of learning styles. To support the 3-D learning essential to both medical education and health care, anatomical societies need to provide answers to the following questions: Do the opportunities of dissection (visual, tactile, time, discovery, group process, mentoring) contribute to short- and long-term learning of 3-D information? If so, how? Does dissection offer significant advantages over other methods for learning, confirming, and using 3-D information in anatomy? Answers to these questions will provide a rational basis for decisions about curricular changes in anatomy courses (if, where, and when dissection should occur). This, in turn, will link these changes to society's ultimate purposes for medical education and health care rather than to the fiscal concerns of the businesses of health care and medical education, which is the current practice.

Craniofacial distraction osteogenesis: a review of the literature: Part 1: clinical studies

A review of the literature dealing with distraction osteogenesis (DO) of the craniofacial skeleton, provided by a PUBMED search (National Library of Medicine, NCBI; revised 3 April 2000) from 1966 to December 1999 was conducted. Key words used in the search were distraction, lengthening, mandible, mandibular, maxilla, maxillary, midface, midfacial, monobloc, cranial, craniofacial and maxillofacial. This search revealed 285 articles. One hundred and nine articles were clinically orientated and were analysed in detail in this study. The type of distraction, indications, age, type of surgery, distraction rates and rhythms, latency and contention periods, amount of lengthening, follow-up period, relapse, complications and the nature of the distraction device were analysed. This review revealed that 828 patients underwent DO of the craniofacial skeleton; 579 underwent mandibular DO, 129 maxillary DO, 24 simultaneous mandibular and maxillary DO and 96 midfacial and/or cranial DO. Craniofacial DO has proven to be a major advance for the treatment of numerous congenital and acquired craniofacial deformities. Treatment protocols and success criteria for craniofacial DO are suggested on the basis of these results. There is still, however, a lack of sufficient data, especially on follow-up and relapse, so that treatment strategies have to be validated by long-term studies in the future.

Placement of endosteal implants in the zygoma after maxillectomy: a Cadaver study using surgical navigation

Endosteal implants facilitate obturator prosthesis fixation in tumor patients after maxillectomy. Previous clinical studies have shown, however, that the survival of implants placed into available bone after maxillectomy is generally poor. Nevertheless, implants positioned optimally in residual zygomatic bone provide superior stability from a biomechanical point of view. In a pilot study, the authors assessed the precision of VISIT, a computer-aided surgical navigation system dedicated to the placement of endosteal implants in the maxillofacial area. Five cadaver specimens underwent hemimaxillectomy. The cadaver head was matched to a preoperative high-resolution computed tomograph by using implanted surgical microscrews as fiducial markers. The position of a surgical drill relative to the cadaver head was determined with an optical tracking system. Implants were placed into the zygomatic arch, where maximum bone volume was available. The results were assessed using tests for localization accuracy and postoperative computed tomographic scans of the cadaver specimens. The localization accuracy of landmarks on the bony skull was 0.6 +/- 0.3 mm (average +/- SD), as determined with a 5-df pointer probe; the localization accuracy of the tip of the implant burr was 1.7 +/- 0.4 mm. The accuracy of the implant position compared with the planned position was 1.3 +/- 0.8 mm for the external perforation of the zygoma and 1.7 +/-1.3 mm for the internal perforation. Eight of 10 implants were inserted with maximal contact to surrounding bone, and two implants were located unfavorably. Reliable placement of implants in this region is difficult to achieve. The technique described in this article may be very helpful in the management of patients after maxillary resection with poor support for obturator prostheses.

A novel modular retention system for midfacial distraction osteogenesis

Distraction osteogenesis of the midface offers new possibilities for the treatment of large sagittal discrepancies between the upper and lower jaws. The use of an extraoral halo-borne distractor, which allows free three-dimensional vector control, may cause problems in the connection between the midface and the distractor. To overcome these difficulties, we present a new modular retention system to gain bone anchorage whenever a toothborne appliance is not suitable. Distraction osteogenesis with an extraoral appliance is therefore possible even in edentulous elderly patients. We have used this system successfully in 11 patients.

Positioning of dental implants using computer-aided navigation and an optical tracking system: case report and presentation of a new method

A navigation system for computer-aided surgery (Virtual Patient System, VPS) has been described in previous studies for different indications in oral and maxillofacial surgery. The aim of the system is the intraoperative transfer of preoperative planning on radiographs or CT scans on the patient, in real-time, and independent of the position of the patient's head. Until now an electromagnetic tracking system has been used for intra-operative position measurement. For placement of dental implants, the electromagnetic tracking system is not suitable since the motor of the implant drill leads to a considerable distortion of the magnetic field, thus direct visualization of drilling the implant socket was not possible. To overcome this problem, an optical tracking system which is not disturbed by conductive materials was integrated in the VPS system. The first patient operated on with this system had a posttraumatic loss of the upper incisors; three implants have been placed according to the prosthetic axis previously planned on radiographs and CT scans. The experience gained in this intervention led to the conclusion that computer-aided surgery provides a valuable tool in implant dentistry.