The role of a posteriorly inclined condylar neck in condylar resorption after orthognathic surgery

Conservative and minimally invasive approaches to control idiopathic condylar resorption: a scoping review

Idiopathic condylar resorption (ICR) is an uncommon disease with multiple names that challenges orthodontic and surgical treatments. The aim of this study was to investigate the existing conservative and minimally invasive approaches to controlling ICR. A scoping literature review was conducted. Inclusion criteria were young patients with degenerative joint disease based on the Research Diagnostic Criteria for Temporomandibular Disorders or Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) protocols, or ICR based on the DC/TMD expanded taxonomy protocol. Six electronic databases and the grey literature were searched, without restriction on year or language. Two reviewers independently performed the study selection and data extraction. Ten studies were selected from the 13,953 records identified. The total sample size was 424 patients; the female-to-male ratio was 7:1 and the mean age of the patients was 25.7 years. The main primary outcomes were pain, mandibular dysfunction, and condylar resorption. There is no guarantee of definitive success in the early management of ICR, despite the promising approaches studied, and there is no specific protocol to be followed. Therefore, close post-surgical follow-up is still required. This study highlights the need to standardize the nomenclature and diagnostic criteria, and assess the status of condylar activity/severity in future research.

Global network mapping research findings on orthognathic surgery and temporomandibular disorder

OBJECTIVES

The objective of this work is to assess the relationship between orthognathic surgery and temporomandibular disorders literature through a bibliometric analysis.

METHODS

A bibliographic search in line with the STROBE guidelines and the concepts of the Leiden Manifesto was performed on the Web of Science using the terms orthognathic surgery AND temporomandibular. A citation analysis and establishment of the more cited articles were performed. A graphical representation of the keywords was created with VOSviewer.

RESULTS

A total of 810 articles were analyzed in this study. The research revealed a significant increase in publications on this topic, particularly in English language articles and a high H-index. The publications represented 55 nations, with the highest number of articles coming from the USA. The discussion of highly cited articles covered various aspects such as the relationship between orthognathic surgery and TMD, including condylar resorption or displacement, predisposing factors, dentoskeletal and occlusion patterns, anatomical factors, osteotomy techniques, condylar positioning techniques, and emerging technologies for improved TMJ stability.

CONCLUSION

The analysis reveals an increasing research interest in this field, with a significant number of publications in English and a high citation rate per article, indicating the impact of the research. Various factors associated with TMD in orthognathic surgery are explored, including condylar alterations, predisposing factors, occlusion patterns, and surgical techniques. The study underscores the importance of thorough assessment, treatment, and monitoring of TMD in orthognathic surgery patients, while acknowledging the need for further research and consensus in management strategies.

Effect of the magnitude of condylar head displacement on the TMJ function in skeletal class II patients undergoing different degrees of mandibular advancement: A retrospective comparative study

PURPOSE

This study aimed to compare the condylar head displacement (CHD) after bilateral sagittal split ramus osteotomy (BSSO) between different degrees of mandibular advancement in skeletal class II patients and to evaluate whether the temporomandibular joint (TMJ) function would be affected.

PATIENTS AND METHODS

Fifty-nine patients (118 condyles) were included in this retrospective study and were divided into three groups based on the distance of mandibular advancement. The CHD in three directions, x (sagittal direction), y (coronal direction), and z (axial direction), was measured before operation (T0), immediately after operation (T1), and at least 6 months after operation (T2), and the TMJ function of patients was followed up and scored using the Helkimo index system. All the abovementioned data were statistically analyzed, and p < 0.05 was considered the statistical difference standard.

RESULT

During the BSSO surgery, the condyle was predominantly displaced in a lateral, posterior, and superior direction whenever in T1 and T2, even though the degree of CHD was different. Regarding the amount of CHD, the large advancement group was higher than the other two groups in T1 and T2 (p＜0.01). The Helkimo index scores of the three groups were evaluated, and there was no significant statistical difference between the Ai and Di index of the three groups.

CONCLUSION

In our center, CHD occurred in lateral, posterior, and superior directions following mandibular advancement in skeletal class II patients, with a positive correlation between the CHD and the mandibular advancement; however, the TMJ function of the three groups did not show significant differences.

Condylar positional changes and remodeling following bimaxillary anterior segment osteotomy with and without Le Fort I osteotomy: a three-dimensional comparative analysis

OBJECTIVE

To evaluate 3D condylar displacement and long-term remodeling following the correction of bimaxillary protrusion by anterior segment osteotomy (ASO) with and without Le Fort I surgery.

MATERIALS AND METHOD

This retrospective study included 32 adults with bimaxillary protrusion who underwent ASO alone (group 1) or with concomitant Le Fort I osteotomy (group 2). Subject's computed tomography scans at basic (T0), immediate postoperatively (T1), and at 1 year or more follow-up (T2) were collected. The condyle displacement was measured at superior-inferior, lateromedially, and anteroposterior surfaces, while condyle remodeling was measured at the superior, lateral, anterior, medial, and posterior surfaces. All 3D analyses were performed using 3D Slicer software (4.11.2).

RESULTS

At T1, 52.7%, 86.7%, and 94.4% of condyles in group 1 were displaced inferiorly, laterally, and posteriorly, respectively, as well as 75%, 89.2%, and 53.5% of condyles in group 2, which had not fully returned to the original preoperative positions at T2. Condylar remodeling was observed in both groups at T2, and no significant difference was found in the overall condylar volume between T1 and T2 in both groups. Patients in group 2 exhibited significant bone resorption at both lateral and anterior surfaces compared to group 1 (P = 0.000 and 0.01, respectively).

CONCLUSION

This study's results demonstrated that ASO is associated with a degree of condylar changes even if the posterior mandible is not osteomized. The positional changes vary between bimaxillary ASO alone and those with simultaneous Le Fort I osteotomy. However, both groups' condyle volume remained stable at the long-term follow-up.

