Postoperative Condylar Position by Sagittal Split Ramus Osteotomy With and Without Bone Graft

The Evaluation of Condylar Position Change in the Asymmetric Mandible Following Sagittal Split Osteotomy

BACKGROUND

The change of condyle position following orthognathic surgery affects the stability of treatments. This study aims to assess the correlation between the amount of condyles' position change and the severity of mandibular asymmetry following BSSO.

MATERIALS AND METHODS

This is a cross-sectional study. Subjects with asymmetric mandibular prognathism following BSSO were studied. Subjects were classified into 2 groups: group 1, subjects had mandibular asymmetry without occlusal cant and underwent BSSO. Group 2, subjects had mandibular asymmetry with occlusal cant and underwent BSSO+ Lefort I osteotomy. The condyle position was evaluated using cone-beam computer tomography (CBCT). Pearson's correlation test was used to assess any correlation between the condyle changes and the change in the mandible in sagittal and anterior-posterior directions.

RESULTS

A total of 44 subjects were studied. In group 1, the condyle tilted outward in the deviated condyle and inward in the non-deviated condyle immediately after osteotomy. After 12 months, both condyles showed a rotation relative to the original position. In group 2, the condyles of the deviated sides and non-deviated sides moved inferiorly after surgery (condylar sagging), which was more significant in the non-deviated sides. The condyle rotation was similar to group 1. The severity of asymmetry and occlusal cant correlate with the condylar position change in the two groups.

CONCLUSION

The severity of mandibular asymmetry correlates with the amount of condyles' position change immediately after BSSO. However, the condyles tend to return to their original position 12 months later.

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

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

Effects of sagittal split Ramus osteotomy on condylar position and Ramal orientation in patients with mandibular asymmetry

OBJECTIVE

The purpose of this study is to assess the impact of Sagittal Split Ramus Osteotomy (SSRO) on the alignment of the condyle and orientation of the Ramal segment following surgery in patients operated for the correction of mandibular asymmetry.

METHODS

A total of 27 patients who underwent SSRO were enrolled in this study, and study groups were defined as asymmetric (study group) and symmetric (control group) using linear measurements from the dental midline based on a three-dimensional coordinate system. Differences on preoperative and postoperative values of anterior (AJS), posterior (PJS) and superior joint spaces (SJS), condylar axial angle (CAA), Sagittal Ramal Angle (SRA), and Coronal Ramal Angles (CRA) of study and control groups were measured and compared. The data was analyzed using the "Wilcoxon signed-ranks test" to identify differences between groups.

RESULTS

Differences between preoperative and postoperative values of CRA and SRA of the contralateral group showed statistically significant results with p-values of 0.007 and 0.005, respectively. A statistically significant change in CAA angle was found in the control and deviation groups (p = 0.018 and p = 0.010, respectively).

CONCLUSIONS

SSRO has inevitable effects on the condylar and ramal orientation. Individuals with asymmetry require particular attention throughout the planning process and beyond. Conjunctive modalities and modifications should be considered and utilized when necessary. Future studies with larger sample sizes, homogenous follow-up periods, and more comprehensive clinical data are needed to substantiate understanding of the response of the condylar segment.

CLINICAL RELEVANCE

Orthognathic surgeries inevitably alter the alignment and harmony of temporomandibular structures and may result in change of AJS, PJS, SJS, CAA, SRA, and LRA, which may change the biomechanics of joint and lead to several complications like temporomandibular disorders. Especially in cases with midline asymmetry needs special consideration from planning till the end of the treatment to achieve best results. In severe cases, conjunctive modalities and modifications and other alternatives such as inverted-L osteotomies should be considered.

Remodeling of the Temporomandibular Joint After Mandibular Setback Surgery: A 3D Cephalometric Analysis

BACKGROUND

Condylar adaptations following orthognathic surgery remain an area of interest. Prior studies do not use 3-dimensional imaging modalities and lack standardization in the choice of osteotomy and movement when assessing condylar changes.

PURPOSE

The purpose of this study was to use 3-dimensional cephalometry to measure the association between osteotomy type (sagittal split osteotomy [SSO] vs vertical ramus osteotomy [VRO]) and changes in condylar volume and position.

STUDY DESIGN, SETTING, AND SAMPLE

This is a retrospective cohort study from January 2021 through December 2022 of patients at Bellevue Hospital in New York City, New York who were treated with either SSO or VRO for the correction of Class III skeletal malocclusion.

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

The primary predictor was the type of mandibular osteotomy, sagittal split osteotomy, and vertical ramus osteotomy.

MAIN OUTCOME VARIABLES

The primary outcomes were changes in condylar volume (change measured in mm3) and relative position (anterior-posterior change utilizing the Pullinger and Hollinder method).

COVARIATES

Covariates included patient age, sex, setback magnitude, temporomandibular joint symptoms, and fixation method for SSO patients.

