Computer-aided planning in orthognathic surgery-systematic review

Accuracy of the CAD/CAM technique compared with the conventional technique used for stand-alone genioplasty

The benefit of the computer-aided design and manufacturing (CAD/CAM) technique for stand-alone genioplasty remains uncertain and was evaluated in this study. Patients who underwent a conventional genioplasty (n = 20) or genioplasty with the CAD/CAM technique (n = 20), and for whom cephalometry and photogrammetry were performed before and 6 months after surgery, were included. Deviations from predictions of the soft tissue pogonion (Pg'), lip inferior point to aesthetic line (Li-Esth), facial convexity angle (FCA), mentolabial angle (MLA), and ratios of soft to hard tissue movements were calculated. No significant deviation was observed for Pg' in either the conventional group (3.85 ± 4.36 mm; 1.91 ± 1.11 mm) or CAD/CAM group (1.28 ± 1.16 mm; 2.81 ± 3.08 mm), for horizontal and vertical movements, respectively. However, for forward movement, deviation from the prediction of Pg´ in the CAD/CAM group was significantly lower than that in the conventional group (P = 0.015). Deviations of Li-Esth, MLA, and FCA did not differ significantly between the groups. No definite preference for the CAD/CAM technique could be established, because deviations from predictions were not significant in either of the technique groups and lay within the clinically acceptable range.

Advancements in computer-assisted orthognathic surgery: A comprehensive review and clinical application in South Korea

OBJECTIVES

Orthognathic surgery (OS) has evolved with technological advancements, notably through the implementation of computer-assisted orthognathic surgery (CAOS). This article aims to elucidate various types of CAOS and their efficiency and accuracy, supplemented by a thorough literature review focusing on their clinical applications in South Korea.

STUDY SELECTION, DATA, AND SOURCES

A comprehensive search strategy was employed, including systematic reviews, meta-analyses, randomized controlled trials, and observational studies published until December 2023 in the PubMed, MEDLINE, and Google Scholar databases. The literature search was limited to articles written in English.

RESULTS

Static CAOS demonstrated high precision, reduced operative time, and high accuracy, suggesting its potential reliability in orthognathic procedures. Dynamic CAOS presented a promising avenue for exploration, showing an accuracy comparable to that of traditional methods. The critical considerations for CAOS include accuracy, time efficiency, and cost-effectiveness. Recent studies have indicated advancements in the time efficiency of static CAOS. Static CAOS requires less equipment and is more cost-effective than dynamic CAOS.

CONCLUSIONS

CAOS offers clear advantages over conventional OS in terms of surgical convenience and accuracy in implementing the surgical plan. To achieve recognition as the gold standard method for maxillofacial deformity treatment, CAOS must overcome its limitations and undergo continuous verification via well-designed studies.

CLINICAL SIGNIFICANCE

The introduction of CAOS, mainly static CAOS with high precision and reduced surgical time, signifies a notable advancement in OS. However, rigorous studies are warranted to validate CAOS as the gold standard for treating maxillofacial deformities.

Deep learning for 3D cephalometric landmarking with heterogeneous multi-center CBCT dataset

Cephalometric analysis is critically important and common procedure prior to orthodontic treatment and orthognathic surgery. Recently, deep learning approaches have been proposed for automatic 3D cephalometric analysis based on landmarking from CBCT scans. However, these approaches have relied on uniform datasets from a single center or imaging device but without considering patient ethnicity. In addition, previous works have considered a limited number of clinically relevant cephalometric landmarks and the approaches were computationally infeasible, both impairing integration into clinical workflow. Here our aim is to analyze the clinical applicability of a light-weight deep learning neural network for fast localization of 46 clinically significant cephalometric landmarks with multi-center, multi-ethnic, and multi-device data consisting of 309 CBCT scans from Finnish and Thai patients. The localization performance of our approach resulted in the mean distance of 1.99 ± 1.55 mm for the Finnish cohort and 1.96 ± 1.25 mm for the Thai cohort. This performance turned out to be clinically significant i.e., ≤ 2 mm with 61.7% and 64.3% of the landmarks with Finnish and Thai cohorts, respectively. Furthermore, the estimated landmarks were used to measure cephalometric characteristics successfully i.e., with ≤ 2 mm or ≤ 2° error, on 85.9% of the Finnish and 74.4% of the Thai cases. Between the two patient cohorts, 33 of the landmarks and all cephalometric characteristics had no statistically significant difference (p < 0.05) measured by the Mann-Whitney U test with Benjamini-Hochberg correction. Moreover, our method is found to be computationally light, i.e., providing the predictions with the mean duration of 0.77 s and 2.27 s with single machine GPU and CPU computing, respectively. Our findings advocate for the inclusion of this method into clinical settings based on its technical feasibility and robustness across varied clinical datasets.

Virtual Versus Conventional Planning in Orthognathic Surgery: A Systematic Review and Meta-analysis

Objectives

The purpose of this study was to compare the accuracy of hard tissues movements planned to result of the maxillary and mandibular positions between conventional surgical planning (CSP) and virtual surgical planning (VSP) in patients undergoing orthognathic surgery.

Methods

A systematic electronic search was carried out in six databases and gray literature with no restriction of publication date and language. Clinical observational studies that compared accuracy of maxillary position between CSP and VSP were included. Linear measurements of the mandible in the transverse plane and linear measurements of the maxilla in the vertical, horizontal and transverse planes were considered for analysis, comparing planned to postoperative outcomes of CSP and VSP. Cochrane tool was used to assess bias risk. A meta-analysis was performed to summarize similar results by using the Review Manager 5.3 software. Significance level was set at 5%.

Results

Six studies (2 RCT and 4 retrospective cohorts) were included according to inclusion and eligibility criteria, involving 255 patients. The inter-rater reliability of selection and eligibility was excellent (k = 0.8315 and k = 0.9329, respectively). Two studies presented that VSP seemed to have better results than CSP regarding linear measurements of the mandible in the transverse plane. Results from CSP and VSP were similar in accuracy for hard tissue in vertical plane of maxillary position (I2 = 0%; p = 0.17), although VSP was more accurate in horizontal plane (I2 = 0%; p = 0.02).

