Stereolithography for Craniofacial Surgery

Tracheal intubation in patients with Pierre Robin sequence: development, application, and clinical value based on a 3-dimensional printed simulator

Background: The main clinical manifestations of patients with Pierre Robin sequence (PRS) include micrognathia, the glossoptosis and dyspnoea. The difficulty of tracheal intubation (TI) in such patients is increased. Objective: The purpose of the study was to evaluate the reliability and efficacy of the PRS simulator. Methods: A PRS simulator was developed by using 3-dimensional (3D) printing technology under computer-aided design. A total of 12 anaesthesiologists each trained 5 times for TI on the PRS Training Simulator-1 and recorded the simulation time. After the training, they were randomly divided into three groups with a total of 12 nontrained anaesthesiologists, and the simulation was completed on PRS Simulator-2, 3 and 4. The simulation time was recorded, and the performance was evaluated by three chief anaesthesiologists. Then, all 24 anaesthesiologists completed the questionnaire. Results: A PRS simulator developed by 3D printing was used to simulate the important aspects of TI. The average number of years worked was 6.3 ± 3.1 years, and 66.7% were female. The time for the 12 anaesthesiologists to complete the training gradually decreased (p < 0.01). Compared with the trained anaesthesiologists, the simulation time of TI in the nontrained anaesthesiologists was much longer (all p < 0.01). In addition, the simulation performance of the trained anaesthesiologists was relatively better (all p < 0.01). Conclusion: The reliability and efficacy of the PRS simulator is herein preliminarily validated, and it has potential to become a teaching and training tool for anaesthesiologists.

The Utility of 3D Printing for Surgical Planning and Patient-Specific Implant Design in Maxillofacial Surgery: A Narrative Review

Maxillofacial reconstructive implants are typically created in standard shapes and have a widespread application in head and neck surgery. During surgical procedures, the implant must be correctly bent according to the architecture of the particular bones. Bending takes practice, especially for untrained surgeons. Furthermore, repeated bending may increase internal stress, resulting in fatigue in vivo under masticatory loading and an array of consequences, including implant failure. There is a risk of fracture, screw loosening, and bone resorption. Resorption, infection, and displacement are usually associated with the use of premade alloplastic implants and autogenous grafts. Recent technological breakthroughs have led to the use of patient-specific implants (PSIs) developed by computer-designed additive manufacturing in reconstructive surgery. The use of computer-designed three-dimensional (3D)-printed PSI allows for more precise restoration of maxillofacial deformities, avoiding the common difficulties associated with premade implants and increasing patient satisfaction. Additive manufacturing is something that refers to a group of additive manufacturing methods. This technique has been quickly used in a variety of surgical procedures. The exponential expansion of this technology can be attributed to its enormous surgical value. Adding 3D printing to a medical practice can be a rewarding experience with stunning results.

New frontiers in Dental Technology: An Overview

The pace of technological advance across science is staggeringly fast. Our ability to translate some of the potential developments in technology into concepts/products/devices that can assist dentists in caring for patients is key to ensuring that both the profession and the people we care for derive full benefit from these new technologies. This overview will focus in four areas: research and how we gather and interpret data to inform health care; the diagnosis and prevention of disease; planning care; and new concepts in terms of achieving desired health outcomes for patients. Some of the technological advances will be in their infancy and others close to or indeed clinical reality. The objective of this overview is to show where we are in terms of the cutting edge of technology and to whet the appetite for things to come.

3D printing for preoperative planning and surgical training: a review

Surgeons typically rely on their past training and experiences as well as visual aids from medical imaging techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) for the planning of surgical processes. Often, due to the anatomical complexity of the surgery site, two dimensional or virtual images are not sufficient to successfully convey the structural details. For such scenarios, a 3D printed model of the patient's anatomy enables personalized preoperative planning. This paper reviews critical aspects of 3D printing for preoperative planning and surgical training, starting with an overview of the process-flow and 3D printing techniques, followed by their applications spanning across multiple organ systems in the human body. State of the art in these technologies are described along with a discussion of current limitations and future opportunities.

