Accuracy of virtual planning in orthognathic surgery: a systematic review

Patient-specific reference model estimation for orthognathic surgical planning

PURPOSE

Accurate estimation of reference bony shape models is fundamental for orthognathic surgical planning. Existing methods to derive this model are of two types: one determines the reference model by estimating the deformation field to correct the patient's deformed jaw, often introducing distortions in the predicted reference model; The other derives the reference model using a linear combination of their landmarks/vertices but overlooks the intricate nonlinear relationship between the subjects, compromising the model's precision and quality.

METHODS

We have created a self-supervised learning framework to estimate the reference model. The core of this framework is a deep query network, which estimates the similarity scores between the patient's midface and those of the normal subjects in a high-dimensional space. Subsequently, it aggregates high-dimensional features of these subjects and projects these features back to 3D structures, ultimately achieving a patient-specific reference model.

RESULTS

Our approach was trained using a dataset of 51 normal subjects and tested on 30 patient subjects to estimate their reference models. Performance assessment against the actual post-operative bone revealed a mean Chamfer distance error of 2.25 mm and an average surface distance error of 2.30 mm across the patient subjects.

CONCLUSION

Our proposed method emphasizes the correlation between the patients and the normal subjects in a high-dimensional space, facilitating the generation of the patient-specific reference model. Both qualitative and quantitative results demonstrate its superiority over current state-of-the-art methods in reference model estimation.

Evaluation of soft tissue profile changes following autogenous fat or onlay PEEK augmentation versus sliding genioplasty for correction of deficient chin: Randomized controlled clinical trial

AIM

The study was conducted to evaluate soft tissue profile changes using autogenous fat augmentation or onlay PEEK versus sliding genioplasty for correction of deficient chin in patients with retruded chin.

MATERIAL AND METHODS

Thirty-three patients with deficient chins were included in the study. The patients were distributed into 3 groups: the fat augmentation group as intervention I, the PEEK augmentation group as intervention II, and the osseous genioplasty group as control group. Preoperative and postoperative CBCT were performed for all patients. With the aid of MIMICS,3-MATIC, and PROPLAN software, diagnosis, virtual planning, and evaluation were performed. The Face-Q questionnaire was used to assess patient satisfaction.

RESULTS

There was a statistically significant difference regarding soft tissue relapse in the fat group after 6 months when compared to the control group (mean difference= 0.770), while there was no statistically significant difference regarding soft tissue relapse between PEEK and control group (mean difference= -0.060). Intragroup comparison has shown no statistically significant difference regarding soft tissue relapse within all groups between follow-up periods (P = 0.1389 for the fat group, P = 0.8739 for the peek group, and P = 0.8410 for the control group). All patients showed a statistically significant increase in scores of satisfaction with the chin between follow-up periods (P = 0.0165, P = 0.0150, and P = 0.0293) respectively.

CONCLUSIONS

Fat augmentation can be a good intervention choice in mild-moderate deficient cases. PEEK PSI has a stable surgical outcome.

A Systematic Review of the Application of Computational Technology in Microtia

Microtia is a congenital and morphological anomaly of one or both ears, which results from a confluence of genetic and external environmental factors. Up to now, extensive research has explored the potential utilization of computational methodologies in microtia and has obtained promising results. Thus, the authors reviewed the achievements and shortcomings of the research mentioned previously, from the aspects of artificial intelligence, computer-aided design and surgery, computed tomography, medical and biological data mining, and reality-related technology, including virtual reality and augmented reality. Hoping to offer novel concepts and inspire further studies within this field.

The online attention analysis on orthognathic surgery research

OBJECTIVES

Altmetrics is one of the fields of bibliometrics that seeks to assess the impact and interest of a given subject through Internet users. The aim of this study is to make an altmetric analysis of the orthognathic surgery literature.

METHODS

A literature search was conducted using Dimensions app up to December 2023. A list of the 100 most mentioned articles on the topic was compiled. A Google Trends search was performed with same strategy to visualize important data regarding internet search. Charts and tables were created using Microsoft Excel and VOSviewer software to allow bibliometric visualization.

RESULTS

There was a very poor correlation between the number of mentions and the number of citations (r = 0.0202). Most articles discussed on technical innovations associated to orthognathic surgery, majority related to virtual planning (n = 26). Other topics considered interesting to internet readers were complications (n = 18), surgical technique (n = 14), and psychological aspects/quality of life (n = 13).

CONCLUSION

Online interest in orthognathic surgery closely aligns with the level of academic interest but is also influenced by factors such as location and economic status. The internet is a powerful tool for disseminating scientific research to a broad audience, making it more accessible and engaging than traditional academic channels.

OrthoCalc: The six degrees of freedom measurement workflow of rotational and displacement changes for maxilla positioning evaluation

BACKGROUND

This study is undertaken to establish the accuracy and reliability of OrthoCalc, a 3D application designed for the evaluation of maxillary positioning.

METHODS

We registered target virtual planned models, maxillary models from pre-operative and post-operative CT scans, and post-operative intra-oral scans to a common reference system, allowing for digital evaluation. To assess rotational changes, we introduced a novel measurement method based on virtual cuboid models. Displacement errors were calculated based on proposed registration matrices. We also compared OrthoCalc to established commercial medical software as a benchmark.

RESULTS

Statistical significance calculated showed no significant differences between OrthoCalc and commercial software. the biggest error of 0.04 degree in rotation change was found in the yaw. A maximum displacement change of 0.75 mm was found in the X direction.

CONCLUSIONS

Our study validates OrthoCalc as a precise and reliable tool for assessing maxillary position changes with six degrees of freedom in orthognathic surgery, endorsing its clinical utility.

Validation of a fully automatic three-dimensional assessment of orthognathic surgery

The aim of the present study was to propose and validate FAST3D: a fully automatic three-dimensional (3D) assessment of the surgical accuracy and the long-term skeletal stability of orthognathic surgery. To validate FAST3D, the agreement between FAST3D and a validated state-of-the-art semi-automatic method was calculated by intra-class correlation coefficients (ICC) at a 95 % confidence interval. A one-sided hypothesis test was performed to evaluate whether the absolute discrepancy between the measurements produced by the two methods was statistically significantly below a clinically relevant error margin of 0.5 mm. Ten subjects (six male, four female; mean age 24.4 years), class II and III, who underwent a combined three-piece Le Fort I osteotomy, bilateral sagittal split osteotomy and genioplasty, were included in the validation study. The agreement between the two methods was excellent for all measurements, ICC range (0.85-1.00), and fair for the rotational stability of the chin, ICC = 0.54. The absolute discrepancy for all measurements was statistically significantly lower than the clinical relevant error margin (p < 0.008). Within the limitations of the present validation study, FAST3D demonstrated to be reliable and may be adopted whenever appropriate in order to reduce the work load of the medical staff.

Enhancing skeletal stability and Class III correction through active orthodontist engagement in virtual surgical planning: A voxel-based 3-dimensional analysis

INTRODUCTION

Skeletal stability after bimaxillary surgical correction of Class III malocclusion was investigated through a qualitative and quantitative analysis of the maxilla and the distal and proximal mandibular segments using a 3-dimensional voxel-based superimposition among virtual surgical predictions performed by the orthodontist in close communication with the maxillofacial surgeon and 12-18 months postoperative outcomes.