Conclusion

VSP presented better accuracy for transverse movements in mandible of asymmetric patients. VSP showed to be more accurate for movements in the horizontal plane, and qualitative analysis seemed to be more effective for transverse movements.

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

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

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Are Virtually Designed 3D Printed Surgical Splints Accurate Enough for Maxillary Reposition as an Intermediate Orthognathic Surgical Guide

Background and Aim

The accuracy of the virtually-designed 3D-printed surgical splints requires investigation for the practical use of surgical plan in the operating room. This study aimed to compare the validity of the 3D-printed and the conventional intermediate splints and evaluate the outcomes after the surgical application of the 3D-printed splint compared with the predicted values.

Methods

In this study, ten patients with dentofacial deformity were recruited. Participants were analyzed by the conventional surgical planning and virtual surgical planning. The intermediate surgical splints were created by the conventional and 3D-printing methods. Maxillary movements in 3 spatial directions were measured in an articulator after the application of both splints. Correlation and agreement between the two methods were tested by intraclass correlation coefficient (ICC). After the confirmation of 3D printed splint validity for each patient, the surgery was performed using 3D printed splints. It is assumed that ideally cephalometric prediction values are going to be obtained using conventional acrylic splints (gold standard). So, as a second objective, the outcome of the surgically-applied 3D-printed splint was evaluated and compared with the predicted values and finally analyzed by the paired t-test.

Results

Based on the observations, there was an excellent agreement between the virtually-designed 3D-printed and conventional intermediate surgical splints (ICC ranged between 0.83 and 0.99 for linear values). There was a good cumulative agreement of ICC greater than 0.80. Overall, the mean linear measurements were not different between conventional and 3D-printed splint on the articulator. Also, there were no significant differences between the linear and angular measurements of 2D-cephalometric prediction and postoperation values.

Conclusion

The results showed cautiously the acceptable accuracy of the 3D-printed splints for several parameters in three spatial dimensions within the laboratory and clinical settings.

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.

Accuracy of Segmented Le Fort I Osteotomy with Virtual Planning in Orthognathic Surgery Using Patient-Specific Implants: A Case Series

Background: When maxillary transversal expansion is needed, two protocols of treatment can be used: a maxillary orthodontic expansion followed by a classical bimaxillary osteotomy or a bimaxillary osteotomy with maxillary segmentation. The aim of this study was to assess the accuracy of segmented Le Fort I osteotomy using computer-aided orthognathic surgery and patient-specific titanium plates in patients who underwent a bimaxillary osteotomy for occlusal trouble with maxillary transversal insufficiencies. Methods: A virtual simulation of a Le Fort I osteotomy with maxillary segmentation, a sagittal split ramus osteotomy, and genioplasty (if needed) was conducted on a preoperative three-dimensional (3D) model of each patient’s skull using ProPlan CMF 3.0 software (Materialise, Leuven, Belgium). Computer-assisted osteotomy saw-and-drill guides and patient-specific implants (PSIs, titanium plates) were produced and used during the surgery. We chose to focus on the maxillary repositioning accuracy by comparing the preoperative virtual surgical planning and the postoperative 3D outcome skulls using surface superimpositions and 13 standard dental and bone landmarks. Errors between these preoperative and postoperative landmarks were calculated and compared to discover if segmental maxillary repositioning using PSIs was accurate enough to be safely used to treat transversal insufficiencies. Results: A total of 22 consecutive patients—15 females and 7 males, with a mean age of 27.4 years—who underwent bimaxillary computer-assisted orthognathic surgery with maxillary segmentation were enrolled in the study. All patients presented with occlusion trouble, 13 with Class III malocclusions (59%) and 9 (41%) with Class II malocclusions. A quantitative analysis revealed that, overall, the mean absolute discrepancies for the x-axis (transversal dimension), y-axis (anterior−posterior dimensions), and z-axis (vertical dimension) were 0.59 mm, 0.74 mm, and 0.56 mm, respectively. The total error rate of maxillary repositioning was 0.62 mm between the postoperative cone-beam computed tomography (CBCT) and the preoperatively planned 3D skull. According to the literature, precision in maxilla repositioning is defined by an error rate (clinically relevant) at each landmark of <2 mm and a total error of <2 mm for each patient. Conclusions: A high degree of accuracy between the virtual plan and the postoperative result was observed.

Three-Dimensional Comparison of the Maxillary Surfaces through ICP-Type Algorithm: Accuracy Evaluation of CAD/CAM Technologies in Orthognathic Surgery

PURPOSE

This retrospective study aims to compare the accuracy of two different CAD/CAM systems in orthognathic surgery. The novelty of this work lies in the method of evaluating the accuracy, i.e., using an Iterative Closest Point (ICP) algorithm, which matches a pair of 2D or 3D point clouds with unknown dependencies of the transition from scan s_(k) to scan s_(k+1).

METHODS

The study population was composed of ten patients who presented to the Maxillofacial Surgery Department of the University "Sapienza" of Rome for the evaluation and management of skeletal malocclusions. The patients were divided into two groups, depending on the technique used: group 1: splintless group (custom-made cutting guide and plates); group 2: splint group (using a 3D-printed splint). STL files were imported into Geomagic^® Control X™ software, which allows for comparison and analysis using an ICP algorithm. The RMSE parameter (3D error) was used to calculate the accuracy. In addition, data were compared in two different patient subgroups. The first subgroup only underwent a monobloc Le Fort I osteotomy (p-value = 0.02), and the second subgroup underwent a Le Fort I osteotomy associated with a segmental osteotomy of the maxilla (p-value = 0.23).

RESULTS

Group 1 showed a 3D error of 1.22 mm ± SD 0.456, while group 2 showed a 3D error of 1.63 mm ± SD 0.303. These results have allowed us to compare the accuracy of the two CAD/CAM systems (p-value = 0.09).

