A review of computer-aided oral and maxillofacial surgery: planning, simulation and navigation

Virtual registration of comminuted bone fracture and preoperative assessment of reconstructed bone model using the Procrustes algorithm based on CT dataset

A research work was undergone in a virtual bone reduction process for reconstruction of the comminuted pelvic bone fracture using a CT scan dataset of patients. This includes segmentation, 3D model optimization and bone registration technique. The accuracy of the reconstructed bone model was validated using Finite Element Method. Analysed and applied various segmentation techniques to segregate the injured bone structure. The ICP (Iterative Closest Point), Procrustes algorithm and Canny edge detection algorithm were applied to understand the bone registration process for surgery in detail. The average RMS error, mean absolute distance, mean absolute deviation, and mean signed distance of the reconstructed bone model using proposed algorithms involving 10 patient datasets in a group were found to be 1.77, 1.48, 1.51 and -0.31 mm respectively. The calculated RMS error value proved minimal error in semi-automatic registration than other existing automatic registration techniques. Therefore, the proposed approach is suitable for virtual bone reduction for comminuted pelvic bone fracture. This method could also be implemented for various other bone fracture reconstruction requirements.

Preclinical dental students self-assessment of an improved operative dentistry virtual reality simulator with haptic feedback

To test and evaluate the second installment of DENTIFY, a virtual reality haptic simulator for Operative Dentistry (OD), on preclinical dental students, by focusing on user performance and self-assessment. Twenty voluntary unpaid preclinical dental students, with different background experience, were enrolled for this study. After the completion of an informed consent, a demographic questionnaire, and being introduced to the prototype (on the first testing session), three testing sessions followed (S1, S2, S3). Each session involved the following steps: (I) free experimentation; (II) task execution; S3 also included (III) completion of questionnaires associated with the experiment (total of 8 Self-Assessment Questions (SAQ)); and (IV) guided interview. As expected, drill time decreased steadily for all tasks when increasing prototype use, verified by RM ANOVA. Regarding performance metrics (Comparisons by Student's t-test and ANOVA) recorded at S3, in overall, a higher performance was verified for participants with the following characteristics: female, non-gamer, no previous VR experience and with over 2 semesters of previous experience of working on phantom models. The correlation between the participants' performance (drill time), for the four tasks, and user self-assessment evaluation, verified by Spearman's rho analysis, allowed to conclude that a higher performance was observed in students who responded that DENTIFY improved their self perception of manual force applied. Regarding the questionnaires, Spearman's rho analysis showed a positive correlation between the improvement DENTIFY inputs on conventional teaching sensed by students, also enhancing their interest in learning OD, their desire to have more simulator hours and the improvement sensed on manual dexterity. All participating students adhered well to the DENTIFY experimentation. DENTIFY allows for student self-assessment and contributes to improving student performance. Simulators with VR and haptic pens for teaching in OD should be designed as a consistent and gradual teaching strategy, allowing multiplicity of simulated scenarios, bimanual manipulation, and the possibility of real-time feedback to allow for the student's immediate self-assessment. Additionally, they should create performance reports per student to ensure self-perception/criticism of their evolution over longer periods of learning time.

Application of digital positioning guide plates for the surgical extraction of multiple impacted supernumerary teeth: A case report and review of literature

BACKGROUND

An extra tooth in the normal tooth sequence in any region of the dental arch is regarded as a supernumerary tooth (SNT). Due to the large variation in location and morphology, the extraction of impacted SNTs is an extensive and complex procedure with high risks of several complications. This report presents a rare case of seven impacted SNTs in the bilateral upper and lower arch that were successfully extracted with the use of digital positioning guide plates.

