Relapse of skeletal class III with anterior open bite after bimaxillary orthognathic surgery depending on maxillary posterior impaction and mandibular counterclockwise rotation

Factors affecting unusual postoperative vertical downward movement of mandible after surgery-first approach using intraoral vertical ramus osteotomy

BACKGROUND

In very rare cases, patients who have undergone surgery-first approach with intraoral vertical ramus osteotomy (IVRO) exhibit unusual downward movements of mandible even up to 1-year post surgery, which makes it difficult for orthodontists to stabilize the occlusion during the postoperative orthodontic period. The aim of this study was to identify factors affecting the unusual downward movement of the mandible 1-year after the surgery-first approach using IVRO, while focusing on cephalometric values.

METHODS

This retrospective cohort study sample was divided into two groups based on the amount of vertical movement of the B-point 1-year post surgery (Group S, predictable upward movement; Group U, unpredictable downward movement greater than 2 mm). To evaluate cephalometric changes between the two groups, cephalograms were obtained before surgery, 1 day after surgery, 1 month after surgery, and 1 year after surgery. The data were analyzed using the independent t-test, Mann-Whitney U test with Bonferroni correction, Pearson correlation analysis, and multiple regression analysis.

RESULTS

At the initial examination, Group U showed a shallower anterior overbite. The vertical surgical change in the B-point was statistically different between the two groups (p < 0.001), indicating that group U exhibited more upward movement of the mandible during surgery. Group U showed significant downward movement of the mandible 1 month after surgery, and this finding persisted until 1 year postoperatively. Clockwise rotation of the mandible was also observed. Surgical vertical movement of the B-point showed a strong correlation with postoperative vertical movement of mandible (r = -0.674; p < 0.001) along a linear relationship, indicating that the amount of postoperative vertical downward movement of the mandible increased as the amount of surgical upward movement of the B-point increased (R2 = 0.449; p < 0.001).

CONCLUSIONS

This study revealed that unusual downward movement of the mandible after a surgery-first approach using IVRO is correlated with the amount of upward movement during the surgery. When planning surgery, in cases in which a significant upward movement of the mandible is anticipated, orthodontists should prepare for the possibility of subsequent unusual downward movement and a tendency for the anterior overjet to decrease during the postoperative orthodontic period.

Comparison of the skeletal stability after mandibular counter-clockwise rotation in three surgical procedures

The treatment of mandibular deformities with an anterior open bite is challenging. In this study, skeletal stability after mandibular osteotomies was evaluated to determine the best treatment for mandibular prognathism with an anterior open bite in three procedures: intraoral vertical ramus osteotomy (IVRO), conventional sagittal split ramus osteotomy (conv-SSRO), and SSRO without bone fixation (nonfix-SSRO). Patients who underwent mandibular osteotomy to correct skeletal mandibular protrusion were included. Changes in skeletal and soft tissues were assessed using lateral cephalograms taken before (T1), 3 ± 2 days (T2), and 12 ± 3 months (T3) after surgery. Thirty-nine patients were included: nine in the IVRO group and 11 and 19 in the conv- and nonfix-SSRO groups, respectively. The mandibular plane angles (MPAs) of the T2-T1 were - 2.7 ± 2.0 (p = 0.0040), - 3.7 ± 1.7 (p < 0.0001), and - 2.3 ± 0.7 (p < 0.0001) in the IVRO, conv-SSRO, and nonfix-SSRO groups, respectively. The skeletal relapse of the MPAs was not related to the MPA at T2-T1, and it was approximately 1.3° in the conv-SSRO group. The skeletal relapse of the MAPs was significantly correlated with the MPA of T2-T1 in the IVRO (p = 0.0402) and non-fix-SSRO (p = 0.0173) groups. When the relapse of the MPAs was less than 1.3°, the MPA of T2-T1 was calculated as 2.5° in the nonfix-SSRO group. When the MPA of T2-T1 is less than 2.5°, non-fix SSRO may produce a reliable outcome, and when it is more than 2.5°, conv-SSRO may produce better outcomes.

