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

Digital Innovations in Orthognathic Surgery: A Systematic Review of Virtual Surgical Planning, Digital Transfer, and Conventional Model Surgery

OBJECTIVES

Orthognathic surgery has evolved due to the use of virtual surgical planning (VSP) and digital model surgery, which are technological advancements replacing conventional approaches with accurate personalised digital models made from computed tomography (CT) or magnetic resonance imaging (MRI) scans. Their integration has enhanced surgical efficiency, patient satisfaction and communication among surgeons and patients, while some challenges such as cybersecurity issues and the requirement for information technology backup have also been noted in hospitals.

MATERIALS AND METHODS

From January 2013 to October 2024, this systematic review aimed at orthognathic surgery virtual planning; it was carried out on the basis of a digital library with 437 works from PubMed, Embase, Cochrane, Web of Science and Scopus searched through an initial selection of specific keywords. The final step is filtering out irrelevant studies through scrutiny, resulting in 25 original interventional studies that met inclusion criteria for quality control purposes via bias analysis.

RESULTS

In relation to the future of orthognathic surgery, it can be advanced by improving VSP, digital transfer techniques and conventional model surgery with technical innovations that need to meet the challenges. The integration of Artificial Intelligence (AI) into VSP can be an opportunity for its development in the sphere of accuracy and visualisation during surgery with augmented reality (AR) utilisation. Among them are the real-time data integration offered by digital transfer techniques, but they are hindered in cost and standardisation. On the other hand, conventional model surgery may revolutionise with three-dimensional (3D) printing; however, there is a long way to go for conventional model surgery to address time constraints as well as ecological concerns. Compatibility issues, training needs and ethical considerations represent three major obstacles that must be tackled successfully so that surgery will have a bright future.

CONCLUSION

Case complexity and patient preferences are important factors that should be considered before making a decision about orthognathic surgery. VSP offers precision for complicated cases. Real-time guidance can be achieved using digital transfer techniques, whereas traditional model surgery provides a tactile, hands-on experience. Analysing digital innovations jointly will enhance orthognathic patient care and education while improving patient safety.

Artificial Intelligence in the Surgery-First Approach: Harnessing Deep Learning for Enhanced Condylar Reshaping Analysis: A Retrospective Study

Background: The surgery-first approach (SFA) in orthognathic surgery eliminates the need for pre-surgical orthodontic treatment, significantly reducing overall treatment time. However, reliance on a compromised occlusion introduces risks of condylar displacement and remodeling. This study employs artificial intelligence (AI) and deep learning to analyze condylar behavior, comparing the outcomes of SFA to the traditional surgery-late approach (SLA). Methods: A retrospective analysis was conducted on 77 patients (18 SFA and 59 SLA) treated at Perugia Hospital between 2016 and 2022. Preoperative (T0) and 12-month postoperative (T1) cone-beam computed tomography (CBCT) scans were analyzed using the 3D Slicer software and its Dental Segmentator extension, powered by a convolutional neural network (CNN). This automated approach reduced segmentation time from 7 h to 5 min. Pre- and postoperative 3D models were compared to assess linear and rotational deviations in condylar morphology, stratified via dentoskeletal classification and surgical techniques. Results: Both the SFA and SLA achieved high surgical accuracy (<2 mm linear deviation and <2° rotational deviation). The SFA and SLA exhibited similar rates of condylar surface remodeling, with minor differences in resorption and formation across dentoskeletal classifications. Mean surface changes were 0.41 mm (SFA) and 0.36 mm (SLA, p < 0.05). Conclusions: Deep learning enables rapid, precise CBCT analysis and shows promise for the early detection of condylar changes. The SFA does not increase adverse effects on condylar morphology compared to SLA, supporting its safety and efficacy when integrated with AI technologies.

Comparison of Accuracy in Mandible-First and Maxilla-First Approaches in Bimaxillary Orthognathic Surgery: A Meta-Analysis

