The Accuracy and Stability of Intentional Change of Frontal-Ramal Inclination in Orthognathic Surgery for Facial Asymmetry Patients.

Facial asymmetry can be defined as differences in the left and right sides of the face, and most of the patients with facial asymmetry have different left and right frontal-ramal inclinations (FRIs). Restoring the symmetry of both FRIs is important in the surgery of facial asymmetry patients, but it is very difficult to achieve perfect symmetry through conventional orthognathic surgery. However, by using 3-dimensional (3D) virtual planning and CAD/CAM technolo gies, intentional change of FRIs can be possible so the symmetry can be improved. The purpose of this study is to evaluate the surgical accuracy and long-term stability of intentional change of FRIs by 3D virtual surgery, CAD/CAM-assisted orthognathic surgery for patients with facial asymmetry. The study included 20 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2019 to December 2021. To evaluate the accuracy of surgery, 3D facial cone beam computed tomography (CBCT) taken immediately after surgery (T1) and virtual surgery data (Tv) were measured and the difference values were calculated. The evaluation of the long-term stability of intentional change of FRI was performed by measuring T1 and T2 (3D facial cone beam computed tomography images taken 6 mo after surgery) and the difference values were calculated. The difference values of FRIs in the left and right proximal segments of each patient were calculated. And then, for comparison depending on the direction of rotation, increased FRI groups (n=20, medial rotation) and decreased FRI groups (n=20, lateral rotation) were analyzed separately. As a result, all difference values at both (ΔT1-Tv) and (ΔT2-T1) were <1 degree. As a result of analyzing the entire FRI by dividing it into decreasing and increasing groups, the mean value of (ΔT1-Tv) was 0.225 degrees for the decreasing group and 0.275 degrees for the increasing group. It means that the proximal segment moved less than the movement implemented by the virtual surgery through actual surgery but it shows a very small error, which means that the overall operation almost accurately implements the virtual surgical planning. Compared with (ΔT1-Tv), the mean value of (ΔT2-T1) showed a much smaller error value, and no specific tendency was observed. This indicates that the stability after surgery is very good. Based on this study, using 3D virtual surgery planning and CAD/CAM technologies for treating patients with facial asymmetry was very useful, and surgery could be performed accurately and predictably. In particular, left-right symmetry was almost perfectly achieved through virtual simulation and could be implemented through actual surgery. Therefore, it can be said that the use of these 3D technologies is recommended for the surgical approach of facial asymmetry.

The Efficacy of 3D Virtual Surgery, CAD/CAM, and 3D Printing Technology for Maxillomandibular Advancement in Obstructive Sleep Apnea Patients.

OBJECTIVE: Maxillomandibular advancement (MMA) is the most effective surgical method for treating obstructive sleep apnea, and it moves the maxillomandibular complex forward to increase the entire upper airway volume. By using 3-dimensional (D) virtual surgery, computer-aided design/computer-aided manufacturing, and 3D printing technologies, it is possible to overcome all the limitations of conventional methods. MATERIALS AND METHODS: In this study, (modified) MMA was performed by applying 3D technologies to obstructive sleep apnea patients. Virtual surgery was done as surgical plan, cutting guides, and customized plates were made by computer-aided design/computer-aided manufacturing and 3D printing technologies for surgical procedures. RESULTS: After surgery, all patients improved their appearance, quality of sleep, and sleep apnea level were dramatically improved. Through these results, it was found that there are many advantages in using 3D technologies for preparing and implementing MMA. CONCLUSIONS: It was confirmed that the accuracy and efficiency of surgery were increased by applying 3D technologies. This suggests that 3D technologies are very useful tools in surgical area.

Surgical Accuracy of 3D Virtual Surgery and CAD/CAM-Assisted Orthognathic Surgery for Skeletal Class III Patients.

Orthognathic surgery is an effective surgical method to achieve functionality and facial esthetics for mandibular prognathism. If surgery is performed with a conventional method, errors may occur in the surgical preparation process and the surgical procedures, and there is a limitation in that the accuracy of surgery is determined according to the surgeon's experience and tactual sense. However, with the recent development of three-dimensional (3D) virtual planning and CAD/CAM technology, more 3D and predictable surgical planning and more accurate and time-saving surgery have become possible. The purpose of this study is to evaluate the surgical accuracy of 3D Virtual Surgery, CAD/CAM-Assisted Orthognathic surgery for Skeletal Class III Patients. The study included 18 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2020 to December 2021. To evaluate the accuracy of the virtual planning, 3D facial cone-beam computed tomography taken immediately after surgery (T1) and virtual surgery data (Tv) were superimposed in each patient. Landmarks were set on each of the maxillary segment, mandibular distal segment, and left and right mandibular proximal segment, and the difference between T1 and Tv was compared 3D on the x , y , and z -axis. (ΔT: T1-Tv). As a result, the average distance between Tv and T1 at each landmark, all landmarks except for the posterior nasal spine of the maxillary segment showed <1 mm. In particular, the differences across the x and z -axis were very small, while the difference across the y -axis tend to be large. The comparison of the position of each segment in virtual surgery and actual surgery was as follows. It can be seen that all segments were located slightly downward, and the medial pole of the mandibular proximal segment was located posterolateral and the lateral pole was located anteromedial after the actual surgery compared with the virtual planning. It means that the proximal segment was slightly rotated, but the difference was within 1 mm, so it can be considered that the surgery was accurate. Base on this study, orthognathic surgery using 3D virtual surgery planning and CAD/CAM technologies was very accurate. By applying these cutting-edge technologies to clinical practice, it was possible not only to increase the predictability of surgery but also to improve the convenience of surgery. Therefore, it is thought that it will be important for clinicians to make continuous efforts to applicate cutting-edge technologies to be developed in the future to patient diagnosis and surgery.