METHODS

A comprehensive secondary data analysis was conducted on deidentified preoperative (1 month before surgery [T1]) and 12-18 months postoperative (midterm [T2]) cone-beam computed tomography scans, along with virtual surgical planning (VSP) data obtained by Dolphin Imaging software. The sample for the study consisted of 17 patients (mean age, 24.8 ± 3.5 years). Using 3D Slicer software, automated tools based on deep-learning approaches were used for cone-beam computed tomography orientation, registration, bone segmentation, and landmark identification. Colormaps were generated for qualitative analysis, whereas linear and angular differences between the planned (T1-VSP) and observed (T1-T2) outcomes were calculated for quantitative assessments. Statistical analysis was conducted with a significance level of α = 0.05.

RESULTS

The midterm surgical outcomes revealed a slight but significantly less maxillary advancement compared with the planned position (mean difference, 1.84 ± 1.50 mm; P = 0.004). The repositioning of the mandibular distal segment was stable, with insignificant differences in linear (T1-VSP, 1.01 ± 3.66 mm; T1-T2, 0.32 ± 4.17 mm) and angular (T1-VSP, 1.53° ± 1.60°; T1-T2, 1.54° ± 1.50°) displacements (P >0.05). The proximal segments exhibited lateral displacement within 1.5° for both the mandibular right and left ramus at T1-VSP and T1-T2 (P >0.05).

CONCLUSIONS

The analysis of fully digital planned and surgically repositioned maxilla and mandible revealed excellent precision. In the midterm surgical outcomes of maxillary advancement, a minor deviation from the planned anterior movement was observed.

Comparing CBCT to model scanner for dental model scanning. An in vitro imaging accuracy study

OBJECTIVE

The aim of this study is to compare the accuracy of cone beam computed tomography (CBCT) for dental model scanning to the accuracy of model scanners.

METHODS

Subjects from private practice were collected and scanned according to specific selection criteria. A total of 10 STL files were produced and used as reference files. They were printed with a three-dimensional (3D) printer and then scanned with CBCT and model scanner. For trueness evaluation, all models were scanned once with both equipments. Each file derived from each scan was compared with the corresponding reference model file. For the precision measurements, the physical model from the first master reference model file was scanned 10 times with each equipment and compared with the reference STL file. A reverse engineering software was used for all 3D best-fit comparisons.

RESULTS

With regard to the measurement of trueness of each method, the calculated mean root mean square (RMS) value was 0.06±0.01mm for the CBCT, and 0.15±0.02mm for the model scanner. There was a significant difference between the two methods (P<0.01). For the evaluation of precision of each scanner, the mean RMS value was 0.0056±0.001mm for the CBCT, and 0.153±0.002mm for model scanner. There was a significant difference between the two methods (P<0.01).

CONCLUSIONS

Cone Beam Computed Tomography seems to be an accurate method for scanning dental models. CBCT performs better than model scanners to scan dental models in terms of trueness and precision.

A modified pull-through approach with a pedicled bone flap for oral and oropharyngeal cancer resection: a feasibility study

PURPOSE

Compromised swallowing, speaking, and local complications are the major disadvantages of established approaches to the posterior tongue and oropharynx. The mandibular split involves an esthetically unpleasant bipartition of the lower lip and is prone to bony non-union or sequestration. The conventional pull-through technique on the other hand lacks the secure reattachment of the lingually released soft tissues.

METHODS

The feasibility of a new modified pull-through approach was tested on three anatomical specimens. CAD/CAM cutting guides were used to design a retentive bone flap to properly refixate the genioglossus and geniohyoid muscles after the procedure. The radiographic assessment and treatment planning was performed on 12 cadavers. The entire procedure was tested surgically via dissection in three of those cases. This procedure was then applied in a clinical case.

RESULTS

Precise repositioning and dynamic compression of bony segments was possible reproducibly and without injury to adjacent structures. In all dissected cases, a median lingual foramen was found and in two cases vessels entering it could be dissected Radiologic anatomical landmarks were sufficient in all 12 cases to perform the clinical planning procedure. Clinically, the osteotomized segment demonstrated good blood supply and plateless repositioning was verified postoperatively via cone beam scan.

CONCLUSION

The method presented is safe and easy to perform. Individual cutting guides improve the safety and accuracy of the procedure, potentially eliminating the need for osteosynthesis. We provide the anatomical and radiologic basis for clinical evaluation of this pedicled bone flap procedure and present the clinical application of this modified pull-through approach.

Exploring the relationship between the number of systematic reviews and quality of evidence: an orthognathic surgery-based study

OBJECTIVE

We analyzed the quality and quantity of systematic reviews (SRs) of orthognathic surgery, the most frequently published topic in maxillofacial surgery.

STUDY DESIGN

We searched the PubMed database for SRs of orthognathic surgery with no restriction on the language of publication date. We assessed the certainty of evidence presented according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol and the Leiden Manifesto using the Grading of Recommendations Assessment, Development, and Evaluation approach. We analyzed the data using descriptive statistics, Pearson´s correlation test, and linear regression.

RESULTS

Of the 171 SRs evaluated, approximately one fifth presented evidence with a high level of certainty. The number of orthognathic surgery SRs has been increasing, and many SRs were published after very similar topics had already been published. There is no relationship between the impact factor and the certainty of evidence.

CONCLUSIONS

An excessive number of SRs of orthognathic surgery are published, and many SRs are superfluous, simply reporting previous findings. Clinicians should not base treatment decisions solely on the evidence presented in SRs, and journal editors and reviewers should evaluate these SRs more critically, particularly when they address topics that have already been covered in the literature.

Redefining precision and efficiency in orthognathic surgery through virtual surgical planning and 3D printing: a narrative review

Orthognathic surgery, essential for addressing jaw and facial skeletal irregularities, has historically relied on traditional surgical planning (TSP) involving a series of time-consuming steps including two-dimensional radiographs. The advent of virtual surgical planning (VSP) and 3D printing technologies has revolutionized this field, bringing unprecedented precision and customization to surgical processes. VSP facilitates 3D visualization of the surgical site, allowing for real-time adjustments and improving preoperative stress for patients by reducing planning time. 3D printing dovetails with VSP, offering the creation of anatomical models and surgical guides, enhancing the predictability of surgical outcomes despite higher initial setup and material costs. The integration of VSP and 3D printing promises innovative and effective solutions in orthognathic surgery, surpassing the limitations of traditional methods. Patient-reported outcomes show a positive post-surgery impact on the quality of life, underlining the significant role of these technologies in enhancing self-esteem and reducing anxiety. Economic analyses depict a promising long-term fiscal advantage with these modern technologies, notwithstanding the higher initial costs. The review emphasizes the need for large-scale randomized controlled trials to address existing research gaps and calls for a deeper exploration into the long-term impacts and ethical considerations of these technologies. In conclusion, while standing on the cusp of a technological renaissance in orthognathic surgery, it is incumbent upon the medical fraternity to foster a collaborative approach, balancing innovation with scrutiny to enhance patient care. The narrative review encourages the leveraging of VSP and 3D printing technologies for more efficient and patient-centric orthognathic surgery, urging the community to navigate uncharted territories in pursuit of precision and efficiency in the surgical landscape.