Controversial Aspects of Diagnostics and Therapy of Idiopathic Condylar Resorption: An Analysis of Evidence- and Consensus-Based Recommendations Based on an Interdisciplinary Guideline Project

Idiopathic condylar resorption (ICR), though a rare event, is associated with severe detrimental sequelae for the patient. To date, the etiology remains unknown, and treatment strategies are highly controversial. Therefore, the aim of this study is to present an analysis of the consensus- and evidence-based approach to ICR by a German interdisciplinary guideline project of the AWMF (Association of the Scientific Medical Societies in Germany). Following a systematic literature search, including 56 (out of an initial 97) publications, with a predominantly low level of evidence (LoE), two independent working groups (oral and maxillofacial surgery and interdisciplinary, respectively) voted on a draft comprising 25 recommendations in a standardized anonymized and blinded Delphi procedure. While the results of the votes were relatively homogeneous, the interdisciplinary phase required a significantly higher number of rounds (p < 0.001). Most of the controversial recommendations were related to initial imaging (with consensus on CT/CBCT as the current diagnostic standard for imaging), pharmacotherapy (no recommendation due to lack of evidence), discopexy (no recommendation possible due to low LoE) and timing of orthognathic surgery (with consensus on two-staged procedures after invasive TMJ surgery, except for single-stage procedures if combined with total joint reconstruction). Overall, the Delphi procedure resulted in an interdisciplinary guideline offering the best possible evidence- and consensus-based expertise to date in the diagnosis and treatment of ICR.

Modeling the effect of bilateral sagittal split osteotomy on posterior, superior and medial space dimensions of the temporomandibular joint: a retrospective controlled cohort study

BACKGROUND

To model the effect of isolated bilateral sagittal split osteotomy (BSSO) on changes in posterior (PSD), superior (SSD), and medial space dimensions (MSD) of the temporomandibular joint.

METHODS

Using a retrospective cohort study design, pre- and postoperative (immediately after surgery; 1 year follow-up) cone-beam computed tomography measurements of 36 patients who had undergone BSSO for mandibular advancement were compared with a control group of 25 subjects from whom a mandibular odontogenic cyst was removed under general anesthesia. Generalized estimation equation (GEE) models were used to examine the independent effects of study group, preoperative condylar position, and time points on PSD, SSD, and MSD adjusting for covariates (age, sex, and mandibular advancement).

RESULTS

No significant differences were found regarding changes in PSD (p = 0.144), SSD (p = 0.607), or MSD (p = 0.565) between the BSSO and control groups. However, the preoperative posterior condylar position showed significant effects on PSD (p < 0.001) and MSD (p = 0.043), while the preoperative central condylar position demonstrated a significant effect on PSD (p < 0.001).

CONCLUSION

The data suggest that preoperative posterior condylar position is a significant effect modifier of PSD and MSD over time in this cohort.

Analysis of micrognathia with obstructive sleep apnea syndrome improved by a combination of Le Fort I with horseshoe osteotomies, mandibular distraction osteogenesis, and genioplasty

The relationship between microgenia and obstructive sleep apnea syndrome is well known. 27-year-old woman. She underwent a combination of Le Fort I with horseshoe osteotomies and mandibular distraction osteogenesis and genioplasty. She was satisfied with the aesthetics of her face, with an AHI of 7.8/h.

Condylar resorption following mandibular advancement or bimaxillary osteotomies: A systematic review of systematic reviews

Several systematic reviews have been published on the effects of mandibular surgery on condylar remodeling without reaching a consensus. The purpose of this systematic review of systematic reviews was to assess the impact of mandibular advancement or bimaxillary surgeries on condylar resorption. A literature search, using several electronic databases, was carried out by two reviewers independently. Article preselection was based on titles and abstracts, and final article selection based on full-text analysis of preselected studies. After final study selection, the quality of studies was assessed using the AMSTAR 2 tool. A decision algorithm was subsequently established to choose the best body of evidence. From an initial yield of 1'848 articles, 23 systematic reviews were identified for further analysis, with ten studies being included in the final selection. Despite the generally low quality of the reviews, certain associations could be made: young patients, female patients, and those with a high mandibular plane angle are more prone to condylar resorption following mandibular advancement osteotomies, especially if anterior rotation of the mandible is performed during surgery. Patients undergoing bimaxillary surgery also appear to have a higher risk of developing condylar resorption. In conclusion, these results confirm the multi-factorial nature of condylar resorption, stressing the need for well-controlled prospective studies with long-term follow-up to clearly identify potential risk factors associated with orthognathic surgery.

Examination of factors affecting condylar bone changes following surgical-orthodontic treatment

OBJECTIVE

To identify factors affecting condylar bone changes following surgical-orthodontic treatment.

METHODS

A total of 200 patients with dentofacial deformities were classified into skeletal Classes I, II, and skeletal Class III groups consisting of 61 and 139 subjects, respectively. Temporomandibular joints (TMJs) were evaluated using clinical findings and computed tomography images before treatment, immediately before surgery, and 6 months after surgery.

RESULTS

Condylar bone changes occurred at a significantly higher rate after surgery in both groups. Factors related to condylar bone changes following surgical-orthodontic treatment included skeletal Class I or II, disc displacement, and condylar bone changes before treatment. There were three cases with condylar bone changes after surgery that were diagnosed with condylar resorption and skeletal Class II and anterior disc displacement before surgery.

CONCLUSION

Condylar resorption could occur when the load on the condyle increases after orthognathic surgery and exceeds the permissible limit.

Long-term three-dimensional condylar remodeling during presurgical orthodontics and after orthognathic surgery of mandibular retrognathia with high mandibular plane angle

OBJECTIVES

Patients with high mandibular plane facial morphology are the most dominant facial type who experience TMJ abnormalities with resultant condylar resorption, affecting the orthodontic and orthognathic treatment outcomes. The study aimed to quantitatively assess the three-dimensional condylar remodeling during the presurgical orthodontics and after orthognathic surgery of the retrognathic mandible with a high mandibular plane angle. The study also investigated the correlation between the resultant remodeling based on the hypothesis that condylar resorption following orthognathic surgery is a part of a progressive presurgical resorption process.

