Modification of planned postoperative occlusion in orthognathic surgery, based on computer-aided design/computer-aided manufacturing-engineered preoperative surgical simulation

Establishing a point-of-care additive manufacturing workflow for clinical use

Additive manufacturing, or 3-Dimensional (3-D) Printing, is built with technology that utilizes layering techniques to build 3-D structures. Today, its use in medicine includes tissue and organ engineering, creation of prosthetics, the manufacturing of anatomical models for preoperative planning, education with high-fidelity simulations, and the production of surgical guides. Traditionally, these 3-D prints have been manufactured by commercial vendors. However, there are various limitations in the adaptability of these vendors to program-specific needs. Therefore, the implementation of a point-of-care in-house 3-D modeling and printing workflow that allows for customization of 3-D model production is desired. In this manuscript, we detail the process of additive manufacturing within the scope of medicine, focusing on the individual components to create a centralized in-house point-of-care manufacturing workflow. Finally, we highlight a myriad of clinical examples to demonstrate the impact that additive manufacturing brings to the field of medicine.

Positional changes in the mandibular proximal segment after intraoral vertical ramus osteotomy: Surgery-first approach versus conventional approach

Objective

To compare postoperative positional changes in the mandibular proximal segment between the conventional orthognathic surgery (CS) and the surgery-first approach (SF) using intraoral vertical ramus osteotomy (IVRO) in patients with Class III malocclusion.

Methods

Thirty-eight patients with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into two groups according to the use of preoperative orthodontic treatment CS group (n = 18) and SF group (n = 20). Skeletal changes in both groups were measured using computed tomography before (T0), 2 days after (T1), and 1 year after (T2) the surgery. Three-dimensional (3D) angular changes in the mandibular proximal segment, condylar position, and maxillomandibular landmarks were assessed.

Results

The mean amounts of mandibular setback and maxillary posterior impaction were similar in both groups. At T2, the posterior portion of the mandible moved upward in both groups. In the SF group, the anterior portion of the mandible moved upward by a mean distance of 0.9 ± 1.0 mm, which was statistically significant (p < 0.001). There were significant between-group differences in occlusal changes (p < 0.001) as well as in overjet and overbite. However, there were no significant between-group differences in proximal segment variables.

Conclusions

Despite postoperative occlusal changes, positional changes in the mandibular proximal segment and the position of the condyles were similar between CS and SF, which suggested that SF using IVRO achieved satisfactory postoperative stability. If active physiotherapy is conducted, the proximal segment can be adapted in the physiological position regardless of the occlusal changes.

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.

Use of 3-D printing technologies in craniomaxillofacial surgery: a review

Three-dimensional (3-D) printing is a method of manufacturing in which materials like plastic or metal are deposited onto one another in layers to produce a 3-D object. Because of the complex anatomy of craniomaxillofacial structures, full recovery of craniomaxillofacial tissues from trauma, surgeries, or congenital malformations is extremely challenging. 3-D printing of scaffolds, tissue analogs, and organs has been proposed as an exciting alternative to address some of these key challenges in craniomaxillofacial surgery. There are four broad types of 3-D printing surgical applications that can be used in craniomaxillofacial surgery: contour models (positive-space models to allow preapplication of hardware before surgery), guides (negative-space models of actual patient data to guide cutting and drilling), splints (negative-space models of virtual postoperative positions to guide final alignment), and implants (negative-space 3-D printed implantable materials or 3-D printed molds into which nonprintable materials are poured). 3-D printing technology is being successfully used for surgeries for head and neck malignancies, mandibular reconstruction, orthognathic surgeries, for mandibulectomies after osteoradionecrosis, orbital floor fracture surgeries, nasal reconstruction, and cranioplasties. The excitement behind 3-D printing continues to increase and hopefully will drive improvements in the technology and its surgical applications, especially in craniomaxillofacial region. This present review sets out to explore use of 3-D printing technologies in craniomaxillofacial surgery.

[Application of bone-support guide by three-dimensional printing technique in maxillary LeFortⅠosteotomy]

OBJECTIVE

This study aimed to investigate the application of an osteotomy template and a repositioning template manufactured by three-dimensional (3D) printing technique in maxillary LeFortⅠosteotomy.