Management Strategies for Open Bite Relapse: A Systematic Review and Meta-Analysis

The purpose of orthodontic therapy is to correct malocclusion and produce a stable outcome that endures over time. Long-term stability can be difficult to achieve, and many patients relapse after treatment, particularly in instances of open bite relapse (OBR). This systematic review aimed to analyze different types of management strategies for OBR and conduct a meta-analysis to find the best method of dealing with relapse. A comprehensive search was carried out across six major online databases using relevant keywords pertaining to our study, including "open bite relapse," "orthodontic retention," "orthodontic surgery," "orthodontic appliance," "orthodontic management," "orthodontic treatment," "orofacial myofunctional therapy (OMT)," "skeletal anchorage," and "treatment follow-up period." Eleven studies were selected after the application of relevant inclusion and exclusion strategies. The mean follow-up period of treatment for the studies ranged from six months to 4.5 years. Of all the management strategies assessed, OMT was found to be the least effective for OBR management. Surgical management modalities, such as mandibular repositioning and molar intrusion using skeletal anchorage, in conjunction with the usage of orthodontic appliances, were found to be noticeably effective, especially in the cases of participants who were <18 years of age. However, when utilized on a singular basis, either of them was found to be lacking the desired effect. The overall odds ratio (OR) of 0.48 (0.37, 0.64) and risk ratio (RR) of 0.62 (0.51, 0.74) were obtained after the meta-analysis of the different interventions for OBR, indicating statistical significance. There were only 11 studies included in the study, so it's possible that not all management strategies for OBR were fully understood. The limited number of studies may also have affected the generalizability of the findings. Although statistical differences were obtained to a certain degree, more clinical trials are needed to assess the effect of such surgical modalities as a viable management tool for OBR, since these represent a significant limiting factor in terms of the overall cost of the treatment placed upon the patient. Prior to the start of the research, registration was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. The research protocol was created to meet the goals and was properly filed with the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42023401991).

Comparative study of stability between two different fixation systems after orthognathic surgery in mandibular prognathism skeleton

OBJECTIVE

This study is intended to compare the skeleton stability of bioabsorbable and titanium systems after orthognathic surgery in mandibular prognathism patients.

STUDY DESIGN

A Retrospective study of 28 mandibular prognathism patients who underwent BSSRO setback surgery at Chulalongkorn University. Both titanium and the bioabsorbable group would take lateral cephalometrics immediately postoperative in 1-week(T0), 3(T1), 6(T2), and 12(T3) months. These radiographs were analyzed with Dolphin imaging programTM. The vertical, horizontal, and angular indices were measured. To compare immediately postoperative and follow-up periods within the group, the Friedman difference was used, and the Man-Whitney U test was used between the two groups.

RESULT

The measurements within the group presented no statistically significant differences. But this study showed that at T0-T1, there was a statistically significant difference between the two groups in the mean of Me in horizontal linear measurement. T0-T2 found differences between Me in both horizontal and vertical linear measurements, and the difference between ANB. The differences between B-point, Pog, and Me in vertical linear measurements at T0-T3 were also reported.

CONCLUSION

The significant difference values were within the normal range which indicated that using the bioabsorbable system could be well maintained as well as the titanium system.

STATEMENT OF CLINICAL RELEVANCE

The second operation for removing titanium plate and screw after conventional orthognathic surgery may leads patient discomforts. While a resorbable system might be the role change if the stability is place on the same level.

Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Affect Surgical Movement and Stability?

PURPOSE

Orthognathic surgery (OGS) using the surgery-first approach (SFA) can decrease treatment time and increase patient satisfaction. Clockwise rotation (CWR) of the maxillomandibular complex to correct mandibular prognathism leads to optimized functional, aesthetic, and stable outcomes. This study examined the combined effect of SFA and CWR of the maxillomandibular complex to correct mandibular prognathism by comparing the surgical movement before (T0) and immediately after OGS (T1) and the stability between T1 and 12 months after OGS (T2).

