Orthognathic positioning system: intraoperative system to transfer virtual surgical plan to operating field during orthognathic surgery

A New Method to Design and Manufacture a Low-Cost Custom-Made Template for Mandible Cut and Repositioning Using Standard Plates in BSSO Surgery

In this study, a new methodology for designing and creating a custom-made template for maxillofacial surgery has been developed. The custom-made template can be used both for cutting and repositioning of the mandible arches for executing a BSSO (bilateral sagittal split osteotomy) treatment. The idea was developed in order to give the possibility of using a custom-made template with standard plates, thus reducing long times, high costs and low availability of custom-made plates; this represents the proof of novelty of the proposed template, based on a well-established methodology. The methodology was completely developed in the CAD virtual environment and, after the surgeons' assessment, an in-vitro experiment by a maxillofacial surgeon was performed in order to check the usability and the versatility of the system, thanks to the use of additive manufacturing technologies. When computer-aided technologies are used for orthognathic surgery, there are significant time and cost savings that can be realised, as well as improved performance. The cost of the whole operation is lower than the standard one, thanks to the use of standard plates. To carry out the procedures, the proposed methodology allows for inexpensive physical mock-ups that enable the BSSO procedure to be performed.

Accuracy of computer-assisted design and manufactured three-dimensional device for condylar positioning in mandibular bilateral sagittal split osteotomy (clinical trial)

INTRODUCTION

Aligning dental arches in orthognathic treatment after undergoing LeFort I osteotomy or bilateral sagittal split osteotomy (BSSO) relies on occlusal splints, which do not provide precise control over the condylar head.

AIM OF THE STUDY

To clinically and radiographically assess the accuracy of computer-assisted design and manufactured (CAD/CAM) surgical guide for condylar positioning in a BSSO.

MATERIALS AND METHODS

The study recruited 8 patients with a non-syndromic dentofacial deformity who underwent a BSSO. Surgery was planned according to CAD/CAM technology. After osteotomy, a pre-operative guide was used, followed by a repositioning guide. Computed tomography scans were conducted on all patients 1 week pre-operatively, immediately, and 3 months postoperatively.

RESULTS

The data are presented as median values with the 25th and 75th percentiles. Eight patients (37.50% females and 62.50% males) between the ages of 19 and 24 underwent BSSOs. The surgical procedure successfully corrected their skeletal deformities. The absolute change between immediate postoperative and pre-operative condylar angle was 0.15 (0.00-0.3). The absolute change between 3 months postoperative and pre-operative condylar angle was 0.20 (0.00-0.30).

CONCLUSION

The stability of the condylar head in position is well assessed by 3-dimensional condylar positioning devices designed and manufactured by CAD/CAM technology in the mandibular BSSO.

Comparison of Patient-Specific Condylar Positioning Devices and Manual Methods in Orthognathic Surgery: A Prospective Randomized Trial

BACKGROUND

This study investigated whether patient-specific condylar positioning devices (CPDs) are beneficial compared to the conventional manual positioning of the condyles.

METHODS

In this prospective, randomized trial, patients undergoing orthognathic surgery with a bilateral sagittal split osteotomy of the mandible were included. The ascending ramus was positioned with computer-aided designed and computer-aided manufactured (CAD/CAM) patient-specific devices in the CPD group and manually in the control group. Postoperatively, cone-beam computed tomography (CBCT) was performed to align the virtually planned position with the postoperative result.

RESULTS

Thirty patients were enrolled in the study, with 14 randomized to the CPD group and 16 to the control group. In the CPD group, the ascending ramus differed in the postoperative CBCT scan from the virtually planned position by 0.8 mm in the left/right, 0.8 mm in the front/back, and 1.3 mm in the cranial/caudal direction. The corresponding control-group values were 1.1 mm, 1.3 mm, and 1.6 mm. CPD and controls differed significantly for the left/right movement of the rami (p = 0.04) but not for the other directions or rotations (p > 0.05).

CONCLUSIONS

The results demonstrate that both methods are accurate, and postoperative results matched the virtually planned position precisely. It can be assumed that the described CPDs are beneficial when a condylar position different from the preoperative is desired.

Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion

OBJECTIVES

This study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy.

MATERIALS AND METHODS

Patients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect.

RESULTS

A total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0-T1 (p = 0.02), T0-T2 (p = 0.03), and T0-T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group.

CONCLUSIONS

We found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback.

CLINICAL RELEVANCE

It is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Materials and Applications of 3D Printing Technology in Dentistry: An Overview

PURPOSE

This narrative review aims to provide an overview of the mechanisms of 3D printing, the dental materials relevant to each mechanism, and the possible applications of these materials within different areas of dentistry.

METHODS

Subtopics within 3D printing technology in dentistry were identified and divided among five reviewers. Electronic searches of the Medline (PubMed) database were performed with the following search keywords: 3D printing, digital light processing, stereolithography, digital dentistry, dental materials, and a combination of the keywords. For this review, only studies or review papers investigating 3D printing technology for dental or medical applications were included. Due to the nature of this review, no formal evidence-based quality assessment was performed, and the search was limited to the English language without further restrictions.

RESULTS

A total of 64 articles were included. The significant applications, applied materials, limitations, and future directions of 3D printing technology were reviewed. Subtopics include the chronological evolution of 3D printing technology, the mechanisms of 3D printing technologies along with different printable materials with unique biomechanical properties, and the wide range of applications for 3D printing in dentistry.

CONCLUSIONS

This review article gives an overview of the history and evolution of 3D printing technology, as well as its associated advantages and disadvantages. Current 3D printing technologies include stereolithography, digital light processing, fused deposition modeling, selective laser sintering/melting, photopolymer jetting, powder binder, and 3D laser bioprinting. The main categories of 3D printing materials are polymers, metals, and ceramics. Despite limitations in printing accuracy and quality, 3D printing technology is now able to offer us a wide variety of potential applications in different fields of dentistry, including prosthodontics, implantology, oral and maxillofacial, orthodontics, endodontics, and periodontics. Understanding the existing spectrum of 3D printing applications in dentistry will serve to further expand its use in the dental field. Three-dimensional printing technology has brought about a paradigm shift in the delivery of clinical care in medicine and dentistry. The clinical use of 3D printing has created versatile applications which streamline our digital workflow. Technological advancements have also paved the way for the integration of new dental materials into dentistry.

Deep learning-enabled 3D multimodal fusion of cone-beam CT and intraoral mesh scans for clinically applicable tooth-bone reconstruction

High-fidelity three-dimensional (3D) models of tooth-bone structures are valuable for virtual dental treatment planning; however, they require integrating data from cone-beam computed tomography (CBCT) and intraoral scans (IOS) using methods that are either error-prone or time-consuming. Hence, this study presents Deep Dental Multimodal Fusion (DDMF), an automatic multimodal framework that reconstructs 3D tooth-bone structures using CBCT and IOS. Specifically, the DDMF framework comprises CBCT and IOS segmentation modules as well as a multimodal reconstruction module with novel pixel representation learning architectures, prior knowledge-guided losses, and geometry-based 3D fusion techniques. Experiments on real-world large-scale datasets revealed that DDMF achieved superior segmentation performance on CBCT and IOS, achieving a 0.17 mm average symmetric surface distance (ASSD) for 3D fusion with a substantial processing time reduction. Additionally, clinical applicability studies have demonstrated DDMF's potential for accurately simulating tooth-bone structures throughout the orthodontic treatment process.