MATERIALS AND METHODS

The study included adults with mandibular retrognathism and high mandibular plane angle who have computed tomography scans (CT) obtained before any treatment (T0), after completion of presurgical treatment before surgery (T1), and at long-term follow-up after surgery (T2). DICOM of CT scan was gathered and processed using ITK-SNAP and 3D Slicer software. The interval between T0 and T1 was represented as a presurgical phase, while between T1 and T2 was defined as a postsurgical phase (T1-T2).

RESULTS

Twenty-five patients (50 condyles) were included with a mean age of 23 ± 3.2 years. The mean of the follow-up during the presurgical phase was 19.8 ± 7.1 months and 15.5 ± 5.5 months during the postsurgical phase. The condylar volume during the presurgical phase (T0-T1) was relatively stable (- 3.3 ± 37.2mm³). However, during the postsurgical phase (T1-T2), the volume was significantly reduced - 113.8 ± 98.3mm³ (P < 0.001). Localized condylar surface resorption during the postsurgical phase was significantly higher than during the presurgical phase (P < 0.05). No correlation was found between the localized condylar surface remodeling during the presurgical and postsurgical phases. However, a negative statistically significant correlation existed between the overall condylar volume changes during the presurgical and postsurgical phases (r = 0.502, P < 0.001).

CONCLUSION

Significant condylar resorption following orthognathic surgery of the retrognathic mandible with a high mandibular plane angle might occur regardless of the presurgical status of the condyle.

CLINICAL RELEVANCE

The study provided an evidence to be discussed with the patients and considered throughout the treatment of mandibular retrognathia with high mandibular plane angle.

Signs and Symptoms of Temporomandibular Dysfunction and Radiographic Condylar Morphology in Patients with Idiopathic Condylar Resorption

Background: Little is known about the clinical characteristics of idiopathic condylar resorption (ICR). The aim of this study was to examine the signs and symptoms of temporomandibular dysfunction (TMD) and evaluate the morphological characteristics of the condyles in patients with ICR. Methods: Sixty patients with ICR (41 in the bilateral ICR group and 19 in the unilateral ICR group) and forty-one healthy controls were examined. Signs and symptoms of TMD were described, and three-dimensional models of the condyles were measured and analyzed. Results: In total, 81.7% of ICR patients had self-reported symptoms and 78.3% of ICR patients had objective-found signs. The anteroposterior diameter, transverse diameter, height, maximal sectional area, volume of the condyles, axial angle, and the distance from the posterior point of the condyle to the Saggittal standard line were significantly smaller in the ICR condyles compared with the controls (p < 0.05). The condylar neck angle was significantly larger in the ICR condyles compared with the controls (p < 0.05). Conclusions: Most patients with ICR had signs and symptoms of TMD. The prevalence of clicking and opening−closing deviation was significantly different between the bilateral and the unilateral ICR groups. In patients with ICR, the size of the condyles decreased significantly; the condyles also rotated inward, moved forward, and inclined posteriorly.

[Condylar displacement following orthognathic surgery]

The overview of the current literature in the research of mandibular condyle displacement after orthognathic surgeries was done. The correct postoperative mandibular condyle position is considered as one of the determinants of the stability of treatment results.

Treatment of severe mandibular deficiency following TMJ ankyloses by distraction osteogenesis and orthodontic treatment with microimplants

Severe mandibular deficiency caused by temporomandibular joint (TMJ) ankyloses produces functional and aesthetic problems that require complicated long-term treatment. In this case report, we describe the benefits of using microimplant mechanics for controlling the direction of distraction during distraction osteogenesis and for performing the movement of teeth. We also present its remarkable results and long-term stability. A 20-year-old girl presented with a convex profile due to severe mandibular retrognathia after a history of several TMJ surgeries for bilateral TMJ ankyloses. Mandibular distraction osteogenesis (MDO) was performed, and elastics were placed between the microimplants to control the direction of distraction. Subsequently, after retraction of the maxillary anterior teeth and distalisation of the whole mandibular dentition, the facial profile was markedly improved, and good interdigitation was obtained. The six-year follow-up retention and overall stability were satisfactory with good interdigitation and jaw function.

Short-Term Stability After Segmental Le Fort I Maxillary Impaction Surgery With Mandibular Autorotation in Seven High-Angle Class II Patients: A Case Series

PURPOSE

To retrospectively evaluate skeletal stability after Le Fort I maxillary impaction surgery and mandibular autorotation without bilateral sagittal split osteotomy (BSSO) in high-angle class II patients.

MATERIALS AND METHODS

Seven female high-angle class II patients who underwent maxillary impaction surgery and mandibular autorotation without bilateral sagittal split osteotomy were included in this study. Surgical changes and relapse were measured on lateral cephalograms taken preoperatively and at 1 month, 6 months and 1 year postoperatively.

RESULTS

The horizontal movement of the maxilla at point A was 5.8 ± 3.3 mm backward, and the upward movement at the posterior nasal spine was 3.3 ± 1.4 mm. The mean horizontal change at point A during the 1-year follow-up period was 0.1 ± 0.2 mm, and the vertical change at posterior nasal spine was 0.2 ± 1.3 mm, which were not statistically significant. The horizontal surgical change at point B was 4.0 ± 1.8 mm forward and the vertical surgical change at point B was 4.7 ± 1.8 mm upward. Postoperative relapse was 10.9% and 13.7% in the horizontal and vertical directions, respectively.

CONCLUSIONS

Le Fort I maxillary impaction surgery with mandibular autorotation may be 1 of the suitable procedures for high-angle class II patients.

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.