A New Approach to Virtual Occlusion in Orthognathic Surgery Planning Using Mixed Reality-A Technical Note and Review of the Literature

Orthognathic surgery plays a vital role in correcting various skeletal discrepancies of the maxillofacial region. Achieving optimal occlusion is a fundamental aspect of orthognathic surgery planning, as it directly influences postoperative outcomes and patient satisfaction. Traditional methods for setting final occlusion involve the use of dental casts which are time-consuming, prone to errors and cannot be easily shared among collaborating specialties. In recent years, advancements in digital technology have introduced innovative approaches, such as virtual occlusion, which may offer enhanced accuracy and efficiency in orthognathic surgery planning. Furthermore, the emergence of mixed reality devices and their 3D visualization capabilities have brought about novel benefits in the medical field, particularly in computer-assisted planning. This paper presents for the first time a prototype tool for setting virtual occlusion during orthognathic surgery planning using mixed reality technology. A complete walkthrough of the workflow is presented including an explanation of the implicit advantages of this novel tool. The new approach to defining virtual occlusion is set into context with other published methods of virtual occlusion setting, discussing advantages and limitations as well as concepts of surgical occlusion for orthognathic surgery.

Computer-assisted planning and patient-specific plates in orthognathic surgery: a global study

OBJECTIVE

Using computer-assisted surgery (CAS) and patient-specific plates (PSP) in orthognathic surgery has shown improved accuracy and efficiency compared with traditional techniques. This study analyzed current global trends in planning and investigated the reasons for CAS and PSP use.

STUDY DESIGN

A survey of 29 multiple choice questions was distributed to AO Foundation Craniomaxillofacial e-mail subscribers biweekly between July 14, 2021 and September 2, 2021. Questions focused on specifics of respondents' preoperative workup, methods of data collection, and the use of cutting guides and patient-specific plates. Objective clinical outcomes and subjective surgeon reasons for use were also investigated.

RESULTS

Of the 557 responses, 420 (75.4%) participant responses were eligible for analyses. Most (302/420, 71.9%) respondents used CAS when performing orthognathic surgery, although regional differences were observed. Almost all respondents in North America implemented CAS in their surgery plan (44/46, 95.7%) compared with only 47.4% (18/38) in the Middle East/North Africa. Surgeons with 10 to 15 years of experience were far more likely to incorporate CAS. More than half (175/301, 58.1%) of CAS users also used PSP, of which 43% (68/158) did so for maxillary-only cases, 3.2% (5/158) used PSP for mandible-only surgeries, and 42.4% (67/158) used PSP for both. Surgeons' primary reasons for using CAS and PSP were accuracy (200/253, 79.1%), efficiency (196/253, 77.5%), and ease of preoperative planning (150/253, 59.3%). Most (77.9%) surgeons perceived that CAS was equal to or faster than traditional surgery.

CONCLUSIONS

Our study shows differences in use regionally and with surgeon experience. Surgeons primarily use CAS and PSP in orthognathic surgery to increase accuracy and efficiency, minimize intraoperative deviations from the surgical plan, and reduce total surgical time.

Construction of a virtual reality platform for computer-aided navigation Lingnan bone setting technique

To establish a standard Traditional Chinese medicine (TCM) bone setting technique, standardize the operation and inherit the TCM bone setting technique. This project was based on the interactive tracking of bone setting techniques with a dedicated position tracker, the motion tracking of bone setting techniques based on RGBD (Red Green Blue Depth) cameras, the digital analysis of bone setting techniques, and the design of the virtual reality platform for bone setting techniques. These key technical researches were combined to construct an interactive bone setting technique. The virtual simulation system can reproduce the implementation process of the expert's bone setting technique. The user can observe the implementation of the manipulative technique from multiple angles; through human-computer interaction, the whole process of implementation of the bone setting technique can be simulated, and the movement and reduction of the affected bone can be observed at the same time. It can be used as a teaching and training system for assisting bone setting techniques. Students can use the system to carry out repeated self-training, and can instantly compare with the standard techniques of the expert database, breaking the traditional teaching mode of 'expected and unspeakable' and avoid directly using patients. Therefore, this research makes it possible to reduce teaching costs, reduce risks, improve teaching quality, and make up for the lack of teaching conditions. It is very positive for the inheritance of the traditional Chinese 'intangible culture' of bone setting techniques, and to promote the digitalization and standardization of bone setting techniques.

Virtual surgical planning in craniomaxillofacial surgery: a structured review

Craniomaxillofacial (CMF) surgery is a challenging and very demanding field that involves the treatment of congenital and acquired conditions of the face and head. Due to the complexity of the head and facial region, various tools and techniques were developed and utilized to aid surgical procedures and optimize results. Virtual Surgical Planning (VSP) has revolutionized the way craniomaxillofacial surgeries are planned and executed. It uses 3D imaging computer software to visualize and simulate a surgical procedure. Numerous studies were published on the usage of VSP in craniomaxillofacial surgery. However, the researchers found inconsistency in the previous literature which prompted the development of this review. This paper aims to provide a comprehensive review of the findings of the studies by conducting an integrated approach to synthesize the literature related to the use of VSP in craniomaxillofacial surgery. Twenty-nine related articles were selected as a sample and synthesized thoroughly. These papers were grouped assigning to the four subdisciplines of craniomaxillofacial surgery: orthognathic surgery, reconstructive surgery, trauma surgery and implant surgery. The following variables - treatment time, the accuracy of VSP, clinical outcome, cost, and cost-effectiveness - were also examined. Results revealed that VSP offers advantages in craniomaxillofacial surgery over the traditional method in terms of duration, predictability and clinical outcomes. However, the cost aspect was not discussed in most papers. This structured literature review will thus provide current findings and trends and recommendations for future research on the usage of VSP in craniomaxillofacial surgery.

Accuracy of hard and soft tissue prediction using three-dimensional simulation software in bimaxillary osteotomies: A systematic review

INTRODUCTION

Orthognathic surgery is considered nowadays as a revolutionary treatment option for treating skeletal discrepancies and severe malocclusions in the sagittal, vertical and transverse dimensions. This surgery allows both the restoration of facial harmony and the achievement of satisfactory dental occlusion. The technology of computer-assisted surgeries including virtual surgical simulation programs and planning software greatly contributes to providing a three-dimensional simulation and precise mobilization of the maxilla and/or mandible, thus allowing the prediction of the final outcome in soft tissues. This study aims to systematically review the available scientific literature about the accuracy of the hard and soft tissue predictions delivered by the many promoted three-dimensional simulation software.

MATERIAL AND METHODS

An electronic search was conducted on various databases: Medline via PubMed, The Cochrane Library, EBSCO-host, and Web of Science. The search was established on a well-defined research question following PICO principle: population, intervention, comparator and outcome. Search evaluation and the assessment of risk of bias were undertaken in each study following its type and design.

RESULTS

Fifteen studies were included for qualitative analysis. Seven studies evaluated the accuracy of soft tissue prediction, seven focused more on the accuracy of hard tissue and one study assessed both hard and soft tissue prediction accuracy delivered by the simulation software. Moreover, three studies were judged to be low risk and four were classified as high risk. Included studies revealed that hard tissue prediction is highly accurate and reliable, leading to clinically acceptable results. Yet, soft tissue prediction is unclear due to various factors that bias its results. Caution should therefore be taken when providing information about the soft tissue planning to patients.