CONCLUSIONS

The ICP algorithm provided a reproducible method of comparison. The splintless method would seem more accurate (p-value = 0.02) in transferring the surgical programming into the operating room when only a Le Fort I osteotomy is to be performed.

In Vivo Accuracy of a New Digital Planning System in Terms of Jaw Relation, Extent of Surgical Movements and the Hierarchy of Stability in Orthognathic Surgery

This retrospective cohort study compares the virtual planned and postoperative jaw positions in patients undergoing orthognathic surgery. Surgery was virtually planned with the Digital Münster Model Surgery system (DMMS). Primary outcome: Spatial difference in the maxillo-mandibulo relation between virtual planning and postoperative result. Secondary outcome: Possible relationship between the measured differences and surgical movements as well as the postoperative stability according to Proffit. Ninety female and sixty-one male patients were included in the study. The average translation errors were 0.54 ± 0.50 mm (anteroposterior), 0.37 ± 0.33 mm (mediolateral), and 0.33 ± 0.28 mm (superoinferior). Orientation errors were 0.86 ± 0.79 degrees (yaw), 0.54 ± 0.48 degrees (roll), and 0.90 ± 0.72 degrees (pitch). The surgical procedures do not differ with respect to their error sizes. Maxilla forward and class II maxilla up with mandible forward are the most precise procedures. Most significant differences were found in the anteroposterior direction, whereby the extent of the surgical movement has no effect on the magnitude of the error. The process of planning with the DMMS followed by surgery is highly accurate and shows error values well below the clinically accepted limit of two millimeters in translation and four degrees in rotation.

Post-Operative Patients’ Satisfaction and Quality of Life Assessment in Adult Patients with Obstructive Sleep Apnea Syndrome (OSAS)

Background: The treatment for severe OSAS includes maxillomandibular advancement surgical option in selected cases. The aim of this study was to evaluate the post-operative impact of bimaxillary surgery on satisfaction and consequently the quality of life of these patients. Methods: This study included 18 patients with severe OSAS who received maxillomandibular advancement surgery. Patients were divided into Group A (operated by CAD/CAM) and Group B (conventional surgery). The impact of bimaxillary surgery on satisfaction and quality of life of these patients was evaluated by utilizing post-operative life quality and Rustemeyer’s patient-satisfaction-based survey. Results: A total of 18 adult OSAS patients (Group A: 11 patients, Group B: 7 patients) with a mean age of 44.39 years (SD ± 9.43) were included. Mean follow-up period was 32.64 months (SD ± 21.91). No intra-operative complications were seen in any patients. Post-operative complication was seen in one patient and the mandible did not integrate. According to the results, overall post-operative satisfaction score was 79.72% (SD ± 9.96). There was no significant difference among those in Group A and Group B. Conclusion: Maxillomandibular advancement surgery seems to be beneficial in terms of patients’ satisfaction in severe adult OSAS patients and can be considered as a valuable option in selected cases.

The Accuracy of Jaws Repositioning in Bimaxillary Orthognathic Surgery in Patients with Cleft Lip and Palate Compared to Non-Syndromic Skeletal Class III Patients

Background: The present study aims to compare the accuracy of jaw repositioning in bimaxillary orthognathic surgery using digital surgical planning in cleft lip and palate patients and in non-syndromic skeletal class III patients in order to investigate if orthognathic surgery achieves different results in the first group of patients. Method: This study included 32 class III adult patients divided into 2 groups: cleft lip and palate (A, n = 16) and non-cleft (B, n = 16). For each patient, a 2D pre-surgical visual treatment objective was performed by the surgeon to predict hard tissue changes, and the surgical outcome was compared with that planned by using cephalometric measurement (ANB, SNA, SNB, Ar-Go-Me, S-Ar-Go). The statistical analysis showed equivalence between obtained and planned results for each measurement both in group A and in group B, but the difference between the planned and the obtained result was smaller in group B regarding ANB angle. Conclusions: Digital surgical planning ensures better predictability of the surgical results and higher accuracy of surgery in complex patients, such as those with cleft lip and palate.

3D Printing and Virtual Surgical Planning in Oral and Maxillofacial Surgery

Compared to traditional manufacturing methods, additive manufacturing and 3D printing stand out in their ability to rapidly fabricate complex structures and precise geometries. The growing need for products with different designs, purposes and materials led to the development of 3D printing, serving as a driving force for the 4th industrial revolution and digitization of manufacturing. 3D printing has had a global impact on healthcare, with patient-customized implants now replacing generic implantable medical devices. This revolution has had a particularly significant impact on oral and maxillofacial surgery, where surgeons rely on precision medicine in everyday practice. Trauma, orthognathic surgery and total joint replacement therapy represent several examples of treatments improved by 3D technologies. The widespread and rapid implementation of 3D technologies in clinical settings has led to the development of point-of-care treatment facilities with in-house infrastructure, enabling surgical teams to participate in the 3D design and manufacturing of devices. 3D technologies have had a tremendous impact on clinical outcomes and on the way clinicians approach treatment planning. The current review offers our perspective on the implementation of 3D-based technologies in the field of oral and maxillofacial surgery, while indicating major clinical applications. Moreover, the current report outlines the 3D printing point-of-care concept in the field of oral and maxillofacial surgery.

Computed tomography imaging superimposition protocols to assess outcomes in orthognathic surgery: a systematic review with comprehensive recommendations

OBJECTIVES

A systematic review was performed to analyze the current evidence on three-dimensional (3D) computed tomography (CT) superimposition protocols used to assess dentomaxillofacial changes after orthognathic and orthofacial surgery. Accuracy, reproducibility, and efficiency were evaluated.

METHODS

The search was divided into Main Search (PubMed, EMBASE, Cochrane Library, LILACS, and SciELO), Grey Literature search (Google Scholar and Open Grey), and Manual search. Thirteen studies were included. Of these, 10 reported data on accuracy, 10 on reproducibility and five on efficiency. Seven proposed or evaluated methods of voxel-based superimposition, three focused on the surface-based technique, one compared surface- and voxel-based superimposition protocols, one used the maximum mutual information algorithm, and one described a landmark-based superimposition method. Cone-beam computed tomography (CBCT) was the most common imaging technique, being used in 10 studies.