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.

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.

Patient-Specific Plates for Genioplasty: A Case Report

A 20-year-old male patient presented with a retruded chin and crowding of the upper front tooth region. The patient's problem list included skeletal class II malocclusion, retruded chin, and shallow mentolabial sulcus. A treatment plan was curated using clinical examination, cephalometric analysis, and 3D measurements, which included the advancement genioplasty of 5 mm. Osteotomy cut was planned digitally by computer-aided surgical simulation technology (Dolphin Software, Dolphin Imaging Systems, California, USA) and then transferred to Geomagic Software (3D Systems, North Carolina, USA) where patient-specific plates were designed. The patient-specific plates were 3D printed using selective laser melting. Intraoperatively, the osteotomy cut was given using a surgical guide, and an advancement of 5 mm was performed, fixing the segments using patient-specific plates. The outcome was compared with the curated treatment plan to assess accuracy. The primary objective of the case report is to provide a digital method of the treatment plan and surgical accuracy in genioplasty using patient-specific plates.

A learning curve in 3D virtual surgical planned orthognathic surgery

OBJECTIVES

To assess the surgical accuracy of 3D virtual surgical planned orthognathic surgery and the influence of posterior impaction and magnitude of the planned movements on a possible learning curve.

MATERIALS AND METHODS

This prospective cohort study included subjects who underwent bimaxillary surgery between 2016 and 2020 at the Department of Oral and Maxillofacial Surgery of the Radboud University Medical Center, Nijmegen. 3D virtual surgical planning (VSP) was performed with CBCT data and digitalized dentition data. By using voxel-based matching with pre- and postoperative CBCT data the maxillary movements were quantified in six degrees of freedom. The primary outcome variable, surgical accuracy, was defined as the difference between the planned and achieved maxillary movement.

RESULTS

Based on 124 subjects, the surgical accuracy increased annually from 2016 to 2020 in terms of vertical translations (0.82 ± 0.28 mm; p = 0.038) and yaw rotations (0.68 ± 0.22°; p = 0.028). An increase in surgical accuracy was observed when combining all six degrees of freedom (p = 0.021) and specifically between 2016 and 2020 (p = 0.004). An unfavorable learning curve was seen with posterior impaction and with a greater magnitude of movements.

CONCLUSION

The present study demonstrated a significant increase in surgical accuracy annually and therefore supports the presence of a learning curve.

CLINICAL RELEVANCE

Cases with planned maxillary posterior impaction and/or a great magnitude of jaw movements should be transferred from the 3D VSP with extra care to obtain a satisfactory surgical accuracy.

Investigating the accuracy of mandibulectomy and reconstructive surgery using 3D customized implants and surgical guides in a rabbit model

BACKGROUND

This study aimed to analyze the accuracy of the output of three-dimensional (3D) customized surgical guides and titanium implants in a rabbit model, and of mandibulectomy, reconstructive surgery, and surgical outcome; additionally, the correlation between surgical accuracy and surgical outcomes, including the differences in surgical outcome according to surgical accuracy, was analyzed.

RESULTS

The output of implants was accurately implemented within the error range (- 0.03-0.03 mm), and the surgical accuracy varied depending on the measured area (range - 0.4-1.1 mm). Regarding surgical outcomes, angle between the mandibular lower borders showed the most sensitive results and distance between the lingual cusps of the first molars represented the most accurate outcomes. A significant correlation was noted between surgical accuracy in the anteroposterior length of the upper borders pre- and postoperatively and the angle between the mandibular lower borders (regression coefficient = 0.491, p = 0.028). In the group wherein surgery was performed more accurately, the angle between the mandibular lower borders was reproduced more accurately (p = 0.021). A selective laser melting machine accurately printed the implants as designed. Considering the positive correlation among surgical accuracy in the mandibular upper borders, angle between the mandibular lower borders, and more accurately reproduced angle between the mandibular lower borders, the angle between the mandibular lower borders is considered a good indicator for evaluating the outcomes of reconstructive surgery.

CONCLUSION

To reduce errors in surgical outcomes, it is necessary to devise a positioner for the surgical guide and design a 3D surgical guide to constantly maintain the direction of bone resection. A fixed area considering the concept of three-point fixation should be selected for stable positioning of the implant; in some cases, bilateral cortical bone fixation should be considered. The angle between the mandibular lower borders is a sensitive indicator for evaluating the outcomes of reconstructive surgery.

Review of Enhanced Handheld Surgical Drills

The handheld drill has been used as a conventional surgical tool for centuries. Alongside the recent successes of surgical robots, the development of new and enhanced medical drills has improved surgeon ability without requiring the high cost and consuming setup times that plague medical robot systems. This work provides an overview of enhanced handheld surgical drill research focusing on systems that include some form of image guidance and do not require additional hardware that physically supports or guides drilling. Drilling is reviewed by main contribution divided into audio-, visual-, or hardware-enhanced drills. A vision for future work to enhance handheld drilling systems is also discussed.

Accuracy of Three-Dimensional Soft-Tissue Prediction Considering the Facial Aesthetic Units Using a Virtual Planning System in Orthognathic Surgery

Virtual surgical planning (VSP) is commonly used in orthognathic surgery. A precise soft-tissue predictability would be a helpful tool, for determining the correct displacement distances of the maxilla and mandible. This study aims to evaluate the soft-tissue predictability of the VSP software IPS CaseDesigner^® (KLS Martin Group, Tuttlingen, Germany). Twenty patients were treated with bimaxillary surgery and were included in the study. The soft-tissue simulation, done by the VSP was exported as STL files in the engineering software Geomagic Control X^TM (3D systems, RockHill, SC, USA). Four months after surgery, a 3D face scan of every patient was performed and compared to the preoperative simulation. The quality of the soft-tissue simulation was validated with the help of a distance map. This distance map was calculated using the inter-surface distance algorithm between the preoperative simulation of the soft-tissue and the actual scan of the postoperative soft-tissue surface. The prediction of the cranial parts of the face (upper cheek, nose, upper lip) was more precise than the prediction of the lower areas (lower cheek, lower lip, chin). The percentage of correctly predicted soft-tissue for the face in total reached values from 69.4% to 96.0%. The VSP system IPS CaseDesigner^® (KLS Martin Group; Tuttlingen, Germany) predicts the patient’s post-surgical soft-tissue accurately. Still, this simulation has to be seen as an approximation, especially for the lower part of the face, and continuous improvement of the underlying algorithm is needed for further development.

Plaster Casts vs. Intraoral Scans: Do Different Methods of Determining the Final Occlusion Affect the Simulated Outcome in Orthognathic Surgery?

