Application of Rapid Prototyping for Temporomandibular Joint Reconstruction

Comparing the use of conventional and three-dimensional printing (3DP) in mandibular reconstruction

Background

There are a number of clinical disorders that require mandibular reconstruction (MR). Novel three-dimensional (3D) printing technology enables reconstructions to be more accurate and beneficial to the patient. However, there is currently no evidence identifying which techniques are better suited for MR, based on the type of clinical disorder the patient has. In this study, we aim to compare 3D techniques with conventional techniques to identify how best to reconstruct the mandible based on the clinical cause that necessitates the reconstructive procedure: cancerous or benign tumours, clinical disorders, infection or disease and trauma or injury.

Methods

PubMed, Scopus, Embase and Medline were searched to identify relevant papers that outline the clinical differences between 3D and conventional techniques in MR. Data were evaluated to provide a clear outline of suitable techniques for surgery.

Results

20 of 2749 papers met inclusion criteria. These papers were grouped based on the clinical causes that required MR into four categories: malignant or benign tumour resection; mandibular trauma/injury and other clinical disorders.

Conclusions

The majority of researchers favoured 3D techniques in MR. However, due to a lack of standardised reporting in these studies it was not possible to determine which specific techniques were better for which clinical presentations.

Impact of technology in temporomandibular joint reconstruction surgeries: A systematic review

OBJECTIVES

The digital technologies, in recent years, have integrated with temporomandibular joint reconstruction surgeries (TRS). Therefore, a systematic study was conducted to assess the impact of digital technologies in TRS. Besides, a brief comparison between the CAD/CAM and 3D printing (3DP) technologies is presented.

MATERIALS & METHODS

We searched in PubMed, ProQuest and Science direct using PRISMA guidelines. Population = Patients undergoing TRS, Intervention=CAD/CAM or 3DP, Comparison= conventional TRS (cTRS) vs technology integrated TRS (tiTRS), Outcome= Advantages/disadvantages of technology and Subjective/objective symptoms, Study design= Type of study. The quality of observational study was assessed using ROBINS-1 Assessment tool.

RESULTS

Out of 632 articles, 30 articles for CAD/CAM and 3DP were included in the study. A majority of TRS were done for ankylosis (new or re-entry), earlier failed surgery, osteoarthritis and neoplastic cases. The articles were divided into two groups. Group I: CAD/CAM(n = 16), Group II: 3DP (n = 14).

DISCUSSION

tiTRS had definite advantages over cTRS with lesser surgery time, defined osteotomies, précised implant fitting and better final result outcome however, evidence for tiTRS in long-term follow-up is inconclusive. The cost, time, infrastructure and ethical/regulatory issues are the downsides of assisted surgeries. It was observed that 3DP technology is versatile and its adaptation in the fabrication of customized implants has outpaced CAD/CAM technology. However, literature data is feeble qualitatively and quantitatively.

CONCLUSION

The TRS has leveraged the flexibility and precision of assisted surgeries. In future, tiTRS could successfully replace cTRS, provided that shortcomings should be dealt so that the technology can benefit the masses.

Facial Reconstruction: A Systematic Review of Current Image Acquisition and Processing Techniques