ANALYSES

Univariate comparisons were performed between independent variables and study outcomes. Volume changes were compared within each predictor using paired t-tests. Position changes were compared within each predictor using χ2 tests. If there were multiple significant univariate predictors, multiple regression models were created to predict volume and position changes. A P < .05 value was considered statistically significant.

RESULTS

The final sample comprised 30 condyles derived from 30 subjects. Mean age was 22.7 years (SD = 5.7) and mean setback was 3.9 mm (SD = 0.9). Twenty two condyles (73.3%) were subject to SSO with fixation, while the remaining 8 (26.7%) condyles were subject to intraoral VRO without fixation. When compared to VRO, condyles manipulated with SSO had greater volume loss (-177.2 vs -60.9 mm3; P = .03) and positional change (68.2 vs 12.5%; P < .01). Self-reported measures of postoperative pain, internal derangement, and myofascial symptoms were not significantly associated with either volume or positional changes.

CONCLUSIONS AND RELEVANCE

The SSO resulted in greater postoperative condylar volume loss and positional changes. These volume and positional changes were not correlated with self-reported temporomandibular disorder symptoms.

Does the Posterior Bending Osteotomy In Bilateral Sagittal Split Osteotomy Affect the Condyle Position in Asymmetric Patients?

PURPOSE

To measure and compare changes in postoperative condylar position following bilateral sagittal split osteotomy in patients with asymmetry treated using a posterior bending osteotomy (PBO) and conventional methods (shaving of premature contacts).

METHODS

Participants were randomized to either the PBO or conventional group. The inclusion criteria were the need bilateral sagittal split osteotomy or bimaxillary asymmetric surgery (menton deviation >4 mm). The primary outcome variable was changes in the condylar position in the axial, coronal, and sagittal planes 6 months after surgery, whereas the secondary outcome variable was changes in temporomandibular joint symptoms. Covariates included surgery type, deformity type, age, and sex. Categorical and numerical variables were analyzed using Fisher exact χ² test and 2-way analysis of covariance.

RESULTS

The study sample comprised 42 patients with a mean age of 23.3 years; 57.5% were women. The alteration in the coronal condyle angle was 0.8⁰ ± 0.86⁰ in the PBO and 2.72⁰ ± 0.81⁰ in the conventional group. The differences in the condylar position in the coronal plane were not statistically significant (P = .129). The alteration in the axial condyle angle was 2.31⁰ ± 1.74⁰ in the PBO group and 5.65⁰ ± 1.65⁰ in the conventional group. The alteration in the sagittal plane was 0.44⁰ ± 1.52⁰ in PBO and 0.47⁰ ± 1.44⁰ in the conventional group. Alterations in axial (P = .194) and sagittal (P = .976) condylar positions were insignificant. In the conventional group, statistically significant differences were found in the axial (P = .002) and coronal (P = .002) planes, and the condyle turned inward in both planes. There were no statistically significant differences between the groups or within the groups in the sagittal plane (P > 0,5). In PBO and conventional groups, joint noise examination revealed positive results in 11 and 6 patients preoperatively and 1 and 2 patients postoperatively, respectively. A statistically significant decrease in joint noise was detected in the PBO group (P = 0,04). The maximum mouth opening without pain was 5.95 ± 1.47 in the PBO group and 7.91 ± 1.39 in the conventional group, respectively. The alteration was not statistically significant between the groups but was significant within the groups (P < .001).

CONCLUSIONS

PBO effectively prevents premature contact between mandibular segments in facial asymmetry.

Three dimensional condylar positional and morphological changes following mandibular reconstruction based on CBCT analysis: a prospective study

OBJECTIVE

This study aimed to evaluate the condylar positional changes following mandibular reconstruction with preservation of the condylar head using Cone-Beam Computed Tomography (CBCT). Also, to assess joint space changes and the overall volumetric space compared to the preoperative status.

METHODOLOGY

This prospective study included 30 patients (60 joints) subjected to unilateral mandibular resection and reconstruction with preservation of the condylar head. The Helkimo index and preoperative (T1), two weeks postoperative (T2), and follow-up CBCTs (T3) after at least six months were gathered and processed to evaluate the condylar position and TMJ joint space using Anatomage Invivo 6. A student's t-test and repeated-measures ANOVA statistics were used. A P value of less than 0.05 was considered statistically significant.

RESULTS

Thirty patients (14 males, 16 females) with a mean age of 40.01 ± 12.7 years (a range of 18.1-62.9 years) were included. On the tumor side, there were significant variances in the vertical and mediolateral condylar positions between the three-time points (T1, T2, T3). Immediately after the operation, the condyles were significantly displaced in a downward direction at T2, which became larger after the last follow-up period (T3) (p = 0.007). The condylar positions at the anteroposterior direction were relatively stable without significant differences between the three times points (p = 0.915). On the non-tumor side, the condylar positions were relatively stable in the mediolateral and anteroposterior positions. In the tumor side, all of the TMJ spaces were significantly increased in size following the mandibular reconstructions (T2 and T3). However, on the non-tumor side, the anterior, posterior, and medial joint spaces were significantly changed postoperatively.