A virtual occlusal adjustment in orthognathic surgery has many advantages; however, the haptic information offered by plaster casts is missing when using intraoral scans. Feeling the interferences may be helpful in defining the best possible occlusion. Whether the use of a virtual occlusal adjustment instead of the conventional approach has a significant effect on the postsurgical position of the jaws is a question that remains unanswered. This study compares a virtual method to the conventional method of defining the final occlusion. Twenty-five orthognathic patients were included. Bimaxillary and single-jaw orthognathic surgery (mandible only) was simulated. The two methods were compared regarding discrepancies in the simulated postsurgical position of the mandible, measured three-dimensionally using MeshLab (MeshLab 2020.12 3D). An analysis using SPSS revealed no significant differences between the tested methods (p-values: 0.580 to 0.713). The mean absolute discrepancies ranged from 0.14 mm to 0.72 mm, laying within the scope of the clinically acceptable inaccuracies of an osteosynthesis in orthognathic surgery. The lack of haptic information in virtual planning had no relevant influence on the definition of the final occlusion and the simulated postsurgical outcome. However, in individual cases, plaster models might still be helpful in finding the adequate occlusion, especially in the sagittal dimension and in cases of patients with an anterior open bite, but this remains to be tested.

Computer Aided Orthognathic Surgery: A General Method for Designing and Manufacturing Personalized Cutting/Repositioning Templates

Orthognathic surgery allows broad-spectrum deformity correction involving both aesthetic and functional aspects on the TMJ (temporo-mandibular joint) and on the facial skull district. The combination of Reverse Engineering (RE), Virtual Surgery Planning (VSP), Computer Aided Design (CAD), Additive Manufacturing (AM), and 3D visualization allows surgeons to plan, virtually, manipulations and the translation of the human parts in the operating room. This work’s aim was to define a methodology, in the form of a workflow, for surgery planning and for designing and manufacturing templates for orthognathic surgery. Along the workflow, the error chain was checked and the maximum error in virtual planning was evaluated. The three-dimensional reconstruction of the mandibular shape and bone fragment movements after segmentation allow complete planning of the surgery and, following the proposed method, the introduction of both the innovative evaluation of the transversal intercondylar distance variation after mandibular arch advancement/set and the possibility of use of standard plates to plan and realize a customized surgery. The procedure was adopted in one clinical case on a patient affected by a class III malocclusion with an associated open bite and right deviation of the mandible with expected good results. Compared with the methods from most recent literature, the presented method introduces two elements of novelty and improves surgery results by optimizing costs and operating time. A new era of collaboration among surgeons and engineer has begun and is now bringing several benefits in personalized surgery.

Reduction malarplasty using a simulated surgical guide for asymmetric/prominent zygoma

Background

The present study introduces a reduction malarplasty using a three-dimensional (3D)-printed surgical guide and evaluates the guide’s technical applicability.

Methods

Twenty malarplasties were performed for 12 subjects with zygomatic asymmetry/prominency using the current method. 3D reconstruction of the craniomaxillofacial region and fine dental occlusion was made with image data from computed tomograpy and dental scanning. A computer-assisted surgical simulation was performed for reduction malarplasty and a surgical guide was designed for later 3D printing. The manufactured surgical guide was introduced to the operation field to guide the surgery; its surgical accuracy was confirmed by comparing five corresponding points from preoperative simulation and postoperative data.

Results

We successfully performed the reduction malarplasty with the surgical guide. The accuracy level of surgery fell to 0.93 mm of total median difference for the corresponding zygoma points of preoperative simulations and postoperative zygoma. The anterior and upper points showed less error level (0.59 and 0.73 mm difference, respectively) than did other points.

Conclusions

We developed a computer-assisted surgical technique using a surgical guide for asymmetrical/prominent zygoma which proved to be simple, practical, and accurate; it is expected to help surgeons perform reduction malarplasty with ease and accuracy.

Digital planning and individual implants for secondary reconstruction of midfacial deformities: A pilot study

Objective

To evaluate the feasibility and accuracy of implementing three‐dimensional virtual surgical planning (VSP) and subsequent transfer by additive manufactured tools in the secondary reconstruction of residual post‐traumatic deformities in the midface.

Methods

Patients after secondary reconstruction of post‐traumatic midfacial deformities were included in this case series. The metrical deviation between the virtually planned and postoperative position of patient‐specific implants (PSI) and bone segments was measured at corresponding reference points. Further information collected included demographic data, post‐traumatic symptoms, and type of transfer tools.

Results

Eight consecutive patients were enrolled in the study. In five patients, VSP with subsequent manufacturing of combined predrilling/osteotomy guides and PSI was performed. In three patients, osteotomy guides, repositioning guides, and individually prebent plates were used following VSP. The median distances between the virtually planned and the postoperative position of the PSI were 2.01 mm (n = 18) compared to a median distance concerning the bone segments of 3.05 mm (n = 12). In patients where PSI were used, the median displacement of the bone segments was lower (n = 7, median 2.77 mm) than in the group with prebent plates (n = 5, 3.28 mm).

Conclusion

This study demonstrated the feasibility of VSP and transfer by additive manufactured tools for the secondary reconstruction of complex residual post‐traumatic deformities in the midface. However, the median deviations observed in this case series were unexpectedly high. The use of navigational systems may further improve the level of accuracy.

To evaluate the feasibility and accuracy of implementing three‐dimensional virtual surgical planning (VSP) and subsequent transfer by additive manufactured tools in the secondary reconstruction of residual post‐traumatic deformities in the midface. This study demonstrated the feasibility of VSP and transfer by additive manufactured tools for the secondary reconstruction of complex residual post‐traumatic deformities in the midface. However, the median deviations observed in this case series were unexpectedly high. The use of navigational systems may further improve the level of accuracy.

Intraoperative condylar positioning techniques on mandible in orthognathic surgery

PURPOSE

The surgical condylar displacement often resulted in relapse and serious symptoms of temporomandibular joint disorders (TMD) after orthognathic surgery. To minimize the displacement, numerous techniques have been proposed. To verify their accuracy in positioning and effectiveness in preventing postoperative TMD and relapse, we reviewed the literature related to intraoperative condylar positioning techniques on the mandible in this study.

METHODS

The literature on condylar positioning techniques was reviewed with 2 charts, including the non-computer-assisted and the computer-assisted positioning methods. The pre- and postoperative alterations of condyles, the postoperative temporomandibular joint (TMJ) function, and surgical relapse were analyzed regarding the techniques. The clinical usage and characteristics were reviewed as well.

RESULTS

A total of 22 articles, including 907 patients, have been reported since 2001. Nearly all methods reach a considerable positioning accuracy within the range of 1-2 mm and 1-2° from the preoperative position. We ranked the accuracy of the methods from high to low: CAD/CAM CPDs>CAD/CAM titanium plate positioning>manual positioning>computer-assisted navigation systems>imaging positioning systems. Most skeletal class II and class III patients achieved great occlusion and had no TMJ dysfunction or relapse after condylar positioning.