Changes in Condylar Position Within 12 Months After Bilateral Sagittal Split Ramus Osteotomy With and Without Le Fort I Osteotomy by Using Cone-Beam Computed Tomography

PURPOSE

This study aimed to evaluate the condylar position changes in 12 months after bilateral sagittal split ramus osteotomy (BSSO) with and without a Le Fort I osteotomy in patients with Class III malocclusion and the influence of the 2 surgical approaches on the condylar position.

METHODS

In this prospective cohort study, patients with skeletal Class III malocclusion who underwent orthognathic surgery between 2017 and 2019 were included. The main predictive variable is the effect of increasing Le Fort I osteotomy on condyle position, which is divided into BSSO-only group and BSSO + Le Fort I osteotomy group. The main outcome variables were the displacement of the condylar head and the rotation/inclination of the condylar long axis before and after surgery. Other study variables were according to the degree of asymmetry of the left and right side of the mandible, the measured values of both sides were divided into mandibular deviation and nondeviation. The cone-beam volumetric imaging images were obtained before surgery (T1) and immediately after surgery (T2), 3 months (T3), 6 months (T4), and 12 months (T5) after surgery by computerized tomography (CT). One-way ANOVA and Tukey test was used for correlation analysis. The p-value is set to 0.05.

RESULTS

Twenty-four adult patients diagnosed with skeletal Class III malocclusion were included in this study, 12 patients (male/female = 6:6, mean age 21.8 years) who underwent BSSO + Le Fort I osteotomy and 12 patients (male/female = 6:6, mean age 19.8 years) who underwent BSSO-only. The position of the bilateral condylar head in both surgery groups was adjusted continuously during the 12 months after the operation. Immediately and 12 months after surgery, both sides of the condylar long axis in the BSSO with Le Fort I osteotomy group and the BSSO-only surgery group rotated inward, tilted forward, and tilted inward. In the BSSO with Le Fort I osteotomy group, the rotation and tilt angle changes of the condylar long axis on both sides were stable 6 months after surgery.

CONCLUSIONS

The addition of Le Fort I osteotomy did not significantly change the rotation and tilt direction of the condylar long axis and could accelerate the stability of the condylar long axis after BSSO surgery.

Long-term stability and condylar remodeling after mandibular advancement: A 5-year follow-up

INTRODUCTION

This study evaluated whether presurgical characteristics, the magnitude of mandibular advancement, and changes in mandibular plane angle are correlated with long-term stability and postsurgical condylar remodeling and adaptations using 3-dimensional imaging.

METHODS

Forty-two patients underwent bilateral sagittal split osteotomies for mandibular advancement using rigid fixation. Cone-beam computed tomography (CBCT) scans were acquired before surgery (T1), immediately after surgery (T2), and at long-term follow-up (T3). The average follow-up period was 5.3 ± 1.7 years after surgery. Anatomic landmark identification on the cone-beam computed tomographies and subsequent quantification of the changes from T1 to T2 and T2 to T3 were performed in ITK-SNAP (version 2.4; itksnap.org) and 3DSlicer (version 4.7; http://www.slicer.org) software. Surgical displacements, mandibular plane angle changes, and skeletal stability were measured relative to cranial base superimposition, whereas condylar remodeling was measured relative to regional condylar registration. Partial correlation coefficients were used to assess relationships between clinical and surgical variables, condylar remodeling, and long-term surgical relapse while controlling for variability in the length of follow-up.

RESULTS

B-point relapsed more than 2 mm posteriorly in 55% of the patients. The only variables strongly associated with the posterior movement of B-point long-term were mesial yaw of the condyle during surgery (P ≤0.01) and the length of follow-up from T2 to T3 (P ≤ 0.01). There was no relationship between the magnitude of advancement or presurgical mandibular plane angle and relapse or condylar resorption. Condylar resorption was strongly associated with relapse of B-point in the posterior direction (P ≤0.01) and clockwise rotation of the mandibular plane long-term (P ≤0.01). Twenty-nine percent of subjects showed resorption of more than 2 mm in the inferior direction at the lateral pole, and 17% of the subjects showed resorption of more than 2 mm in the inferior direction at condylion. Compared with male subjects, females exhibited significantly greater condylar remodeling (P ≤0.01) and slightly greater relapse at B-point (P ≤0.05).

CONCLUSIONS

Surgical relapse at B-point may occur slowly over time and is primarily due to condylar resorption in mandibular advancement patients. Mesial yaw of the condyle during surgery may lead to condylar resorption postsurgically. In addition, females are at greater risk of condylar resorption postsurgically.

Computed tomography assessment of mandibular morphologic changes and the inferior mandibular border defect after sagittal split ramus osteotomy

OBJECTIVE

This study aimed to assess mandibular morphologic changes to the condyle, ramus, mandibular body, and inferior mandibular border defect after sagittal split ramus osteotomy in class II and III patients.

STUDY DESIGN

The relationships among the condyle, ramus, and mandibular body measured by computed tomography preoperatively and postoperatively were assessed and factors related to the reduction of the condylar square and mandibular inferior border defect were examined.

RESULTS

Patients included 72 female patients with jaw deformity (36 skeletal class II cases, 36 skeletal class III cases). Postoperative reduction of the condylar square was significantly correlated with preoperative condylar height in patients with class II (P = .0297) vs preoperative condylar height and preoperative mandibular height in patients with class III (P < .0001). A mandibular inferior border defect was found in 18 of 72 class II sides (25.0%) and was significantly related to the position of the osteotomy line and attachment side of the inferior border cortex (P < .0001).

CONCLUSIONS

This study's findings suggest that the postoperative reduction of the condyle could be associated with preoperative condylar height. However, the mandibular inferior border defect in class II advancement surgery could be independently associated with technical factors in sagittal split ramus osteotomy.