The fitting accuracy of pre-bend reconstruction plates and their impact on the temporomandibular joint

BACKGROUND

Various causes for bone defects of the lower jaw have been described. As a result, patients often suffer from compromised aesthetics and a loss of, or reduction in, important physiological functions, such as swallowing, breathing, and speaking. A change in the shape of the lower jaw can impair the natural occlusion and leads to an atypical or modified position of the temporomandibular joint. Titanium reconstruction plates are the standard approach to jaw reconstruction, and are used for temporary bridging of a jaw defect or fixation of a bone graft. Conventionally these plates are intraoperatively adjusted to the mandible by the surgeon. Computer-aided manufacturing, computer-aided design, and rapid prototyping have gained increasing importance in the field of medicine, as they allow the production of individual models of the lower jaw, with the possibility of preoperatively bending the reconstruction plates. In this retrospective study, the accuracy of pre-bent titanium plates and their effect on the temporomandibular joint situation in comparison with intraoperatively curved plates will be discussed.

MATERIALS AND METHODS

Patients who attended our department for lower jaw reconstruction between March 2013 and February 2015 were included in this retrospective study. Within that time 20 patients were treated with pre-bent reconstruction plates (group 1). 20 comparable patients were selected with reconstruction and conventional intraoperative bending (group 2). To evaluate the accuracy of the plates and the condylar position, postoperative cone beam computed tomograms and computed tomograms were used to assess the bone-plate distance at 12 defined points and four angles in axial reconstruction. The results were compared, statistically evaluated, and discussed.

RESULTS

Regarding the maximum bone-plate distances and the sum of distances, there was a significant difference between the accuracy of the pre-bent and the conventionally bent reconstruction plates (p = 0.022, p = 0.048). Regarding the condylar position, there was no significant difference between both methods (p = 0.867).

CONCLUSION

The results of this study show that a better fitting accuracy can be achieved using pre-bent plates. Preparation of the plates proves to be advantageous and meaningful, especially in complex bone defects and deformations of the lower jaw. Nevertheless, concerning the position of the temporomandibular joint, no significant difference could be ascertained between the shown methods, contradicting several studies.

3D printing in dentistry

3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.

Three-Dimensional Printing: Custom-Made Implants for Craniomaxillofacial Reconstructive Surgery

Craniomaxillofacial reconstructive surgery is a challenging field. First it aims to restore primary functions and second to preserve craniofacial anatomical features like symmetry and harmony. Three-dimensional (3D) printed biomodels have been widely adopted in medical fields by providing tactile feedback and a superior appreciation of visuospatial relationship between anatomical structures. Craniomaxillofacial reconstructive surgery was one of the first areas to implement 3D printing technology in their practice. Biomodeling has been used in craniofacial reconstruction of traumatic injuries, congenital disorders, tumor removal, iatrogenic injuries (e.g., decompressive craniectomies), orthognathic surgery, and implantology. 3D printing has proven to improve and enable an optimization of preoperative planning, develop intraoperative guidance tools, reduce operative time, and significantly improve the biofunctional and the aesthetic outcome. This technology has also shown great potential in enriching the teaching of medical students and surgical residents. The aim of this review is to present the current status of 3D printing technology and its practical and innovative applications, specifically in craniomaxillofacial reconstructive surgery, illustrated with two clinical cases where the 3D printing technology was successfully used.

Advancing the field of 3D biomaterial printing

3D biomaterial printing has emerged as a potentially revolutionary technology, promising to transform both research and medical therapeutics. Although there has been recent progress in the field, on-demand fabrication of functional and transplantable tissues and organs is still a distant reality. To advance to this point, there are two major technical challenges that must be overcome. The first is expanding upon the limited variety of available 3D printable biomaterials (biomaterial inks), which currently do not adequately represent the physical, chemical, and biological complexity and diversity of tissues and organs within the human body. Newly developed biomaterial inks and the resulting 3D printed constructs must meet numerous interdependent requirements, including those that lead to optimal printing, structural, and biological outcomes. The second challenge is developing and implementing comprehensive biomaterial ink and printed structure characterization combined with in vitro and in vivo tissue- and organ-specific evaluation. This perspective outlines considerations for addressing these technical hurdles that, once overcome, will facilitate rapid advancement of 3D biomaterial printing as an indispensable tool for both investigating complex tissue and organ morphogenesis and for developing functional devices for a variety of diagnostic and regenerative medicine applications.