CONCLUSION

Both the non-computer-assisted and computer-assisted condylar positioning techniques reach considerable accuracy in locating the preoperative condyle position and preventing TMJ dysfunction and surgical relapse. Different levels of surgeons and cases can benefit from multiple suggested positioning methods. Further research with large samples and long-term follow-up is worth looking forward to upgrading the current methods, improving the clinical utility, and developing new positioning techniques.

Surgical accuracy in 3D planned bimaxillary osteotomies: intraoral scans and plaster casts as digital dentition models

The aim of this study was to assess whether the use of intraoral scans (IOS) is an eligible alternative to conventional plaster casts in terms of surgical accuracy of three-dimensionally planned bimaxillary osteotomies. This retrospective cohort study included patients who underwent bimaxillary surgery between 2016 and 2020 in the Department of Oral and Maxillofacial Surgery at Radboud University Medical Center, Nijmegen. Three-dimensional virtual planning was performed with the use of plaster casts in one group and IOS in the other group. Cone beam computed tomography scans were acquired preoperatively and at 1 week following surgery. By using voxel-based matching, the maxillary movements were quantified in six degrees of freedom. The primary outcome variable, surgical accuracy, was defined as the difference between the planned maxillary movements and those achieved. Of 152 patients, 113 were documented with plaster casts and 39 with IOS. The surgical accuracy was comparable in terms of maxillary vertical, sagittal, and transverse translations, as well as roll and yaw. Maxillary pitch (difference 0.55 ± 0.26°; P = 0.001) was in favour of the IOS group. This study demonstrated that IOS can be used as an alternative to conventional plaster casts in the three-dimensional planning of bimaxillary osteotomies.

Randomized Clinical Trial of the Accuracy of Patient-Specific Implants versus CAD/CAM Splints in Orthognathic Surgery

Background:

The maxilla position is essential for the aesthetic and functional outcomes of orthognathic surgery. Previous studies demonstrated the advantages of patient-specific implants in orthognathic surgery. However, more data are needed to confirm the superiority of patient-specific implants over surgical splints created with computer-aided design/computer-aided manufacturing (CAD/CAM). This randomized controlled trial aimed to compare the accuracy of patient-specific implants and CAD/CAM splints for maxilla repositioning in orthognathic surgery.

Methods:

Patients (n = 64) who required orthognathic surgery were randomly assigned to use either patient-specific implants (patient-specific implant group) or CAD/CAM surgical splints (splint group) to reposition the maxilla. The outcome evaluation was completed by comparing virtual plans with actual results. The primary outcome was the discrepancies of the centroid position of the maxilla. Other translation and orientation discrepancies of the maxilla were also assessed.

Results:

The authors analyzed 27 patients in the patient-specific implant group and 31 in the splint group. The maxilla position discrepancy was 1.41 ± 0.58 mm in the patient-specific implant group and 2.20 ± 0.94 mm in the splint group; the between-group difference was significant (p < 0.001). For the patient-specific implant group, the largest translation discrepancy was 1.02 ± 0.66 mm in the anteroposterior direction, and the largest orientation discrepancy was 1.85 ± 1.42 degrees in pitch. For the splint group, the largest translation discrepancy was 1.23 ± 0.93 mm in the mediolateral direction, and the largest orientation discrepancy was 1.72 ± 1.56 degrees in pitch.

Conclusion:

The result showed that using patient-specific implants in orthognathic surgery resulted in a more accurate maxilla position than CAD/CAM surgical splints.

CLINICAL QUESTION/LEVEL OF EVIDENCE:

Therapeutic, I.

Bone marrow space volume of the mandible influencing intraoperative blood loss in bilateral sagittal split osteotomy: A pilot Study

The aim of this study was to investigate whether the bone marrow space volume of the mandible affects blood loss during bilateral sagittal split osteotomy (BSSO). Sixteen patients who underwent BSSO in our hospital were included in this study. Bone marrow space volume of the mandible was measured by analyzing images from computed tomography. Blood loss during BSSO was measured by weighing gauze, measuring suctioned blood, and adjusting for the volume of irrigation solution used during BSSO. Mean blood loss during BSSO for the 16 patients was 200.5 ml, and patients were divided into: Group I, with less than mean blood loss; and Group II, with greater than mean blood loss. Total bone marrow space volume was significantly greater in Group II (12,450.7 ± 2644.3 mm³) than in Group I (9130.3 ± 3005.8 mm³; P<0.05). A correlation between bone marrow space volume and blood loss during BSSO was suggested, and these results are beneficial for surgeons planning and preparing the orthognathic surgery.

Accurate transfer of bimaxillary orthognathic surgical plans using computer-aided intraoperative navigation

Objective

To examine the accuracy of computer-aided intraoperative navigation (Ci-Navi) in bimaxillary orthognathic surgery by comparing preoperative planning and postoperative outcome.

Methods

The study comprised 45 patients with congenital dentomaxillofacial deformities who were scheduled to undergo bimaxillary orthognathic surgery. Virtual bimaxillary orthognathic surgery was simulated using Mimics software. Intraoperatively, a Le Fort I osteotomy of the maxilla was performed using osteotomy guide plates. After the Le Fort I osteotomy and bilateral sagittal split ramus osteotomy of the mandible, the mobilized maxilla and the distal mandibular segment were fixed using an occlusal splint, forming the maxillomandibular complex (MMC). Realtime Ci-Navi was used to lead the MMC in the designated direction. Osteoplasty of the inferior border of the mandible was performed using Ci-Navi when facial symmetry and skeletal harmony were of concern. Linear and angular distinctions between preoperative planning and postoperative outcomes were calculated.

Results

The mean linear difference was 0.79 mm (maxilla: 0.62 mm, mandible: 0.88 mm) and the overall mean angular difference was 1.20°. The observed difference in the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was < 1 mm in 40 cases.

Conclusions

This study demonstrates the role of Ci-Navi in the accurate positioning of bone segments during bimaxillary orthognathic surgery. Ci-Navi was found to be a reliable method for the accurate transfer of the surgical plan during an operation.

Accuracy of Virtually Planned Maxillary Distraction in Cleft Patients - An Evaluative Study

Introduction:

Maxillary distraction may be used to treat severe maxillary hypoplasia in cleft lip and palate (CLP) patients. Three-dimensional (3D) planning has been shown to increase the accuracy of distraction and reduce operative time and complications. The aim of the study was to measure the accuracy of internal maxillary distraction after 3D planning in CLP patients, to add evidence to validate the virtual osteotomy and distraction procedure.

Materials and Methods:

Eleven CLP patients with severe maxillary hypoplasia underwent maxillary distraction using internal distractors. Virtual planning was used to design the osteotomies, the distractor position, and the distraction vector. Cutting and positioning guides transferred this information to the surgical procedure. Four to six month postoperative computed tomography-scan was done before distractor removal; anatomical reference points were compared to the virtual planning to determine accuracy.