Introduction: Plastic and reconstructive surgery is based on a culmination of technological advances, diverse techniques, creative adaptations and strategic planning. 3D imaging is a modality that encompasses several of these criteria while encouraging the others. Imaging techniques used in facial imaging come in many different modalities and sub-modalities which is imperative for such a complex area of the body; there is a clear clinical need for hyper-specialized practice. However, with this complexity comes variability and thus there will always be an element of bias in the choices made for imaging techniques. Aims and Objectives: The aim of this review is to systematically analyse the imaging techniques used in facial reconstruction and produce a comprehensive summary and comparison of imaging techniques currently available, including both traditional and novel methods. Methods: The systematic search was performed on EMBASE, PubMed, Scopus, Web of Science and Cochrane reviews using keywords such as "image technique/acquisition/processing," "3-Dimensional," "Facial," and "Reconstruction." The PRISMA guidelines were used to carry out the systematic review. Studies were then subsequently collected and collated; followed by a screening and exclusion process with a final full-text review for further clarification in regard to the selection criteria. A risk of bias assessment was also carried out on each study systematically using the respective tool in relation to the study in question. Results: From the initial 6,147 studies, 75 were deemed to fulfill all selection criteria and selected for meta-analysis. The majority of papers involved the use of computer tomography, though the use of magnetic resonance and handheld scanners using sonography have become more common in the field. The studies ranged in patient population, clinical indication. Seminal papers were highlighted within the group of papers for further analysis. Conclusions: There are clearly many factors that affect the choice of image acquisition techniques and their potential at being ideal for a given role. Ultimately the surgical team's choice will guide much of the decision, but it is crucial to be aware of not just the diagnostic ability of such modalities, but their treatment possibilities as well.

Medical 3D Printing Cost-Savings in Orthopedic and Maxillofacial Surgery: Cost Analysis of Operating Room Time Saved with 3D Printed Anatomic Models and Surgical Guides

RATIONALE AND OBJECTIVE

Three-dimensional (3D) printed anatomic models and surgical guides have been shown to reduce operative time. The purpose of this study was to generate an economic analysis of the cost-saving potential of 3D printed anatomic models and surgical guides in orthopedic and maxillofacial surgical applications.

MATERIALS AND METHODS

A targeted literature search identified operating room cost-per-minute and studies that quantified time saved using 3D printed constructs. Studies that reported operative time differences due to 3D printed anatomic models or surgical guides were reviewed and cataloged. A mean of $62 per operating room minute (range of $22-$133 per minute) was used as the reference standard for operating room time cost. Different financial scenarios were modeled with the provided cost-per-minute of operating room time (using high, mean, and low values) and mean time saved using 3D printed constructs.

RESULTS

Seven studies using 3D printed anatomic models in surgical care demonstrated a mean 62 minutes ($3720/case saved from reduced time) of time saved, and 25 studies of 3D printed surgical guides demonstrated a mean 23 minutes time saved ($1488/case saved from reduced time). An estimated 63 models or guides per year (or 1.2/week) were predicted to be the minimum number to breakeven and account for annual fixed costs.

CONCLUSION

Based on the literature-based financial analyses, medical 3D printing appears to reduce operating room costs secondary to shortening procedure times. While resource-intensive, 3D printed constructs used in patients' operative care provides considerable downstream value to health systems.

Autotransplantation of third molars with completely formed roots to replace compromised molars with the computer-aided rapid prototyping

OBJECTIVE

To describe a method to fabricate donor tooth replica to assist surgeons in preparation of recipient socket during tooth autotransplantation.

MATERIALS AND METHODS

A total of 28 compromised molars in 27 patients were transplanted with third molars using computer-aided rapid prototyping (CARP) technique. Surgery time and extra-alveolar time were documented. Postoperatively, the distance between cervix of transplanted tooth and the alveolar wall was measured. The degree of postoperative pain experienced was assessed with visual analog scale at day 1, 3, and 7.

RESULTS

From 28 clinical cases, the average extra-alveolar time and surgery time were 2.5 minutes (±1.3) and 44 minutes (±6.8), respectively. Postoperatively, the average distance between cervix of transplanted tooth and the alveolar wall was 0.87 mm (±0.15) at the mesial-cervix, 0.95 mm (±0.17) at the distal-cervix, 0.88 mm (±0.18) at the buccal-cervix, and 0.95 mm (±0.13) at the lingual-cervix. The value of visual analog scale score significantly decreased from day 1 to day 3.

CONCLUSIONS

CARP is a reliable technique for fabrication of tooth like surgical replicas in conventional autotransplantation.

CLINICAL SIGNIFICANCE

CARP technique minimized extra-oral time, reduced iatrogenic damage, and consequently increased the survival rate of tooth autotransplantation.

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.