CONCLUSION

After mandibular reconstruction with condylar preservation, the condylar position and volumetric measurement immediately changed noticeably and continued to be a permanent change over time compared to relatively stable condyles on the non-tumor side. According to Helkimo index, patients become adapted to the postoperative changes without significant differences between the two sides.

Changes in strain energy density in the temporomandibular joint disk after sagittal split ramus osteotomy using a computed tomography-based finite element model

PURPOSE

We evaluated the changes in the strain energy density (SED) in the temporomandibular joint (TMJ) disk after sagittal split ramus osteotomy (SSRO) at three time points. A finite element model (FEM) based on real patient-based computed tomography (CT) data was used to examine the effect of SSRO on the TMJ.

METHODS

Measurements of the condylar position and angulation in CT images and FEM analyses were performed for 17 patients scheduled to undergo SSROs at the following time points: before surgery, immediately after surgery, and 1 year after surgery. SED on the entire disk was calculated at each of the three time points using FEM. Furthermore, the relationship between individual SED values and the corresponding condylar position was also evaluated.

RESULTS

No significant change was observed in the condylar position at the three time points. The FEM analysis showed that SED was the highest and lowest immediately after and 1 year after surgery, respectively. A possible SED distribution imbalance between the left and right joints was improved 1 year after SSRO. Concerning the effect of fossa morphometry and condylar position, wide and deep glenoid fossae and a more posterior condylar position tended to show lower SED.

CONCLUSION

SED in the articular disk temporarily increased after surgery and significantly decreased 1 year after surgery compared with that before surgery. SSRO generally improved the imbalance between the left and right joints. Thus, SSRO, which improves maxillofacial morphology, may also improve components of temporomandibular disorders.

Systematic mapping review of orthognathic surgery

STUDY DESIGN

Systematic mapping review AIM AND SCOPE: The objective of this mapping review was to identify, describe, and organize clinical research currently available from systematic reviews and primary studies regarding co-interventions and different surgical modalities used in orthognathic surgery (OS) and their outcomes.

METHODS

Systematic reviews (SRs), randomized controlled trials, and observational studies that evaluated perioperative OS co-interventions and surgical modalities were identified in an exhaustive search of MEDLINE, EMBASE, Epistemonikos, Lilacs, Web of Science, and CENTRAL. Grey literature was also screened.

RESULTS

Included were 35 SRs and 253 primary studies, 103 from SRs, and another 150 identified in our search. Overall, SR quality was rated as critically low, with only two SRs rated as of high quality. 19 questions on population, interventions, comparisons, and outcomes (PICO) extracted from the SRs focused on osteosynthesis methods, surgical cutting devices, and use of antibiotics, corticosteroids, and induced hypotension. Also identified were 15 research gaps. Evidence bubble maps were created to graphically depict the available evidence.

CONCLUSION

Future high-quality research, both primary and secondary, is needed to address the knowledge gaps identified in this systematic mapping review.

Three-dimensional morphological and biomechanical analysis of temporomandibular joint in mandibular and bi-maxillary osteotomies

Orthognathic surgery is a typical approach for treating maxillofacial deformities. However, orthognathic surgery results in positional changes in the condyles. In a previous review, the effects of orthognathic surgery on temporomandibular joints (TMJs) are not provided. Hence, in this study, we investigate the morphological changes in TMJs after mandibular and bi-maxillary osteotomies. The relationship between the morphological parameters of TMJs and symptoms of temporomandibular disorders (TMDs) is discussed. Finite element contact stress analysis is performed, and the results show that the two abovementioned surgeries can improve maxillofacial deformities, although the positions of the condyles are changed. Moreover, preoperative stress asymmetry of the left and right TMJs is observed, which remain after the surgeries. TMD patient-specific analysis shows that three joint spaces (medial joint space, lateral joint space, superior joint space) are significantly correlated with TMD symptoms.

Positional changes of the mandibular condyle in unilateral sagittal split ramus osteotomy combined with intraoral vertical ramus osteotomy for asymmetric class III malocclusion

OBJECTIVES

In the present study, the effects of sagittal split ramus osteotomy (SSRO) combined with intraoral vertical ramus osteotomy (IVRO) for the treatment of asymmetric mandible in class Ⅲ malocclusion patients were assessed and the postoperative stability of the mandibular condyle and the symptoms of temporomandibular joint disorder (TMD) evaluated.