Results:

A high accuracy (point dislocation <1.5 mm) was found in 90% of the points of the surface of the maxilla; the majority of the zygomatic screws were placed within a distance of 0.8–1 mm from their planned position.

Discussion:

The high accuracy achieved through virtual planning promotes optimal distractor placement; a customized distraction vector has a direct effect on the final position of the maxilla.

Randomized Controlled Clinical Trial to Assess the Utility of Computer-Aided Intraoperative Navigation in Bimaxillary Orthognathic Surgery

ABSTRACT

Accurate application of the preoperative surgical plan in actual surgical settings is of paramount importance in orthognathic surgery. This randomized controlled clinical trial aimed to evaluate the accuracy of computer-aided intraoperative navigation (Ci-Navi) compared with that of conventional navigation methods in bimaxillary orthognathic surgery. Fifty-two patients were randomly divided into 2 groups. Group A (n = 26) patients underwent surgery assisted with Ci-Navi and group B (n = 26) patients underwent surgery assisted with conventional intraoperative navigation methods. During the operation, after LeFort I osteotomy, the mobile maxilla was repositioned to the designated position either using assistance from real-time Ci-Navi (group A) or using an intermediate splint (group B). Intra- and intergroup linear and angular differences between preoperative planning and postoperative outcomes were calculated. In group A, the overall mean linear difference was 0.79 mm (0.62 mm for the maxilla and 0.88 mm for the mandible) and the overall mean angular difference was 1.20°. In 23 cases, the difference from the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was less than 1 mm. In group B, the overall mean linear difference was 1.98 mm (1.76 mm for the maxilla and 2.02 mm for the mandible) and the overall mean angular difference was 2.08°. The difference from the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was less than 1 mm in 15 cases. This study demonstrates the utility of Ci-Navi is superior to the conventional methods in aiding the accurate repositioning of bony segments in bimaxillary orthognathic surgery.

A novel CAD/CAM composite occlusal splint for intraoperative verification in single-splint two-jaw orthognathic surgery

Background

Previous computer-generated splints were designed and produced without modification than the traditional occlusal splints, which did not facilitate surgeon's intraoperative judgment in the single-splint two-jaw orthognathic surgery. Modifications of the digital occlusal splint can be achieved using computer-aided design and computer-aided manufacturing (CAD/CAM) software. This study reported the design, clinical application and validation of a novel CAD/CAM occlusal splint.

Methods

The maxillary and mandibular segments were fixed into the final occlusal splint and moved to the planned position according to the 3-dimensional simulation. The composite occlusal splint has 4 orthogonal bars to facilitate intraoperative assessment of the dental and skeletal midline, facial soft tissue midline, occlusal plane, upper tooth show, facial symmetry and facial bone position. To validate the surgical outcome, 5 parameters including pitch, roll and yaw rotations, midline deviation and chin position were measured on the virtual plan and the postoperative cone-beam computed tomography images to quantify the difference.

Results

The results showed no significant differences in the 5 parameters between the simulation and postoperative images. The root-mean-square difference between the conventional splints and CAD/CAM surgical splint ranged from 0.18 to 0.31 mm by superimposition of the two image models. All patients were satisfied with the treatment outcomes. Overall, this novel occlusal splint is ideal for verification of the maxillomandibular position during surgery.

Conclusion

The novel composite occlusal splint provided useful and informative check to verify the maxillomandibular complex (MMC) position and facial appearance in single-splint two-jaw orthognathic surgery.

Orthognathic Surgery: A Bibliometric Analysis of the Top 100 Cited Articles

PURPOSE

An increasing number of articles on orthognathic surgery are published every year. This paper aims to provide a list of the top 100 cited articles on orthognathic surgery to help any professional level with interest in this topic and to map the trends of orthognathic surgery publications over time.

METHODS

A bibliographic search (retrospective study) following STROBE guidelines was performed on Google Scholar (GS) and Dimensions with the term "orthognathic surgery" in the title, abstract, and keywords. The number of citations, citations per year, authors, and publication year were evaluated. A ranking was created in GS citations order with the top 100 cited articles and variables discussed individually. A graphical illustration of keywords was created using VOSviewer. These steps are fundamental in creating this list and relating it to all published articles on the topic.

RESULTS

A helpful list of the top 100 articles was developed to help professionals in entirely different manners. Virtual planning and complications in orthognathic surgery were the most cited topics, with a 95% confidence interval (P < .05). Some curiosities are discussed, such as increasing interest in surgery first and the relation between airway/obstructive sleep apnea and orthognathic surgery.

CONCLUSIONS

Bibliometric and altmetric analysis for free using Google Scholar and Dimensions is laborious but possible. Bibliometrics is a powerful tool to become actualized at any health professional level, from students to academics; and could save considerable effort and time for parties interested in the topic. Appropriate keywords are a crucial step to wider article dissemination.

A comparison of postoperative, three-dimensional soft tissue changes in patients with skeletal class III malocclusions treated via orthodontics-first and surgery-first approaches

The aim of this retrospective study was to compare three-dimensional (3D) soft tissue and hard tissue changes between orthodontics-first approach (OFA) and surgery-first approach (SFA) after mandibular setback surgery. All patients underwent bilateral sagittal split osteotomy, and were examined by lateral cephalograms and 3D optical scanner before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Three standard angles (FMA, U1 to FH, IMPA) were measured as hard tissue change and the 2 sets of 3D data were superimposed, and volumetric differences were calculated as soft tissue change. Statistical analyses were performed by using unpaired t-tests. Differences with P < 0.05 were considered significant. A total of 39 patients with mandibular prognathism were included in this study. The OFA group consisted of 24 patients and the SFA group of 15 patients. The SFA group exhibited more labial inclination from T1 to T2 (p = 0.008) and T2 to T3 (p = 0.003) than did the OFA group. There were no significant changes at maxilla and mandible at each term of T0, T1, T2 and T3 (p > 0.05), but compared to before surgery, mandibular volume in SFA group significant increased at 1year (p = 0.049) after surgery. We found that the soft tissue changes after the SFA differed significantly from those after the OFA; thus, soft tissue predictions require more care. An analysis of our data compared with OFA and SFA for the patient with mandibular prognathism confirm that the mandibular soft tissue changes by postoperative orthodontic treatment and occlusal relationship in SFA.

Fusion of intra-oral scans in cone-beam computed tomography scans

PURPOSE

The purpose of this study was to evaluate the clinical accuracy of the fusion of intra-oral scans in cone-beam computed tomography (CBCT) scans using two commercially available software packages.

MATERIALS AND METHODS

Ten dry human skulls were subjected to structured light scanning, CBCT scanning, and intra-oral scanning. Two commercially available software packages were used to perform fusion of the intra-oral scans in the CBCT scan to create an accurate virtual head model: IPS CaseDesigner® and OrthoAnalyzer™. The structured light scanner was used as a gold standard and was superimposed on the virtual head models, created by IPS CaseDesigner® and OrthoAnalyzer™, using an Iterative Closest Point algorithm. Differences between the positions of the intra-oral scans obtained with the software packages were recorded and expressed in six degrees of freedom as well as the inter- and intra-observer intra-class correlation coefficient.