Application of 3-Dimensional Printing Technology to Kirschner Wire Fixation of Adolescent Condyle Fracture

Condyle fractures are common in children and are increasingly treated with open reduction. Three-dimensional printing has developed into an important method of assisting surgical treatment. This report describes the case of a 14-year-old patient treated for a right condyle fracture at the authors' hospital. Preoperatively, the authors designed a surgical guide using 3-dimensional printing and virtual surgery. The 3-dimensional surgical guide allowed accurate alignment of the fracture using Kirschner wire without additional dissection and tissue injury. Kirschner wire fixation augmented by 3-dimensional printing technology produced a good outcome in this adolescent condyle fracture.

Surgical planning and microvascular reconstruction of the mandible with a fibular flap using computer-aided design, rapid prototype modelling, and precontoured titanium reconstruction plates: a prospective study

The standard of mandibular reconstruction has increased since the introduction of computer-assisted design (CAD) and rapid prototype modelling (RPM) for surgical planning. Between 2008 and 2013, a prospective pilot study of 20 patients was planned to compare the outcomes of patients treated by mandibular reconstruction who had CAD and RPM-guided operations using a precontoured titanium plate, with the outcomes of patients treated conventionally. We recorded the time taken for reconstruction, total operating time, and whether this type of planning could improve the results of mandibular reconstruction. We found significant differences in the incidence of dental malocclusion (p=0.03) and exposure of the titanium plate (p=0.009). The mean operating time for reconstruction in the preoperative planning group was 135 (37)min compared with 176 (58)min in the conventional group (p=0.04). Preoperative planning using CAD and RPM can increase the accuracy of microvascular mandibular reconstruction and reduce the operating time for reconstruction.

Digital design and individually fabricated titanium implants for the reconstruction of traumatic zygomatico-orbital defects

Autogenous bone graft is the preferred method for the reconstruction of maxillofacial defects. As an additional choice, the aim of this study was to develop and test the application of individual digital planning, rapid prototyping titanium implants, and functional long-term results in the reconstruction of traumatic zygomatico-orbital defects. Six patients were treated with 3-dimensional digital surgery designs, digital locating template, and individually fabricated titanium implants. All patients were followed for a minimum of 18 months with a mean of 51.8 months. The recovery of facial contour and function was satisfactory in 4 patients. In the other 2 patients, 1 implant was removed after implant exposure caused by infection, and the other implant was removed because of persistent diplopia. Although the risk of implant exposure exists, individual digital planning procedures, rapid prototyping, digital locating templates, and titanium implants are still effective methods for reconstructing traumatic zygomatico-orbital defects. We believe that the appropriate choice of surgical cases is of great importance when using individually designed titanium implants to restore maxillofacial defects. The patient's age, health, medical history, local infection, location and extent of the bony defect, and remaining soft tissue volume should all be taken into consideration.

Evaluation of a patient specific femoral alignment guide for hip resurfacing

A novel alternative to conventional instrumentation for femoral component insertion in hip resurfacing is a patient specific, computed tomography based femoral alignment guide. A benchside study using cadaveric femora was performed comparing a custom alignment guide to conventional instrumentation and computer navigation. A clinical series of twenty-five hip resurfacings utilizing a custom alignment guide was conducted by three surgeons experienced in hip resurfacing. Using cadaveric femora, the custom guide was comparable to conventional instrumentation with computer navigation proving superior to both. Clinical femoral component alignment accuracy was 3.7° and measured within ± 5° of plan in 20 of 24 cases. Patient specific femoral alignment guides provide a satisfactory level of accuracy and may be a better alternative to conventional instrumentation for initial femoral guidewire placement in hip resurfacing.