RESULTS

The accuracy of most methods was high, showing mean differences smaller than voxels' dimensions, ranging between 0.05 and 1.76 mm for translational accuracy, and 0.10-1.09° for rotational accuracy. The overall reproducibility was considered good as demonstrated by the small mean error (range: 0.01-0.26 mm) and high correlation coefficients (range: 0.53-1.00). Timing to complete virtual superimposition techniques ranged between a few seconds up to 40 min.

CONCLUSIONS

Voxel-based superimposition protocols presented the highest accuracy and reproducibility. Moreover, superimposition protocols that used automated processes and involved only one software were the most efficient.

Review the Impact of Mandibular Setback Surgery for the Correction of Class III Malocclusion on the Upper Airway Space

AIM: This study aimed to review the scientific evidence related to the effect of mandibular setback surgery for the correction of Class III malocclusion on the changes in volume and anatomical structures’ positions of the upper airway within at least 1 year follow-up. METHODS: An electronic research was conducted on PubMed, Google scholar, and Elsevier up to April 20, 2021, the inclusion criteria were prospective or retrospective studies aiming to compare the changes in upper airway space following isolated mandibular setback through at least 1 year of follow-up. RESULTS: A total of 84 studies were retrieved, only 12 studies met the eligibility criteria. Their methods of measurement were using lateral cephalometry, CT, or Cone-beam computed tomography. Most of them showed narrowing in the Pharyngeal airway space, with some variability within the follow-up periods. Impact on the possibility of obstructive sleep apnea (OSA) was discussed in most of the included studies. CONCLUSION: Narrowing of upper airway volume is associated with isolated mandibular setback surgeries within 1 year of follow-up. However, OSA was not necessarily a consequence. Any predisposing factors for OSA should be considered before isolated mandibular setback surgery.

Virtual Analysis of Segmental Bimaxillary Surgery: A Validation Study

PURPOSE

Three-dimensional (3D) assessment of orthognathic surgery is often time consuming, relies on manual re-identification of anatomical landmarks or is limited to non-segmental osteotomies. The purpose of the present study was to propose and validate an automated approach for 3D assessment of the accuracy and postoperative outcome of segmental bimaxillary surgery.

METHODS

A semi-automatic approach was developed and validated for virtual surgical analysis (VSA) of segmental bimaxillary surgery using a pair of pre- and postoperative (2 weeks) cone-beam computerized tomography (CBCT) scans. The output of the VSA, the accuracy of the surgical outcome, was calculated as 3D translational and rotational differences between the planned and postoperative movements of the individual bone segments. To evaluate the reliability of the proposed VSA, intra-class correlation coefficients (ICC) were calculated at a 95% confidence interval on measurements of 2 observers. The VSA was deemed reliable if the ICC was excellent (> 0.80) and the absolute difference of the repeated intra- and inter-observer translational and rotational measurements were significantly lower (p < 0.05) than a hypothesized clinical relevant threshold of 1 voxel (0.45 mm) and 1 degree, respectively.

RESULTS

A total of 10 subjects (6 male; 4 women; mean age 24.4 years) with skeletal class 2 and 3, who underwent segmental bimaxillary surgery, 3-piece Le Fort I, bilateral sagittal split osteotomy and genioplasty, were recruited. The intra- and inter-observer reliability was excellent, ICC range [0.96 - 1.00]. The range of the mean absolute difference of the repeated intra- and inter-observer translational and rotational measurements were [0.07 mm (0.05) - 0.20 mm (0.19)] and [0.11˚ (0.08) - 0.63˚ (0.42)], respectively. This was significantly lower than the hypothesized clinical relevant thresholds (P < .001).

CONCLUSION

The validation showed that the VSA has excellent reliability for quantitative assessment of the postoperative outcome and accuracy of segmental bimaxillary surgery.

This is not a pipe - But how harmful is electronic cigarette smoke

This issue of the Biomedical Journal tells us about the risks of electronic cigarette smoking, variations of SARS-CoV-2 and ACE2, and how COVID-19 affects the gastrointestinal system. Moreover, we learn that cancer immunotherapy seems to work well in elderly patients, how thyroid hormones regulate noncoding RNAs in a liver tumour context, and that G6PD is a double-edged sword of redox signalling. We also discover that Perilla leaf extract could inhibit SARS-CoV-2, that artificial neural networks can diagnose COVID-19 patients and predict vaccine epitopes on the Epstein-Barr Virus, and that men and women have differential inflammatory responses to physical effort. Finally, the surgical strategies for drug-resistant epilepsy, computer-supervised double-jaw surgery, dental pulp stem cell motility, and the restitution of the brain blood supply after atherosclerotic stroke are discussed.

Vertical stability of different orthognathic treatments for correcting skeletal anterior open bite: a systematic review and meta-analysis

BACKGROUND

Several orthognathic procedures have been applied to correct skeletal anterior open bites (SAOB). Which method is most stable has been debated and no consensus has been reached and there is no conclusive evidence for clinicians to use.

OBJECTIVE

To analyse whether maxillary, mandibular, or bimaxillary surgery provides a better stability.

MATERIALS AND METHODS

A systematic search was conducted up to December 2020 using PubMed, EMBASE, Medline, Scopus, Web of Science, Cochrane CENTRAL, and Google Scholar. We made direct comparisons among the controlled trials and also made indirect comparisons via subgroup analysis on the aspects of occlusional, skeletal, and dento-alveolar stability to assess the overall stability of each method.