CONCLUSIONS

Computer assisted 3D simulation protocols allow for more precise repositioning of the maxilla and/or mandible compared to conventional 2D methods. However, 3D soft tissue prediction using simulation software remains less accurate, especially in the labial region.

Novel Procedure for Automatic Registration between Cone-Beam Computed Tomography and Intraoral Scan Data Supported with 3D Segmentation

In contemporary practice, intraoral scans and cone-beam computed tomography (CBCT) are widely adopted techniques for tooth localization and the acquisition of comprehensive three-dimensional models. Despite their utility, each dataset presents inherent merits and limitations, prompting the pursuit of an amalgamated solution for optimization. Thus, this research introduces a novel 3D registration approach aimed at harmonizing these distinct datasets to offer a holistic perspective. In the pre-processing phase, a retrained Mask-RCNN is deployed on both sagittal and panoramic projections to partition upper and lower teeth from the encompassing CBCT raw data. Simultaneously, a chromatic classification model is proposed for segregating gingival tissue from tooth structures in intraoral scan data. Subsequently, the segregated datasets are aligned based on dental crowns, employing the robust RANSAC and ICP algorithms. To assess the proposed methodology's efficacy, the Euclidean distance between corresponding points is statistically evaluated. Additionally, dental experts, including two orthodontists and an experienced general dentist, evaluate the clinical potential by measuring distances between landmarks on tooth surfaces. The computed error in corresponding point distances between intraoral scan data and CBCT data in the automatically registered datasets utilizing the proposed technique is quantified at 0.234 ± 0.019 mm, which is significantly below the 0.3 mm CBCT voxel size. Moreover, the average measurement discrepancy among expert-identified landmarks ranges from 0.368 to 1.079 mm, underscoring the promise of the proposed method.

Face the Future-Artificial Intelligence in Oral and Maxillofacial Surgery

Artificial intelligence (AI) has emerged as a versatile health-technology tool revolutionizing medical services through the implementation of predictive, preventative, individualized, and participatory approaches. AI encompasses different computational concepts such as machine learning, deep learning techniques, and neural networks. AI also presents a broad platform for improving preoperative planning, intraoperative workflow, and postoperative patient outcomes in the field of oral and maxillofacial surgery (OMFS). The purpose of this review is to present a comprehensive summary of the existing scientific knowledge. The authors thoroughly reviewed English-language PubMed/MEDLINE and Embase papers from their establishment to 1 December 2022. The search terms were (1) "OMFS" OR "oral and maxillofacial" OR "oral and maxillofacial surgery" OR "oral surgery" AND (2) "AI" OR "artificial intelligence". The search format was tailored to each database's syntax. To find pertinent material, each retrieved article and systematic review's reference list was thoroughly examined. According to the literature, AI is already being used in certain areas of OMFS, such as radiographic image quality improvement, diagnosis of cysts and tumors, and localization of cephalometric landmarks. Through additional research, it may be possible to provide practitioners in numerous disciplines with additional assistance to enhance preoperative planning, intraoperative screening, and postoperative monitoring. Overall, AI carries promising potential to advance the field of OMFS and generate novel solution possibilities for persisting clinical challenges. Herein, this review provides a comprehensive summary of AI in OMFS and sheds light on future research efforts. Further, the advanced analysis of complex medical imaging data can support surgeons in preoperative assessments, virtual surgical simulations, and individualized treatment strategies. AI also assists surgeons during intraoperative decision-making by offering immediate feedback and guidance to enhance surgical accuracy and reduce complication rates, for instance by predicting the risk of bleeding.

Reproducibility and reliability of digital occlusal planning for orthognathic surgery

The digital articulation of dental models is gradually replacing the conventional physical approach for occlusal prediction planning. This study was performed to compare the accuracy and reproducibility of free-hand articulation of two groups of digital and physical dental models, 12 Class I (group 1) and 12 Class III (group 2). The models were scanned using an intraoral scanner. The physical and digital models were independently articulated 2 weeks apart by three orthodontists to achieve the maximum inter-digitation, with coincident midlines and a positive overjet and overbite. The occlusal contacts provided by the software color-coded maps were assessed and the differences in the pitch, roll, and yaw were measured. The reproducibility of the achieved occlusion of both the physical and digital articulation was excellent. The z-axis displayed the smallest absolute mean differences of 0.10 ± 0.08 mm and 0.27 ± 0.24 mm in the repeated physical and repeated digital articulations, respectively, both in group 2. The largest discrepancies between the two methods of articulation were in the y-axis (0.76 ± 0.60 mm, P = 0.010) and in roll (1.83° ± 1.72°, P = 0.005). The overall measured differences were< 0.8 mm and< 2°. Despite the steep learning curve, digital occlusal planning is accurate enough for clinical applications.

Accuracy of Patient-Specific Implants in Virtually Planned Segmental Le Fort I Osteotomies

(1) Background: In orthognathic surgery, segmental Le Fort I osteotomies are a valuable method to correct maxillary deformities or transversal discrepancies. However, these procedures are technically challenging, and osteosynthesis can be prone to error. (2) Methods: In this retrospective, monocentric cohort study, patients were enrolled who underwent a virtually planned segmental maxillary osteotomy during their combined treatment. Positioning and osteosynthesis were achieved by either a 3D-printed splint and conventional miniplates or patient-specific implants (PSI). The preoperative CT data, virtual planning data, and postoperative CBCT data were segmented. The deviation of all the segments from the desired virtually planned position was measured using the analysis function of IPS CaseDesigner. (3) Results: 28 Patients in the PSI Group and 22 in the conventional groups were included. The PSI group showed significantly lower deviation from the planned position anteroposteriorly (-0.63 ± 1.62 mm vs. -1.3 ± 2.54 mm) and craniocaudally (-1.39 ± 1.59 mm vs. -2.7 ± 3.1 mm). For rotational deviations, the pitch (0.64 ± 2.59° vs. 2.91 ± 4.08°), as well as the inward rotation of the lateral segments, was positively influenced by PSI. (4). Conclusions: The presented data show that patient-specific osteosynthesis significantly reduces deviations from the preoperative plan in virtually planned cases. Transversal expansions and vertical positioning can be addressed better.

Characteristics of orthognathic multidisciplinary team clinics in England. Part 2: A qualitative study

OBJECTIVE

The aim of the study was to explore the orthodontist's perspective of the strengths and weaknesses of their current multidisciplinary team (MDT) design for orthognathic treatment.

PARTICIPANTS AND METHODS

This was a qualitative study using online interviews of orthodontic consultants across England. The data were analysed using thematic analysis. This was the second part of a two-part study, where the first part, an online questionnaire survey, identified the variation in design of orthognathic MDTs across England and was the source of the 19 participants for this study.

RESULTS

Seven themes were identified that influenced the design of orthognathic MDTs across England. Close working relationship with the team, access to closed surgery space to conduct the MDT and access to 3D planning were identified as definite strengths of some MDT clinics. Lack of a team psychologist and long waiting lists were identified as weaknesses of some orthognathic MDTs. Teaching and training within MDT clinics were highlighted as a strength of MDTs where surgery spaces were not restricted due to the pandemic. Finally, there was general agreement about revising the orthognathic minimum dataset for records collection as it was not thought to be in the patient's best interest.

CONCLUSION

This study was able to identify key areas considered to be determinants of a successful orthognathic MDT design from the orthodontic consultant's perspective. Orthodontic consultants across England prioritised the need for a psychologist in the orthognathic MDT to improve the effectiveness of these clinics.