METHODS

This prospective cohort study enrolled patients with skeletal Class III malocclusion who underwent SFA involving Le Fort I osteotomy and bilateral sagittal split osteotomy, with or without genioplasty. Based on the occlusal plane (OP) change at T0-T1, the patients were divided into CWR (OP > 4°) and control (C) groups (OP ≤ 4°). The predictor variable was OP change at T0-T1. The primary outcome variable was the stability of pogonion (Pog) at T1-T2. The covariates included demographic factors, cephalometric measurements (anterior facial height, posterior facial height, OP, mandibular plane angle, incisor mandibular plane angle, overjet, and overbite), and 3-dimensional landmark displacement (anterior nasal spine, A-point, upper central incisor, upper first molar, lower central incisor, lower first molar, Pog, gonion, and condylion). An independent t-test was used to compare between these 2 groups when appropriate. The level of significance was set at P < .05.

RESULTS

The sample included 28 patients (17 females) in the C group and 36 (24 females) in the CWR group; the mean ages were 23.89 ± 3.35 and 24.08 ± 4.02 years, respectively. For the surgical movement at T0-T1, the CWR group showed an association with vertical movement of the maxilla at posterior nasal spine (P = .005), anterior nasal spine (P < .001), and A-point (P < .001) and horizontal backward movement of the mandible at B-point (P < .001), Pog (P < .001), and gonion (P = .042). At T1-T2, all landmarks remained stable without clinically significant difference between the 2 groups.

CONCLUSION

Surgical movement in the CWR group could vertically displace the maxilla and setback mandible more than that in the C group. Postoperative skeletal stability remained the same between the 2 groups at 1 year after OGS.

Does Maxillomandibular Counterclockwise Rotation Affect Surgical Stability in Class III Skeletal Patients with High Plane Angle? A Retrospective Longitudinal Study

Purpose

In class III, skeletal patients with high plane angle, counterclockwise rotation of maxillomandibular units is necessary. The study was aimed to evaluate the long-term stability of the change of mandibular plane in patients with class III deformity.

Materials and Methods

This is a retrospective longitudinal clinical study. Patients with class III skeletal deformity and high plane angles who underwent maxillary advancement and superior repositioning with mandibular set back were studied. The change of mandibular plane (MP) was predictive factors of the study. Age, gender, the amount of movement of the maxillary advancement, and mandibular set back following orthognathic surgeries were variables. The amount of relapse at the A and B points 12 months after orthognathic surgeries was outcomes of the study. Pearson correlation test was used to determine any correlation between relapse at the A and B points following bimaxillary orthognathic surgery.

Results

Fifty-one patients were studied. The mean of MP changes immediately after osteotomies was 4.66 (1.64) degrees. The horizontal relapse at B point 12 months after surgeries was 1.08 (0.81) mm, and the vertical relapse was 1.38 (0.44) mm. There was a correlation between the horizontal and vertical relapse with MP change (P = 0.001).

Conclusion

It seems that the counterclockwise rotation of maxillomandibular units in patients with class III skeletal deformity and high plane angle may be associated with the vertical and horizontal relapse that was noticed at the B point.

Complications on maxilar impaction: A systematic review and meta-analysis

OBJECTIVES

Maxillary impactions are seen as an orthognathic surgical movement that increases the number of complications. The aim of this paper is to research literature on this topic, with special attention to avoiding of complications.

METHODS

A systematic review was carried out according to the PRISMA guidelines. The PROSPERO registration has been performed. A risk of bias assessment was carried out with RevMan and graphics were created. A total of 20 articles were included in this systematic review.

RESULTS

Some interesting and conclusive facts about maxillary impactions. Relapses are not common due to the higher bone contact. Bleeding is a common complication due to the location of palatal artery. Aesthetic and functional complications can arise, especially in the nasal region. Bimaxillary orthognathic surgeries has a higher incidence of complications.

CONCLUSIONS

Today it is not possible to confirm that maxillary impactions alone are responsible for a higher incidence of complications due to the complexity of the three-dimensional movements. Some surgical steps could be safer and cause fewer complications.

Relapse and temporomandibular joint dysfunction (TMD) as postoperative complication in skeletal class III patients undergoing bimaxillary orthognathic surgery: A systematic review

Objectives

The aim of this study was to determine Relapse and TMD as postoperative complication in skeletal class III patients undergoing bimaxillary orthognathic surgery.