Rapid Prototyping as an Auxiliary in Mandibular Reconstructions

The reconstruction of mandible is a challenge with regard to aesthetic and reconstructive demands. The etiology of mandibular fractures is variable, trauma, pathology, bone infections. There are many materials that provide an excellent form of rehabilitation for these defects, where the autogenous graft presents important characteristics that favor a greater success rate. Furthermore, the rapid prototyping method is quite interesting, because it brings a series of advantages to the surgeon, like reducing the operative time, among others. The purpose of the present article is to describe a clinical case of a patient with mandible bone defect caused by gunshot perforation, treated through iliac crest bone graft with planning through rapid prototyping. The mandibular reconstruction can present a real challenge for the surgeon. Biomodels should be required in complex cases because they help to decrease surgical time and to increase the predictability of the procedure.

Protection of Inferior Alveolar Neurovascular Bundle in Alveolar Bone Operation

PURPOSE

The aim of this study was to investigate the protection of the inferior alveolar neurovascular bundle in alveolar bone operation in conditions such as chronic osteomyelitis and cementoma.

PATIENTS AND METHODS

The study enrolled 7 cases, 4 with chronic osteomyelitis and 3 with cementoma with pain. Computed tomography scan and 3-dimensional reconstruction were performed for the diseases. Data were processed by ProPlan CMF 1.3 software. The edge of lesion was defined and the inferior alveolar nerve was marked. Template was designed to guide the osteotomy line. Piezosurgery was used for osteotomy, with the avoidance of nerve canal. Current perception threshold (CPT) was performed to evaluate the nerve function after operation.

RESULTS

The CPT difference of the affected side before and after operation showed no statistically significant differences compared with that of the unaffected side (P = 0.0556).

CONCLUSIONS

Digital template protects the inferior alveolar neurovascular bundle with the aid of piezosurgery during alveolar bone resection, which obtained satisfying clinical results. As powerful assistive tools of functional surgery, digital template and piezosurgery achieve both the purposes of treatment and function.

3D printing technology used in severe hip deformity

This study was designed to assess the use of a 3D printing technique in total hip arthroplasty (THA) for severe hip deformities, where new and improved approaches are needed. THAs were performed from January 2015 to December 2016. Bioprosthesis artificial hip joints were used in both conventional and 3D printing hip arthroplasties. A total of 74 patients (57 cases undergoing conventional hip replacements and 17 undergoing 3D printing hip replacements) were followed-up for an average of 24 months. The average age of the patients was 62.7 years. Clinical data between the patients treated with different approaches were compared. Results showed that the time to postoperative weight bearing and the Harris scores of the patients in the 3D printing group were better than those for patients in the conventional hip replacement group. Unfortunately, the postoperative infection and loosening rates were higher in the 3D printing group. However, there were no significant differences in femoral neck anteversion, neck shaft, acetabular or sharp angles between ipsilateral and contralateral sides in the 3D printing group (P>0.05). The femoral neck anteversion angle was significantly different between the two sides in the conventional hip replacement group (P<0.05). Based on these results, we suggest that the 3D printing approach provides a better short-term curative effect that is more consistent with the physiological structure and anatomical characteristics of the patient, and we anticipate that its use will help improve the lives of many patients.

3D-printing techniques in a medical setting: a systematic literature review

BACKGROUND

Three-dimensional (3D) printing has numerous applications and has gained much interest in the medical world. The constantly improving quality of 3D-printing applications has contributed to their increased use on patients. This paper summarizes the literature on surgical 3D-printing applications used on patients, with a focus on reported clinical and economic outcomes.

METHODS

Three major literature databases were screened for case series (more than three cases described in the same study) and trials of surgical applications of 3D printing in humans.

RESULTS

227 surgical papers were analyzed and summarized using an evidence table. The papers described the use of 3D printing for surgical guides, anatomical models, and custom implants. 3D printing is used in multiple surgical domains, such as orthopedics, maxillofacial surgery, cranial surgery, and spinal surgery. In general, the advantages of 3D-printed parts are said to include reduced surgical time, improved medical outcome, and decreased radiation exposure. The costs of printing and additional scans generally increase the overall cost of the procedure.