Preliminary development of a workstation for craniomaxillofacial surgical procedures: introducing a computer-assisted planning and execution system

INTRODUCTION

Facial transplantation represents one of the most complicated scenarios in craniofacial surgery because of skeletal, aesthetic, and dental discrepancies between donor and recipient. However, standard off-the-shelf vendor computer-assisted surgery systems may not provide custom features to mitigate the increased complexity of this particular procedure. We propose to develop a computer-assisted surgery solution customized for preoperative planning, intraoperative navigation including cutting guides, and dynamic, instantaneous feedback of cephalometric measurements/angles as needed for facial transplantation and other related craniomaxillofacial procedures.

METHODS

We developed the Computer-Assisted Planning and Execution (CAPE) workstation to assist with planning and execution of facial transplantation. Preoperative maxillofacial computed tomography (CT) scans were obtained on 4 size-mismatched miniature swine encompassing 2 live face-jaw-teeth transplants. The system was tested in a laboratory setting using plastic models of mismatched swine, after which the system was used in 2 live swine transplants. Postoperative CT imaging was obtained and compared with the preoperative plan and intraoperative measures from the CAPE workstation for both transplants.

RESULTS

Plastic model tests familiarized the team with the CAPE workstation and identified several defects in the workflow. Live swine surgeries demonstrated utility of the CAPE system in the operating room, showing submillimeter registration error of 0.6 ± 0.24 mm and promising qualitative comparisons between intraoperative data and postoperative CT imaging.

CONCLUSIONS

The initial development of the CAPE workstation demonstrated that integration of computer planning and intraoperative navigation for facial transplantation are possible with submillimeter accuracy. This approach can potentially improve preoperative planning, allowing ideal donor-recipient matching despite significant size mismatch, and accurate surgical execution for numerous types of craniofacial and orthognathic surgical procedures.

Inaccuracies in additive manufactured medical skull models caused by the DICOM to STL conversion process

INTRODUCTION

The process of fabricating physical medical skull models requires many steps, each of which is a potential source of geometric error. The aim of this study was to demonstrate inaccuracies and differences caused by DICOM to STL conversion in additively manufactured medical skull models.

MATERIAL AND METHODS

Three different institutes were requested to perform an automatic reconstruction from an identical DICOM data set of a patients undergoing tumour surgery into an STL file format using their software of preference. The acquired digitized STL data sets were assessed and compared and subsequently used to fabricate physical medical skull models. The three fabricated skull models were then scanned, and differences in the model geometries were assessed using established CAD inspection software methods.

RESULTS

A large variation was noted in size and anatomical geometries of the three physical skull models fabricated from an identical (or "a single") DICOM data set.

CONCLUSIONS

A medical skull model of the same individual can vary markedly depending on the DICOM to STL conversion software and the technical parameters used. Clinicians should be aware of this inaccuracy in certain applications.

Exploratory benchtop study evaluating the use of surgical design and simulation in fibula free flap mandibular reconstruction

Background

Surgical design and simulation (SDS) is a useful tool to help surgeons visualize the anatomy of the patient and perform operative maneuvers on the computer before implementation in the operating room. While these technologies have many advantages, further evidence of their potential to improve outcomes is required. The present benchtop study was intended to identify if there is a difference in surgical outcome between free-hand surgery completed without virtual surgical planning (VSP) software and preoperatively planned surgery completed with the use of VSP software.

Methods

Five surgeons participated in the study. In Session A, participants were asked to do a free-hand reconstruction of a 3d printed mandible with a defect using a 3d printed fibula. Four weeks later, in Session B, the participants were asked to do the same reconstruction, but in this case using a preoperatively digitally designed surgical plan. Digital registration computer software, hard tissue measures and duration of the task were used to compare the outcome of the benchtop reconstructions.

Results

The study revealed that: (1) superimposed images produced in a computer aided design (CAD) software were effective in comparing pre and post-surgical outcomes, (2) there was a difference, based on hard tissue measures, in surgical outcome between the two scenarios and (3) there was no difference in the time it took to complete the sessions.