RESULTS

Finally 16 cohort studies were identified. At the occlusional level, pooled change in overbite was 0.21 mm in maxillary surgery, 0.37 mm in bimaxillary surgery, and -0.32 mm in mandibular surgery. At the skeletal level, pooled sella-nasion-Point A angle (SNA) was -0.12 degrees in bimaxillary surgery, -0.37 degrees in maxillary surgery and -0.20 degrees in mandibular surgery. The sella-nasion to palatal plane angle (SNPP) relapsed to a statistically significant degree in all samples received single maxillary surgery. Relapse of the sella-nasion-Point B angle (SNB) was 0.47 degrees in mandibular setback, -1.8 degrees in mandibular advancement, and -0.48 degrees in maxillary surgery. The Sella-Nasion to mandibular plane angle (SNMP) relapsed more in procedures involving bilateral sagittal split osteotomy than in other procedures. As for dento-alveolar changes, intrusion of molars and extrusion of incisors took place in most patients.

CONCLUSIONS

Bimaxillary surgery produced the most beneficial post-operative increase in overbite, maxillary surgery led to a lesser but still positive overbite change, and mandibular surgery correlated with some extent of relapse. Skeletally, bimaxillary surgery was more stable than maxillary surgery at both SNA and SNPP; SNB was more stable in mandibular setback than advancement; and SNMP was unstable in both mandibular and bimaxillary surgeries versus maxillary surgery with comparable surgical changes. Dento-alveolar compensation helped maintain a positive overbite.

REGISTRATION NUMBER

CRD42020198088.

Virtually-Planned Orthognathic Surgery Achieves an Accurate Condylar Position

PURPOSE

Accuracy in orthognathic surgery with virtual planning has been reported, but detailed analysis of accuracy according to anatomic location, including the mandibular condyle, is insufficient. The purpose of this study was to compare the virtual plan and surgical outcomes and analyze the degree and distribution of errors according to each anatomic location.

PATIENTS AND METHODS

This retrospective cohort study evaluated skeletal class III patients, treated with bimaxillary surgery. The primary predictor was anatomic locations that consisted of right and left condyles, maxilla, and the distal segment of the mandible. Other variables were age and gender. The primary outcome was surgical accuracy, defined as mean 3-dimensional distance error, mean absolute error, and mean error along the horizontal, vertical, and anteroposterior axes between the virtual plan and surgical outcomes. Landmarks were compared using a computational method based on affine transformation with a 1-time landmark setting. The mean errors were visualized with multidimensional scattergrams. Bivariate and regression statistics were computed.

RESULTS

This study included 52 patients, 26 men and 26 women, with a mean age of 21 years and 3 months. The mean 3D distance errors for condylar landmarks, maxillary landmarks, and landmarks on the distal segment of the mandible were 1.03, 1.25, and 2.24 mm, respectively. Condylar landmarks, maxillary landmarks, and the landmarks on the distal segment of the mandible were positioned at 0.49 mm inferior, 0.28 mm anterior, and 1.25 mm inferior, respectively. The landmark errors for the distal segment of the mandible exhibited a wider distribution than those for condylar and maxillary landmarks.

CONCLUSIONS

Agreement between the planned and actual outcome aided by virtual surgical planning was highest for the condyles, followed by the maxilla, and the distal segment of the mandible. It is important to consider the tendency for surgical errors in each anatomic location during operations.

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.

Automatic Registration Between Dental Cone-Beam CT and Scanned Surface via Deep Pose Regression Neural Networks and Clustered Similarities

Computerized registration between maxillofacial cone-beam computed tomography (CT) images and a scanned dental model is an essential prerequisite for surgical planning for dental implants or orthognathic surgery. We propose a novel method that performs fully automatic registration between a cone-beam CT image and an optically scanned model. To build a robust and automatic initial registration method, deep pose regression neural networks are applied in a reduced domain (i.e., two-dimensional image). Subsequently, fine registration is performed using optimal clusters. A majority voting system achieves globally optimal transformations while each cluster attempts to optimize local transformation parameters. The coherency of clusters determines their candidacy for the optimal cluster set. The outlying regions in the iso-surface are effectively removed based on the consensus among the optimal clusters. The accuracy of registration is evaluated based on the Euclidean distance of 10 landmarks on a scanned model, which have been annotated by experts in the field. The experiments show that the registration accuracy of the proposed method, measured based on the landmark distance, outperforms the best performing existing method by 33.09%. In addition to achieving high accuracy, our proposed method neither requires human interactions nor priors (e.g., iso-surface extraction). The primary significance of our study is twofold: 1) the employment of lightweight neural networks, which indicates the applicability of neural networks in extracting pose cues that can be easily obtained and 2) the introduction of an optimal cluster-based registration method that can avoid metal artifacts during the matching procedures.

Three-dimensional accuracy of virtual planning in orthognathic surgery

INTRODUCTION

This study aimed to assess the accuracy of virtual surgical planning (VSP) performed by Dolphin Imaging software (version 11.9; Dolphin Imaging and Management Solutions, Chatsworth, Calif).

METHODS

Ten people requiring bimaxillary surgery and genioplasty were followed up prospectively. All patients had preoperative cone-beam computed tomography, plaster models, and photographs allowing for VSP. Interocclusal intermediate surgical splints were produced using a 3-dimensional (3D) printer. Postoperative images were acquired 15 days after surgery using cone-beam computed tomography. ITK-Snap (version 3.6; Cognitica, Philadelphia, Pa) allowed the segmentation of reliable 3D models. Geomagic Qualify 2013 (3D Systems, Rock Hill, SC) and MeshValmet (version 3.0) were used to identify the differences between VSP and actual surgical results through the root mean square values and the 3D translational displacement (3-axes) of the 3D centroid of each model.

RESULTS

Discrepancies between the VSP and the actual result were found at the mandible (P = 0.013) and the chin (P = 0.013) when considering the root mean square values. In addition, 3D centroid differences were found in the transverse and sagittal direction of the right ramus (P = 0.034 and P = 0.005, respectively) and the sagittal aspect of the left ramus (P = 0.025). Considering 2 mm as a threshold of clinical relevance, almost all the bone fragments (maxilla, proximal, and distal mandibular segments) were accurately corrected by surgery, although not in the chin.

CONCLUSIONS

On the basis of the obtained values, it is possible to consider the Dolphin Imaging software as clinically acceptable for performing virtual orthognathic surgical planning.