CASE SUMMARY

In January 2022, a 21-year-old male was referred to our department with a chief complaint of pain in relation to tooth #36. Clinical examination showed a deep carious lesion with pulpal involvement in tooth #36 and lingual swelling of the bilateral mandibular posterior area. Radiographic examination revealed seven deeply impacted SNTs in the bilateral posterior area and bilateral impacted mandibular third molars. Based on these findings, the patient was diagnosed with bilateral, multiple impacted SNTs and tooth #36 chronic pulpitis. A root canal treatment and an all-ceramic crown restoration for tooth #36 were performed. An individualized digital positioning guide plate was designed by computer-aided design/computer-aided manufacturing technology and cone-beam computed tomography for extraction of the impacted SNTs. During the operation, the digital positioning guide plate allowed rapid positioning and exposure of the SNTs while avoiding adjacent important anatomical structures. At 3-month follow-up, regeneration of bone and soft tissues was visible.

CONCLUSION

The application of digital positioning guide plates is useful for the individualized and minimalized extraction of impacted supernumerary teeth.

A review on AI-based medical image computing in head and neck surgery

Head and neck surgery is a fine surgical procedure with a complex anatomical space, difficult operation and high risk. Medical image computing (MIC) that enables accurate and reliable preoperative planning is often needed to reduce the operational difficulty of surgery and to improve patient survival. At present, artificial intelligence, especially deep learning, has become an intense focus of research in MIC. In this study, the application of deep learning-based MIC in head and neck surgery is reviewed. Relevant literature was retrieved on the Web of Science database from January 2015 to May 2022, and some papers were selected for review from mainstream journals and conferences, such as IEEE Transactions on Medical Imaging, Medical Image Analysis, Physics in Medicine and Biology, Medical Physics, MICCAI, etc. Among them, 65 references are on automatic segmentation, 15 references on automatic landmark detection, and eight references on automatic registration. In the elaboration of the review, first, an overview of deep learning in MIC is presented. Then, the application of deep learning methods is systematically summarized according to the clinical needs, and generalized into segmentation, landmark detection and registration of head and neck medical images. In segmentation, it is mainly focused on the automatic segmentation of high-risk organs, head and neck tumors, skull structure and teeth, including the analysis of their advantages, differences and shortcomings. In landmark detection, the focus is mainly on the introduction of landmark detection in cephalometric and craniomaxillofacial images, and the analysis of their advantages and disadvantages. In registration, deep learning networks for multimodal image registration of the head and neck are presented. Finally, their shortcomings and future development directions are systematically discussed. The study aims to serve as a reference and guidance for researchers, engineers or doctors engaged in medical image analysis of head and neck surgery.

The evaluation of the effect of performing guided lid surgery with enucleation of a cystic lesion; a case report

INTRODUCTION AND IMPORTANCE

Dentigerous cysts are benign odontogenic cysts of developmental origin. Enucleation and marsupialization are still considered the blueprint of cystic lesion treatment.

CASE PRESENTATION

A 23-year-old male patient presented complaining of a minimal swelling in his upper jaw with slight tenderness in his upper anterior teeth. Cone Beam Computed Tomography (CBCT) on the maxilla was requested. The cystic lesion was found to be minimally expansile with intact cortical plates of the maxilla in the affected area. The CBCT was used to fabricate a cutting guide to determine the exact location of the bony window to fully access the lesion. Root canal treatment was done for the affected non-vital teeth. The cuts were done using a piezo-electric device. Complete enucleation was done for the lesion followed by fixation of the cortical bone lid using micro-plates and screws. The case was followed up after 6 months for new bone deposition using CBCT and 1 week, 1 month, and 6 months postoperatively for postoperative pain using the Visual Analogue Scale (VAS).

CLINICAL DISCUSSION

Piezo-electric surgery was used due to the selective cutting merit to cut through bone while preserving the cystic lining intact. Lid surgery aims to maximize the volume of bone deposited in place of the defect by converting the cavity of the cystic lesion into a contained defect.

CONCLUSION

Guided lid surgery using a piezo-electric device could be a useful technique for cystic enucleation regarding the new bone formation and pain level.