Materials and methods

Data was obtained by database searching using The Cochrane Central Register of Controlled Trials (central), PUBMED, SCOPUS, EMBASE, Google scholar, National Medical library, New Delhi. The titles and abstracts of the electronic search results were screened and evaluated by two observers for eligibility according to the inclusion and exclusion criteria.

Results

5261 articles were retrieved for the review. Among these, 3474 duplicate articles were removed. 418 studies were selected based on the eligibility criteria. For the present review, 30 articles were included after elimination according to the inclusion criteria. The Prisma diagram flowchart demonstrates our selection scheme. Quality assessment criteria to evaluate the studies were decided by two review authors in accordance with CONSORT guidelines. Each study was assessed using the evaluation method described in the Cochrane Handbook for Systematic Reviews. Among the 30 studies included in the review, marked degree of relapse in the mandible was noted from 3 months - 1 year postoperatively in 8 studies, 5 studies reported both TMD prevalence and relapse, whereas only 4 studies reported TMD disorder alone.

Conclusion

Complications of relapse and TMD are associated with bimaxillary orthognathic surgery procedures. More RCTs and CCTs are needed in this regard to get better quality evidence. This review was registered with PROSPERO: CRD42020211342.

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.

Postsurgical changes of mandible based on vertical dimension increase in Skeletal Class III deformities

The aim of this study was to evaluate the postsurgical mandibular changes after surgery based on vertical dimension increase in skeletal Class III deformities. Patients who underwent mandibular setback surgery for skeletal Class III malocclusion correction with surgery-first orthognathic treatment were enrolled in the study. Lateral cephalograms were obtained at initial visit, immediately after surgery, 6 months after surgery, and at post-treatment. Postsurgical change of the mandible based on the vertical dimension increase was estimated using a diagrammatic method before surgery and this amount was compared with the actual amount of mandibular forward movement at 6 months after the surgery, using a paired t-test and Bland-Altman plot. Thirty patients (16 men and 14 women; mean age, 22.6 years) with skeletal Class III deformities had undergone mandibular setback surgery with the surgery-first orthognathic treatment. Immediately after surgery, the mandible setback was 9.4 ± 3.7 mm at pogonion. Six months after surgery, the mandible moved forward at an average of 2.3 ± 1.5 mm which corresponded to the estimated value of 2.2 ± 0.9 mm. The estimated amount of postsurgical movement did not show a statistically significant difference from the actual value on paired t-test (p = 0.349). The Bland-Altman analysis showed that the difference between the two values was within the limits of agreement. The postsurgical changes based on vertical dimension increase in surgery-first orthognathic treatment might be predicted by using a diagrammatic method.

One-year postoperative skeletal stability of 3D planned bimaxillary osteotomies: maxilla-first versus mandible-first surgery

Orthognathic surgery is carried out to correct jaw deformities and to improve facial aesthetics. However, controversy surrounds whether the maxilla- or mandible-first surgery approach leads to better surgical outcomes. In our previous study, we have shown that in most instances, the maxilla-first surgical approach yielded closer concordance with the 3D virtual treatment plan than a mandibular-first procedure. However, the post-operative stability of each approach has not been investigated. Therefore, this one-year follow-up study was set-up and investigated the postoperative skeletal stability of the 3D planned translations and rotations after either the maxilla- or mandible-first surgery. In total, 106 patients who underwent bimaxillary surgery and had an individualized 3D virtual operation plans, received either maxilla-first (n = 53) or mandible-first (n = 53) surgery. 3D printed interocclusal splints were used during surgery to position the jaws. One year postoperatively a cone-beam computed tomography (CBCT) scan was made to assess the effects using the OrthoGnathicAnalyser. The mean sagittal, vertical and transverse relapse was less than 1.8 mm and no significant differences were found in relapse between the maxilla-first or the mandibular-first surgical procedure. Overall, this study shows that 3D virtual planning in combination with an optimised sequencing of osteotomies provides predictable long-term results in bimaxillary surgery.

Is Counterclockwise Rotation With Double Jaw Orthognathic Surgery Stable in the Long-Term in Hyperdivergent Class III Patients?