This meta-analysis compares the accuracy of mandible-first and maxilla-first approaches in bimaxillary orthognathic surgery to improve clinical decision-making. A systematic search was performed in PubMed, Web of Science, Embase, and Cochrane databases up to August 2024. The analysis included randomized controlled trials and cohort studies with a minimum of 10 patients. Data extraction followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and pooled effect estimates for continuous outcomes were calculated using weighted mean difference (WMD) with 95% CIs. Heterogeneity was assessed using Cochran I2 and Q statistics, with a random-effect model applied when I2 exceeded 50%. Seven studies involving 316 patients were included. The analysis showed no significant differences in vertical (WMD: -0.05, 95% CI: -0.57 to 0.48, P = 0.86), transverse (WMD: -0.17, 95% CI: -0.43 to 0.09, P = 0.21), and sagittal (WMD: -0.41, 95% CI: -0.98 to 0.15, P = 0.15) surgical errors between the two approaches. Rotational surgical errors were also similar, including pitch (WMD: 0.07, 95% CI: -0.11 to 0.25, P = 0.29), roll (WMD: 0.01, 95% CI: -0.18 to 0.25, P = 0.69), and yaw (WMD: 0.12, 95% CI: -0.56 to 0.81, P = 0.72). The findings suggest that there is no significant difference in surgical accuracy between mandible-first and maxilla-first approaches. Therefore, the choice of sequence should be based on patient-specific factors rather than a presumed advantage of one method over the other. Further research, including large-scale randomized controlled trials, is needed to confirm these results and evaluate long-term outcomes.

Mandible-First and Maxilla-First Sequencing in Virtual Surgical Planning for Orthognathic Surgery: Comparison of Planned and Actual Outcomes

Background: Recent studies have shown that virtual planning for orthognathic surgery is an accurate and repeatable method. It is also a fact that surgical sequence can affect the results in terms of accuracy. Various studies stated that both approaches offer comparable results when properly planned and implemented; however, further clinical studies are still needed. This study aims to evaluate the effect of virtual surgical planning (VSP) on surgical outcomes and whether it is affected by mandible-first or maxilla-first approaches. Methods: This study analyzed data from 45 patients who underwent orthognathic surgery due to dentofacial deformity. Six of these patients underwent single-jaw orthognathic surgery, and 39 underwent bimaxillary orthognathic surgery (Maxilla-first group: 21, mandible-first group: 18). The displacements of specific landmarks were assessed by comparing preoperative and postoperative conventional computed tomographies with VSP data. Results: This study showed a statistically significant relationship between the measurements made with the 2 methods (r = .944; P = .0001). The fact that the intra-class correlation coefficient value is statistically significant and relatively high and that most of the differences in the Bland-Altman chart fall between the limits of compliance indicates a correlation between the virtual plan and surgical outcomes. In addition, in vertical measurements, the absolute mean difference of the B point and the Pogonion in the Maxilla-first group were statistically significantly higher than in the Mandible-first group (P = .038, P = .011). Conclusions: Our findings corroborate the high accuracy of the VSP reported in previous studies and also demonstrate that VSP with both maxilla-first and mandible-first sequencing achieves high accuracy in the sagittal and coronal planes. Although virtual planning significantly influences accurate surgical outcomes, it is not the sole determinant. Factors like condylar positioning and fixation methods can also impact the final results.

Comprehensive analysis of alar base inclination and lip line cant following orthognathic correction of maxillomandibular asymmetry: A retrospective study

This paper examines the relationship between roll rotation of the jaws and changes in alar base or lip line asymmetry in the coronal plane following orthognathic correction. The study involved patients with preoperative frontal alar base and lip line asymmetries greater than 0.5° (because it corresponds to the minimum asymmetry perception threshold) and underwent bimaxillary orthognathic surgery without (Group I) or with (Group II) genioplasty. The alar base angle (ABA), lip line cant angle (LLCA), maxillary cant angle (MxCA), and mandibular cant angle (MnCA) were measured using preoperative and 12 months postoperative cone beam computed tomography (CBCT) images. Thirty-four patients were included in the study. Significant correlations were found between changes in MxCA and ABA besides between changes in MnCA and LCA in Groups I (P = 0.016, P˂0.001, respectively) and II (P = 0.002, P˂0.001, respectively). The mean of the change in ABA/the change in MxCA and the change in LLCA/the change in MnCA ratios for Group I were 0.59 ± 1.57 and 0.73 ± 0.94, respectively, while those for Group II were 0.46 ± 3.70 and 0.39 ± 2.00, respectively. Angular measurements from jugular and mental foramina points, aligned with the bony midline, offer a convenient tool for predicting alar base and lip symmetry during bimaxillary orthognathic surgery planning.

Mandibular autorotation: a critical virtual parameter in clinical decision-making regarding maxilla-first versus mandible-first sequence

Large degrees of mandibular autorotation during intermediate splint design are prone to transfer error and decrease accuracy. The purpose of this study was to evaluate the amount of mandibular autorotation necessary to design intermediate splints for maxilla- and mandible-first sequences using virtual planning software, to help the clinical decision-making regarding the most adequate sequence for each patient. The influence of specific orthognathic movements (different vertical and sagittal changes at the Le Fort I level, cant correction) and the type of maxillofacial deformity (skeletal Class II, III, anterior open bite) were evaluated to identify those that would require higher levels of autorotation for each sequence. Three-dimensional virtual surgical planning data of 194 patients were reviewed (126 female, 68 male; mean age 26.5 ± 11.0 years; 143 skeletal Class II, 51 skeletal Class III) and subgroup analyses were conducted using the Kruskal-Wallis test and post-hoc pairwise comparisons. As an additional parameter (mandibular autorotation), maxilla-first is indicated for bimaxillary osteotomies with Le Fort I posterior intrusion, anterior open bite, and skeletal Class III, while mandible-first is recommended for Le Fort I global extrusion, especially with maxillary cant correction.