Usability, acceptance, and educational usefulness study of a new haptic operative dentistry virtual reality simulator

BACKGROUND

Dental preclinical training has been traditionally centered onverbal instructions and subsequent execution on phantom heads and plastic training models. However, these present present limitations. Virtual Reality (VR) and haptic simulators have been proposed with promising results and advantages and have showed usefullness in the preclinical training environment. We designed DENTIFY, a multimodal immersive simulator to assist Operative Dentistry learning, which exposes the user to different virtual clinical scenarios while operating a haptic pen to simulate dental drilling.

OBJECTIVE

The main objective is to assess DENTIFY's usability, acceptance, and educational usefulness to dentists, in order to make the proper changes and, subsequently, to test DENTIFY with undergraduate preclinical dental students.

METHODS

DENTIFY combines an immersive head mounted VR display, a haptic pen in which the pen itself has been replaced by a 3D printed model of a dental turbine and a controller with buttons to adjust and select the scenario of the simulation, along with 3D sounds of real dental drilling. The user's dominant hand operated the virtual turbine on the VR-created scenario, while the non-dominant hand is used to activate the simulator and case selection. The simulation sessions occurred in a controlled virtual environment. We evaluated DENTIFY's usability and acceptance over the course of 13 training sessions with dental professionals, after the users performed a drilling task in virtual dental tissues.

RESULTS

The conducted user acceptance indicates that DENTIFY shows potencial enhancing learning in operative dentistry as it promotes self-evaluation and multimodal immersion on the dental drilling experience.

CONCLUSIONS

DENTIFY presented significant usability and acceptance from trained dentists. This tool showed to have teaching and learning (hence, pedagogical) potential in operative dentistry.

A randomized controlled trial: evaluation of efficiency and safety of a novel surgical guide in the extraction of deeply impacted supernumerary teeth in the anterior maxilla

Background

Preoperative X-ray and cone-beam computed tomography (CBCT) are helpful for locating supernumerary teeth, but the images cannot be transferred to the operation. To design a novel surgical guide plate for intraoperative navigation, we transfer the patient's oral CBCT and gypsum model scan data to a computer for analysis. In our study, we evaluate the efficiency and safety of a novel surgical guide plate for the extraction of deeply impacted supernumerary teeth (DIMSNT) in the anterior maxilla.

Methods

Forty patients treated at the Department of School & Hospital of Stomatology, Wenzhou Medical University from March 2019 to December 2020 with DIMSNT (type II/III according to Liu et al.) in the anterior maxilla were randomly divided into 2 groups (20 patients for each group) for the extraction. For group I, a novel surgical guide was selected using CBCT and gypsum model scan. In contrast, for group II who underwent freehand surgery, only the CBCT data was used. The evaluation of operation time, complications, satisfaction score, and the number of cases that underwent extraction immediately after removing the bone were performed to assess the efficiency and safety of this novel surgical plate.

Results

All patients completed the surgery successfully. The guides for group I had a good application effect. Group I's operation time (23.35±5.39 min) was shorter than group II (29.60±9.76 min) (P=0.0194). The average pain degree of group I (1.8±1.08) was significantly less than group II (2.82±1.68) (P<0.05). The average swelling score of group I (34) was significantly less than group II (44.7). Patient satisfaction was significantly higher in group I (8.95±1.05) than in group II (7.90±1.51) (P=0.0152).

Conclusions

The novel surgical guide assisted with DIMSNT extraction have been effective in improving the quality of the surgery, patient satisfaction, and reduce its difficulty and duration. We can construct a surgical guide plate to guide the incision and osteotomy in DIMSNT surgery through the data analysis of DIMSNT on computer, which has a broad application prospect for clinical use.

Trial registration

Chinese Clinical Trial Registry ChiCTR2100054523.