METHODS

The patient group consisted of eight patients with maxillary hypoplasia who underwent LeFortⅠosteotomy. The mean age at the time of surgery was 25.6 years old. All patients were scanned using cone beam computed tomography (CBCT) to create a 3D model of the maxillary. The osteotomy and repositioning templates of the LeFortⅠosteotomy were manufactured by 3D printing technique. All bones were cut by the same doctor with extensive orthognathic surgery experience. One part of the template guided the osteotomy, and the other repositioned the maxilla during operation. Postoperative CBCT scan was performed, and the virtual plan was compared with the postoperative surgical result using an image fusion of the CBCT dataset by analyzing measurements between six landmarks relative to three reference planes. Statistical analysis was performed, and accuracy was reported using SPSS 16.0 software package.

RESULTS

Primary healing of incisions was observed in all patients, and no serious complications were observed. The maximum mean values were 1.35 mm, and the displacement error was UL6 to the coronal plane. The maximum standard deviation was 0.85, and the maximum standard error was 0.30, which was acceptable by clinical standards.

CONCLUSIONS

The application of osteotomy and repositioning templates manufactured by 3D printing technique in maxillary LeFortⅠosteotomy was safe and can enable doctors to complete a surgery accurately.

Accuracy of 3-Dimensional Virtual Surgical Simulation Combined With Digital Teeth Alignment: A Pilot Study

PURPOSE

To evaluate the accuracy of virtual surgical simulation combined with digital teeth alignment and the applicability of this technique to the diagnosis and establishment of a 3-dimensional (3D) visualized treatment objective for orthognathic surgery by comparing virtual simulation images with actual post-treatment images.

MATERIALS AND METHODS

This retrospective study included patients who underwent computed tomography (CT) before and after treatment. The 3D digital images were constructed from the initial CT images and dental cast scan data, and virtual surgical simulation combined with digital teeth alignment was performed. Accuracy of the virtual simulation was analyzed by comparing the distances of skeletal and dental landmarks in the horizontal, sagittal, and coronal reference planes with those on post-treatment images using the Wilcoxon signed rank test. Intraclass correlation coefficients were calculated to evaluate the degree of concordance between the 2 images.

RESULTS

The study sample included 11 patients (mean age, 18.8 yr). Most landmarks had differences smaller than 2 mm in the 3 reference planes between virtual simulation and post-treatment images; these differences were not statistically significant (P > .05). Most skeletal landmarks, except the A point, B point, and gonion, showed normal to high concordance between the virtual simulation and post-treatment images in the 3 reference planes (P < .05); dental landmarks exhibited a broad range of concordance.

CONCLUSION

The 3D virtual surgical simulation combined with digital teeth alignment using pretreatment CT images yielded results sufficiently accurate to be used for the diagnosis and establishment of visualized treatment objectives for orthognathic surgery.

Surgical applications of three-dimensional printing: a review of the current literature & how to get started

Three dimensional (3D) printing involves a number of additive manufacturing techniques that are used to build structures from the ground up. This technology has been adapted to a wide range of surgical applications at an impressive rate. It has been used to print patient-specific anatomic models, implants, prosthetics, external fixators, splints, surgical instrumentation, and surgical cutting guides. The profound utility of this technology in surgery explains the exponential growth. It is important to learn how 3D printing has been used in surgery and how to potentially apply this technology. PubMed was searched for studies that addressed the clinical application of 3D printing in all surgical fields, yielding 442 results. Data was manually extracted from the 168 included studies. We found an exponential increase in studies addressing surgical applications for 3D printing since 2011, with the largest growth in craniofacial, oromaxillofacial, and cardiothoracic specialties. The pertinent considerations for getting started with 3D printing were identified and are discussed, including, software, printing techniques, printing materials, sterilization of printing materials, and cost and time requirements. Also, the diverse and increasing applications of 3D printing were recorded and are discussed. There is large array of potential applications for 3D printing. Decreasing cost and increasing ease of use are making this technology more available. Incorporating 3D printing into a surgical practice can be a rewarding process that yields impressive results.