MATERIALS AND METHODS

A total of 82 patients who underwent orthognathic surgery for the treatment of facial asymmetry or mandibular asymmetry at the Department of Oral and Maxillofacial Surgery, Dong-A University Hospital, from 2016 to 2021 were selected. The patients that underwent SSRO with IVRO were assigned to Group I (n=8) and patients that received bilateral SSRO (BSSRO) to Group II (n=10, simple random sampling). Preoperative and postoperative three-dimensional computed tomography (CT) axial images obtained for each group were superimposed. The condylar position changes and degree of rotation on the superimposed images were measured, and the changes in condyle based on the amount of chin movement for each surgical method were statistically analyzed.

RESULTS

Group I showed a greater amount of postoperative chin movement. For the amount of mediolateral condylar displacement on the deviated side, Groups I and II showed an average lateral displacement of 0.07 mm and 1.62 mm, respectively, and statistically significantly correlated with the amount of chin movement (P=0.004). Most of the TMD symptoms in Group I patients who underwent SSRO with IVRO showed improvement.

CONCLUSION

When a large amount of mandibular rotation is required to match the menton to the midline of the face, IVRO on the deviated side is considered a technique to prevent condylar torque. In the present study, worsening of TMD symptoms did not occur after orthognathic surgery in any of the 18 patients.

Orthognathic Surgery of the Mandible

Orthognathic surgery performed in conjunction with orthodontic treatment is commonly performed to correct skeletal irregularities and realign the maxillomandibular relationship to improve occlusal function and facial esthetics. A thorough understanding of soft tissue esthetics, skeletal and occlusal relationships, and surgical techniques is required to obtain successful results. Surgical techniques have evolved greatly throughout history, as technological advances such as virtual surgical planning have become available and widely used to obtain predictable movements with minimized complications. The aim of this article is to review the orthognathic surgical procedures of the mandible, with particular attention to the indications, contraindications, preoperative assessment, surgical technique, and possible complications encountered.

Modified Intraoral C-Osteotomy

ABSTRACT

Repeated sagittal split osteotomy might impose an increased risk for damage of the inferior alveolar nerve. Another contemporary orthognathic issue is surgical management of malocclusion following condylar resorption. Here we describe a modified C-osteotomy technique as a proposed solution for these difficulties in orthognathic surgery. The modified C-osteotomy might induce less stress on the condyles reducing the risk for relapse subsequent to condylar resorption, as well as reduce the risk of inferior alveolar nerve damage.

The Anatomical Basis for Plate Fixation in BSSO to Minimize Condylar Torquing: A Comparative CT Study of Mandibular Advancement and Setback

Introduction

Condylar displacement after bilateral sagittal-split osteotomy (BSSO) occur in the sagittal plane as clockwise/counter-clockwise rotation of the ramus, in the coronal plane as medial/lateral inclination, or in the axial plane as medial/lateral condylar torquing. The purpose of this prospective CT study was to evaluate the role of plate fixation in minimizing condylar torquing or rotational changes in the axial plane.

Materials and Methods

This prospective study was carried out on 26 patients, 13 of whom underwent advancement BSSO and 13 setback BSSO, without maxillary LeFort I osteotomies. All mandibular movements were symmetrical. Fixation of the osteotomized segments was achieved with a single 4-hole plate and monocortical screws. In case of mandibular setbacks, a straight plate was used, whereas an inset-bent plate was used for advancements. Computed tomography scans were obtained preoperatively and postoperatively to measure condylar rotation or torqueing in the axial plane. An increase in condylar angle on axial slices was considered as lateral condylar torquing, whereas a decrease was considered as medial condylar torquing.

Results

A mean medial condylar torquing of 0.2° was noted postoperatively in case of setbacks (p > 0.05 not significant). This suggested minimal condylar torquing, indicating that the proximal and distal segments maintained contact at the anterior vertical osteotomy fixed with a straight plate. In case of advancements, a mean lateral condylar torquing of 2.2° was noted postoperatively (p < 0.005, highly significant). This suggested that the proximal segment flare at the anterior vertical osteotomy site was maintained by inset-bent plate fixation.

Conclusion

The gaps between the proximal and distal segments created by mandibular advancement and setback should be maintained. An attempt to close these gaps, especially in mandibular advancement, will result in an unfavourable axial condylar torque. Consequently, the areas of bony contact between the proximal and distal osteotomy sites created by mandibular advancement and setback should be maintained as well.

Maintaining the space between the mandibular ramus segments during bilateral sagittal split osteotomy does not influence the stability

BACKGROUND/PURPOSE

Three-dimensional computer-assisted orthognathic surgery allows to simulate the space between the mandibular ramus segments, i.e. intersegmental gap, for the correction of facial asymmetry. The purposes of the study were to estimate the screws- and mandible bone-related changes from the early postoperative period to the period after the debonding and to measure the association between the intersegmental gap volume and the screws- and mandible bone-related changes.