Application evaluation of virtual reality technology in dental implant training: a new dental implant training system: A CONSORT-compliant trial

To evaluate the application of virtual reality technology in a dental implant training system.A 3-dimensional model of mandible was established by Mimics17.0 software based on the Digital Imaging and Communications in Medicine data obtained from cone beam computed tomography scanning of the patient in mandibular. Thirty physicians were divided into 2 groups. The virtual reality dental implant training system was used for group A, while conventional theoretical knowledge training and clinical demonstration were performed in group B. All young physicians have a 1-month study. After training, all the physicians in groups A and B would conduct a questionnaire survey according to the training situation, which was compared between the 2 groups. The success rate of the operation was also evaluated and compared.The median scores in the 5 dimensions of postoperative assessment of group A was 9/9/9/8/8, and of group B was 6/7/6/7/7. The scores of the 5 dimensions were significantly higher than those of group B (P < .05), indicating that group A has a better grasp of the simulator. After the training of simulated mandibular implants in group A, the deviations in the 4 dimensions of mesiodistal, buccal and tongue, depth, and angle were significantly lower than those of group B (P < .05). Group A has smaller deviations in each of the 4 dimensions than those in group B, indicating group A has a higher operation success rate.We independently develop a set of virtual surgery system for dental implant training, which can be used for teaching and training, with good operability and predictability, to achieve a breakthrough in dental implant surgery training.

Automatic mandible segmentation from CT image using 3D fully convolutional neural network based on DenseASPP and attention gates

PURPOSE

In cranio-maxillofacial surgery, it is of great clinical significance to segment mandible accurately and automatically from CT images. However, the connected region and blurred boundary in teeth and condyles make the process challenging. At present, the mandible is commonly segmented by experienced doctors using manually or semi-automatic methods, which is time-consuming and has poor segmentation consistency. In addition, existing automatic segmentation methods still have problems such as region misjudgment, low accuracy, and time-consuming.

METHODS

For these issues, an automatic mandibular segmentation method using 3d fully convolutional neural network based on densely connected atrous spatial pyramid pooling (DenseASPP) and attention gates (AG) was proposed in this paper. Firstly, the DenseASPP module was added to the network for extracting dense features at multiple scales. Thereafter, the AG module was applied in each skip connection to diminish irrelevant background information and make the network focus on segmentation regions. Finally, a loss function combining dice coefficient and focal loss was used to solve the imbalance among sample categories.

RESULTS

Test results showed that the proposed network obtained a relatively good segmentation result, with a Dice score of 97.588 ± 0.425%, Intersection over Union of 95.293 ± 0.812%, sensitivity of 96.252 ± 1.106%, average surface distance of 0.065 ± 0.020 mm and 95% Hausdorff distance of 0.491 ± 0.021 mm in segmentation accuracy. The comparison with other segmentation networks showed that our network not only had a relatively high segmentation accuracy but also effectively reduced the network's misjudgment. Meantime, the surface distance error also showed that our segmentation results were relatively close to the ground truth.

CONCLUSION

The proposed network has better segmentation performance and realizes accurate and automatic segmentation of the mandible. Furthermore, its segmentation time is 50.43 s for one CT scan, which greatly improves the doctor's work efficiency. It will have practical significance in cranio-maxillofacial surgery in the future.

Proposal for the Fusion of Ultrasound and Computed Tomography Images for Image Shift Correction in Craniomaxillofacial Soft Tissue Surgery

ABSTRACT

Surgical navigation has greatly improved the accuracy of craniomaxillofacial bone surgery and is widely used in the clinic. However, during surgery, craniomaxillofacial soft tissue is always deformed due to traction and compression, which leads to intraoperative image drift. This, in turn, impacts navigation accuracy. In order to improve navigation accuracy, this technical note presents a preliminary proposal for fusion imaging technology, which combines ultrasound and computed tomography to address navigational image drift in craniomaxillofacial soft tissue surgery.