RESULTS

The tested software packages, IPS CaseDesigner® and OrthoAnalyzer™, showed a high level of accuracy compared to the gold standard. The accuracy was calculated for all six degrees of freedom. It was noticeable that the accuracy in the cranial/caudal direction was the lowest for IPS CaseDesigner® and OrthoAnalyzer™ in both the maxilla and mandible. The inter- and intra-observer intra-class correlation coefficient showed a high level of agreement between the observers.

CLINICAL RELEVANCE

IPS CaseDesigner® and OrthoAnalyzer™ are reliable software packages providing an accurate fusion of the intra-oral scan in the CBCT. Both software packages can be used as an accurate fusion tool of the intra-oral scan in the CBCT which provides an accurate basis for 3D virtual planning.

Accuracy of virtual planning in orthognathic surgery: a systematic review

BACKGROUND

The elaboration of a precise pre-surgical plan is essential during surgical treatment of dentofacial deformities. The aim of this study was to evaluate the accuracy of computer-aided simulation compared with the actual surgical outcome, following orthognathic surgery reported in clinical trials.

METHODS

Our search was performed in PubMed, EMBASE, Cochrane Library and SciELO for articles published in the last decade. A total of 392 articles identified were assessed independently and in a blinded manner using eligibility criteria, out of which only twelve articles were selected for inclusion in our research. Data were presented using intra-class correlation coefficient, and linear and angular differences in three planes.

RESULTS

The comparison of the accuracy analyses of the examined method has shown an average translation (< 2 mm) in the maxilla and also in the mandible (in three planes). The accuracy values for pitch, yaw, and roll (°) were (< 2.75, < 1.7 and < 1.1) for the maxilla, respectively, and (< 2.75, < 1.8, < 1.1) for the mandible. Cone-beam computed tomography (CBCT) with intra-oral scans of the dental casts is the most used imaging protocols for virtual orthognathic planning. Furthermore, calculation of the linear and angular differences between the virtual plan and postoperative outcomes was the most frequented method used for accuracy assessment (10 out of 12 studies) and a difference less than 2 mm/° was considered acceptable and accurate. When comparing this technique with the classical planning, virtual planning appears to be more accurate, especially in terms of frontal symmetry.

CONCLUSION

Virtual planning seems to be an accurate and reproducible method for orthognathic treatment planning. However, more clinical trials are needed to clearly determine the accuracy and validation of the virtual planning in orthognathic surgery.

A new model of customized maxillary guide for orthognathic surgery: Precision analysis

PURPOSE

To evaluate the surgical accuracy of a new Maxillary Bone-Dental-Supported guide (MBDS) for osteotomy and maxillary positioning in orthognathic surgeries.

MATERIALS AND METHODS

The customized MBDS were prototyped through CAD-CAM technology (computer-aided design and manufacturing). The planning image (CT0) was superimposed on the computed tomography scan post-treatment (CT1) and the mean of positional differences between them were obtained tridimensionally at the axes: mediolateral (X), anteroposterior (Y) and vertical (Z).

RESULTS

Eleven patients were selected according to the inclusion and exclusion criteria. The mediolateral movement showed the best precision, with a greater mean difference of 0.34 mm at the CI point (central incisor) and less than 0.02 mm at the RM point (right molar). In the vertical direction, the largest mean discrepancy found was 0.50 mm and on the y-axis, anteroposterior, was 0.74 mm, as well as two at the CI point. The skeletal SNA point, on the other hand, showed the smallest average discrepancies: 0.10 mm (x-axis), 0.03 mm (y-axis) and 0 mm (z-axis). Overall, 99.24% of the discrepancies found were less than 2 mm.

CONCLUSION

Our results suggests that the double support, osseous and dental, present in that new guide, favored the positional stability of the maxilla and promoted better control of its vertical axis. Furthermore, the function of an osteotomy guide increases the predictability and security of the surgical procedure.

Accuracy of maxillary repositioning surgery using CAD/CAM customized surgical guides and fixation plates

The advent of three-dimensional imaging and computer-aided surgical simulation (CASS) have brought about a paradigm shift in surgical planning. The aim of this study was to assess the accuracy of maxillary repositioning surgery using computer-aided design and manufacturing (CAD/CAM) customized titanium surgical guides and fixation plates. Thirty consecutive adult patients, 13 male and 17 female, with a mean age of 29.2 years and 25.5 years, respectively, requiring Le Fort I maxillary osteotomy, with or without simultaneous mandibular surgery, were evaluated retrospectively. All orthognathic surgeries were performed by one experienced surgeon. The pre-surgical and post-surgical volumetric imaging were superimposed to assess the linear and angular differences between the planned and actual positions of the maxilla following surgery. With the use of the CAD/CAM titanium surgical guides and fixation plates, all surgical movements were within 2mm and 4° of the planned movements, which is considered clinically insignificant. The overall root mean square error between the planned and actual surgical movements was 0.38mm in the transverse dimension, 0.64mm in the anteroposterior dimension, and 0.55mm in the vertical dimension. In regard to the centroid of the maxilla, the absolute angular difference of the maxillary centroid was 1.06° in pitch, 0.47° in roll, and 0.49° in yaw. Maxillary repositioning surgery can be performed with high accuracy using CAD/CAM titanium surgical guides and fixation plates.

Clinical Accuracy of 3D-Planned Maxillary Positioning Using CAD/CAM-Generated Splints in Combination With Temporary Mandibular Fixation in Bimaxillary Orthognathic Surgery

Study Design

The aim of this study was to evaluate the accuracy of 3-dimensional (3D)-planned maxillary positioning by using computer-assisted design (CAD)/computer-assisted manufacturing (CAM) splints combined with temporary mandibular fixation in bimaxillary orthognathic surgery. In orthognathic surgery, customized splints work sufficiently well to transfer preoperative planning into the operation site for transverse und sagittal positioning of the maxilla. The vertical positioning is more difficult due to the non-fixed mandibular reference. Therefore, the combined use of CAD/CAM splints and temporary mandibular fixation to the zygomatic region was applied for transferring the 3D-planned maxillary position into the operation site from 2012 until 2015 in our hospital.

Objective

In addition to the general accuracy, the precision should therefore be checked especially in the vertical plane compared to axial and sagittal plane.

Methods

In this retrospective study, we calculated the deviation of 5 occlusal landmarks of the maxilla in 35 consecutive patients by fusing preoperative 3D planning images and postoperative computed tomography scans after bimaxillary surgery.

Results

The overall median deviation of maxillary positioning between plan and surgical result was 0.99 mm. The accuracy of left-right positioning was median 0.96 mm. Anterior-posterior positioning of the maxilla showed a median accuracy of 0.94 mm. Just slightly higher values were determined for the upward-downward positioning (median 1.06 mm).

Conclusions

This demonstrates the predictability of maxillary positioning by using CAD/CAM splints in combination with temporary mandibular fixation in all 3 axes.