Evaluation of condylar surface CT values related to condylar height reduction after orthognathic surgery

This study was performed to evaluate the relationship between condylar height reduction and changes in condylar surface computed tomography (CT) values in jaw deformity patients following orthognathic surgery. Mandibular advancement by sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy was performed in class II patients, and mandibular setback by SSRO with Le Fort I osteotomy was performed in class III patients. The maximum CT values (pixel values) at five points on the condylar surface and the condylar height, ramus height, condylar square, ramus angle, and gonial angle in the sagittal plane were measured preoperatively and 1 year postoperatively. Disc position was classified as anterior disc displacement (ADD) or other types by using magnetic resonance imaging (MRI). Ninety-two condyles of 46 female patients were prepared for this study. Their temporomandibular joints (TMJs) were divided into two groups based on class (46 joints in class II and 46 joints in class III) and two groups based on the findings (25 joints with ADD and 67 joints with other findings). ADD with and without reduction was observed in two joints in the class III group and in 23 joints in the class II group. The distribution of ADD incidence had not changed 1 year after surgery. Condylar height decreased 1 year after surgery in both class II patients (mandibular advancement) (p < 0.0001) and class III patients (mandibular setback) (p = 0.0306). Similarly, condylar height decreased 1 year after surgery both in patients who showed ADD (p = 0.0087) and those with other types (p = 0.0023). Significant postoperative increases at all angle sites on the condylar surface were found in the class II (p < 0.05) and ADD (p < 0.05) groups. This study showed that an enhanced condylar surface CT value might be one sign of condylar height reduction related to sequential condylar resorption, in combination with ADD.

Outcomes of treatment with genioplasty and temporomandibular joint anchorage surgery

BACKGROUND

Anterior Disc Displacement without Reduction (ADDwoR) in adolescence can result in condylar resorption which produces mandibular retrusion/deviation (MR/D) in adulthood. This study aims to analyze the therapeutic effect of simultaneous genioplasty and temporomandibular joint (TMJ) anchorage surgery on ADDwoR with MR/D patients.

METHODS

During 2016-2018, ADDwoR with MR/D cases were included and underwent TMJ anchorage surgery and genioplasty guided by digital design. Pre-/Post-surgical clinical manifestations, facial photography, radiographic data, facial shape satisfaction of clinicians/patients/third-party were recorded and analyzed.

RESULTS

A total of 32 cases (52 joints) were included. The average age was 24.09. Ratio of male/female was 4/28. Visual analog pain scale (VAS) score pre-/post-surgical ranged from 3 to 9 and 0-3, with an average of 6.03 and 1.18 (p < 0.01). Maximal mouth opening pre-/post-surgical ranged from 16 to 33 mm and 33-40 mm, with an average of 22.43 mm and 36.46 mm (p < 0.01). MRI was completed and showed stable disc reduction without recurrence 1 year postoperatively. MR/D was corrected and a better face shape was obtained. The satisfaction rate of clinicians, patients and third-parties was 92.375%, 94.156% and 94.218%, with an average of 93.583%.

CONCLUSION

For ADDwoR with MR/D patients, simultaneous TMJ anchorage surgery and genioplasty can improve TMJ symptoms/functions, correct facial appearance, and enhance the degree of satisfaction. The postoperative effect is stable, safe and reliable, which is worthy of clinical promotion.

Condylar form alteration on skeletal class II patients that underwent orthognathic surgery: An overview of systematic reviews

Background

Bilateral sagittal split osteotomy (BSSO) is commonly considered as the surgical technique of election for the treatment of skeletal class II with mandibular hypoplasia. After orthognathic surgery, condylar resorption can occur as a surgical relapse, which may affect the temporomandibular joint. Objective: This study aimed to summarise published systematic review that assess if orthognathic surgery with mandibular advancement performed on skeletal class II patients results in condylar form alteration.

Material and Methods

A literature search was performed using the electronic databases PubMed, Web of Science, Cochrane Library, Embase along with several sources of grey literature. Selection Criteria: Inclusion criteria were systematic reviews published until December 2019, of skeletal class II patients aged more than 18 years old that underwent BSSO with mandibular advancement surgery. Data collection: The electronic search identified 37 publications. Four publications fulfilled the inclusion criteria and were included in this meta-analysis. Qualitative assessment of the selected studies was performed using the Assessment of Multiple Systematic Reviews – AMSTAR 2 checklist.

Results

Four systematic reviews were included in this review. Despite its low incidence all studies reported condylar resorption. However, there were methodological limitations in all assessed articles.

Conclusions

The alteration of the condylar form may be a consequence of BSSO with mandibular advancement surgery. Additional high quality prospective research assisted by 3D-imaging technology is needed to allow more definite conclusions.

Key words:Evidence-based orthodontics, TMJ, Class II, mandibular advancement, malocclusion, Angle class II.

Biomechanical effect of asymmetric mandibular prognathism treated with BSSRO and USSRO on temporomandibular joints: a three-dimensional finite element analysis

Asymmetric mandibular prognathism is a clinically common skeletal dentomaxillofacial deformity. Unilateral sagittal split ramus osteotomy (USSRO) is an effective alternative procedure to bilateral sagittal split ramus osteotomy (BSSRO) for some patients. However, the biomechanical effect of temporomandibular joint (TMJ) of USSRO has not been fully studied. This study aims to evaluate the stress distribution changes in the TMJ of asymmetric mandibular prognathism treated with BSSRO/USSRO, to validate the clinical feasibility of USSRO. Nineteen patients with mandibular prognathism patients who were treated with BSSRO (n=12) and USSRO (n=7) had preoperative and postoperative computed tomographic scanning. Preoperative and postoperative 3-dimensional finite element analysis (FEA) of functional TMJ movements were made on one BSSRO patient and one USSRO patient. In all patients, the ANB angle and mandibular deviation were significantly improved postoperatively. There was no significant difference in the postoperative ANB angle and mandibular deviation between the BSSRO group and the USSRO group. In two preoperative FEA models, the maximum stresses of non-deviation side TMJ structures were greater than the deviation side during functional movements. The unbalanced stress distribution was corrected postoperatively in both BSSRO/USSRO FE models. Both BSSRO/USSRO can improve the ANB angle and mandibular deviation. The bilateral TMJ structure in patients with asymmetric mandibular prognathism had unbalanced stress, which could be significantly improved with the USSRO as effectively as BSSRO.