Stability and surgical complications of tooth-borne and bone-borne appliances in surgical assisted rapid maxillary expansion: a systematic review

The objective of this systematic review was to evaluate the stability and complications of tooth-borne (TB), bone-borne (BB) and hybrid (TB-BB) appliances in surgically assisted rapid maxillary expansion (SARME). Database searches were conducted (PubMed, Embase, Cochrane Library and SciELO), as well as a grey literature search (Google Scholar) and hand searches of reference lists. Forty-six articles were included after study selection (κ=0.854). After eligibility assessment, 16 articles and one article from the grey literature were processed (κ=0.866) and six articles were selected by hand searching, for a total of 23 articles included. Regarding stability, TB appliances showed width relapse rates ranging from 4 to 35% in canines, from 1 to 37% in premolars and from 0.2 to 49.5% in molars. In BB appliances, width relapse rates were 1.7-21% in canines, 1.5% in premolars and 4.6-11.5% in molars. In hybrid appliances, the width relapse rate was 14% in premolars, with a 1.8% overexpansion reported in the molar region. In TB and BB appliances, skeletal relapse rates were similar on the nasal floor (11-53% and 41.6%, respectively) and at the level of the maxilla (18% and 16%, respectively). The most common complications were bone resorption in TB appliances (18.14%) and appliance-related complications in BB appliances (17.9%). The risk of bias was high in 19 studies, medium in three studies and low in one study. The TB and BB appliances used in SARME were considered to have a high long-term stability. BB appliances appeared to have fewer relapses than TB appliances due to a more parallel distribution of forces exerted. However, relapse appears to be highly influenced by postorthodontic treatments, where arch-form coordination is achieved in the consolidation period with the purpose of overexpansion correction, alignment and final vertical adjustments. Further randomised controlled trials with long-term data and large sample sizes are needed to support evidence-based clinical decision-making and to allow meta-analytic studies of stability outcomes regarding the type of anchorage in SARME.

Minimally invasive intraoral proportional condylectomy with a three-dimensionally printed cutting guide

The aim of this study was to describe the steps of a minimally invasive surgical technique used to perform a proportional intraoral condylectomy with a three-dimensionally (3D) printed cutting guide. The technique consists of two steps: virtual surgical planning and intraoral condylectomy. During virtual surgical planning, the mandibular ramus was measured bilaterally, the height of the proportional condylectomy was planned virtually, and a cutting guide was 3D printed. In the intraoral condylectomy, the mandibular condyle was approached intraorally, the 3D printed cutting guide was positioned in the sigmoid notch, and the proportional condylectomy was performed. The protocol reported in this technical note is the sum of knowledge acquired from a series of studies published previously by the authors, who have jointly developed a surgical technique that is both minimally invasive and accurate for the treatment of condylar hyperplasia.

The Accuracy of Jaws Repositioning in Bimaxillary Orthognathic Surgery with Traditional Surgical Planning Compared to Digital Surgical Planning in Skeletal Class III Patients: A Retrospective Observational Study

Background: Technological progress has led to the transition to digital methods to perform surgical planning and to obtain surgical splints with CAD/CAM technologies. The present study aimed to compare the accuracy of jaw repositioning in bimaxillary orthognathic surgery using traditional and digital surgical planning in skeletal class III patients. Methods: This study included 60 skeletal class III patients divided into two groups based on the method used to perform surgical planning: traditional (T, n = 30) and digital (D, n = 30). For each patient, a 2D presurgical Visual Treatment Objective (VTO) was prepared and the outcome of the surgery was compared with that planned by using determined cephalometric measurements (ANB, SNA, SNB, Ar-Go-Me, S-Ar-Go). Statistical analysis showed that the measurements planned and those obtained after surgery were equivalent in Group D. For Group T, the analysis showed equivalence only for one of the considered measurements (ANB). By comparing the results of the two groups, Group D presented a lower level of error than Group T. Conclusions: Digital surgical planning performed significantly better in terms of accuracy of jaw repositioning than the traditional protocol.

3-Dimensional prediction of pre-surgical decompensation after atypical extractions and soft tissue simulation for ortho-surgical management of skeletal Class III malocclusion: A case report

Three dimensional imaging systems whether in the form of digital models, facial scanning or dolphin software play an important role in proper diagnosis and treatment planning of the orthosurgical cases. This case report highlights importance of three-dimensional treatment planning in the ortho-surgical management of the patient with skeletal Class III malocclusion involving atypical extraction. On clinical examination, patient had concave profile, prominent chin, deficient midface, flat cheekbone contour and prominent nasal projection. He had Class III molar and canine relation bilaterally with missing 12 (previously extracted), negative overbite and overjet with discordant maxillomandibular midlines. After 3-dimensional digital model set-up for occlusion planning and dolphin simulation for soft tissue prediction, extraction of left maxillary lateral incisor was planned followed by maxillary advancement and mandibular setback surgery and finish the occlusion in Class II molar relationship. After the orthodontic and orthognathic surgical treatment, the skeletal and dental imbalance was corrected, and most of the treatment objectives were achieved and patient was extremely satisfied with his facial profile. The treatment results were stable at the 3 years follow-up.

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.

Objective computerised assessment of residual ridge resorption in the human maxilla and maxillary sinus pneumatisation

OBJECTIVES

Atrophic resorption of the maxillary alveolar ridge is a complication that makes implantological rehabilitation critical. Our aim was to develop a novel computer aided procedure for the accurate quantitative assessment of maxillary residual ridge resorption including pneumatisation of the maxillary sinus that goes beyond previously described approaches and to apply it to a large dataset.

MATERIALS AND METHODS

To develop and refine the method, we performed a retrospective analysis using computed tomography data from 405 patients to generate segmented, three-dimensional models of zygomaticomaxillary bones and maxillary sinuses. Using anatomical landmarks and orientation lines or planes, all models were aligned automatically to subsequently generate cross-sectional images (n = 2835), enabling the classification of atrophy as well as the quantification of volumes and caudal extensions of the maxillary sinuses.