A novel visualization system of using augmented reality in knee replacement surgery: Enhanced bidirectional maximum correntropy algorithm

BACKGROUND AND AIM

Image registration and alignment are the main limitations of augmented reality (AR)-based knee replacement surgery. This research aims to decrease the registration error, eliminate outcomes that are trapped in local minima to improve the alignment problems, handle the occlusion and maximize the overlapping parts.

METHODOLOGY

Markerless image registration method was used for AR-based knee replacement surgery to guide and visualize the surgical operation. While weight least square algorithm was used to enhance stereo camera-based tracking by filling border occlusion in right-to-left direction and non-border occlusion from left-to-right direction.

RESULTS

This study has improved video precision to 0.57-0.61 mm alignment error. Furthermore, with the use of bidirectional points, that is, forward and backward directional cloud point, the iteration on image registration was decreased. This has led to improve the processing time as well. The processing time of video frames was improved to 7.4-11.74 frames per second.

CONCLUSIONS

It seems clear that this proposed system has focused on overcoming the misalignment difficulty caused by the movement of patient and enhancing the AR visualization during knee replacement surgery. The proposed system was reliable and favourable which helps in eliminating alignment error by ascertaining the optimal rigid transformation between two cloud points and removing the outliers and non-Gaussian noise. The proposed AR system helps in accurate visualization and navigation of anatomy of knee such as femur, tibia, cartilage, blood vessels and so forth.

Application of a surgical guide in the extraction of impacted mesiodentes: a randomized controlled trial

OBJECTIVE

To explore and evaluate the application of a surgical guide in the extraction of impacted mesiodentes.

MATERIALS AND METHODS

Patients with impacted mesiodentes approachable from the labial side of the maxilla were randomly divided into three groups. The surgical guide for group I was made using cone beam computed tomography (CBCT) and dental cast, whereas the surgical guide for group II was only made using CBCT data. Group I and group II were first evaluated to determine whether guide use could accurately locate the cementoenamel junction (CEJ) of the mesiodentes, and the impacted mesiodentes were extracted with the help of the surgical guide. Group III underwent an operation without a guide. For all patients, the preoperative design time, tooth searching time, operation time, complications, and costs were measured.

RESULTS

The guides for group I and group II could locate the CEJ of the mesiodentes accurately, with good application effect during the operation. Group I and group II required additional preoperative design time compared with group III. However, the tooth searching time and operation time in groups I and II were significantly reduced compared with those in group III. Group I and group II showed no intraoperative complications, and two cases in group III showed imprecision during localization. The overall cost for group III was higher than that of group I or group II. But group I and group II required extra visits and costs.

CONCLUSIONS

Despite some limitations, the surgical guide assisted with mesiodentes extraction and can improve the quality of the operation quality as well as reducing its economic burden, difficulty, and duration. Through proper design, we can create a high-quality surgical guide using only CBCT data.

CLINICAL RELEVANCE

The surgical guide can be used as an important assistive tool in alveolar surgery.

Fully Automatic Robot-Assisted Surgery for Mandibular Angle Split Osteotomy

With the development of computer-assisted surgery, preoperational design is detailed in software. However, it is still a challenge for surgeons to realize the surgical plan in the craniofacial surgery. Robot-assisted surgery has advantages of high accuracy and stability. It is suitable for the high-stress procedures like drilling, milling, and cutting. This study aims to verify the feasibility for automatic drilling without soft tissues in model test based on an industrial robot platform.This study chose the data from digital laboratory in Shanghai 9th People's Hospital. The mandibular was reconstructed in software and surgical plan was also designed. Then, the coordinate data was input to the robot's software and matrix conversion was calculated by 4 marked points. The trajectory generation was calculated by inverse kinematics for target coordinates and robot coordinates. The model was fixed and calibrated for automatic drilling. At last, the accuracy was calculated by optic scanning instrument.The installment and preparation cost 10 minutes, the drilling procedure cost 12 minutes. The outside position error was (1.71 ± 0.16) mm, the inside position error was (1.37 ± 0.28) mm, the orientation error was (3.04 ± 1.02)°. Additionally, a total of 5 beagles were tested, with an accuracy error of (2.78 ± 1.52) mm. No postoperative complications occurred.This is the first study reported for robot-assisted automatic surgery in craniofacial surgery. The result shows it is possible to realize the automatic drilling procedure under the condition of no interference like soft tissues. With the development of artificial intelligence and machine vision, robot-assisted surgery may help surgeons to fulfill more automatic procedures for craniofacial surgery.

