Computer-assisted preoperative simulation for positioning and fixation of plate in 2-stage procedure combining maxillary advancement by distraction technique and mandibular setback surgery

Virtual surgical planning and augmented reality for fixation of plate during Le Fort I osteotomy

PURPOSE

Computed tomography (CT) imaging is utilized during virtual surgical planning (VSP) in orthognathic surgery to simulate the surgical scenario, thereby aiding the actual surgery. Various surgical strategies exist to enhance accuracy in Le Fort I osteotomy, but an ideal planning and treatment approach has not yet been defined. The purpose of this study was to assess the accuracy of markerless Augmented Reality (AR), utilizing the iterative closest point algorithm for real-time tracking without 3D-printed surgical guides, wafers, or physical markers. The study explores the integration of VSP and an intraoperative markerless AR-assisted system for Le Fort I osteotomy in orthognathic surgery.

METHODS

Six patients were enrolled in the study. We conducted a markerless AR-assisted orthognathic surgery utilizing VSP containing a virtual plate model. To assess accuracy, the postoperative 3-dimensional reconstructed CT image was compared to the VSP.

RESULTS

Distance maps visualizing the distances between VSP and the postoperative CT scan revealed an accuracy with a standard deviation (SD) of 0.81 mm (81.0% within 1 mm) in terms of the maxillary position.

CONCLUSIONS

This approach facilitated the movement and positioning of the maxillary bone along with fixation and setting of titanium plates. The simulation of the surgical procedure made the process more straightforward, enabling us to perform the actual surgery with greater precision. The markerless AR-assisted surgery shows potential in orthognathic surgery, aiding surgeons to prepare and execute surgical procedures more accurately. The future studies anticipate the integration of artificial intelligence, robotic technology, and AR for further improvements in orthognathic surgery.

Surgical Precision Analysis of Orthognathic Surgery Combined With Invisible Orthodontic

BACKGROUND

This study aimed to explore the changes in hard tissue after applying invisible orthodontic-orthognathic treatment and the digital design, and to explore the accuracy of the treatment effect of maxillofacial tissue after invisible orthodontic treatment and orthognathic treatment.

METHODS

From September 2020 to January 2022, 25 patients with class III skeletal malocclusion and 7 patients with class II skeletal malocclusion, were treated with invisible orthodontic treatment and orthognathic combined treatment. Orthodontic treatment with preoperative invisible orthodontic treatment followed by orthodontic surgery. All patients had cephalometric lateral films after surgery to analyze orthognathic surgery's goals and surgical effects of orthognathic surgery and the digital design. Measure the angle of the sella-nasion-A point angle, angle of sella-nasion-B point, ANB angle, maxillary convex angle, mandibular plane (MP) angle, 1-SN angle, 1-MP angle, etc, and compare surgery outcome with digital design.

RESULT

All patients were satisfied with the effect and no complications occurred. Angle of sella-nasion-A point, angle of sella-nasion-B point, ANB angle, maxillary convex angle, MP angle, 1-SN angle, and 1-MP angle had no significant difference between the postoperative effect and the purpose of digital design ( P >0.05), there was no apparent deviation between the upper and lower jaw and the chin ( P >0.05).

CONCLUSION

The combined invisible orthodontic treatment and orthognathic treatment are accurate and effective, and are worthy of promotion. It supplements traditional orthognathic therapy and is suitable for corresponding patients.

Utilization of desktop 3D printer-fabricated "Cost-Effective" 3D models in orthognathic surgery

Background

In daily practice, three-dimensional patient-specific jawbone models (3D models) are a useful tool in surgical planning and simulation, resident training, patient education, and communication between the physicians in charge. The progressive improvements of the hardware and software have made it easy to obtain 3D models. Recently, in the field of oral and maxillofacial surgery, there are many reports on the benefits of 3D models. We introduced a desktop 3D printer in our department, and after a prolonged struggle, we successfully constructed an environment for the "in-house" fabrication of the previously outsourced 3D models that were initially outsourced. Through various efforts, it is now possible to supply inexpensive 3D models stably, and thus ensure safety and precision in surgeries. We report the cases in which inexpensive 3D models were used for orthodontic surgical simulation and discuss the surgical outcomes.

Review

We explained the specific CT scanning considerations for 3D printing, 3D printing failures, and how to deal with them. We also used 3D models fabricated in our system to determine the contribution to the surgery. Based on the surgical outcomes of the two operators, we compared the operating time and the amount of bleeding for 25 patients who underwent surgery using a 3D model in preoperative simulations and 20 patients without using a 3D model. There was a statistically significant difference in the operating time between the two groups.

Conclusions

In this article, we present, with surgical examples, our in-house practice of 3D simulation at low costs, the reality of 3D model fabrication, problems to be resolved, and some future prospects.

Digital planning workflow for partial maxillectomy using an osteotomy template and immediate rehabilitation of maxillary Brown II defects with prosthesis

BACKGROUND

There is increasing evidence of benefits for the rehabilitation of Brown II defects with prosthesis in surgery. However, the current literature is sparse for maxillary tumour resection using osteotomy templates.

OBJECTIVES

To assess the accuracy of maxillectomy using a custom fabricated osteotomy template and to evaluate the prosthesis for surgical accuracy, appearance and functioning (speech, swallowing and occlusal force).

METHODS

Ten patients with Brown II defects caused by tumour resection were treated with precise partial maxillectomy using an osteotomy template. The immediate rehabilitation of the Brown II defect was completed with a prefabricated prosthesis. The post-operative three-dimensional images and the pre-operative virtual images were superimposed, and average deviation and maximum deviation were calculated. Speech intelligibility, swallowing, appearance and University of Washington Quality of Life Questionnaire (UW-QoL) were examined at 1, 3 and 6 months after surgery. Occlusal force was examined post-operatively at 6 months.

RESULTS

The maximum deviation between the actual and virtual surgery was 5.12 ± 0.44 mm, with an average of 1.02 ± 0.17 mm. Speech intelligibility, swallowing and UW-QoL improved significantly (P < .05) after wearing the prosthesis. The recovery index of the occlusal force on the affected side was 20.19%-32.28%. The skewed degree of the mouth corner, the difference in the height of the left and right lips, the maximum deviation distance and the change area volume decreased significantly (P < .05).

CONCLUSION

The precise rehabilitation of maxillary Brown II defects can be achieved using a prosthesis fabricated with an osteotomy template. The prosthesis restored appearance and functional capabilities (such as speech and occlusal force).