RESULTS

We developed and implemented an accurate and reproducible workflow for the semi-automated analysis of volumetric maxillary images. Comprehensive statistical analysis of the large quantitative dataset revealed various correlations of maxillary process heights and sinus volumes with atrophy class, age and region and identified conjectural trends over the patient group.

CONCLUSIONS

The method was used successfully to process a large dataset to classify atrophy, to measure alveolar height parameters, and to quantify maxillary sinus volume, bottom volume and pneumatisation.

CLINICAL RELEVANCE

Apart from the anthropometric value of the generated dataset, the method could be applied to provide additional and more accurate data to assess the necessity of bone augmentation in the context of three-dimensional planning before implantation.

Outcome of facial contour asymmetry after conventional two-dimensional versus computer-assisted three-dimensional planning in cleft orthognathic surgery

Computer-assisted 3D planning has overcome the limitations of conventional 2D planning-guided orthognathic surgery (OGS), but difference for facial contour asymmetry outcome has not been verified to date. This comparative study assessed the facial contour asymmetry outcome of consecutive patients with unilateral cleft lip and palate who underwent 2D planning (n = 37)- or 3D simulation (n = 38)-guided OGS treatment for correction of maxillary hypoplasia and skeletal Class III malocclusion between 2010 and 2018. Normal age-, gender-, and ethnicity-matched individuals (n = 60) were enrolled for comparative analyses. 2D (n = 60, with 30 images for each group) and 3D (n = 43, with 18 and 25 images for 2D planning and 3D simulation groups, respectively) photogrammetric-based facial contour asymmetry-related measurements were collected from patients and normal individuals. The facial asymmetry was further verified by using subjective perception of a panel composed of 6 blinded raters. On average, the facial contour asymmetry was significantly (all p < 0.05) reduced after 3D virtual surgery planning for all tested parameters, with no significant differences between post-OGS 3D simulation-related values and normal individuals. No significant differences were observed for pre- and post-OGS values in conventional 2D planning-based treatment, with significant (all p < 0.05) differences for all normal individuals-related comparisons. This study suggests that 3D planning presents superior facial contour asymmetry outcome than 2D planning.

Relevance of 3D virtual planning in predicting bony interferences between distal and proximal fragments after sagittal split osteotomy

After sagittal split osteotomy, the mandibular distal and proximal fragments do not always align themselves passively to one another, resulting in bony interferences and subsequent anomalous settlement of the condyles. Predicting these interferences could be an important ancillary procedure for avoiding intra- and postoperative surgical complications, rendering orthognathic surgery more effective and safer. This study evaluated the relevance of virtual surgical planning in assessing the displacement of the proximal segments after virtual distal segment repositioning, for predicting bony interferences between the segments and thus avoiding related intra- and postoperative surgical complications. The presence of interferences between the distal and proximal segments was compared between virtually predicted (computer-assisted simulation surgery, Dolphin software) and real cases in 100 consecutive patients diagnosed with dentofacial deformities who underwent orthognathic surgery with mandibular repositioning (using a short lingual osteotomy (SLO)). The results indicated that clockwise rotation of the mandible was the mandibular movement most prone to segment interference. Furthermore, virtual planning was sensitive (100%) but had low specificity (51.6%) in predicting proximal and distal segment interferences. This low specificity was due to the software-based automated design of the mandibular osteotomy, where the length of the distal segment was longer than the real SLO, and the mandibular ramus sagittal split was located just behind Spix's spine. Thus, more precise simulated osteotomies are needed to further validate the accuracy of virtual planning for this purpose.

Segmentation of dental cone-beam CT scans affected by metal artifacts using a mixed-scale dense convolutional neural network

PURPOSE

In order to attain anatomical models, surgical guides and implants for computer-assisted surgery, accurate segmentation of bony structures in cone-beam computed tomography (CBCT) scans is required. However, this image segmentation step is often impeded by metal artifacts. Therefore, this study aimed to develop a mixed-scale dense convolutional neural network (MS-D network) for bone segmentation in CBCT scans affected by metal artifacts.

METHOD

Training data were acquired from 20 dental CBCT scans affected by metal artifacts. An experienced medical engineer segmented the bony structures in all CBCT scans using global thresholding and manually removed all remaining noise and metal artifacts. The resulting gold standard segmentations were used to train an MS-D network comprising 100 convolutional layers using far fewer trainable parameters than alternative convolutional neural network (CNN) architectures. The bone segmentation performance of the MS-D network was evaluated using a leave-2-out scheme and compared with a clinical snake evolution algorithm and two state-of-the-art CNN architectures (U-Net and ResNet). All segmented CBCT scans were subsequently converted into standard tessellation language (STL) models and geometrically compared with the gold standard.

RESULTS

CBCT scans segmented using the MS-D network, U-Net, ResNet and the snake evolution algorithm demonstrated mean Dice similarity coefficients of 0.87 ± 0.06, 0.87 ± 0.07, 0.86 ± 0.05, and 0.78 ± 0.07, respectively. The STL models acquired using the MS-D network, U-Net, ResNet and the snake evolution algorithm demonstrated mean absolute deviations of 0.44 mm ± 0.13 mm, 0.43 mm ± 0.16 mm, 0.40 mm ± 0.12 mm and 0.57 mm ± 0.22 mm, respectively. In contrast to the MS-D network, the ResNet introduced wave-like artifacts in the STL models, whereas the U-Net incorrectly labeled background voxels as bone around the vertebrae in 4 of the 9 CBCT scans containing vertebrae.

CONCLUSION

The MS-D network was able to accurately segment bony structures in CBCT scans affected by metal artifacts.

Impact of surgical maxillomandibular advancement upon pharyngeal airway volume and the apnoea-hypopnoea index in the treatment of obstructive sleep apnoea: systematic review and meta-analysis

Background

A systematic review was carried out on the effect of surgical maxillomandibular advancement (MMA) on pharyngeal airway (PA) dimensions and the apnoea-hypopnoea index (AHI) in the treatment of obstructive sleep apnoea (OSA), with the aim of determining whether increased PA in the context of MMA is the main factor conditioning the subsequent decrease in AHI.