Total joint reconstruction using computer-assisted surgery with stock prostheses for a patient with bilateral TMJ ankylosis.

BACKGROUNDS: The purpose of this study is to discuss the total joint reconstruction surgery for a patient with recurrent ankylosis in bilateral temporomandibular joints (TMJs) using three-dimensional (3D) virtual surgical planning, computer-aided manufacturing (CAD/CAM)-fabricated surgical guides, and stock TMJ prostheses. CASE PRESENTATION: A 66-year-old female patient, who had a history of multiple TMJ surgeries, complained of severe difficulty in eating and trismus. The 3D virtual surgery was performed with a virtual surgery software (FACEGIDE, MegaGen implant, Daegu, South Korea). After confirmation of the location of the upper margin for resection of the root of the zygoma and the lower margin for resection of the ankylosed condyle, and the position of the fossa and condyle components of stock TMJ prosthesis (Biomet, Jacksonville, FL, USA), the surgical guides were fabricated with CAD/CAM technology. Under general anesthesia, osteotomy and placement of the stock TMJ prosthesis (Biomet) were carried out according to the surgical planning. At 2 months after the operation, the patient was able to open her mouth up to 30 mm without complication. CONCLUSION: For a patient who has recurrent ankylosis in bilateral TMJs, total joint reconstruction surgery using 3D virtual surgical planning, CAD/CAM-fabricated surgical guides, and stock TMJ prostheses may be an effective surgical treatment option.

Anterior Segmental Osteotomy Using Customized Spider-Plates Based on Computer-aided Surgery System.

Anterior segmental osteotomy (ASO) is considered the treatment modality of choice in patients with the bimaxillary dentoalveolar protrusion. However, this meticulous surgical technique accompanies a number of possible disadvantages. The considerable time required before, during, and after the operation, limited movement of the segment, damage of the mental nerve, loss of tooth vitality, loss of a tooth or teeth, or indeed total loss of the anterior segments are those that affect the result of the surgery. Recently, the authors have devised a computer-aided surgical simulation programme and fabricated the customized osteotomy guides and the spider-shaped plates based on the programme. They were then applied to a 28-year-old patient with the complaint of a bimaxillary dentoalveolar protrusion. This approach helped to overcome several problems related to ASO reported earlier.

The accuracy and stability of the maxillary position after orthognathic surgery using a novel computer-aided surgical simulation system.

BACKGROUND: Many reports have been published on orthognathic surgery (OGS) using computer-aided surgical simulation (CASS). The purpose of this study was to evaluate the accuracy of the maxillary repositioning and the stability of the maxilla in patients who underwent OGS using a newly developed CASS program, a customized osteotomy guide, and a customized miniplate. METHODS: Thirteen patients who underwent OGS from 2015 to 2017 were included. All patients underwent a bimaxillary operation. First, a skull-dentition hybrid 3D image was rendered by merging the cone beam computed tomography (CBCT) images with the dentition scan file. After virtual surgery (VS) using the FaceGide® program, patient-customized osteotomy guides and miniplates were then fabricated and used in the actual operation. To compare the VS with the actual surgery and postoperative skeletal changes, each reference point marked on the image was compared before the operation (T0) and three days (T1), four months (T2), and a year (T3) after the operation, and with the VS (Tv). The differences between ΔTv (Tv-T0) and ΔT1 (T1-T0) were statistically compared using tooth-based reference points. The superimposed images of Tv and T1 were also investigated at eight bone-based reference points. The differences between the reference points of the bone surface were examined to evaluate the stability of the miniplate on the maxilla over time. RESULTS: None of the patients experienced complications. There were no significant differences between the reference points based on the cusp tip between ΔTv and ΔT1 (p > 0.01). Additionally, there were no significant differences between the Tv and T1 values of the bone surface (p > 0.01). The mean difference in the bone surface between Tv and T1 was 1.01 ± 0.3 mm. Regarding the stability of the miniplate, there were no significant differences between the groups. The difference in the bone surface between T1 and T3 was - 0.37 ± 0.29 mm. CONCLUSIONS: VS was performed using the FaceGide® program, and customized materials produced based on the VS were applied in actual OGS. The maxilla was repositioned in almost the same manner as in the VSP plan, and the maxillary position remained stable for a year.