Conclusion

The study revealed that the participants were more consistent in the preoperatively digitally planned surgery than they were in the free hand surgery.

Pilot study: evaluation of the use of the convergent interview technique in understanding the perception of surgical design and simulation

BACKGROUND

It is important to understand the perceived value of surgical design and simulation (SDS) amongst surgeons, as this will influence its implementation in clinical settings. The purpose of the present study was to examine the application of the convergent interview technique in the field of surgical design and simulation and evaluate whether the technique would uncover new perceptions of virtual surgical planning (VSP) and medical models not discovered by other qualitative case-based techniques.

METHODS

Five surgeons were asked to participate in the study. Each participant was interviewed following the convergent interview technique. After each interview, the interviewer interpreted the information by seeking agreements and disagreements among the interviewees in order to understand the key concepts in the field of SDS.

RESULTS

Fifteen important issues were extracted from the convergent interviews.

CONCLUSION

In general, the convergent interview was an effective technique in collecting information about the perception of clinicians. The study identified three areas where the technique could be improved upon for future studies in the SDS field.

Craniomaxillofacial surgery planning based on 3D models derived from Cone-Beam CT data

INTRODUCTION

Individual planning of complex maxillofacial corrections may require 3D models which can be manufactured based on DICOM datasets. The gold standard for image acquisition is still high-resolution multi-slice computed tomography (MSCT). However, appropriate datasets for model fabrication can be acquired by modern Cone-Beam CT (CBCT) devices that have been developed specifically for maxillofacial imaging. The clinical utility of individual models fabricated on the basis of CBCT datasets was assessed.

METHODS

In five patients affected by different deficiencies of the maxillofacial skeleton, preoperative imaging was performed with ILUMA CBCT. Segmentation of hard tissues was performed manually by thresholding. Corresponding STL datasets were created and exported to an industrial service provider (Alphaform, Munich, Germany) specializing in rapid prototyping, and 3D models were fabricated by the selective laser sintering (SLS) technique. For variance analysis, landmark measurements were performed on both virtual and 3D models. Subsequently, maxillofacial surgery was performed according to the model-based planning.

RESULTS

All CBCT-based DICOM datasets could be used for individual model fabrication. Detailed reproduction of individual anatomy was achieved and a topographic survey showed no relevant aberrance between the virtual and real models. The CBCT-based 3D models were therefore used for planning and transfer of different maxillofacial procedures.

CONCLUSIONS

CBCT-based datasets can be used for the fabrication of surgical 3D models if the correct threshold is set. Preoperative workflow and patient comfort is improved in terms of the fast-track concept by using this "in-house" imaging technique.

Application of visible light-based projection stereolithography for live cell-scaffold fabrication with designed architecture

One-step scaffold fabrication with live cell incorporation is a highly desirable technology for tissue engineering and regeneration. Projection stereolithography (PSL) represents a promising method owing to its fine resolution, high fabrication speed and computer-aided design (CAD) capabilities. However, the majority of current protocols utilize water-insoluble photoinitiators that are incompatible with live cell-fabrication, and ultraviolet (UV) light that is damaging to the cellular DNA. We report here the development of a visible light-based PSL system (VL-PSL), using lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as the initiator and polyethylene glycol diacrylate (PEGDA) as the monomer, to produce hydrogel scaffolds with specific shapes and internal architectures. Furthermore, live human adipose-derived stem cells (hADSCs) were suspended in PEGDA/LAP solution during the PSL process, and were successfully incorporated within the fabricated hydrogel scaffolds. hADSCs in PEG scaffolds showed high viability (>90%) for up to 7 days after fabrication as revealed by Live/Dead staining. Scaffolds with porous internal architecture retained higher cell viability and activity than solid scaffolds, likely due to increased oxygen and nutrients exchange into the interior of the scaffolds. The VL-PSL should be applicable as an efficient and effective tissue engineering technology for point-of-care tissue repair in the clinic.

Computer-assisted design and rapid prototype modeling in microvascular mandible reconstruction

OBJECTIVES/HYPOTHESIS

To evaluate the use of computer-assisted design and rapid prototype modeling to improve the speed and accuracy of mandibular reconstruction.