[Application of digital positioning guide plate in extraction of impacted supernumerary teeth]

OBJECTIVE

To explore the application of digital positioning guide plate in extraction of impacted supernumerary teeth and evaluate its clinical efficacy.

METHODS

From March to August, 2019, 30 patients with labial impacted supernumerary teeth treated in the Department of Oral and Maxillofacial Surgery, Stomatological Hospital, Southern Medical University were enrolled in this study. Fifteen of the patients were treated with digital positioning guide plate to remove the impacted supernumerary teeth (test group). According to the CBCT data and the dentition model of the patients, the positioning guide plate was positioned by avoiding the important anatomical structure with the tooth-bone surface as the support to design the soft tissue incision line and bone tissue exposure range. The other 15 patients who were treated without the use of the guide plate for operation served as the control group. The design time, tooth searching time, operation time and complications were compared between the two groups.

RESULTS

The positioning guide plate was well attached during the operation and allowed quick location of the supernumerary teeth while helping to expose the supernumerary teeth and avoid the damage of the adjacent important anatomical structures. The pre-operative design time was 50 ± 5 min in the test group and 0 min in the control group. The average time of tooth finding in the test group was 5±2 min, as compared with 10±3 min in the control group (t=15.40, P < 0.01); the average time of operation was significantly shorter in the test group than in the control group (25±4 min vs 45±6 min; t=35.50, P < 0.01). No intraoperative complications occurred in the test group, and slight deviation occurred in one case in the control group.

CONCLUSIONS

The application of digital positioning guide plate in extraction of embedded supernumerary teeth can significantly shorten the time of tooth finding, reduce the difficulty of operation, and improve the quality of operation.

Computer-Based 3D Simulations to Formulate Preoperative Planning of Bridge Crane Technique for Thoracic Ossification of the Ligamentum Flavum

Background

The bridge crane technique is a novel surgical technique for the treatment of thoracic ossification of the ligamentum flavum (TOLF), but its preoperative planning has not been studied well, which limits the safety and efficacy of surgery to some extent. The purpose of this study was to investigate the method of application and effect of computer-aided preoperative planning (CAPP) on the bridge crane technique for TOLF.

Material/Methods

This retrospective multi-center included 40 patients with TOLF who underwent the bridge crane technique from 2016 to 2018. According to the utilization of CAPP, patients were divided into Group A (with CAPP, n=21) and Group B (without CAPP, n=19). Comparisons of clinical and radiological outcomes were carried out between the 2 groups.

Results

The patients in Group A had higher post-mJOA scores and IR of neurological function than those in Group B (p<0.05). Group A had shorter surgery time, fewer fluoroscopic images, and lower incidence of complications than Group B. In Group A, there was a high consistency of all the anatomical parameters between preoperative simulation and postoperative CT (p>0.05). In Group B, there were significant differences in 3 anatomical parameters between postoperative simulation and postoperative CT (p<0.05). In Group B, the patients with no complications had higher post-SVOR and lower SVRR and height of posterior suspension of LOC in postoperative CT than those in postoperative simulation (p<0.05).

Conclusions

CAPP can enable surgeons to control the decompression effect accurately and reduce the risk of related complications, which improves the safety and efficacy of surgery.