METHODS

This cone-beam computed tomography (CBCT)-assisted retrospective study assessed the stability of the bicortical positional screw fixations in maintaining the space between the mandibular ramus segments after bilateral sagittal split osteotomy in correction of 31 patients with malocclusion and facial asymmetry. The primary predictor variable was the CBCT-based intersegmental gap volume at early postoperative period (T1). The primary outcome variables were CBCT-based screws- and bone-related measurement changes between the T1 and T2 (at debonding) periods.

RESULTS

No significant differences were observed in screws-related linear and angular measurements between T1 and T2 virtual models. Some of mandible bone-related linear and angular measurements had significant differences (P < 0.05) between the T1 and T2 images, but with no clinical repercussion such as need of revisionary surgery. The gap volume and the screws- and bone-related changes had no significant correlations.

CONCLUSION

This study contributes to the multidisciplinary-related literature by demonstrating that the bicortical positional screws-based fixation technique in maintaining the three-dimensional-simulated space between the mandibular ramus segments is a stable and clinically acceptable option for correction of facial asymmetry associated with malocclusion, regardless of intersegmental gap size.

Differences of condylar changes after orthognathic surgery among Class II and Class III patients

BACKGROUND/PURPOSE

The nature of susceptibility to condylar resorption after orthognathic surgery can be different between skeletal Class II and Class III populations, which was addressed by few in the past. The aim of the present study was to use cone-beam computed tomographic (CBCT) images to investigate the displacement and morphological changes of temporomandibular joints (TMJs) in patients received orthodontic treatment combined with orthognathic surgery.

METHODS

Both Class III (n = 34) and Class II (n = 17) patients were compared through overall and regional superimpositions of the initial and posttreatment CBCTs. Two-sample t-test was used to identify significance between group differences. Pearson's correlation coefficient was used to address changes of TMJ and the amount of setback or advancement.

RESULTS

The axial ramal angle increased significantly in Class III group and decreased in Class II groups after orthognathic surgery (p < FDR_p). For condylar dimensions, significant widths and lengths reductions were noted only in Class II group. However, no significant difference was found after comparing subgroup differences according to one-jaw and two-jaw options, nor any significant correlation found between the condylar changes and the amount of surgical movements.

CONCLUSION

The nature of condylar susceptibility could result more from different skeletal patterns than the amount of surgical movements. However, the direction of mandibular surgery may contribute to different changes of condylar angle in axial section.

Evaluation of Condylar Positional, Structural, and Volumetric Status in Class III Orthognathic Surgery Patients

BACKGROUND AND OBJECTIVES

The need to evaluate the condylar remodeling after orthognathic surgery, using three-dimensional (3D) images and volume rendering techniques in skeletal Class III patients has been emphasized. The study examined condylar positional, structural, and volumetric changes after bimaxillary or single-jaw maxillary orthognathic surgeries in skeletal Class III patients using the cone-beam computed tomography.

MATERIALS AND METHODS

Presurgical, postsurgical, and one-year post-surgical full field of view (FOV) cone-beam computed tomography (CBCT) images of 44 patients with skeletal Class III deformities were obtained. Group 1 underwent a bimaxillary surgery (28 patients: 24 females and 4 males), with mean age at the time of surgery being 23.8 ± 6.0 years, and Group 2 underwent maxillary single-jaw surgery (16 patients: 8 females and 8 males), with mean age at the time of surgery being 23.7 ± 5.1 years. After the orthognathic surgery, the CBCT images of 88 condyles were evaluated to assess their displacement and radiological signs of bone degeneration. Three-dimensional (3D) condylar models were constructed and superimposed pre- and postoperatively to compare changes in condylar volume.

RESULTS

Condylar position was found to be immediately altered after surgery in the maxillary single-jaw surgery group, but at the one-year follow-up, the condyles returned to their pre-surgical position. There was no significant difference in condylar position when comparing between pre-surgery and one-year follow-up in any of the study groups. Condylar rotations in the axial and coronal planes were significant in the bimaxillary surgery group. No radiological signs of condylar bone degeneration were detected one year after the surgery. Changes in condylar volume after surgery were found to be insignificant in both study groups.

CONCLUSIONS

At one year after orthognathic surgery, there were no significant changes in positional, structural, or volumetric statuses of condyles.

A new 3D analysis on displacement of proximal segment after bilateral sagittal split osteotomy for class III asymmetry

OBJECTIVES

We aimed to quantify the displacement of the proximal segment after bilateral sagittal split osteotomy in patients with class III asymmetry and evaluate if the displacement was related to the movement of the distal segment.

MATERIAL AND METHODS

Forty adults with class III asymmetry corrected by bimaxillary surgery were studied. Cone-beam computed tomography taken before and 1 week after surgery was used to measure the displacement of proximal segments and movement of the distal segment in terms of translation and rotation. The relationship between the displacemnt of the proximal segment and the movement of the distal segment was evaluated.