STUDY DESIGN

Case-control study.

METHODS

Between 2005 and 2011, 38 subjects underwent fibula free flap mandibular reconstruction using computer-assisted design and rapid prototype modeling. Titanium plates were prebent using the models prior to surgery. Direct plate bending on the native mandible to accurately restore occlusion would not have been possible in 11 patients with exophytic tumors, nine patients with pathologic fractures, and 10 patients with a prior segmental mandibulectomy. Computer-generated cutting guides were utilized to facilitate fibular osteotomies.

RESULTS

The mean operative time for subjects was 8.8 ± 1.0 hours compared to the mean operative time defect-matched control group, for whom computer-assisted design and models were not used, of 10.5 ± 1.4 hours (P = .0006). Comparison of the preoperative and postoperative mandibles demonstrated that the mean change in position of selected bony landmarks (condyles, gonions, and gnathion) was less in the subject group than in the control group (4.11 ± 3.09 mm vs. 6.92 ± 5.64 mm, respectively; P = .001) Comparison of postoperative mandibles with preoperative virtual plans showed a mean deviation of 2.40 ± 2.06 mm from planned fibular segment lengths and 3.51 ± 2.69° from planned angles between fibular segments.

CONCLUSIONS

Computer-assisted design and rapid prototype modeling have the potential to increase the speed and accuracy of mandibular reconstruction. We believe these technologies are particularly useful for cases in which the original architecture of the mandible has been distorted or destroyed.

Evaluation of the effect of computed tomography scan protocols and freeform fabrication methods on bone biomodel accuracy

OBJECTIVE

To assess the effect of computed tomography (CT) scan protocols (radiation amounts) and fabrication methods on biomodel accuracy and variability.

SAMPLE

Cadaveric femur of a Basset Hound.

PROCEDURES

Retroreconstructions (n = 158) were performed of 16 original scans and were visually inspected to select 17 scans to be used for biomodel fabrication. Biomodels of the 17 scans were made in triplicate by use of 3 freeform fabrication processes (stereolithography, fused deposition modeling, and 3-D printing) for 153 models. The biomodels and original bone were measured by use of a coordinate measurement machine.

RESULTS

Differences among fabrication methods accounted for 2% to 29% of the total observed variation in inaccuracy and differences among method-specific radiation configurations accounted for 4% to 44%. Biomodels underestimated bone length and width and femoral head diameter and overestimated cortical thickness. There was no evidence of a linear association between thresholding adjustments and biomodel accuracy. Higher measured radiation dose led to a decrease in absolute relative error for biomodel diameter and for 4 of 8 cortical thickness measurements.

CONCLUSIONS AND CLINICAL RELEVANCE

The outside dimensions of biomodels have a clinically acceptable accuracy. The cortical thickness of biomodels may overestimate cortical thickness. Variability among biomodels was caused by model fabrication reproducibility and, to a lesser extent, by the radiation settings of the CT scan and differences among fabrication methods.

Additive manufacturing for microvascular reconstruction of the mandible in 20 patients

OBJECTIVES

The aim of this study was to evaluate the use of model mandibles made preoperatively by additive manufacturing, which were used to prebend reconstruction plates prior to mandibular resection and reconstruction with microvascular bony flaps.

MATERIALS AND METHODS

Computer Tomography (CT) or Cone Beam Tomography (CBT) scans acquired preoperatively were used to obtain DICOM data sets to produce a model of the mandible using rapid prototyping. This model was used as a template to prebend and then sterilize a 2.3 or 2.7 reconstruction plate, which was used to reconstruct the mandible with a microvascular bony flap. This technique was used in 20 consecutive patients who required mandibular resection and reconstruction because of a tumour or osteoradionecrosis.

RESULTS

The prebent plate was used in all patients intraoperatively without the need for any further bending. The average time to bend a plate on a nonsterile model was 0.42 h (range 0.25-0.68 h). This is felt to represent the minimum amount of time saved during the operation. Additive manufacture of the mandible prior to resection and reconstruction with a microvascular flap is a useful technique which reduces the operating time.