PURPOSE

To evaluate the long-term postsurgical stability of counterclockwise rotation of the occlusal plane (OP) in double-jaw orthognathic surgery in patients with hyperdivergent Class III malocclusion.

MATERIALS AND METHODS

This retrospective cohort study evaluated the postsurgical stability of orthognathic surgery in patients with skeletal Class III malocclusion and counterclockwise rotation of the maxillomandibular complex with an OP change of at least -2°. Patients were evaluated with lateral cephalometric analysis before surgery, immediately after surgery, and at longest follow-up. The primary predictor variable was the change in angle of the OP and the Frankfort horizontal (FH) after surgery. The primary outcome variable was stability of the OP at longest follow-up. Other study variables were age, gender, and the following cephalometric measurements: mandibular plane angle; gonial angle; angle formed by the sella, nasion, and B point; maxillary height; angle of the palatal plane to the line connecting the sella and nasion; and distances of the posterior nasal spine and A point to the FH and of the A point to the vertical line passing from the nasion. The Mann-Whitney U test was used to compare stability between groups because the variables were not normally distributed. Bonferroni correction was used to evaluate P values. The χ² test and Fisher exact test, where appropriate, were used to compare the proportions of groups. A P value less than .05 was accepted as statistically significant.

RESULTS

The sample was composed of 15 adult patients (mean age at surgery, 23.5 yr; 40% men). The median duration of follow-up was 48 months (interquartile range, 36 to 60 months). The groups had similar demographic properties and similar surgical changes. Ten patients showed very stable results with an OP-FH change no greater than 1°. Four patients showed unstable results with an OP-FH change of 2.25 ± 0.5° during the follow-up period. The change in the mandibular plane angle was notable between patients with stability and those with instability, which was the variable most affected by relapse of the OP.

CONCLUSION

This study found long-term postsurgical skeletal stability of counterclockwise rotation of the OP during double-jaw orthognathic surgery in patients with high angle Class III malocclusion after a median follow-up of 48 months.

[Evaluation for vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior open-bite]

OBJECTIVE

To evaluate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior openbite.

METHODS

A retrospective multicenter cohort study was conducted to investigate vertical stability after various orthognathic surgical treatment plans for skeletal class Ⅲ malocclusion with anterior openbite. From 2010-2016, 122 patients from two domestic stomatological hospitals were included in our study. Patients were divided into four groups according to their treatment plans, namely, bilateral sagittal split ramus osteotomy (BSSRO), intraoral vertical ramus osteotomy (IVRO), BSSRO+Le Fort Ⅰ, and IVRO+Le Fort Ⅰ. All patients followed a standardized examination procedure at 6 and 24 months post-treatment. The observation indexes include overbite, mandibular plane angle, and intermaxillary angle.

RESULTS

1) The significantly reduced ratio of the overbite in the BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than the BSSRO and IVRO groups at 6 and 24 months post-treatment. 2) The significantly increased ratio of the mandibular plane in BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than BSSRO and IVRO groups at 6 and 24 months post-treatment. 3) The significantly increased ratio of the intermaxillary angles in BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ groups were less than the BSSRO and IVRO groups at 6 months post-treatment, while there was no statistical difference at 24 months post-treatment.

CONCLUSIONS

Bimaxillary surgery (BSSRO+Le Fort Ⅰ and IVRO+Le Fort Ⅰ) is more effective than mandibular surgery to control vertical relapse.

Is There a Difference in Stability After Intraoral Vertical Ramus Osteotomy Between Vertically High-Angle and Normal-Angle Patients?

PURPOSE

Few studies have evaluated the relapse pattern of intraoral vertical ramus osteotomy (IVRO) for the correction of mandibular prognathism with a high angle. The aim of this study was to measure the association between vertical facial types (high and normal mandibular plane angle) and relapse after IVRO for the management of mandibular prognathism.

MATERIALS AND METHODS

The retrospective cohort study sample (skeletal Class III patients) was divided into 2 groups according to the angle of the sella-nasion plane relative to the mandibular plane (SN-MP) at the initial examination. Lateral cephalograms were analyzed for the predictor (facial type) and outcome (cephalometric changes over time) variables before surgery, 7 days after surgery, and 12 months after surgery. The 2 groups were matched for sample size (n = 20 in each). Data were analyzed using repeated-measures analysis of variance with Bonferroni correction.