RESULTS

After surgery, the deviated proximal segment was displaced forward and to the deviated side, rotated downward, tilted, and turned to the opposite side. The opposite proximal segment was displaced forward and rotated downward. The roll rotation of the proximal segment was correlated with the left/right movement and roll rotation of the distal segment.

CONCLUSION

Early after orthognathic correction for class III asymmetry, the deviated proximal segment was displaced in a direction favorable for correction of asymmetry. The roll rotation of the proximal segment was affected by the transverse movement and roll rotation of the distal segment.

CLINICAL RELEVANCE

Knowledge of the ability and limitation of the proximal segment rotation improves the virtual simulation.

Three-dimensional assessment of condylar position following orthognathic surgery using the centric relation bite and the ramal reference line: A retrospective clinical study

Orthognathic surgery (OGS) is a relatively common procedure for solving functional and aesthetic problems in facial and jaw areas in patients with dentofacial deformities. The positioning of the mandibular condylar segment during OGS has an impact on the surgical outcome. This study aimed to investigate the changes in the condyle-fossa relationship three dimensionally after OGS using the centric relation (CR) bite and the ramal reference line (RRL).Thirty-two patients with skeletal malocclusion underwent OGS. Condylar repositioning was performed using the CR bite, as previously reported. A RRL was added to the existing method and used during the surgery. Cone-beam computed tomography scans were acquired at 4 time points. Sixty-four condyles were evaluated in the coronal, sagittal, and axial views. Two groups were created according to the amount of mandible setback (SB1 vs SB2), and another 2 groups were created according to the maxillary operation (1-jaw vs 2-jaw). Each was then compared at the 4 time points. Differences between the values before (T0) and a year after surgery (T3) were also investigated. The positions of the pogonion and the menton were examined at T2 and T3 for the simple evaluation of relapse.The change in the condylar position was significant over a time-course (P < .001) but not between T0 and T3 (P > .05). Neither the setback amount nor the maxillary operation affected the positional change (P > .05). There were no significant changes between T2 and T3 in the relapse evaluation.This condylar repositioning method using the CR bite and a RRL showed stable results after OGS. This method is noninvasive and cost-effective and can be easily performed even by an inexperienced surgeon because it reduces errors in repositioning the condyle during OGS.

Computer-Aided Surgical Simulation for Yaw Control of the Mandibular Condyle and Its Actual Application to Orthognathic Surgery: A One-Year Follow-Up Study

Background: Favourable occlusal interdigitation and an optimized position of the mandibular condyle after surgery are essential for obtaining favourable results. The position of the condyle is determined during the operation. However, it is difficult to maintain the condyle’s original position post-surgery despite the efforts of the surgeons. Indeed, a degree of rotation of the condyle is unavoidable, since it is difficult to verify whether the condyle is positioned correctly during surgery. Purpose: To maximize contact between the bone segments, the condyle was rotated around the vertical axis using surgical simulations. We examined changes to the condyle-fossa relationship after comparing virtual surgery to actual surgery. Methods: From 2015 to 2017, 20 patients were diagnosed with skeletal malocclusion and participated in computer-aided surgical simulation before undergoing orthognathic surgery. In the simulation, the mandibular condyles were rotated around the vertical axis, and the proximal segments were fixed to the distal segments using a customized miniplate and positioning device during actual surgery. This study investigated the relationship between the condyle and fossa using cone-beam computed tomography for several different time periods (preoperative (T0), virtual surgery (Tv), postoperative three days (T1) and one year (T2)). Results: The coronal and sagittal view exhibited significant differences in the mean values between T1and T0, Tv, and T2 for all joint spaces. As a result of the distance, the mean value of T2 in both the superior joint space (JS) and the lateral JS was significantly higher than that of Tv. In contrast, the mean value of Tv in the medial JS was significantly higher than that of T2. Moreover, the mean value of T2 on the axial plane was significantly larger than the values of Tv and T1. The mean value of T0 was also significantly larger than those of Tv and T1, and the mean value of Tv was larger than that of T1. Although the condyle was rotated, it exhibited a tendency to return to its preoperative position. There was no statistically significant difference in functional evaluation between T0 and T2. Conclusion: Our method of using yaw control for the condyle during virtual surgery and transferring this technique to the actual surgery can improve the conventional surgical technique by positioning the proximal segment in a pre-planned position, thus achieving optimal results.

WITHDRAWN: Treatments for adults with prominent lower front teeth

BACKGROUND

Prominent lower front teeth may be associated with a large or prognathic lower jaw (mandible) or a small or retrusive upper jaw (maxilla). Edward Angle, who may be considered the father of modern orthodontics, classified the malocclusion in this situation as Class III. The individual is described as having a negative or reverse overjet as the lower front teeth are more prominent than the upper front teeth.

OBJECTIVES

The purpose of this systematic review was to evaluate different treatments of Angle Class III malocclusion in adults.