Pilot study of a surgical robot system for zygomatic implant placement

Zygomatic implant technology has been regarded as an alternative treatment to massive grafting surgery in the severe atrophic maxillary. Nowadays, the assistant method with a real-time surgical navigation has been applied to reduce the risks of zygomatic implant placement. However, the accuracy of the complex operation is highly dependent on the experience of the surgeon. In order to avoid disadvantages of traditional surgical navigation systems, a novel surgical robot system for the zygomatic implant placement has been designed and developed. Firstly, the drilling trajectory of the zygomatic implant placement is designed through the pre-operative planning system. Secondly, the real-time positions of the surgical instruments are constantly updated with the guidance of the optical tracker. Finally, through a coordinate transformation algorithm, the drilling performance can be conducted with the control of a six degree of freedom robot. In order to evaluate the accuracy of the robot, phantom experiments had been carried out. The angle, entry point and exit point deviation of the robotic system are 1.52 ± 0.58°, 0.79 ± 0.19 mm, and 1.49 ± 0.48 mm, respectively. Meanwhile, a comparison between the robotic and manual operation demonstrates that the use of the surgical robot system for the zygomatic implant placement can improve the accuracy of the operation.

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).

Development and preliminary evaluation of an autonomous surgical system for oral and maxillofacial surgery

BACKGROUND

Human-related factors affect the accuracy and safety of the oral and maxillofacial surgery (OMS). This study proposed an autonomous surgical system aiming to conduct the OMS under the assistance and surveillance of the surgeon.

METHODS

A markerless navigation module and a compact OMS robot were seamlessly integrated into this system. The specifications of each module and the working concept of the system were elaborated in this paper. A drilling experiment was conducted on five 3D-printed mandible models to test the pose detecting capability and evaluate the operational performance.

RESULTS

The experiment showed that this system could successfully guide the robot finishing the operation regardless of the mandible pose. The accuracy of software and hardware are acceptable and potential performance improvement can be achieved in positioning accuracy.

CONCLUSION

This system proposed a novel concept and a practical solution to decrease the human-related factors on the OMS, which may change the role of the surgeon in the future operating room and finally benefit the outcomes of OMS.

Relapse tendency after BSSO surgery differs between 2D and 3D measurements: A validation study

Bilateral sagittal split ramus osteotomy (BSSO) surgery is used to correct various dento-skeletal deformities. Clinical outcomes are critically dependent on accurate and proper positioning of skeletal units created by BSSO. Monitoring skeletal changes postoperatively is a major part of follow-up. Between January 2015 and December 2015, 24 patients underwent BSSO surgery without any other segmental osteotomy (mean age, 29.9 ± 14.2 [range, 17-67] years; 18 females). Cephalometric X-rays and cone-beam computed tomography scans were performed 6 weeks and 12 months postoperatively. We compared the position displacement at three mandibular points at both postoperative time points using 2- and 3-dimensional analysis separately and examined the relationship between these methods. Horizontally in at least in 14/24 patients, the difference between 2-dimensional and 3-dimensional measurements was >1 mm. Vertically in at least in 16/24 patients, the difference between 2-dimensional and 3-dimensional measurements was >1 mm. A scatter plot with orthogonal regression indicated the relationships between the 2-dimensional measurement and the corresponding 3-dimensional measurement in the horizontal and vertical directions. Skeletal relapse with 2-dimensional-measurements differed significantly from the 3-dimensional measurements. There was no evidence of a relationship between the two types of measurements regarding the direction and the location of the landmarks.

A review of haptic simulator for oral and maxillofacial surgery based on virtual reality

INTRODUCTION

Traditional medical training in oral and maxillofacial surgery (OMFS) may be limited by its low efficiency and high price due to the shortage of cadaver resources. With the combination of visual rendering and feedback force, surgery simulators become increasingly popular in hospitals and medical schools as an alternative to the traditional training.

AREAS COVERED

The major goal of this review is to provide a comprehensive reference source of current and future developments of haptic OMFS simulators based on virtual reality (VR) for relevant researchers.