RESULTS

The normal-angle group (group N, SN-MP from 27° to 37°) and high-angle group (group H, SN-MP >37°) were not significantly different in terms of gender and age at the initial examination. Seven days after surgery, the mandibles in group H moved 2.5 mm more superiorly than those in group N (P = .013); consequently, the amount of overbite correction in group H was approximately 2 mm greater than that in group N (P = .002). Nevertheless, 12 months after surgery, there was no statistically significant difference in relapse of the maxilla and mandible between the 2 groups. In the 2 groups, the mandible moved approximately 0.7 mm superiorly during retention.

CONCLUSIONS

These findings suggest that IVRO is a clinically acceptable and stable treatment modality for mandibular prognathism with a high angle.

Is Counterclockwise Rotation of the Maxillomandibular Complex Stable Compared With Clockwise Rotation in the Correction of Dentofacial Deformities? A Systematic Review and Meta-Analysis

PURPOSE

To compare postsurgical skeletal stability between counterclockwise rotation (CCWR) of the maxillomandibular complex (MMC) and clockwise rotation (CWR) of the MMC for the correction of dentofacial deformities.

MATERIALS AND METHODS

To address the study purpose, we designed and implemented a systematic review with meta-analysis based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A search strategy was developed, and a search of major databases-PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL)-was conducted to find all pertinent articles published from inception through March 2016. The inclusion criteria were randomized controlled trials, controlled clinical trials, retrospective studies, and case series with the aim of comparing postsurgical stability of CCWR and CWR of the MMC. The analysis was performed using lateral cephalometric analysis of postsurgical mean values and correlation between the surgical and postsurgical changes of the occlusal plane angle and linear changes at A point and B point. A weighted mean difference analysis using a random-effects model with 95% confidence intervals was performed.

RESULTS

A total of 133 patients were enrolled from 3 studies (CCWR, n = 83; CWR, n = 50). All included studies were at moderate risk of bias. There was a statistically significant difference between CCWR and CWR of the MMC in the postsurgical changes of the occlusal plane angle (P = .034), but no statistically significant difference was found in the correlation between the surgical and postsurgical changes of the occlusal plane angle in the 2 groups. There was no statistically significant difference between CCWR and CWR of the MMC for stability between assessments immediately after surgery and at longest follow-up relative to the vertical and horizontal positions at A point and B point (P > .05).

CONCLUSIONS

CCWR compared with CWR for the correction of dentofacial deformities in the absence of pre-existing temporomandibular joint pathology is skeletally stable relative to the postsurgical changes of the occlusal plane, as well as the vertical and horizontal changes of the maxilla and mandible.

Accuracy of virtual surgical planning in two-jaw orthognathic surgery: comparison of planned and actual results

OBJECTIVE

This study aims to evaluate the accuracy of virtual surgical planning in two-jaw orthognathic surgery via quantitative comparison of preoperative planned and postoperative actual skull models.

STUDY DESIGN

Thirty consecutive patients who required two-jaw orthognathic surgery were included. A composite skull model was reconstructed by using Digital Imaging and Communications in Medicine (DICOM) data from spiral computed tomography (CT) and STL (stereolithography) data from surface scanning of the dental arch. LeFort I osteotomy of the maxilla and bilateral sagittal split ramus osteotomy (of the mandible were simulated by using Dolphin Imaging 11.7 Premium (Dolphin Imaging and Management Solutions, Chatsworth, CA). Genioplasty was performed, if indicated. The virtual plan was then transferred to the operation room by using three-dimensional (3-D)-printed surgical templates. Linear and angular differences between virtually simulated and postoperative skull models were evaluated.

RESULTS

The virtual surgical planning was successfully transferred to actual surgery with the help of 3-D-printed surgical templates. All patients were satisfied with the postoperative facial profile and occlusion. The overall mean linear difference was 0.81 mm (0.71 mm for the maxilla and 0.91 mm for the mandible); and the overall mean angular difference was 0.95 degrees.