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

Background

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

Review

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

Conclusions

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

A Modified Novel Technique for Condylar Positioning in Mandibular Bilateral Sagittal Split Osteotomy Using Computer-Assisted Designed and Computer-Assisted Manufactured Surgical Guides

Current techniques for orthognathic surgery after Le Fort I osteotomy and bilateral sagittal split osteotomy (BSSO) rely on intermediate and final occlusal splints for proper positioning of the dental arches without any control in positioning the condyle and ramus segments. Setting the 2 condyles in centric relation in the glenoid fossae at fixation is paramount for condylar function and the accuracy and stability of postoperative occlusion. Usually the 2 ramus segments are manually positioned and fixated in the final position according to the surgeon's experience. This report describes a novel technique to position the condyle and ramus segments in centric relation using skeletal guides designed by computer-assisted designed and computer-assisted manufactured (CAD-CAM) technology. The skeletal guides have a double-U shape designed to be tooth borne on the distal segment and bone borne on the proximal segment. The guides fit on the last molar crown and the anterior border of the ramus; using these reference points will position the mandibular arch and 2 ramus segments in ideal centric occlusion and centric relation. The condyle position in the sagittal, horizontal, and transverse planes was analyzed by computed tomography and differences in measurements were calculated. This technique confirms precise control of the condylar segment in centric relation with stable centric occlusion using CAD-CAM guides during BSSO.

Accuracy of laser-melted patient-specific implants in genioplasty - A three-dimensional retrospective study

PURPOSE

To assess the accuracy of laser-melted patient-specific implants (PSI) with regard to a preoperative virtual treatment plan for genioplasty based on a new analysis method without the use of landmarks.

MATERIALS AND METHODS

A retrospective evaluation of a cohort of Class II and Class III patients who had undergone virtually planned orthognathic surgery (including genioplasty) was carried out. The preoperative virtual treatment plan and the postoperative outcome were fused to calculate the translational and rotational discrepancies between the 3D planning and the actual surgical outcome.

RESULTS

The accuracy of left/right positioning was 0.25 ± 0.28 mm (p < 0.001), that of anterior/posterior positioning was 0.70 ± 0.64 mm (p < 0.001), and that of up/down-positioning was 0.45 ± 0.38 mm (p < 0.001). The rotational discrepancies were less than 2 deg. The virtually planned and postoperative positions of the chin differed significantly from each other (p < 0.001 for all rotational and translational discrepanices).

CONCLUSION

The findings demonstrate that PSIs can transfer the planned virtual genioplasty into the operation theatre with small but significant deviations. However, since no conclusions can be drawn from the results regarding surgical success in terms of shaping the soft tissue profile as well as the esthetic result, no superiority of PSI over traditional plate osteosynthesis can be demonstrated.

Current Orthognathic Practice in India: Do We Need to Change?

The last decade or so has seen paradigm shifts in the various aspects of orthognathic surgery. A lot of these changes are to do with digitalization of the orthodontic-surgical workflow, optimization of surgery-first protocols, virtual surgical planning-based 3D printing solutions and changing patient-health-care dynamics. The aim of this article is to provide evidence-based recommendations that are both practical and economically viable for the current orthognathic practice in India.

Genioplasty with surgical guide using 3D-printing technology: A systematic review

Background

The purpose of this systematic review is to evaluate the current state of the art of making genioplasties using 3D printing technology.

Material and Methods

A multi-database single-reviewer systematic review identified sixteen papers that fulfilled the selection criteria. There were mainly case series and case reports available (Level IV of the Oxford Evidence-based medicine scale); only two prospective study (Level III) evaluated this subject. These articles are analyzed in details and summarized in this review.

Results

The realization of genioplasties with surgical guide using 3D-printing technology could improve predictability and accuracy. It protects anatomical structures in the environment of the surgery, reducing by this way the morbidity and providing safer results. The type of printer and material used as well as the sterilization techniques should be further developed by the authors. The use of open-access software should also be further explored to allow the use of these new technologies by the largest number of surgeons.

Conclusions

Finally, prospective multi-center studies with larger samples should be performed to definitively conclude the benefits of this new technology and allow for its routine use. This article is the first systematic review on this topic. Key words:Genioplasty, printing, three-dimensional, surgery, computer-assisted.

Clinical Study on the Minimally Invasive-Guided Genioplasty Using Piezosurgery and 3D Printed Surgical Guide

INTRODUCTION

A retrospective clinical study was performed regarding the minimally invasive-guided genioplasty technique (MIGG technique) described in a previous clinical note. The aims of this clinical study were to study the incidence of immediate complications with this technique compared with a control group using a nonminimally genioplasty technique, to validate the accuracy of the three-dimensional (3D) printed cutting guide, and to evaluate the duration of the surgery and the satisfaction of the surgeons with this technique.

MATERIALS AND METHODS

One controlled group, including 56 patients, operated with a classical genioplasty and one group, including 24 patients operated with the MIGG technique. The inclusion criteria were patients from 18 years old benefiting from orthognathic surgery for dysmorphic maxillofacial disorders, sleep apneas, or posttraumatic malocclusion; operated by the three same surgeons. A database was retrospectively made, including the demographics parameters, the indication, the type and the duration of surgery, the incidence of complication, and the type of complication. The accuracy of the cutting guide was also studied by the comparison of two distances in the MIGG group on the preoperative surgical simulation and on the postoperative cephalometric radiography. A satisfaction survey for the surgeons of the department regarding the MIGG technique was also analyzed.

CONCLUSION

No statistical difference was found in the incidence of complications between the MIGG group and the control group. Using a guide does not cause more surgical infection. The protection of the inferior alveolar nerve is obvious. The absence of statistical difference is due to the fact that the majority of patients also benefited from the bilateral sagittal split osteotomy during surgery. The 3D-cutting guide used is very accurate: There is indeed no significative difference in the measurements A and B before and after the genioplasty. The MIGG technique is thus a predictable, safe, and easy-to-use technique that should be used routinely by maxillofacial surgeons. It combines the latest technologies in piezosurgery and in 3D-guided surgery by the creation of a validated-accurate 3D-printed cutting guide. This technique is affordable by the use of open-source program and a desktop fused deposit Modeling 3D-printer. Finally, the comfort of the surgeon is improved, and the operating time is decreased.

Accuracy of mandible-independent maxillary repositioning using pre-bent locking plates: a pilot study

The double splint method is considered the gold standard for maxillary repositioning, but the procedure is lengthy and prone to error. Recent splintless methods have shown high repositioning accuracy; however, high costs and technical demands make them inaccessible to many patients. Therefore, a new cost-effective method of mandible-independent maxillary repositioning using pre-bent locking plates is proposed. Plates are bent on maxillary models in the planned position prior to surgery. The locations of the plate holes are replicated during surgery using osteotomy guides made from thermoplastic resin sheets. Pre-bent plates are subsequently fitted onto the maxilla, and plate holes are properly set to reposition the maxilla. The purpose of this study was to evaluate the accuracy of this method for maxillary repositioning and the reproducibility of the plate holes. Fifteen orthognathic surgery patients were evaluated retrospectively by superimposing preoperative simulations over their postoperative computed tomography models. The median deviations in maxillary repositioning and plate hole positioning between the preoperative plan and postoperative results were 0.43mm (range 0-1.55mm) and 0.33mm (range 0-1.86mm), respectively. There was no significant correlation between these deviations, suggesting that the method presented here allows highly accurate and reliable mandible-independent maxillary repositioning.