SEARCH METHODS

The following databases were searched: Cochrane Oral Health Group Trials Register (to 22 March 2012); CENTRAL (The Cochrane Library 2012, Issue 1); MEDLINE via OVID (1950 to 22 March 2012); EMBASE via OVID (1980 to 22 March 2012); LILACs (1982 to 22 March 2012); BBO (1986 to 22 March 2012); and SciELO (1997 to 22 March 2012).

SELECTION CRITERIA

All randomized or quasi-randomized controlled trials of treatments for adults with an Angle Class III malocclusion were included.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the eligibility of the identified reports. Two review authors independently extracted data and assessed the risk of bias in the included studies. The mean differences with 95% confidence intervals were calculated for continuous data.

MAIN RESULTS

Two randomized controlled trials were included in this review. There are different types of surgery for this type of malocclusion but only trials of mandible reduction surgery were identified. One trial compared intraoral vertical ramus osteotomy (IVRO) with sagittal split ramus osteotomy (SSRO) and the other trial compared vertical ramus osteotomy (VRO) with and without osteosynthesis. Neither trial found any difference between the two treatments. The trials did not provide adequate data for assessing effectiveness of the techniques described.

AUTHORS' CONCLUSIONS

There is insufficient evidence from the two included trials, to conclude that one procedure is better or worse than another. The included trials compared different interventions and were at high risk of bias and therefore no implications for practice can be given. Further high quality randomized controlled trials with long term follow-up are required.

Study of condylar positional changes after sagittal split osteotomy for mandibular advancement: A prospective cohort study

PURPOSE

To analyse the possible morphologic and positional changes of the mandibular condyles after orthognathic surgery.

MATERIAL AND METHODS

A prospective cohort study was performed. Patients with mandibular retrognathism were surgically treated to advance the mandible. The study group included seventeen patients (34 condyles) treated with sagittal split osteotomies alone (4 patients) or in combination with maxillary osteotomies (13 patients). Only condyles located on the mandibular side that advance during surgery were studied, therefore only 25 condyles entered this prospective study. Beside it, a group of 6 patients undergoing maxillary surgery as only procedure, maxillary group, was also studied to determinate the influence of maxillary surgery on condylar displacement. Computed tomographies and lateral cephalometric radiographs were performed two weeks before surgery and one year after the surgical procedures. Different variables which analyse the position and morphology of the mandible were studied. The data obtained were analysed statistically by computing R2 values.

RESULTS

In the maxillary group they were small displacements in magnitude and not significant. In the study group, 8 condyles showed morphological changes with alteration on reference points. In the remainder 17 condyles different displacements were noted after surgery. Several of these positional changes were predictable and did not affect postoperative mandibular stability.

CONCLUSIONS

condylar displacements that occur after sagittal split osteotomies for mandibular advancement show significant correlation with the degree of mandibular advancement and can be defined by mathematical formulae. Maxillary osteotomies do not seem to influence condylar position when bimaxillary procedures take place.

Cone-beam computed tomography evaluation on the changes in condylar long axis according to asymmetric setback in sagittal split ramus osteotomy patients

OBJECTIVE

To determine whether the condylar rotation is affected by asymmetric setback in patients undergoing sagittal split ramus osteotomy.

MATERIALS AND METHODS

Thirty patients who underwent bilateral sagittal split ramus osteotomy setback surgery were divided into the two groups, symmetric setback and asymmetric setback, according to the right/left difference of setback amount (<2.0, ≥2.0 mm). Condylar long axis changes were evaluated using the three-dimensional superimposition of before and immediately after surgery cone-beam computed tomography volume images. Evaluations were performed separately in lesser setback and greater setback side in patients undergoing asymmetric setback, whereas both side condyles were evaluated together in patients undergoing symmetric setback. Condylar axis changes on axial view were correlated with setback amount or right/left setback difference using Pearson correlation analysis.

RESULTS

In general, the condylar axis change occurred in a pattern of inward rotation. The condyles in patients undergoing symmetric setback showed 3.4° rotation in average. In case of asymmetric setback, the lesser setback side showed larger value (4.3°) than the greater setback side (2.3°) with a statistical significance. In the correlation analysis, setback amount showed no significant correlation with the condylar axis changes in both groups. However, correlation with right/left setback difference showed a positive correlation in lesser setback side of patients undergoing asymmetric setback.

CONCLUSION

The findings of this study indicate that large amount of setback alone does not contribute to the change in condylar long axis, but asymmetric setback might cause a change in condylar long axis, particularly on the lesser setback side.

Changes in condylar position after BSSRO with and without Le Fort I osteotomy via surgery-first approach in mandibular prognathism with facial asymmetry

OBJECTIVES

This study aimed to evaluate changes in condylar position after bilateral sagittal split ramus osteotomy (BSSRO) with and without Le Fort I osteotomy via the surgery-first approach (SFA) in patients with facial asymmetry.