EXPERT COMMENTARY

Visual rendering, haptic rendering, tissue deformation, and evaluation are key components of haptic surgery simulator based on VR. Compared with traditional medical training, virtual and tactical fusion of virtual environment in surgery simulator enables considerably vivid sensation, and the operators have more opportunities to practice surgical skills and receive objective evaluation as reference.

Computer-assisted teaching of bilateral sagittal split osteotomy: Learning curve for condylar positioning

Bilateral sagittal split osteotomy (BSSO) is a widely-performed procedure in orthognathic surgery for the correction of dentofacial deformity. Condylar positioning is a critical step during BSSO to maximize functional and morphological results. The unsuitable positioning of condyles represents one of the causative mechanisms that may induce temporomandibular joint noxious effects after BSSO. Repositioning devices can assist surgeons in maintaining the preoperative condylar position; however, empirical repositioning methods based on experience gained are still commonly used. Trainee learning curves are difficult to assess. The aim of this study was to evaluate the relevance of computer-assisted surgery in the acquisition of condylar positioning skills. Forty-eight patients underwent BSSO performed by six maxillofacial trainees (four junior residents and two senior experienced residents). A condyle positioning system (CPS) was used by a senior surgeon to record a condylar position score during the procedure. Firstly, scores were recorded when the trainee manually positioned the condyle without access to the CPS score (phase 1) and then when the trainee positioned the condyle and performed osteosynthesis with visual access to the CPS score (phase 2). Six parameters describing condylar three-dimensional motions were assessed: translational motion from top to bottom (TB), back to front (BF), and left to right (LR), axial rotation (AR), sagittal rotation (SR), frontal rotation (FR), and a total score (TS). There were no significant differences between junior and senior residents in condyle positioning without access to the CPS. Condyles were significantly better positioned during phase 2 with access to the CPS (p<0.001). Over time, use of the CPS (phase 2) produced significantly quicker improvements in scores (p = 0.042). For those teaching surgeries to trainees, computer-assisted devices can potentially result in more rapid learning curves than traditional "observations-imitation" models. Use of a CPS by trainees facilitated condylar repositioning that resulted in an accurate occlusal result and avoidance of adverse effects on the temporomandibular joint.

Design, development and clinical validation of computer-aided surgical simulation system for streamlined orthognathic surgical planning

PURPOSE

There are many proven problems associated with traditional surgical planning methods for orthognathic surgery. To address these problems, we developed a computer-aided surgical simulation (CASS) system, the AnatomicAligner, to plan orthognathic surgery following our streamlined clinical protocol.

METHODS

The system includes six modules: image segmentation and three-dimensional (3D) reconstruction, registration and reorientation of models to neutral head posture, 3D cephalometric analysis, virtual osteotomy, surgical simulation, and surgical splint generation. The accuracy of the system was validated in a stepwise fashion: first to evaluate the accuracy of AnatomicAligner using 30 sets of patient data, then to evaluate the fitting of splints generated by AnatomicAligner using 10 sets of patient data. The industrial gold standard system, Mimics, was used as the reference.

RESULT

When comparing the results of segmentation, virtual osteotomy and transformation achieved with AnatomicAligner to the ones achieved with Mimics, the absolute deviation between the two systems was clinically insignificant. The average surface deviation between the two models after 3D model reconstruction in AnatomicAligner and Mimics was 0.3 mm with a standard deviation (SD) of 0.03 mm. All the average surface deviations between the two models after virtual osteotomy and transformations were smaller than 0.01 mm with a SD of 0.01 mm. In addition, the fitting of splints generated by AnatomicAligner was at least as good as the ones generated by Mimics.

CONCLUSION

We successfully developed a CASS system, the AnatomicAligner, for planning orthognathic surgery following the streamlined planning protocol. The system has been proven accurate. AnatomicAligner will soon be available freely to the boarder clinical and research communities.