CONCLUSIONS

Virtual surgical planning and 3-D-printed surgical templates facilitated the diagnosis, treatment planning, and accurate repositioning of bony segments in two-jaw orthognathic surgery.

Botulinum toxin as a therapeutic agent to prevent relapse in deep bite patients

INTRODUCTION

The etiology of deep bite is multifactorial. One of the causes is increased muscular activity. This makes the treatment of deep bite malocclusions difficult and often results in relapse in many cases. In this work we compared patients with surgical orthognathic treatment only and surgical orthognathic treatment with additional injections of botulinum toxin after mandibular advancement for class II division 2 malocclusion.

MATERIAL AND METHODS

This is a prospective study. Adult patients were assessed pretreatment (T1), posttreatment (T2), and long-term after 1 year (T3). In total, 32 patients (mean age, 30.7 years; 23 women and 9 men) reached the study end point (T3); 24 patients were treated without botulinum toxin and 8 patients received preoperative injections of botulinum toxin.

RESULTS

Significant differences between both groups were observed, with a more stable result for the experimental group treated with botulinum toxin.

DISCUSSION

In a selective group of adult patients with a class II division II incisor relationship and with a class II skeletal base, botulinum toxin injections can effectively prevent relapse. This may present an alternative to a conventional myotomy.

Clinical feasibility and efficacy of using virtual surgical planning in bimaxillary orthognathic surgery without intermediate splint

BACKGROUND

Computer-aided jaw surgery has been extensively studied recently. The purpose of this study was to determine the clinical feasibility of performing bimaxillary orthognathic surgery without intermediate splint using virtual surgical planning and rapid prototyping technology.

METHODS

Twelve consecutive patients who underwent bimaxillary orthognathic surgery were included. The presented treatment plan here mainly consists of 6 procedures: (1) data acquisition from computed tomography (CT) of the skull and laser scanning of the dentition; (2) reconstruction and fusion of a virtual skull model with accurate dentition; (3) virtual surgery simulation including osteotomy and movement and repositioning of bony segments; (4) final surgical splint fabrication (no intermediate splint) using computer-aided design and rapid prototyping technology; (5) transfer of the virtual surgical plan to the operating room; and (6) comparison of the actual surgical outcome to the virtual surgical plan.

RESULTS

All procedures of the treatment were successfully performed on all 12 patients. In quantification of differences between simulated and actual postoperative outcome, we found that the mean linear difference was less than 1.8 mm, and the mean angular difference was less than 2.5 degrees in all evaluated patients.

CONCLUSION

Results from this study suggested that it was feasible to perform bimaxillary orthognathic surgery without intermediate splint. Virtual surgical planning and the guiding splints facilitated the diagnosis, treatment planning, accurate osteotomy, and bony segments repositioning in orthognathic surgery.

Effect of occlusal vertical dimension changes on postsurgical skeletal changes in a surgery-first approach for skeletal Class III deformities

INTRODUCTION

The purposes of this study were to investigate the relationship between occlusal vertical dimension (VD) changes and postsurgical skeletal changes in the surgery-first approach and to derive regression models for the final mandibular setback at B-point.

METHODS

This retrospective study included 40 patients (16 men, 24 women; ages, 22.6 ± 4.0 years) who had undergone a bimaxillary surgery-first approach. Using cephalograms generated from cone-beam computed tomography representing the presurgical, postsurgical, and posttreatment stages, skeletal landmarks in the maxilla and mandible were investigated to derive multivariate linear regression-based prediction models. Additionally, a patient classification based on the VD was established and verified to generate regression models for the classified groups.

RESULTS

For the nonincreased VD group, the surgical setback of B-point was its predictor for the final mandibular setback (R(2) at 92%). Meanwhile, the final mandibular setback of the increased VD group was predicted according to the surgical upward movement of pogonion, the postsurgical horizontal position of A-point, and the postsurgical vertical position of the coronoid process (R(2) at 94%).

CONCLUSIONS

The results of this study support the clinical observation that the more increased the vertical occlusal dimension after surgery, the less predictable the position of B-point at the posttreatment stage.