CONCLUSION

3D printing is well integrated in surgical practice and research. Applications vary from anatomical models mainly intended for surgical planning to surgical guides and implants. Our research suggests that there are several advantages to 3D-printed applications, but that further research is needed to determine whether the increased intervention costs can be balanced with the observable advantages of this new technology. There is a need for a formal cost-effectiveness analysis.

Three-dimensional Physical Modeling: Applications and Experience at Mayo Clinic

Radiologists will be at the center of the rapid technologic expansion of three-dimensional (3D) printing of medical models, as accurate models depend on well-planned, high-quality imaging studies. This article outlines the available technology and the processes necessary to create 3D models from the radiologist's perspective. We review the published medical literature regarding the use of 3D models in various surgical practices and share our experience in creating a hospital-based three-dimensional printing laboratory to aid in the planning of complex surgeries.

[Temporo-mandibular ankylosis]

Ankylosis of the temporomandibular joint is defined as a permanent constriction of the jaws with less than 30mm mouth opening measured between the incisors, occurring because of bony, fibrous or fibro-osseous fusion. Resulting complications such as speech, chewing, swallowing impediment and deficient oral hygiene may occur. The overall incidence is decreasing but remains significant in some developing countries. The most frequent etiology in developed countries is the post-traumatic ankylosis occurring after condylar fracture. Other causes may be found: infection (decreasing since the advent of antibiotics), inflammation (rheumatoid arthritis and ankylosing spondylitis mainly) and congenital diseases (very rare). Management relies on surgery: resection of the ankylosis block in combination with bilateral coronoidectomy… The block resection may be offset by the interposition temporal fascia flap, a costochondral graft or a TMJ prosthesis according to the loss of height and to the impact on dental occlusion. Postoperative rehabilitation is essential and has to be started early, to be intense and prolonged. Poor rehabilitation is the main cause of ankylosis recurrence.

Advantages and disadvantages of 3-dimensional printing in surgery: A systematic review

BACKGROUND

Three-dimensional (3D) printing is becoming increasingly important in medicine and especially in surgery. The aim of the present work was to identify the advantages and disadvantages of 3D printing applied in surgery.

METHODS

We conducted a systematic review of articles on 3D printing applications in surgery published between 2005 and 2015 and identified using a PubMed and EMBASE search. Studies dealing with bioprinting, dentistry, and limb prosthesis or those not conducted in a hospital setting were excluded.

RESULTS

A total of 158 studies met the inclusion criteria. Three-dimensional printing was used to produce anatomic models (n = 113, 71.5%), surgical guides and templates (n = 40, 25.3%), implants (n = 15, 9.5%) and molds (n = 10, 6.3%), and primarily in maxillofacial (n = 79, 50.0%) and orthopedic (n = 39, 24.7%) operations. The main advantages reported were the possibilities for preoperative planning (n = 77, 48.7%), the accuracy of the process used (n = 53, 33.5%), and the time saved in the operating room (n = 52, 32.9%); 34 studies (21.5%) stressed that the accuracy was not satisfactory. The time needed to prepare the object (n = 31, 19.6%) and the additional costs (n = 30, 19.0%) were also seen as important limitations for routine use of 3D printing.

CONCLUSION

The additional cost and the time needed to produce devices by current 3D technology still limit its widespread use in hospitals. The development of guidelines to improve the reporting of experience with 3D printing in surgery is highly desirable.

Rapid prototyping modelling in oral and maxillofacial surgery: A two year retrospective study

Background

The use of rapid prototyping (RP) models in medicine to construct bony models is increasing.

Material and Methods

The aim of the study was to evaluate retrospectively the indication for the use of RP models in oral and maxillofacial surgery at Helsinki University Central Hospital during 2009-2010. Also, the used computed tomography (CT) examination – multislice CT (MSCT) or cone beam CT (CBCT) - method was evaluated.