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.

The accuracy of three-dimensional rapid prototyped surgical template guided anterior segmental osteotomy

Background

Surgical guiding templates provided a reliable way to transfer the simulation to the actual operation. However, there was no template designed for anterior segmental osteotomy so far. The study aimed to introduce and evaluate a set of 3D rapid prototyping surgical templates used in anterior segmental osteotomy.

Material and Methods

From August 2015 to August 2017, 17 patients with bimaxillary protrusions were recruited and occlusal-based multi-sectional templates were applied in the surgeries. The cephalometric analysis and 3D superimposition were performed to evaluate the differences between the simulations and actual post-operative outcomes. The patients were followed-up for 12 months to evaluate the incidence rate of complications and relapse.

Results

Bimaxillary protrusion was corrected in all patients with no complication. In radiographic evaluations, there was no statistically significant difference between the actual operations and the computer-aided 3D simulations (p >0.05, the mean linear and angular differences were less than 1.32mm and 1.72° consequently, and 3D superimposition difference was less than 1.4mm). The Pearson intraclass correlation coefficient reliabilities were high (0.897), and the correlations were highly significant (P< 0.001).

Conclusions

The 3D printed surgical template designed in this study can safely and accurately transfer the computer-aided 3D simulation into real practice.

Key words:CAD/CAM; anterior segmental osteotomy; surgical guiding templates; bimaxillary protrusion; virtual surgery simulation.

CAD/CAM splint and surgical navigation allows accurate maxillary segment positioning in Le Fort I osteotomy

Purpose

To evaluate the accuracy of the maxillary segment positioning method using a splint fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) and surgical navigation in patients who required two-jaw surgery.

Methods

Subjects were 35 patients requiring two-jaw surgery. A 3-dimensional (3D) skull model was prepared using cone-beam computed tomography (CBCT) data and dentition model scan data. Two-jaw surgery was simulated using this model, and a splint for maxillary positioning was fabricated by CAD/CAM. Using coordinate transformation software, the coordinate axis of surgical simulation data was merged with the navigation system, and data were imported to the navigation system. The maxillary segment was placed using the CAD/CAM splint, and consistency of the maxillary segment position with that planned by simulation was confirmed using the navigation system. CBCT taken at 4 weeks postoperatively and the prediction image fabricated using surgical simulation were superimposed. Predicted movement distances (PMD) at 6 arbitrary measurement points and actual movement distance (AMD) in surgery were measured. Differences of 3D measurements between the surgical simulation and postoperative results were evaluated.

Results

No significant differences were seen between PMD and AMD at most measurement points on the X and Y axes. Although significant differences between PMD and AMD were seen on the Z axis, no difference was evident between linear distance on the estimated image and postoperative CBCT image at most measurement points in 3D space. Mean error at measurement points between the PMD and AMD ranged from 0.57 mm to 0.78 mm on the X axis, 0.64 mm–1.03 mm on the Y axis, and 0.84 mm–0.90 mm in the Z axis.

Conclusion

Position of the maxillary segment moved by the CAD/CAM splint in Le Fort I osteotomy was almost consistent with the position established by simulation using the navigation system, confirming clinical accuracy.

The use of patient-specific implants in genioplasty and its clinical accuracy: a preliminary study

The purpose of this study was to assess the accuracy and clinical validation of patient-specific implants (PSI) in genioplasty. Fifteen patients with chin deformities were enrolled. Virtual planning was performed with the computer-aided surgical simulation method. The three-dimensional-printed titanium cutting guide and patient-specific plate were designed to guide the osteotomy and allow repositioning and fixation of the chin. The outcome was evaluated by comparing the plan with actual outcomes. All operations were successfully completed with PSIs. There was no difficulty in using patient-specific plates. The largest root-mean-square difference of the chin position was 0.69 mm in mediolateral translation and 2.01° in the yaw orientation. The results of the study indicated that the PSI technique was an accurate method of transferring the virtual plan to the operation field with great efficiency in genioplasty. A significant advantage of the PSI technique is that the patient-specific plate could simultaneously complete the repositioning and fixation of the chin. Intraoperative measurements and reposition guides were no longer required. Operative procedures were greatly simplified.

Craniofacial Microsomia

Clinicians use different diagnostic terms for patients with underdevelopment of facial features arising from the embryonic first and second pharyngeal arches, including first and second branchial arch syndrome, otomandibular dysostosis, oculoauriculovertebral syndrome, and hemifacial microsomia. Craniofacial microsomia has become the preferred term. Although no diagnostic criteria for craniofacial microsomia exist, most patients have a degree of underdevelopment of the mandible, maxilla, ear, orbit, facial soft tissue, and/or facial nerve. These anomalies can affect feeding, compromise the airway, alter facial movement, disrupt hearing, and alter facial appearance.

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

Background

Many reports have been published on orthognathic surgery (OGS) using computer-aided surgical simulation (CASS). The purpose of this study was to evaluate the accuracy of the maxillary repositioning and the stability of the maxilla in patients who underwent OGS using a newly developed CASS program, a customized osteotomy guide, and a customized miniplate.

Methods

Thirteen patients who underwent OGS from 2015 to 2017 were included. All patients underwent a bimaxillary operation. First, a skull-dentition hybrid 3D image was rendered by merging the cone beam computed tomography (CBCT) images with the dentition scan file. After virtual surgery (VS) using the FaceGide® program, patient-customized osteotomy guides and miniplates were then fabricated and used in the actual operation. To compare the VS with the actual surgery and postoperative skeletal changes, each reference point marked on the image was compared before the operation (T0) and three days (T1), four months (T2), and a year (T3) after the operation, and with the VS (Tv). The differences between ΔTv (Tv-T0) and ΔT1 (T1-T0) were statistically compared using tooth-based reference points. The superimposed images of Tv and T1 were also investigated at eight bone-based reference points. The differences between the reference points of the bone surface were examined to evaluate the stability of the miniplate on the maxilla over time.

Results

None of the patients experienced complications. There were no significant differences between the reference points based on the cusp tip between ΔTv and ΔT1 (p > 0.01). Additionally, there were no significant differences between the Tv and T1 values of the bone surface (p > 0.01). The mean difference in the bone surface between Tv and T1 was 1.01 ± 0.3 mm. Regarding the stability of the miniplate, there were no significant differences between the groups. The difference in the bone surface between T1 and T3 was − 0.37 ± 0.29 mm.

Conclusions

VS was performed using the FaceGide® program, and customized materials produced based on the VS were applied in actual OGS. The maxilla was repositioned in almost the same manner as in the VSP plan, and the maxillary position remained stable for a year.