Effectiveness of creating digital twins with different digital dentition models and cone-beam computed tomography

Distortion of dentition may occur in cone-beam computed tomography (CBCT) scans due to artifacts, and further imaging is frequently required to produce digital twins. The use of a plaster model is common; however, it has certain drawbacks. This study aimed to assess the feasibility of different digital dentition models over that of plaster casts. Plaster models, alginate impressions, intraoral scan (IOS) images, and CBCT images of 20 patients were obtained. The desktop model scanner was used to scan the alginate impression twice, five minutes and two hours after impression-making. Using an IOS, the full arch was scanned in segments using CS 3600 and simultaneously with i700 wireless. The digital twins obtained from the alginate impression and IOS were superimposed with those obtained from the plaster cast. The differences and distances at each reference point were measured. Scans of alginate impressions after two hours showed the greatest discrepancies, but these were all less than the CBCT voxel size of 0.39 mm. Alginate impression scans and IOS are suitable supplements to CBCT compared to the plaster model. Accuracy can be improved by scanning the alginate impression within five minutes or by intraoral scanning of the entire arch with segmentation.

Maximizing the Virtual Surgical Planning Session for Orthognathic Surgery

Virtual surgical planning (VSP) and computer-aided design/computer-aided manufacturing have become essential tools for planning orthognathic surgery. Despite widespread use, empirical gaps still exist in the literature regarding the logistics of the orthognathic planning session itself. More precisely, there is a need to explicate the VSP workflow on which specific parameters are needed for a translation into 3D software. Although each surgeon has his/her theoretical framework, none have been elucidated to properly communicate the necessary pieces of information needed to plan the correction of a variety of dentofacial deformities. The authors provide an outline for conducting a successful VSP planning session for orthognathic surgery.

The accuracy of soft tissue movement using virtual planning for non-syndromic facial asymmetry cases-a systematic review

The 3D prediction of post-operative changes is an inevitable tool for the surgical correction of facial asymmetry. The objective is to execute an evidence-based review answering the following question. Does the 3D virtual prediction planning draw reliable and accurate results in the surgical outcome related to the soft tissues of the face in facial asymmetry? This systematic review of the literature is based on the 3D soft tissue prediction planning of facial asymmetry correction to draw conclusions on the reliability and accuracy of these methods in the surgical outcome related to the soft tissues of the face. PubMed, Web of Science, Cochrane, and Ovid databases were adopted for the literature search. Studies published between years 2000 and 2020, aimed at the assessment of soft tissue predictions using software prediction packages for facial asymmetry, were selected. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) was applied. Quadas-2 tool was used for the qualitative evaluation of selected studies. Initial search yielded 248 articles. Twenty articles fulfilled the inclusion and exclusion criteria and selected for qualitative analysis. Finally, 12 articles were selected for quantitative analysis. The results indicate 3D imaging prediction methods provided more accurate information with less distortion for soft tissue prediction regardless of various softwares currently available. The prediction of soft tissue accuracy in facial asymmetry was less accurate in lower face regardless of the type of surgery for facial asymmetry. The mean prediction error was less than 2 mm.

Accuracy of virtual surgical planning in bimaxillary orthognathic surgery with mandible first sequence: A retrospective study

The aim of this study was to verify treatment accuracy using virtual surgical planning (VSP) with a mandible-first sequence and strict surgical protocol to determine what surgical and methodological factors might influence outcomes. VSP transfer accuracy was evaluated retrospectively through a modified method involving voxel-based superimposition in patients who had undergone bimaxillary surgery with a mandible-first sequence to correct dentoskeletal deformities. Data analysis showed that the movements planned and those executed were substantially equivalent (p < 0.01), with the exception of mandibular and maxillary sagittal movements that were 0.72 ± 0.90 mm and 1.41 ± 1.04 mm smaller, respectively, than planned. This study showed that a mandible-first sequence is accurate for transferring virtual surgical planning intraoperatively. There are several factors involved in the proper transfer of virtual planning beyond the software, such as surgical technique and sequencing. Inaccurate sagittal movements and maxillary repositioning seem to depend mainly on surgical factors.

Can Fracture Reduction be Attempted Through a 3D-Printed Guide Template Without Maxillomandibular Fixation?

BACKGROUND

Computer-aided design and manufacturing is widely used in clinical practice. This technology may change existing methods for mandibular fracture management.

PURPOSE

The purpose of this in-vitro study was to determine if the reduction for mandibular symphysis fracture is performed without maxillomandibular fixation (MMF) using 3-dimensional (3D)-printed template.

STUDY DESIGN, SETTING, AND SAMPLE

This was an in-vitro study and had the character of a proof-of-concept study. The study was planned using the existing 20 pairs of intraoral scan and computed tomography data. The mandibular model STL file was created by merging the STL file obtained for the bimaxillary dentitions with the computed tomography DICOM file, and this was set as the original model. In the original model, STL file of fracture model of mandibular symphysis was created using computer-aided design. A template similar to a wafer or an implant guide was manufactured from restoring the own occlusion, and the mandibular fracture model was reduced and fixed using the 3D-printed template and wire, and this was set as the experimental group. The 3D coordinate system error was measured at 6 landmarks and statistically compared using scan data between models of the groups.

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLES

Reduction techniques with MMF or without MMF using guide template for mandibular fracture model.

MAIN OUTCOME VARIABLE(S)

The 3D coordinate system error (mm).

COVARIATES

The position of landmarks.

ANALYSES

The Mann-Whitney U test, student's t-test, and the Kruskal-Wallis test were used to analyze the coordinate errors between the landmarks. A P value of < .05 was considered statistically significant.

RESULTS

The 3D error value of the control and experimental group were 1.06 ± 0.63 mm (range: 0.11 to 2.92 mm) and 0.96 ± 0.48 mm (range: 0.2 to 2.95 mm), respectively. There was no statistical difference between the control and experimental group. There was a statistically significant difference in the lower 2 and lower 3 landmarks compared to the upper 1 (P = .001 and .000, respectively) before and after the reduction in the experimental group.

CONCLUSION AND RELEVANCE

This study demonstrates that the reduction using a 3D-printed guide template for the mandibular symphysis fracture could be possible even without the MMF.

Managing Predicted Post-Orthognathic Surgical Defects Using Combined Digital Software: A Case Report

For facial abnormalities, recent developments in virtual surgical planning (VSP) and the virtual design of surgical splints are accessible. Software companies have worked closely with surgical teams for accurate outcomes, but they are only as reliable as the data provided to them. The current case's aim was to show a fully digitized workflow using a combination of three digital software to correct predicted post-upward sliding genioplasty defects. To reach our goal, we presented a 28-year-old man with long-face syndrome for orthodontic treatment. Before orthognathic surgery, a clinical and paraclinical examination was performed. For a virtual surgical plan, we used the dedicated surgical planning software NemoFab (Nemotec, Madrid, Spain) and Autodesk MeshMixer (Autodesk Inc., San Rafael, CA, USA). To create the design of the digital guides, DentalCAD 3.0 Galway (exocad GmbH, Darmstadt, Germany) and Autodesk MeshMixer (Autodesk Inc., San Rafael, CA, USA) were used. The patient had undergone bilateral sagittal split osteotomy in addition to Le Fort 1 osteotomy and genioplasty, followed by mandible base recontouring ostectomy. Stable fixation was used for each osteotomy. Based on our case, the current orthognathic surgery planning software was not able to perform all the necessary operations autonomously; therefore, future updates are eagerly awaited.