Results

In total 114 RP models were fabricated for 102 patients. The mean age of the patients at the time of the production of the model was 50.4 years. The indications for the modelling included malignant lesions (29%), secondary reconstruction (25%), prosthodontic treatment (22%), orthognathic surgery or asymmetry (13%), benign lesions (8%), and TMJ disorders (4%). MSCT examination was used in 92 and CBCT examination in 22 cases. Most of the models (75%) were conventional hard tissue models. Models with colored tumour or other structure(s) of interest were ordered in 24%. Two out of the 114 models were soft tissue models.

Conclusions

The main benefit of the models was in treatment planning and in connection with the production of pre-bent plates or custom made implants. The RP models both facilitate and improve treatment planning and intraoperative efficiency.

Key words:Rapid prototyping, radiology, computed tomography, cone beam computed tomography.

Preservation of the inferior alveolar neurovascular bundle in the osteotomy of benign lesions of the mandible using a digital template

Our aim was to evaluate the effect of a digital template in the preservation of the inferior alveolar neurovascular bundle during osteotomy for benign lesions of the mandible in 6 patients who were treated with mandibular osteotomies during 2013. Computed tomographic (CT) data were imported into ProPlan CMF 1.4 software. The borders of the lesion and the inferior alveolar canal were marked, and a digital template designed to mark the borders, outline the canal, and guide the osteotomy. A mirror image of the unaffected mandible was used to make a stereolithographic model by a rapid prototyping technique to prefabricate the reconstruction plate for the bone graft. The accuracy of the designs and the templates was evaluated during operation and postoperatively by CT. The sensation of the skin was tested using a Neurometer® CPT (current perception threshold) sensory detector (Neurotron Inc, Baltimore USA) to evaluate the function of the preserved inferior alveolar neurovascular bundle during follow up. With the digital template it was possible to guide removal of the bony lesion while accurately protecting the neurovascular bundle. Follow up for a mean of 8 months (range 5 -12) showed good facial symmetry, a stable occlusion, and recovery of sensation in the lower lip on the affected side. We conclude that a digital template can successfully help the resection of benign lesions of the mandible while preserving the function of the inferior alveolar neurovascular bundle.

Validation of the cone beam computed tomography-based stereolithographic surgical guide aiding autotransplantation of teeth: clinical case-control study

OBJECTIVE

To compare the outcome of cone beam computed tomography (CBCT)-based surgical planning and transfer technique for tooth autotransplantation versus conventional autotransplantation.

STUDY DESIGN

The study material comprised 40 pediatric subjects in whom 48 teeth were transplanted following a case-control design. While the study group (mean age 11 years) underwent CBCT imaging for surgical planning and transfer via stereolithographic tooth replica fabrication, the historical control group (mean age 12 years) was subjected to conventional autotransplantation.

RESULTS

The CBCT-based preoperative planning and the use of a tooth replica decreased the extra-alveolar time and reduced the number of positioning trials with the donor tooth. In the control group, 6 patients showed 1 or more complications, while this was noticed for only 2 study patients.

CONCLUSION

CBCT-based surgical planning of tooth autotransplantation may benefit from a shorter surgical time, while being a less invasive technique, causing fewer failures than a conventional approach.

Modeling porous scaffold microstructure by a reaction-diffusion system and its degradation by hydrolysis

One of the most important areas of Tissue Engineering is the research about bone regeneration and the replacement of its function. To meet this requirement, scaffolds have been developed to allow the cell migration, the growth of bone tissue, the transport of growth factors and nutrients and the renovation of the mechanical properties of bone. Scaffolds are made of different biomaterials and manufactured using various techniques that, in some cases, do not allow full control over the size and orientation of the pores that characterize the scaffold microstructure. From this perspective, we propose a novel hypothesis that a reaction-diffusion system can be used to design the geometrical specifications of the bone matrix. The validation of this hypothesis is performed by simulations of the reaction-diffusion system in a representative tridimensional unit cell, coupled with a model of scaffold degradation by hydrolysis. The results show the possibility that a Reaction-Diffusion system can control features such as the percentage of porosity, trabecular size, orientation, and interconnectivity of pores.