Virtual Planning and 3D Printing in Contemporary Orthognathic Surgery

In-House 3D Printing for Craniofacial Trauma: 7-Year Review

INTRODUCTION

Complex facial trauma presents a challenge to the reconstructive surgeon, as the loss of facial buttresses makes accurate reduction of fractures more and more difficult. Accurate 3D-printed models and virtual surgical planning have become a mainstay in many other aspects of craniomaxillofacial surgery. However, turnaround times from industry produced models frequently preclude their use in the unplanned acute surgical setting.

PURPOSE

We seek to evaluate the use of in-house printed 3D models for facial trauma and the efficacy and safety of the procedures performed with the aid of these models.

METHODS

All patients from January 2017 to August 2023 who received an in-house 3D-printed model to help treat facial fractures were analyzed. Chart review was performed to extract demographic data, fracture type, mechanism, complications, comorbidities, and operative time. Analysis was performed in Microsoft Excel.

RESULTS

A total of 24 patients had 3D models created for facial fractures. The average age was 24.5 years. Motorized vehicles were involved in 15 cases (62.5%). The most commonly injured region was the midface (19 patients; 79.2%), and 8 patients had true panfacial fractures (33.3%). Seventeen patients (71%) had complex fractures involving multiple buttresses. For acute treatments, average time from presentation to operative treatment was 9 days. Average operative time was 268.3 minutes. Three patients (12.5%) had minor complications, including localized infection treated with antibiotics and a small wound dehiscence. Two patients (6.25%) had major complications: a draining sinus tract that required excision and a cicatricial lagophthalmos due to a laceration near the eyelid margin. Ninety-six percent of patients had satisfactory facial contour.

CONCLUSIONS

3D printing anatomical models can be helpful in assisting surgical decision making for patients with facial fractures as well as the process of surgery itself by allowing for prebending of plates. In the acute setting, when turnaround times are short, in-house 3D printing can produce models in a timely fashion to help surgeons operate safely and efficaciously.

Automated condylar seating assessment using a deep learning-based three-step approach

OBJECTIVES

In orthognatic surgery, one of the primary determinants for reliable three-dimensional virtual surgery planning (3D VSP) and an accurate transfer of 3D VSP to the patient in the operation room is the condylar seating. Incorrectly seated condyles would primarily affect the accuracy of maxillary-first bimaxillary osteotomies as the maxillary repositioning is dependent on the positioning of the mandible in the cone-beam computed tomography (CBCT) scan. This study aimed to develop and validate a novel tool by utilizing a deep learning algorithm that automatically evaluates the condylar seating based on CBCT images as a proof of concept.

MATERIALS AND METHODS

As a reference, 60 CBCT scans (120 condyles) were labeled. The automatic assessment of condylar seating included three main parts: segmentation module, ray-casting, and feed-forward neural network (FFNN). The AI-based algorithm was trained and tested using fivefold cross validation. The method's performance was evaluated by comparing the labeled ground truth with the model predictions on the validation dataset.

RESULTS

The model achieved an accuracy of 0.80, positive predictive value of 0.61, negative predictive value of 0.9 and F1-score of 0.71. The sensitivity and specificity of the model was 0.86 and 0.78, respectively. The mean AUC over all folds was 0.87.

CONCLUSION

The innovative integration of multi-step segmentation, ray-casting and a FFNN demonstrated to be a viable approach for automating condylar seating assessment and have obtained encouraging results.

CLINICAL RELEVANCE

Automated condylar seating assessment using deep learning may improve orthognathic surgery, preventing errors and enhancing patient outcomes in maxillary-first bimaxillary osteotomies.

Integrating Virtual Surgical Planning and 3D-Printed Tools with Iliac Bone Grafts for Orbital and Zygomatic Reconstruction in Hemifacial Microsomia Patients

Hemifacial Microsomia (HFM) is the second most common congenital craniofacial malformation syndrome, and the complexity of HFM makes its treatment challenging. The present study aimed to introduce a new approach of utilization of virtual surgical planning (VSP) and 3D-printed surgical adjuncts for maxillofacial reconstruction. Five HFM patients were included in this study. All participants were provided with a full VSP, including the design of osteotomy lines, the design and fabrication of 3D-printed cutting guides, fixation plates, and titanium mesh for implantation. With the assistance of 3D-printed cutting guides and fixation plates, the orbital deformities were corrected, and a 3D-printed titanium mesh combined with iliac cancellous bone graft was applied to reconstruct the zygomatic arch. The surgical accuracy, effectiveness, and bone absorption rate were evaluated. All patients completed the entirely digital treatment process without experiencing severe complications. The surgical adjuncts were effective in aligning the movement of the bone segments with the surgical plan, resulting in mean 3D deviations (1.0681 ± 0.15 mm) and maximum 3D deviations (3.1127 ± 0.44 mm). The image fusion results showed that the patients' postoperative position of the maxilla, zygoma, and orbital rim was consistent with the virtual surgical plan, with only a slight increase in the area of bone grafting. The postoperative measurements showed significant improvement in the asymmetry indices of Er (AI of Er: from 17.91 ± 3.732 to 5.427 ± 1.389 mm, p = 0.0001) and FZ (AI of FZ: from 7.581 ± 1.435 to 4.070 ± 1.028 mm, p = 0.0009) points. In addition, the observed bone resorption rate at the 6-month follow-up across the five patients was 45.24% ± 3.13%. In conclusion, the application of VSP and 3D-printed surgical adjuncts demonstrates significant value in enhancing the precision and effectiveness of surgical treatments for HFM. A 3D-printed titanium mesh combined with iliac cancellous bone graft can be considered an ideal alternative for the reconstruction of the zygomatic arch.

Current Trends in Orthognathic Surgery

Orthognathic surgery has evolved significantly over the past century. Osteotomies of the midface and mandible are contemporaneously used to perform independent or coordinated movements to address functional and aesthetic problems. Specific advances in the past twenty years include increasing fidelity with computer-assisted planning, the use of patient-specific fixation, expanding indications for management of upper airway obstruction, and shifts in orthodontic-surgical paradigms. This review article serves to highlight the contemporary practice of orthognathic surgery.

Orthognathic Surgery with Interdisciplinary Digital Planning in Patients with Geroderma Osteodysplasticum: A Case Report

Patients with geroderma osteodysplasticum (GO) often times have dentofacial deformities and benefit from orthognathic surgery. Because of generalized osteopenia, operations must be prepared even more meticulously than usual, and the higher risk of unfortunate fractures (bad splits) should be explained to the patients in detail. This case report is intended to portray a digital, interdisciplinary and patient-individualized planning of orthognathic surgery. It points out the individual steps that must be considered and how they can be advantageously used in patients with underlying diseases or syndromes such as GO. Through a careful digital representation of the surgical options, production of the digitally modeled splints, 3D printing and good manual surgical implementation, the quality of life of patients with GO can be increased through orthognathic surgery. Both the functions in the oral, maxillofacial region and the patient's appearance in the case presented here benefited from the interdisciplinary, individualized and digital treatment approach.