The Last 40 Years of Orthognathic Surgery: A Bibliometric Analysis

PURPOSE

Bibliometric analyses provide information on the effectiveness, performance, trends, and various other characteristics of research by using mathematical and statistical analysis methods for data related to scientific publications. This study aims to determine the focus of studies in the field of orthognathic surgery, map it, and present the results in a simplified manner through a comprehensive bibliometric analysis of the relevant literature.

METHODS

In this bibliometric analysis study, orthognathic surgery publications from 1980 to 2022 were retrieved from the Web of Science Core Collection database. The independent variables were co-citations, while the outcome variables included cross-country collaboration analysis, keyword analysis, co-citation analysis, and cluster analysis of the co-citation network. Covariates were the number of publications, number of citations, year range, centrality value, and silhouette value. The bibliometric analysis was conducted using CiteSpace, VOSviewer, and R-Studio software.

RESULTS

A total of 7,135 publications and 75,822 references were included in the analysis, and the annual growth rate of publications was 9.52%. The co-citation clustering analysis revealed that the orthognathic surgery literature was organized into 16 subject headings. Patient satisfaction was found to be the most widely published topic. The youngest clusters, representing new topics in the field, were virtual planning and examination of condylar changes after orthognathic surgery.

CONCLUSION

Bibliometric analysis methods were used to evaluate the 40-year history of the orthognathic surgery literature. The analysis identified the most influential publications, the topics in which the literature is divided, and hot spots in the field. By conducting similar bibliometric research studies in the future, the progress and future direction of the literature can be monitored based on evidence.

Monitoring cone-beam CT radiation dose levels in a University Hospital

OBJECTIVE

To present patient dose levels for different CBCT scanners, acquired by a dose monitoring tool in a University Hospital, as a function of field of view (FOV), operation mode, and patient age.

METHODS

An integrated dose monitoring tool was used to collect radiation exposure data [type of CBCT unit, dose-area product (DAP), FOV size, and operation mode] and patient demographic information (age, referral department) performed on a 3D Accuitomo 170 and a Newtom VGI EVO unit. Effective dose conversion factors were calculated and implemented into the dose monitoring system. For each CBCT unit, the frequency of examinations, clinical indications, and effective dose levels were obtained for different age and FOV groups, and operation modes.

RESULTS

A total of 5163 CBCT examinations were analyzed. Surgical planning and follow-up were the most frequent clinical indications. For the standard operation mode, effective doses ranged from 35.1 to 300 µSv and 9.26-117 µSv using 3D Accuitomo 170 and Newtom VGI EVO, respectively. In general, effective doses decreased with increasing age and FOV size reduction.

CONCLUSIONS

Effective dose levels varied notably between systems and operation modes.Operation mode selection and FOV size were indication-oriented, with larger FOV sizes election serving surgical planning and follow-up. Seeing the influence of FOV size on effective dose levels, manufacturers could be advised to move toward patient-specific collimation and dynamic FOV selection. Systematically monitoring patient doses could be recommended for steering future CBCT optimization.

Accuracy and safety of in-house surgeon-designed three-dimensional-printed patient-specific implants for wafer-less Le Fort I osteotomy

OBJECTIVES

The design and fabrication of three-dimensional (3D)-printed patient-specific implants (PSIs) for orthognathic surgery are customarily outsourced to commercial companies. We propose a protocol of designing PSIs and surgical guides by orthognathic surgeons-in-charge instead for wafer-less Le Fort I osteotomy. The aim of this prospective study was to evaluate the accuracy and post-operative complications of PSIs that are designed in-house for Le Fort I osteotomy.

MATERIALS AND METHODS

The post-operative cone beam computer tomography (CBCT) model of the maxilla was superimposed to the virtual surgical planning to compare the discrepancies of pre-determined landmarks, lines, and principal axes between the two models. Twenty-five patients (12 males, 13 females) were included.

RESULTS

The median linear deviations of the post-operative maxilla of the x, y, and z axes were 0.74 mm, 0.75 mm, and 0.72 mm, respectively. The deviations in the principal axes for pitch, yaw, and roll were 1.40°, 0.90°, and 0.60°, respectively. There were no post-operative complications related to the PSIs in the follow-up period.

CONCLUSIONS

The 3D-printed PSIs designed in-house for wafer-less Le Fort I osteotomy are accurate and safe.

CLINICAL RELEVANCE

Its clinical outcomes and accuracy are comparable to commercial PSIs for orthognathic surgery.

TRIAL REGISTRATION

Clinical trial registration number: HKUCTR-2113. Date of registration: 29 July 2016.

Three-Dimensional Accuracy and Stability of Personalized Implants in Orthognathic Surgery: A Systematic Review and a Meta-Analysis

This systematic review aimed to determine the accuracy/stability of patient-specific osteosynthesis (PSI) in orthognathic surgery according to three-dimensional (3D) outcome analysis and in comparison to conventional osteosynthesis and computer-aided designed and manufactured (CAD/CAM) splints or wafers. The PRISMA guidelines were followed and six academic databases and Google Scholar were searched. Records reporting 3D accuracy/stability measurements of bony segments fixated with PSI were included. Of 485 initial records, 21 met the eligibility (566 subjects), nine of which also qualified for a meta-analysis (164 subjects). Six studies had a high risk of bias (29%), and the rest were of low or moderate risk. Procedures comprised either single-piece or segmental Le Fort I and/or mandibular osteotomy and/or genioplasty. A stratified meta-analysis including 115 subjects with single-piece Le Fort I PSI showed that the largest absolute mean deviations were 0.5 mm antero-posteriorly and 0.65° in pitch. PSIs were up to 0.85 mm and 2.35° more accurate than conventional osteosynthesis with CAD/CAM splint or wafer (p < 0.0001). However, the clinical relevance of the improved accuracy has not been shown. The literature on PSI for multi-piece Le Fort I, mandibular osteotomies and genioplasty procedure is characterized by high methodological heterogeneity and a lack of randomized controlled trials. The literature is lacking on the 3D stability of bony segments fixated with PSI.

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.

Accuracy of Orthognathic Surgical Planning using Three-dimensional Virtual Techniques compared with Conventional Two-dimensional Techniques: a Systematic Review

Objectives

The objective was to assess the accuracy of orthognathic surgical planning using three-dimensional virtual planning compared with conventional two-dimensional planning.

Material and Methods

MEDLINE (PubMed), Embase and Cochrane Library search combined with hand-search of relevant journals was conducted to identify randomized controlled trials (RCTs) published in English through August 2^nd, 2022. Primary outcomes included postsurgical accuracy of hard and soft tissue. Secondary outcomes included treatment planning time, intraoperative time, intraoperative blood loss, complications, financial expenses, and patient-reported outcome measures (PROMs). Quality and risk-of-bias assessment were evaluated by Cochrane risk of bias tool and GRADE system.