Comparison of postoperative condylar changes after unilateral sagittal split ramus osteotomy and bilateral sagittal split ramus osteotomy using 3-dimensional analysis

OBJECTIVE

This study aimed to evaluate postoperative changes in the condyle after unilateral sagittal split ramus osteotomy (USSRO) and to compare them with changes occurring after bilateral sagittal split ramus osteotomy (BSSRO).

STUDY DESIGN

For 50 condyles from 25 patients, positional and volumetric changes of condyle were analyzed by using computed tomography images taken before, immediately after, and 6 months after surgery and compared between the USRRO and BSSRO groups.

RESULTS

The condyle showed lateral and inferior displacement immediately after surgery and medial and superior movement at 6 months after surgery in the USSRO and BSSRO groups. No statistically significant difference was found between the 2 groups in the time-course positional change and rotation of the condyle. In the comparison of bodily shift and rotation between operated and nonoperated sides in USSRO group, there were no significant differences between the 2 sides, except for the perioperative rotation pattern on the coronal plane. At 6 months after surgery, the changed volume relative to preoperative condylar volume was only 5.2% in the USSRO group and 2.7% in the BSSRO group.

CONCLUSIONS

The findings from this study suggest that USSRO can be used effectively in appropriately selected patients; however, temporomandibular joint (TMJ) problems may arise when condylar displacement is excessive enough to exceed physiologic tolerances.

Independent risk factors for long-term skeletal relapse after mandibular advancement with bilateral sagittal split osteotomy

The purpose of this retrospective cohort study was to identify the independent risk factors for long-term skeletal relapse following mandibular advancement with bilateral sagittal split osteotomy. Univariate and multivariate linear regression analyses were performed including nine common risk factors for relapse as independent variables and horizontal/vertical long-term (≥2 years) skeletal relapse as dependent variables. Ninety-six patients were analyzed; 66 were female (68.8%) and the average age of the patients was 29.7±10.5 years. Over an average follow-up of 3.8±1.8 years after an initial mandibular advancement of 8.8±2.4 mm, long-term skeletal relapse of 1.6±1.0 mm horizontal and 0.9±0.7 mm vertical was found. Multivariate analysis identified age, preoperative mandibular plane angle (MPA), bimaxillary surgery, counterclockwise mandibular rotation, and the magnitude of mandibular advancement to be significantly associated with horizontal long-term skeletal relapse. Preoperative MPA, counterclockwise mandibular rotation, and the magnitude of mandibular advancement were significantly associated with vertical long-term skeletal relapse. Thus preoperative MPA, the magnitude of mandibular advancement, and counterclockwise mandibular rotation of the mandible were found to be independent risk factors for both horizontal and vertical long-term skeletal relapse. Although long-term skeletal relapse cannot be avoided entirely, understanding the independent risk factors and their contributions will optimize treatment planning and long-term stability.

Anterior open bite due to idiopathic condylar resorption during orthodontic retention of a Class II Division 1 malocclusion

A common dilemma when treating anterior open bite is understanding its etiology. Idiopathic condylar resorption (ICR) can cause open bite in affected individuals. Although it is prudent to not treat patients with ICR until active resorption has ceased, orthodontists may begin treating them because anterior open bite from ICR may not appear before or during their orthodontic treatment. This article reports a 12-year-old female who was diagnosed with ICR 10 months after completion of her orthodontic treatment for a Class II Division 1 malocclusion. When a young patient with a high mandibular angle and previous skeletal or dental Class II malocclusion returns with an open bite during the retention phase, the patient's condyles must be carefully examined to determine whether any temporomandibular joint disorder, such as ICR, is present. Currently, the controversy over the cause and the cure for ICR is continuing to challenge orthodontists in diagnoses and treatments. Orthodontists should closely monitor and offer informed treatment options to patients with risk factors for ICR or signs of its pathology that might develop at any stage of orthodontic treatment, including the retention period.

Three-dimensional quantitative assessment of surgical stability and condylar displacement changes after counterclockwise maxillomandibular advancement surgery: Effect of simultaneous articular disc repositioning

INTRODUCTION

In this study, we quantitatively assessed 3-dimensional condylar displacement during counterclockwise maxillomandibular advancement surgery (CMMA) with or without articular disc repositioning, focusing on surgical stability in the follow-up period.

METHODS

The 79 patients treated with CMMA had cone-beam computed tomography scans taken before surgery, immediately after surgery, and, on average, 15 months postsurgery. We divided the 142 condyles into 3 groups: group 1 (n = 105), condyles of patients diagnosed with symptomatic presurgical temporomandibular joint articular disc displacement who had articular disc repositioning concomitantly with CMMA; group 2 (n = 23), condyles of patients with clinical verification of presurgical articular disc displacement who had only CMMA; and group 3 (n = 14), condyles of patients with healthy temporomandibular joints who had CMMA. Presurgical and postsurgical 3-dimensional models were superimposed using voxel-based registration on the cranial base. Three-dimensional cephalometrics and shape correspondence were applied to assess surgical and postsurgical displacement changes.

RESULTS

Immediately after surgery, the condyles moved mostly backward and medially and experienced lateral yaw, medial roll, and upward pitch in the 3 groups. Condyles in group 1 showed downward displacement, whereas the condyles moved upward in groups 2 and 3 (P ≤0.001). Although condylar displacement changes occurred in the 3 groups, the overall surgical procedure appeared to be fairly stable, particularly for groups 1 and 3. Group 2 had the greatest amount of relapse (P ≤0.05).