Patient specific ankle-foot orthoses using rapid prototyping

BACKGROUND

Prefabricated orthotic devices are currently designed to fit a range of patients and therefore they do not provide individualized comfort and function. Custom-fit orthoses are superior to prefabricated orthotic devices from both of the above-mentioned standpoints. However, creating a custom-fit orthosis is a laborious and time-intensive manual process performed by skilled orthotists. Besides, adjustments made to both prefabricated and custom-fit orthoses are carried out in a qualitative manner. So both comfort and function can potentially suffer considerably. A computerized technique for fabricating patient-specific orthotic devices has the potential to provide excellent comfort and allow for changes in the standard design to meet the specific needs of each patient.

METHODS

In this paper, 3D laser scanning is combined with rapid prototyping to create patient-specific orthoses. A novel process was engineered to utilize patient-specific surface data of the patient anatomy as a digital input, manipulate the surface data to an optimal form using Computer Aided Design (CAD) software, and then download the digital output from the CAD software to a rapid prototyping machine for fabrication.

RESULTS

Two AFOs were rapidly prototyped to demonstrate the proposed process. Gait analysis data of a subject wearing the AFOs indicated that the rapid prototyped AFOs performed comparably to the prefabricated polypropylene design.

CONCLUSIONS

The rapidly prototyped orthoses fabricated in this study provided good fit of the subject's anatomy compared to a prefabricated AFO while delivering comparable function (i.e. mechanical effect on the biomechanics of gait). The rapid fabrication capability is of interest because it has potential for decreasing fabrication time and cost especially when a replacement of the orthosis is required.

Oblique osteotomy and coronoidectomy in extreme prognathism of Apert syndrome

We report a case of oblique osteotomy and coronoidectomy for correction of extreme prognathism in Apert syndrome.A 16-year-old girl presented with a prognathic mandible. A prototype model was formed using computed tomography. After a mock bilateral oblique osteotomy of the mandible, the distal segment did not overlap the proximal segment, and it caused bony impingement between the coronoid process and the subcondyle of the proximal segment. An oblique osteotomy of the mandible was done through a submandibular approach, and bilateral coronoidectomy followed. After surgery, mandibular parameters were reviewed. The mandibular plane-Frankfort horizontal (MP/FH) angle decreased from 44 to 11 degrees; and the mandibular plane-sella nasion (MP/SN) angle, from 52 to 17 degrees. The mandible rotated backward and caudally after the surgery.It is predictable that there will be a bony impingement between the coronoid process and the subcondyle of the proximal segment before surgery, and so an oblique osteotomy and coronoidectomy are planned ahead through an external approach.

Microtechnologies in implant and restorative dentistry: A stroll through a digital dental landscape

This is an explanatory article introducing the combination of various technologies used in implant and restorative dentistry. The aim of the article is to provide an overview of some of the techniques supporting the restorative treatment plan at various stages to provide contemporary, state-of-the-art bridgework based on dental implants. It is a discussion of the way existing technologies used in fields of engineering and medicine are brought together to form a complete process.

Stereolithographic models to guide orbital and oculoplastic surgery

PURPOSE

This paper aims to highlight the potential of stereolithographic models (SLM) as a tool in orbital surgical planning, and provides four examples of their role in facilitating successful surgery.

METHOD

Retrospective case series report.

RESULTS

Case 1: SLM facilitated a successful orbital biopsy of a deep orbital mass by allowing several practice trucut biopsies. Case 2: Complex orbital fracture-repair was facilitated by using a SLM to demonstrate post-trauma and previous post-surgical-intervention bony anatomy. Case 3: Replication of accurate orbital anatomy in a case of severe socket contracture facilitated the selection of Branemark-implant placement sites to prevent inadvertent entry into the cranial cavity. Case 4: SLM prevented unnecessary surgical intervention.

CONCLUSION

SLM are useful tools for pre-operative surgical planning, and have applications in selected complex orbital and oculoplastic cases.