Morpho-functional analysis of the temporomandibular joint following mandible-first bimaxillary surgery with mandible-only patient-specific implants

The aim of this study was to evaluate condylar and glenoid fossa remodeling after bimaxillary orthognathic surgery guided by patient-specific mandibular implants. In total, 18 patients suffering from dentofacial dysmorphism underwent a virtually planned bimaxillary mandibular PSI-guided orthognathic procedure. One month prior to surgery, patients underwent a CBCT scan and optical scans of the dental arches; these datasets were re-acquired 1 month and at least 9 months postsurgery. Three-dimensional models of the condyles, glenoid fossae, and interarticular surface space (IASS) were obtained and compared to evaluate the roto-translational positional discrepancy and surface variation of each condyle and glenoid fossa, and the IASS variation. The condylar position varied by an average of 4.31° and 2.18 mm, mainly due to surgically unavoidable ramus position correction. Condylar resorption remodeling was minimal (average ≤ 0.1 mm), and affected skeletal class III patients the most. Later condylar remodeling was positively correlated with patient age. No significant glenoid fossa remodeling was observed. No postoperative orofacial pain was recorded at clinical follow-up. The procedure was accurate in minimizing the shift in relationship between the bony components of the TMJ and their remodeling, and was effective in avoiding postoperative onset of orofacial pain. An increase in sample size, however, would be useful to confirm our findings.

Skeletal stability after mandible bilateral sagittal split osteotomy - comparison of patient-specific implant and mini-plate fixation: A retrospective study

The aim of the study was to compare the stability of the virtual surgical planning (VSP) and computer-aided design accompanied by patient-specific implants (PSIs) and conventional mini-plates in mandible advancement with bilateral sagittal split osteotomy (BSSO). This retrospective study evaluates the clinical and cephalometric records of 53 patients (12 male, 41 female) treated with BSSO in Helsinki University Hospital. Subjects were divided into two groups: VSP-PSI (21 patients: 4 male and 17 female; mean age 38 years, range 25-53 years); and conventional wafer-based repositioning with mini-plate fixation (32 patients: 8 male and 24 female; mean age 39 years, range 21-56 years). The effect of the amount and direction of the advancement on the stability was also analysed individually. The standardized lateral cephalometric radiographs in three time points were analysed to compare the groups. After surgery (T2), there were no differences between groups in cephalometric variables. During follow-up (T2-T3), the cephalometric variables in both Groups A and B were stable, so there was no difference in stability between the VSP-PSI and the conventional mini-plate groups. During follow-up, the mandibles rotated clockwise or counterclockwise, relapsed towards their original direction, and the changes were statistically significant (jaw relationship; p = 0.018, soft tissue profile; p = 0.025); when the advancement of mandible was >6 mm, the increase in gonial angle compared to mandibles advanced ≤6 mm was statistically significant (p = 0.03). VSP-PSI and conventional mini-plate fixation can be considered equally stable. Large advancements with counterclockwise rotation regardless of fixation method are more susceptible to relapse. VSP-PSI alone cannot solve the relapse-related concerns in mandible osteotomy.

Sequencing in Orthognathic Bimaxillary Surgery: Which Jaw Should Be Operated First? A Scoping Review

Bimaxillary orthognathic surgery is widely used for the correction of dentoskeletal deformities. Surgery sequencing (maxilla or mandible first) remains debated, and guidelines and consensus are lacking. This scoping review summarizes the state of the art and compares the advantages and disadvantages of both approaches. The review was conducted following PRISMA-ScR guidelines. Three electronic databases (PubMed, Scopus, Web of Science) were searched using the PICO protocol and key words in orthognathic surgical sequencing. Four reviewers screened the records independently, and disagreement was resolved by consensus. A total of 23 records met the inclusion criteria. The advantages and disadvantages of the two approaches were compared and assessed for accuracy of reporting. Within the limitations of the present study, available evidence for the intrinsic advantages and the accuracy of the mandible-first sequence supports the choice of this approach in most cases. Nevertheless, each clinical case needs to be evaluated individually, as no dogmatic recommendations can be given for sequencing in bimaxillary orthognathic surgery.