CONCLUSIONS

CMMA has been shown to be a stable procedure for patients with healthy temporomandibular joints and for those who had simultaneous articular disc repositioning surgery.

Condylar changes after orthognathic surgery for class III dentofacial deformity: a systematic review

After orthognathic surgery for class II dentofacial deformity, remodelling of the mandibular condyle will take place. In a number of cases, this may evolve towards a phenomenon of condylar resorption. Yet, studies on the occurrence of this complication after the correction of a class III deformity are scarce. A systematic review of the literature was performed with the aim of identifying reports on condylar resorption or remodelling after orthognathic surgery for class III dentofacial deformity. A search of the international databases yielded 12 eligible studies. Eight studies reported some degree of postoperative condylar remodelling, while symptoms of condylar resorption were only described in a limited group of patients. Thus, the literature may show evidence of condylar remodelling after orthognathic treatment of class III patients, and anecdotal reports of condylar resorption exist. The small sample sizes, heterogeneity in methods and outcomes, and use of two-dimensional radiographs indicate the need for updated long-term research. In the future, the use of cone beam computed tomography data for volumetric and morphological condylar analysis in combination with three-dimensional cephalometry may provide the opportunity to further elucidate this phenomenon and better characterize its aetiology.

Computer-assisted teaching of bilateral sagittal split osteotomy: Learning curve for condylar positioning

Bilateral sagittal split osteotomy (BSSO) is a widely-performed procedure in orthognathic surgery for the correction of dentofacial deformity. Condylar positioning is a critical step during BSSO to maximize functional and morphological results. The unsuitable positioning of condyles represents one of the causative mechanisms that may induce temporomandibular joint noxious effects after BSSO. Repositioning devices can assist surgeons in maintaining the preoperative condylar position; however, empirical repositioning methods based on experience gained are still commonly used. Trainee learning curves are difficult to assess. The aim of this study was to evaluate the relevance of computer-assisted surgery in the acquisition of condylar positioning skills. Forty-eight patients underwent BSSO performed by six maxillofacial trainees (four junior residents and two senior experienced residents). A condyle positioning system (CPS) was used by a senior surgeon to record a condylar position score during the procedure. Firstly, scores were recorded when the trainee manually positioned the condyle without access to the CPS score (phase 1) and then when the trainee positioned the condyle and performed osteosynthesis with visual access to the CPS score (phase 2). Six parameters describing condylar three-dimensional motions were assessed: translational motion from top to bottom (TB), back to front (BF), and left to right (LR), axial rotation (AR), sagittal rotation (SR), frontal rotation (FR), and a total score (TS). There were no significant differences between junior and senior residents in condyle positioning without access to the CPS. Condyles were significantly better positioned during phase 2 with access to the CPS (p<0.001). Over time, use of the CPS (phase 2) produced significantly quicker improvements in scores (p = 0.042). For those teaching surgeries to trainees, computer-assisted devices can potentially result in more rapid learning curves than traditional "observations-imitation" models. Use of a CPS by trainees facilitated condylar repositioning that resulted in an accurate occlusal result and avoidance of adverse effects on the temporomandibular joint.

Idiopathic condylar resorptions: 3-dimensional condylar bony deformation, signs and symptoms

INTRODUCTION

Our aim was to describe 3-dimensional condylar deformation of the temporomandibular joint (TMJ) and symptoms and signs of temporomandibular dysfunction (TMD) in patients with idiopathic condylar resorption (ICR).

METHODS

We included 25 patients with ICR and 25 controls. We performed cone-beam computed tomographic scans and analyzed condylar width, length, and height as well as the condylar axial angle and the condylar neck angle. TMJ cross sections were evaluated for degenerative characteristics and location of bony deformations. Furthermore, symptoms and signs of TMD were described in the ICR group.

RESULTS

In the ICR group, we found statistically significantly reduced condylar width (mean difference, 2.0 mm), height (mean difference, 4.9 mm), and condylar axial angle (mean difference, 10.6°); 84% of the TMJs had a posterior condylar neck angle (control group, 22%). The most common degenerative changes were noncongruent shape of the condyle-fossa relationship (72%), condylar resorption (56%), and nonintact cortex (40%). More than 70% of the joints with bony deformations showed changes along the entire condylar head. Most patients with ICR showed symptoms and signs of TMD; nevertheless, 12% had no signs or symptoms of TMD.

CONCLUSIONS

ICR in the TMJ changes the shape and reduces the size of the condyle. Deformity locations are unspecified, and the entire condyle is often affected. Most patients with ICR have signs or symptoms of TMD; however, a small group was asymptomatic and without clinical signs.

Counterclockwise maxillomandibular advancement surgery and disc repositioning: can condylar remodeling in the long-term follow-up be predicted?

This study investigated predictive risk factors of condylar remodeling changes after counterclockwise maxillomandibular advancement (CCW-MMA) and disc repositioning surgery. Forty-one female patients (75 condyles) treated with CCW-MMA and disc repositioning had cone beam computed tomography (CBCT) scans taken pre-surgery, immediately after surgery, and at an average 16 months post-surgery. Pre- and post-surgical three-dimensional models were superimposed using automated voxel-based registration on the cranial base to evaluate condylar displacements after surgery. Regional registration was performed to assess condylar remodeling in the follow-up period. Three-dimensional cephalometrics, shape correspondence (SPHARM-PDM), and volume measurements were applied to quantify changes. Pearson product-moment correlations and multiple regression analysis were performed. Highly statistically significant correlation showed that older patients were more susceptible to overall condylar volume reduction following CCW-MMA and disc repositioning (P≤0.001). Weak but statistically significant correlations were observed between condylar remodeling changes in the follow-up period and pre-surgical facial characteristics, magnitude of the surgical procedure, and condylar displacement changes. After CCW-MMA and disc repositioning, the condyles moved mostly downwards and medially, and were rotated medially and counterclockwise; displacements in the opposite direction were correlated with a greater risk of condylar resorption. Moreover, positional changes with surgery were only weakly associated with remodeling in the follow-up period, suggesting that other risk factors may play a role in condylar resorption.