Results

Seven RCTs characterised by low, high, and unclear risk of bias fulfilled inclusion criteria. Included studies disclosed conflicting results regarding accuracy of hard and soft tissue as well as treatment planning time. The intraoperative time was shortened, and financial expenses were increased with three-dimensional virtual surgical planning (TVSP), while no planning-related complications were revealed. Comparable improvement in PROMs were reported with TVSP and two-dimensional planning.

Conclusions

Future orthognathic surgical planning will indisputable be performed by three-dimensional virtual planning. The financial expenses, treatment planning time, and intraoperative time will therefore probably decrease due to further development of three-dimensional virtual planning techniques. The hard and soft tissue accuracy between planned position and achieved surgical outcome seems to be improved by three-dimensional virtual planning compared with two-dimensional planning, although results are inconsistent. Further development of three-dimensional virtual planning involving cutting guides and patient-specific osteosynthesis plates are therefore needed to improve the accuracy of orthognathic surgical planning.

Contemporary management of complex craniofacial trauma: virtual planning, navigation and the novel thermoformed cage splints in a strategic, sequential, computer-guided protocol

INTRODUCTION

It was the aim of the study to assess if computerized simulation and the use of thermoformed cage splints are useful to plan cases of complex craniofacial trauma.

MATERIALS AND METHODS

patients with fractures in any of the thirds of the craniofacial skeleton and occlusion impairment. Virtual surgical planning with digital reduction of fractures, navigated planning, thermoformed cage splints were used in all cases. Surgical outcomes were evaluated by computing the surface deviation and occlusograms between planned and postoperative models.

RESULTS

13 patients were enrolled in this study. Accuracy of bone repositioning was evaluated compared with the surgical planning. For the mandible, mean Root Mean Square Error (RMSE) was of 1.67 with a standard deviation (SD) of ±0.75 mm (p < 0.001); for the maxilla, average RMSE was of 0.88 with SD of ±0.52 mm (p < 0.001); and for midfacial and upper third bone segments, average RMSE was of 0.59 with SD of ±0.47 mm (p < 0.001) CONCLUSIONS: Within the limitations of the study it seems that thermoformed cage splints might be a promising alternative to other well-established approaches for accurate occlusal restoration and can be fully integrated within the digital workflow.

Static mandibular condyle positions studied by MRI and condylar position indicator

We compared mandibular condyle positions as determined by magnetic resonance imaging (MRI) and a mechanical device, the condylar position indicator (CPI). Both methods assessed 3 mandibular positions in 10 asymptomatic males and 10 asymptomatic females, aged 23 to 37 years, free from temporomandibular disorders: maximum intercuspation, bimanually manipulated centric relation, and the unguided neuromuscular position. Bite registrations were obtained for bimanual operator guidance and neuromuscular position. 3 T MRI scans of both temporomandibular joints produced 3D data of the most superior condylar points in all 3 mandibular positions. Using mounted plaster casts and the same bite registrations, an electronic CPI displayed 3D data of its condylar spheres in these positions. The results showed interclass correlation coefficients ranging from 0.03 to 0.66 (95% confidence intervals from 0 to 0.8) and significantly different condyle positions between both methods (p = 0.0012, p < 0.001). The implications of the study emphasize that condyle position is unpredictable and variable. Its exact knowledge requires radiological imaging and should not rely on CPI assessments.

A Full Computerized Workflow for Planning Surgically Assisted Rapid Palatal Expansion and Orthognathic Surgery in a Skeletal Class III Patient

In the present case report, we present and discuss the digital workflow involved in the orthodontic/orthognathic combined treatment of a skeletal malocclusion correction in a 17-year-old male patient affected by a skeletal class III, facial asymmetry, sagittal and transversal deficiency of the medium third of the skull, dental crowding, and bilateral cross-bite. The first stage of the treatment involved surgically assisted rapid palatal expansion and occlusal decompensation, using fixed self-ligating appliance. An orthodontic software package (i.e., Dolphin 3D Surgery module) was used to perform virtual treatment objective evaluation by integrating data from cone beam computer tomography acquisition, intraoral scan, and extraoral photographs. The software allowed a comprehensive evaluation of skeletal, dento-alveolar, and soft-tissue disharmonies, qualitative and quantitative simulation of surgical procedure according to skeletal and aesthetic objectives, and, consequently, the treatment of the malocclusion. Using a specific function of the software, the surgical splint was designed according to the pre-programmed skeletal movements, and subsequently, the physical splint was generated with a three-dimensional (3D) printing technology. Once a proper occlusal decompensation was reached, a Le Fort I osteotomy of the maxilla and a bilateral sagittal surgical osteotomy of the mandible were executed to restore proper skeletal relations. The whole treatment time was 8 months. The orthodontic/orthognathic combined treatment allowed to correct the skeletal and the dental imbalance, as well as the improvement of facial aesthetics. Accordingly, the treatment objectives planned in the virtual environment were achieved. Virtual planning offers new possibilities for visualizing the relationship between dental arches and surrounding bone and soft structures in a single virtual 3D model, allowing the specialists to simulate different surgical and orthodontic procedures to achieve the best possible result for the patient and providing an accurate and predictable outcome in the treatment of challenging malocclusions.

Automatic 3-Dimensional Cephalometric Landmarking via Deep Learning

The increasing use of 3-dimensional (3D) imaging by orthodontists and maxillofacial surgeons to assess complex dentofacial deformities and plan orthognathic surgeries implies a critical need for 3D cephalometric analysis. Although promising methods were suggested to localize 3D landmarks automatically, concerns about robustness and generalizability restrain their clinical use. Consequently, highly trained operators remain needed to perform manual landmarking. In this retrospective diagnostic study, we aimed to train and evaluate a deep learning (DL) pipeline based on SpatialConfiguration-Net for automatic localization of 3D cephalometric landmarks on computed tomography (CT) scans. A retrospective sample of consecutive presurgical CT scans was randomly distributed between a training/validation set (n = 160) and a test set (n = 38). The reference data consisted of 33 landmarks, manually localized once by 1 operator(n = 178) or twice by 3 operators (n = 20, test set only). After inference on the test set, 1 CT scan showed "very low" confidence level predictions; we excluded it from the overall analysis but still assessed and discussed the corresponding results. The model performance was evaluated by comparing the predictions with the reference data; the outcome set included localization accuracy, cephalometric measurements, and comparison to manual landmarking reproducibility. On the hold-out test set, the mean localization error was 1.0 ± 1.3 mm, while success detection rates for 2.0, 2.5, and 3.0 mm were 90.4%, 93.6%, and 95.4%, respectively. Mean errors were -0.3 ± 1.3° and -0.1 ± 0.7 mm for angular and linear measurements, respectively. When compared to manual reproducibility, the measurements were within the Bland-Altman 95% limits of agreement for 91.9% and 71.8% of skeletal and dentoalveolar variables, respectively. To conclude, while our DL method still requires improvement, it provided highly accurate 3D landmark localization on a challenging test set, with a reliability for skeletal evaluation on par with what clinicians obtain.

Linear and angular measurement using cone-beam computed tomography to enhance safety in Le Fort I osteotomy with tuberosity cut

OBJECTIVE

The study aimed to evaluate surgical angles for tuberosity cut and linear and angular measurements for all horizontal cuts in Le Fort I osteotomy using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This study included 189 CBCT scans to assess the surgical angles on 3 different sites distal to maxillary second molars relative to the midsagittal plane (MSP) and the buccal cortical plane (BCP) in relation to the descending palatine foramen for tuberosity cut. The linear and angular measurements for all horizontal cuts in Le Fort I osteotomy were also evaluated.