Methods

A search was made of the PubMed, Embase, Google Scholar and Cochrane databases. A total of 496 studies were identified. The inclusion criteria were a diagnosis of moderate to severe OSA, MMA success evaluated by polysomnography, reporting of the magnitude of MMA achieved, PA increase and a minimum follow-up of 6 months.

Results

Following application of the eligibility criteria, eight articles were included. Metaregression analysis showed MMA to significantly increase both pharyngeal airway volume (PAV) (mean 7.35 cm³ (range 5.35-9.34)) and pharyngeal airway space (mean 4.75 mm (range 3.15-6.35)) and ensure a final AHI score below the threshold of 20 (mean 12.9 events/hour).

Conclusions

Although subgroup analysis showed MMA to be effective in treating OSA, more randomised trials are needed to individualise the required magnitude and direction of surgical movements in each patient, and to standardise the measurements of linear and nonlinear PAV parameters.

How accurate is digital-assisted Le Fort I maxillary osteotomy? A three-dimensional perspective

The aim of this study was to evaluate the surgical accuracy of Le Fort I surgery compared to the three-dimensional (3D) virtual planning. Fifty-five patients (29 males, 26 females; age range 15-58 years) with skeletal class III malocclusion, who underwent bimaxillary surgery were included. A validated 3D accuracy assessment tool was utilized to assess the surgical accuracy of the maxillary positioning. For translational movements, the least amount of error was associated with mediolateral translation, whereas the surgical accuracy for anteroposterior and superoinferior translation showed a tendency towards a more posterior and inferior positioning of the maxilla compared to the planning. For rotational movements, the highest discrepancy was observed for pitch. Linear regression showed increased inaccuracy with increasing advancement for anteroposterior, superoinferior and pitch movements. To conclude, 3D virtual planning of maxilla was generally accurate when compared to achieved outcome for skeletal class III patients undergoing bimaxillary surgery.

Accuracy between virtual surgical planning and actual outcomes in orthognathic surgery by iterative closest point algorithm and color maps: A retrospective cohort study

BACKGROUND

To evaluate the accuracy between actual outcomes and virtual surgical planning (VSP) in orthognathic surgery regarding the use of three-dimensional (3D) surface models for registration using iterative closest point (ICP) algorithm and generated color maps.

MATERIAL AND METHODS

Construction of planning and postoperative 3D models in STL files format (M0 and M1, respectively) from CBCT of 25 subjects who had been submitted to bimaxillary orthognathic surgery was performed. M0 and M1 were sent to Geomagic software in semi-automatic alignment surface mesh order of M0 and M1 for registration using ICP algorithm to calculate mean deviation (MD, MD+, MD-, SD) and root mean square (RMS - 3D Error). Color maps were generated to assess qualitative congruence between M0 and M1. From deviation analysis, 3D Error was defined as accuracy measurement. To assess the reproducibility, the workflow was performed by two evaluators multiple times. t-tests were used to assess whether all means of MD, MD+, MD-, SD and 3D Error values would be ≤ - 2 mm and ≥ 2 mm.

RESULTS

High intra and inter evaluators correlation were found, supporting the reproducibility of the workflow. t-tests proved that all MDs and 3D Error values were > - 2 mm and < 2 mm.

CONCLUSIONS

3D error mean was within the standards of clinical success lower than 2 mm. ICP algorithm provided a reproducible method of alignment between 3D models and generated color maps to evaluate 3D congruence but did not answer all methodological parameters regarding the assessment of accuracy in orthognathic surgery.

Comparação de diferentes planejamentos em cirurgia ortognática para tratamento de assimetrias faciais: relato de casos

Introdução: a cirurgia ortognática envolve a correção de desarmonias funcionais e estéticas. A hiperplasia condilar (HC) resulta em crescimento mandibular acentuado, provocando assimetria facial. Para obter previsibilidade e sucesso nos resultados, é imprescindível planejar. Objetivo: descrever e comparar métodos de planejamento e resultados pós-operatórios por meio de relato de três pacientes com assimetria facial. Relato de caso: foram avaliados 03 casos (casos A, B e C) orto-cirúrgicos de pacientes adultos jovens, com média de idade de 22 anos, portadores de má oclusão esquelética de Classe III, com assimetria facial resultante de HC inativa. Esses foram submetidos a análise facial e a dois métodos de planejamento em cirurgia ortognática (convencional e virtual). O caso A foi planejado por meio de imagens bidimensionais (2D) e sequência cirúrgica iniciada pela maxila. O caso B foi planejado por imagens 2D associado ao recurso de simulação em protótipo. E o caso C, planejado exclusivamente em imagens tridimensionais (3D) e simulação virtual. Os casos B e C utilizaram sequência cirúrgica iniciada pela mandíbula. Foi utilizado o software Dolphin Imaging® em todos os planejamentos. Os planejamentos foram transferidos para os procedimentos cirúrgicos por auxílio dos guias em resina acrílica e estereolitografia. Os pacientes dos casos relatados foram avaliados periodicamente no pós-operatório e estavam satisfeitos com os resultados. Conclusão: os planejamentos demonstraram previsibilidade e viabilidade para assimetrias faciais, pois os resultados foram satisfatórios. Houve uma tendência de melhores resultados quando a prototipagem, imagens 3D e sequência operatória iniciada pela mandíbula foram utilizadas no planejamento.

Facial asymmetry: virtual planning to optimize treatment predictability and aesthetic results

Facial asymmetry is a condition that compromises function and social interactions and, consequently, the quality of life. Orthodontic-surgical treatment may be indicated to achieve a stable occlusion and significant improvement in facial aesthetics. The virtual planning of the maxillary, mandibular and chin movements can be done prior to surgery. These movements can be successfully performed with the use of prototyped guides obtained from virtual planning. The aim of this article is to show the state of the art of treatments of facial asymmetries, and emphasize how important is the multi-disciplinary approach to achieve predictable aesthetic and functionally stable results in a patient with facial asymmetry and chin protrusion.