STUDY DESIGN

Eighteen patients (36 condyles) who received surgical-orthodontic treatment using the SFA were included and divided into 2 groups depending on the extent of surgery: BSSRO-only group (n = 12) and BSSRO with Le Fort I osteotomy group (n = 6). Using computed tomography images taken preoperatively, immediately postoperatively, and 6 months postoperatively, surgical and postoperative changes of the condylar position were analyzed 3-dimensionally.

RESULTS

Both groups showed mainly inferolateral displacement with inward rotation immediately after surgery, and superomedial returning movement with outward rotation 6 months after surgery. There was no statistical difference in time-course changes of the condylar position between the 2 groups. In comparing the deviated and nondeviated sides, the deviated side showed significantly greater amount of bodily shift and rotational movement after surgery compared with the nondeviated side in both groups.

CONCLUSIONS

These results suggest that BSSRO via the SFA, either with or without Le Fort I osteotomy, may cause condylar displacement after surgery and that the displaced condyles return to their original position on both the deviated and the nondeviated sides.

Complications associated with orthognathic surgery

While most patients undergo orthognathic surgery for aesthetic purposes, aesthetic improvements are most often followed by postoperative functional complications. Therefore, patients must carefully decide whether their purpose of undergoing orthognathic surgery lies on the aesthetic side or the functional side. There is a wide variety of complications associated with orthognathic surgery. There should be a clear distinction between malpractice and complications. Complications can be resolved without any serious problems if the cause is detected early and adequate treatment provided. Oral and maxillofacial surgeons must have a full understanding of the types, causes, and treatment of complications, and should deliver this information to patients who develop these complications.

Clinical and radiographic evaluation of a computer-generated guiding device in bilateral sagittal split osteotomies

The bilateral sagittal split osteotomy (BSSO) is one of the main orthognathic surgery procedures used for managing skeletal mandibular excess, deficiency or asymmetry. It is known to be a technique-sensitive procedure with high reported incidences of inferior alveolar nerve injury, bad splits and post-surgical relapse. With the increasing use of computer-assisted techniques in orthognathic surgery, the accurate transfer of the virtual plan to the operating room is currently a subject of research. This study evaluated the efficacy of computer-generated device at maintaining the planned condylar position and minimizing inferior alveolar nerve injury during BSSO. The device was used in 6 patients who required isolated mandibular surgery for correction of their skeletal deformities. Clinical evaluation showed good recovery of the maximal incisal opening and a reproducible occlusion in 5 of the 6 patients. Radiographic evaluation showed better control of the condyle position in both the vertical and anteroposterior directions than in the mediolateral direction. The degree of accuracy between the planned and achieved screw positions were judged as good to excellent in all cases. Within the limitations of this study and the small sample size, the proposed device design allowed for good transfer of the virtual surgical plan to the operating room.

Treatments for adults with prominent lower front teeth

BACKGROUND

Prominent lower front teeth may be associated with a large or prognathic lower jaw (mandible) or a small or retrusive upper jaw (maxilla). Edward Angle, who may be considered the father of modern orthodontics, classified the malocclusion in this situation as Class III. The individual is described as having a negative or reverse overjet as the lower front teeth are more prominent than the upper front teeth.

OBJECTIVES

The purpose of this systematic review was to evaluate different treatments of Angle Class III malocclusion in adults.

SEARCH METHODS

The following databases were searched: Cochrane Oral Health Group Trials Register (to 22 March 2012); CENTRAL (The Cochrane Library 2012, Issue 1); MEDLINE via OVID (1950 to 22 March 2012); EMBASE via OVID (1980 to 22 March 2012); LILACs (1982 to 22 March 2012); BBO (1986 to 22 March 2012); and SciELO (1997 to 22 March 2012).

SELECTION CRITERIA

All randomized or quasi-randomized controlled trials of treatments for adults with an Angle Class III malocclusion were included.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the eligibility of the identified reports. Two review authors independently extracted data and assessed the risk of bias in the included studies. The mean differences with 95% confidence intervals were calculated for continuous data.

MAIN RESULTS

Two randomized controlled trials were included in this review. There are different types of surgery for this type of malocclusion but only trials of mandible reduction surgery were identified. One trial compared intraoral vertical ramus osteotomy (IVRO) with sagittal split ramus osteotomy (SSRO) and the other trial compared vertical ramus osteotomy (VRO) with and without osteosynthesis. Neither trial found any difference between the two treatments. The trials did not provide adequate data for assessing effectiveness of the techniques described.

AUTHORS' CONCLUSIONS

There is insufficient evidence from the two included trials, to conclude that one procedure is better or worse than another. The included trials compared different interventions and were at high risk of bias and therefore no implications for practice can be given. Further high quality randomized controlled trials with long term follow-up are required.