RESULTS

The mean surgical angles for tuberosity cut varied from 58.90 to 95.28° and 74.85 to 100.93° according to the MSP and the BCP, respectively. For the horizontal cuts, mean lengths (angles) for posterior buccal and lateral nasal wall osteotomies were 27.44 mm (13.62°) and 33.20 mm (9.60°), respectively, and a mean length of 47.12 mm was measured for nasal septum osteotomy. Additionally, the presence of impacted third molar resulted in significantly higher mean surgical angles than those with fully erupted or without third molars (p < 0.01).

CONCLUSIONS

Overall, angles running through the buccal midpoint of the third molars relative to the MSP (76.56°) or the BCP (92.31°) might be the most appropriate in clinical practice. Furthermore, some caution seems warranted when performing tuberosity cuts with the impacted third molars.

CLINICAL RELEVANCE

To avoid potential damage to the descending palatine artery for tuberosity cut in Le Fort I osteotomy.

Personalized 3D-printed Titanium Cutting Guide and Prefabricated Osteosynthesis Plate for Mandibular Step Osteotomy to Treat Severe Mandibular Prognathism

Mandibular step osteotomy, performed for mandibular prognathism, is a difficult and time-consuming procedure. Virtual computer surgery and computer-aided design & computer-aided manufacturing have demonstrated accurate results in orthognathic surgery, though not used for mandibular step osteotomy yet. In this study, the authors report the case of a 21-year-old man with severe mandibular prognathism, with a reverse overjet of 12 mm. Step osteotomy, a modified method of body osteotomy, was planned virtually and performed using 3-dimensional (3D) printed titanium surgical guides and osteosynthesis plates, using computer-aided design & computer-aided manufacturing. At the 6-month postoperative follow-up, there were no notable complications, and normal healing was observed. Each segment was stably in place with the prefabricated plates. The proximal segments were not sagged medially or laterally. With 3D-printed surgical guides and osteosynthesis plates, intraoperative complications, such as injury to adjacent teeth and nerves, could be avoided. They also showed reasonable accuracy and helped reduce operative time and improve outcomes. Unlike surgical guides made of resin/polyamide, titanium surgical guides can be made thinner, which can reduce the extent of detachment. They also did not undergo any deterioration during the operation. Cutting guides and prefabricated plates using virtual surgical planning and 3D printing have many advantages, including reduced preoperative preparation time and operative time, reduced incidence of intraoperative complications, and improved outcomes. However, limitations still exist and further studies are required.

Condylar repositioning according to digital bite registration method for virtual orthognathic surgery planning: A series of 49 consecutive patients

INTRODUCTION

The accurate mandibular condylar positioning for orthognathic surgical planning is fundamental in obtaining a planned occlusal result. The differences between the position of condyles seen on computed tomography or cone-beam computed tomography (CBCT) scans and during surgery reduce the accuracy of the result. This study aimed to assess the differences between the condylar position recorded on CBCT and a numerical 3-dimensional (3D) model created after mandibular repositioning for orthognathic surgery planning.

METHODS

This study retrospectively evaluated 49 patients who underwent virtual orthognathic surgery planning. The procedure involved recording a computed tomography or CBCT of the skull and dental surface using an intraoral digital scanner. The mandible was repositioned on the numerical 3D model according to the superimposed virtual bite registration in centric relation. Linear and angular measurements of the right and left condyles were recorded before and after mandibular repositioning.

RESULTS

The positions of 98 condyles were compared. Linear measurements of the posterior and superior joint spaces revealed a significant difference. Subgroup analyses displayed statistically significant differences for patients with skeletal Class II malocclusion.

CONCLUSION

According to the digital bite registration method, the difference between the mandibular position recorded on CBCT and on the numerical 3D model after repositioning may have clinical significance. Further studies are needed to validate this theory and test the accuracy of the clinical results.

Comparative Assessment of Perception about Angle Inclination of Mandibular and Maxillary Incisors on the Cephalometric Analysis between Skeletal Class 3 and Orthognathic Cases

Before orthognathic surgery, a thorough diagnosis of the maxillofacial structure is performed for combined orthodontic–surgical treatment planning. One of the tools that are used for this collaboration is the cephalometric radiograph. Cephalometric analysis is a method for measuring the location of specific anatomical landmarks upon a cephalogram. Some of these parameters are more difficult to define accurately in cases of dentofacial deformities. Therefore, the data obtained from different examiners are characterized by high variability. The present study aimed to examine whether there is a significant variation in the physicians’ measurements between orthognathic Class I (normal) cases and the cases of skeletal deformity Class III. The study involved ten physicians with a mean age of 27. All physicians underwent appropriate instruction for reading and analyzing cephalometric radiographs, and all physicians were instructed about their role in the study. Each participant received 100 cephalometric radiographs, consisting of 50 radiographs of patients with a regular facial structure (Class-I = orthognathic) and 50 photographs of patients with a specific skeletal deformity (Class-III = prognathic). According to the Frankfort Horizontal plane, each physician marked the upper incisor (U1) longitudinal axis on the radiograph and the lower incisor (L1) longitudinal axis according to the mandibular plane. Then, we measured the angle degree with the Cephninja® application. Afterward, we performed a statistical analysis of the t-test with Bonferroni correction to check whether there is a significantly large standard deviation between the indices in the orthognathic cases compared to the prognathic cases. In the group of physicians who participated in this sample of these cephalometric radiographs, we found that in prognathic patients, the upper incisor angle measurements showed significantly more t variance relative to those physicians’ corresponding measurements radiographs of orthognathic patients. Variability increases as skeletal deformity become more severe (p = 0.026) in U1 TO FH and (p = 0.014) L1 TO MP. Cephalometric measurements, which are essential for the correct diagnosis and planning of combined orthodontic treatment, suffer from a significant examiner-based bias that is greater as deformity becomes more severe. This conclusion has implications for the accuracy of the model on which the entire plan process of the combined treatment of facial and jaw deformities is based. The surgeon should use CBCT (cone-beam computed tomography) for its three-dimensional superiority over cephalometric imaging, which will result in a more accurate evaluation of surgery planning and performance.

Use of Transcutaneous Electrical Nerve Stimulation (TENS) for the Recovery of Oral Function after Orthognathic Surgery

The oral functions of patients are markedly diminished immediately after orthognathic surgery, and novel approaches are needed to accelerate their recovery. The aim of this study was to examine the usefulness of weekly applications of transcutaneous electrical nerve stimulation (TENS) for this purpose, based on the evidence of its effectiveness in other types of patients with muscle alterations. Maximum jaw opening, bite force, pain, and facial inflammation were compared between patients receiving TENS and those receiving sham-TENS for 30 min at baseline and weekly over a four-week period after orthognathic surgery and were also compared between the before and after of each procedure. TENS was applied at 220 Hz, applying the maximum intensity tolerated by each individual patient. The TENS procedure was identical for all patients, but the device was not turned on in the sham-TENS group. Patients were blinded to their group membership. Results were analyzed separately in skeletal class II and III patients. Improvements in jaw opening and inflammation were significantly greater in the TENS than in the sham-TENS group, attributable to the muscle relaxation achieved with the procedure. Research is warranted on the benefits of a more frequent application of TENS.