Evaluation of Mandibular Condylar Changes in Patients Following Orthognathic Surgery: A Retrospective Study

BACKGROUND

Condylar resorption as a cause of relapse after orthognathic surgery is well known. Several authors have presented evidence of the relation between orthognathic surgery and condylar remodeling and resorption. This study was done to appraise the condylar changes along with the form and function following orthognathic surgery, as well as to assess what factors may have contributed to the problems.

METHODOLOGY

A diagnosis of progressive condylar resorption (PCR) was made by comparison of preoperative and postoperative radiographs (cephalometric radiograms), as well as clinical evaluations. The radiographs were taken for each patient preoperatively and postoperatively, which include immediately after osteotomy, at 6 months and 24 months. Additional radiographs were taken when required. Then, preoperative and postoperative tracings were compared at 24 months postoperatively.

RESULTS AND CONCLUSION

It can be concluded from this study that females of relative low age (<18 years) appeared to be a high-risk factor for the occurrence of condylar alteration including PCR. A steep mandibular plane angle, the low facial height ratio (post/ant), and magnitude of surgery were also significantly related to the occurrence of condylar alteration, but the multivariance regression showed that these parameters had only limited value.

Physiological positioning strategy alters condylar position after mandibular ramus sagittal split osteotomies for mandibular prognathism

OBJECTIVE

The aim of this study was to elucidate the physiological position of the proximal segment for postoperative jaw movement in patients with mandibular prognathism.

METHODS

Twenty-two patients with mandibular prognathism were treated by orthognathic surgery using bilateral mandibular sagittal split ramus osteotomies (SSRO) with a physiological positioning strategy. The skeletal stability was assessed, and the movement of the proximal segment was evaluated by cephalography and computed tomography performed preoperatively, immediately postoperatively, and one year postoperatively.

RESULTS

The patients were divided into two groups: the stable group (SNB relapse <1.5°) and the relapse group (SNB relapse ≥1.5°). In the stable group at one year postoperatively, the average SNB relapse was only 0.29° (7%), the condylar head had moved posteriorly by 0.75 mm, and the proximal segment had rotated counterclockwise by 1.2°.

CONCLUSION

This new physiological positioning strategy improves the position of the condyle compared with the preoperative position in patients with mandibular prognathism.

Idiopathic condylar resorption: The current understanding in diagnosis and treatment

Idiopathic condylar resorption (ICR) is a condition with no known cause, which manifests as progressive malocclusion, esthetic changes, and often pain. Cone-beam computed tomography and magnetic resonance imaging are the most valuable imaging methods for diagnosis and tracking, compared to the less complete and more distorted images provided by panoramic radiographs, and the higher radiation of ^99mtechnetium-methylene diphosphonate. ICR has findings that overlap with osteoarthritis, inflammatory arthritis, physiologic resorption/remodeling, congenital disorders affecting the mandible, requiring thorough image analysis, physical examination, and history-taking. Correct diagnosis and determination of whether the ICR is active or inactive are essential when orthodontic or prosthodontic treatment is anticipated as active ICR can undo those treatments. Several treatments for ICR have been reported with the goals of either halting the progression of ICR or correcting the deformities that it caused. These treatments have varying degrees of success and adverse effects, but the rarity of the condition prevents any evidence-based recommendations.

Condylar resorption after orthognathic surgery: A systematic review

INTRODUCTION

Condylar resorption after orthognathic surgery (CROS) represents a progressive alteration of shape and volume of the mandibular condyle. It is a known factor of surgical relapse. The aim of this systematic review was to discuss the physiopathology, mechanisms, risk factors, diagnosis and treatment of this disease.

MATERIALS AND METHODS

A systematic review of the literature was performed on the Pubmed database from 1970 to 2014, using following terms: ("orthognathic surgery") AND ("condylar resorption" OR "progressive condylar resorption" OR "idiopathic condylar resorption" OR "condylar atrophy" OR "condylolysis"). Papers were included according inclusion and exclusion criterias.

RESULTS

The search leaded to 32 articles. Seventeen were included. CROS was a condylar remodeling secondary to an imbalance between mechanical stress applied to the temporomandibular joints (TMJ) and the host adaptive capacities. It mainly occurred in 14 to 50years old women with pre-existing TMJ dysfunction, estrogen deficiency, class II malocclusion with a high mandibular plane angle, a diminished posterior facial height and a posteriorly inclined condylar neck. Mandibular advancement superior to 10mm, counterclockwise rotation of the mandible and posteriorly condylar repositioning were associated with an increased risk of CROS.

DISCUSSION

Treatment consists in re-operation in case of degradation of the occlusal result after an inactivity period of at least 6 months. Condylectomy with allogenic or autologous reconstruction is an alternative. Prevention is crucial and requires at-risk patient information.

Management of dentoskeletal deformity due to condylar resorption: literature review

OBJECTIVES

The aim of this review was to examine all publicly available literature on the current treatments of the dentoskeletal deformity due to condylar resorption and their outcomes and to suggest management guidelines.

STUDY DESIGN

A systematic review was performed of all literature located on the electronic PubMed database from 1970 to 2012.

RESULTS

The search resulted in 21 papers and 210 cases treated from 1991 to 2012. Orthognathic surgery was the most commonly used option (42%) and was sometimes combined with open joint surgery (19%). Stability was observed, respectively, in 57% and 100% of the orthognathic surgery and open joint surgery cases. Condylectomy and reconstruction with chondrocostal graft or temporomandibular joint total joint prosthesis were used in 19% and 10% of all cases of orthognathic surgery and open joint surgery with good results (95% and 100%, respectively). Osteogenic distraction was anecdotic (1%). Nine percent of all cases received conservative treatment.

CONCLUSIONS

Larger comparative studies are necessary to obtain evidence-based recommendations.