Condylar head remodeling compensating for condylar head displacement by orthognathic surgery

Direction and Range of Condylar Positional Changes in the First-Year Post-surgical Orthodontics Interventions in Adult Patients with Skeletal Class III Deformity: A Systematic Review and Meta-analysis

Objectives

Assess the available scientific literature regarding the direction and extent of condylar positional changes during the first year of post-surgical orthodontics interventions in class III patients.

Materials and Methods

PubMed, Cochrane Library, Embase, and Google Scholar databases were searched up to March 2022 for studies involving the measurement of condylar positional changes after surgical treatment of Class III dentofacial deformity in adults with BSSO without or without Le Fort I osteotomies. The methodological index for non-randomized studies (MINORS) was utilized to assess the risk of bias and quality of non-randomized studies. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Primary outcome was condyle positional changes between the following time points: T0: before treatment, T1: immediately post treatment, T2: 4, 6, or 9 months post treatment, T3: one year post treatment.

Results

Nineteen studies were included in the systematic review. Eleven studies were deemed low quality, and the rest were of medium quality. The meta-analysis included 12 studies and showed statistically significant downward, outward positional changes at T1(Immediately after surgery). Inward Yaw rotation was significant at T1(1-4 month post-surgery) and T2(4-9 months post-surgery).

Conclusion

Surgically induced condylar changes tend to go back to normal within the first year after surgery, except for condylar yaw rotations.

Three-Dimensional Changes of Condylar Position After Bimaxillary Surgery to Correct Skeletal III Malocclusion: Cone Beam Computed Tomography Voxel-Based Superimposition Analysis

BACKGROUND

The stability of the condylar position within the first 3 months after orthognathic surgery in patients with skeletal Class III malocclusion is crucial for subsequent orthodontic treatment.

PURPOSE

The purpose was to compare condylar positional changes 3 months after bimaxillary surgery to correct skeletal Class III deformities, utilizing the conventional two-dimensional combined with cone beam computed tomography voxel-based superimposition analysis.

STUDY DESIGN, SETTING, SAMPLE

This retrospective cohort study included skeletal Class III patients undergoing bimaxillary orthognathic surgery at Khon Kaen University, Thailand, in 2020. Exclusion criteria were patients with temporomandibular disorder symptoms, facial asymmetry prior to the surgery, or surgical complications.

EXPOSURE VARIABLE

The exposure variable was the timing, both preoperatively and 3 months postoperatively. This 3-month postoperative time point was chosen because complete healing of the bimaxillary surgery is expected by then, without any potential influence of condylar changes resulting from subsequent orthodontic treatment.

MAIN OUTCOME VARIABLES

The outcome variables are condylar position measurement, joint space (mm), and axial condylar angle (degrees).

COVARIATES

Demographics (age, sex) and surgical details (direction and amount of movement) were collected as covariates.

ANALYSES

Statistical analysis of condylar positional changes and correlations was performed using paired t-test and linear correlation (P value < .05), respectively.

RESULTS

The sample included 11 subjects (22 condyles), with a mean age of 24 ± 5.24 years. Both two-dimensional measurements and voxel-based three-dimensional superimposition showed significant changes in condylar position 3 months after bimaxillary surgery: inferior (0.45 ± 0.26 mm, P < .001), posterior (0.46 ± 0.39 mm, P = .003), lateral (0.38 ± 0.42 mm, P = .01) displacement, and inward rotation (5.21 ± 2.54°, P < .001). No significant correlation was found between jaw movement distance and condylar changes.

CONCLUSION AND RELEVANCE

To our knowledge, this is the first study to report measures of condylar changes at 3 months, when complete healing of the osteotomies would be expected, using Le Fort I osteotomy for maxillary advancement combined with bilateral sagittal split ramus osteotomy for mandibular setback. These changes are small in magnitude and may be of little relevance to patient care.

Evaluating changes in the condylar head after orthognathic surgery with or without articular disc repositioning: a systematic review

Failures in orthognathic surgery are associated with different factors, including those related to untreated or undiagnosed preoperative temporomandibular joint (TMJ) disorders. This systematic review aimed to assess potential alterations in the condylar head following orthognathic surgery. A systematic search for randomised controlled trials and retrospective studies was performed. For inclusion in the review, studies had to meet the following eligibility criteria according to the PICO framework: Patients: patients with orthognathic deformity and temporomandibular dysfunction (or temporomandibular osteoarthritis); Intervention: patients submitted to orthognathic surgery concomitantly with TMJ disjunction; Control: patients undergoing only orthognathic surgery with or without presurgical data; and Outcome: changes in temporomandibular joint position and volume. Nine studies met all the inclusion criteria and were selected for qualitative analysis. The results of this review show that simultaneous articular disc repositioning and orthognathic surgery provide better results in patients with preoperatively diagnosed condylar osteoarthritic changes. In conclusion, condylar remodelling (resorption/deposition) and its extent are determined by the direction of condylar displacement during surgery. Other factors such as age are also associated with the development of condylar resorption.

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.

Morphological characteristics of coronoid process and revisiting definition of coronoid hyperplasia

The aim of this study was to assess the morphological characteristics of the coronoid process (CP) and define coronoid hyperplasia (CH) using cadaveric mandibles of a Caucasian population. A sample of 151 adult dry cadaveric mandibles (302 CPs) was acquired. Three distances were measured, which included the width, height, and length of CP. The surface area measurements involved area A: above the width distance line; area B: between incisura mandibulae-Alveolar ridge line and width distance line; area C: between distance lines of width and height. Finally, angulations of the CP and gonial angles were identified. Both length and surface area A + B acted as hyperplastic indicators. Based on the selection criteria, a sample of 197 CPs was included. The hooked shape (59%) was most commonly observed. No significant difference existed between left and right sides (p > 0.05). The mean values of length and surface area A + B were 2.2 ± 0.3 cm and 3.3 ± 0.8 cm2, and any values above 2.7 cm (n = 5 CPs- 2.5%) and 5.0 cm2 (n = 9 CPs- 4.6%) were described as hyperplastic, respectively. The presented data could act as quantitative reference for differentiating between normal and hyperplastic conditions.

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 remodelling in a severe class II deep bite dento-skeletal malocclusion treated with an ortho-surgical approach: A five-year follow-up case report

Condylar displacement and remodelling are phenomena closely related to orthognathic surgery and critically involved in occlusal and skeletal stability. The aim of the present case report is to describe over time condylar displacement and surface remodelling after bilateral split sagittal osteotomy (BSSO) in an adult patient with severe class II skeletal malocclusion treated with ortho-surgical approach. A male of 21years comes to our observation. The extraoral examination shows a symmetrical square-shaped face, a convex profile, an acute nasolabial angle and a deep labiomental fold. Intraoral examination reveals a class II division 2 with a 2mm deviation of the mandibular midline to the left and the presence of a scissor bite of the bicuspids between quadrants II and III. The Spee curve and overbite are extremely accentuated (OV 14.3mm) as the overjet (11.1mm). Axiographic reconstructions of CBCT show a normal shape and position of both condyles. The cephalometric analysis shows a reduced lower facial height, a normal upper jaw position, a mandibular underdevelopment masked by a very developed symphysis and an extremely low divergence (FMA 11.2°). BSSO for mandibular setback was performed in the 13th month of orthodontic therapy. Original CBCT data before surgery (T0), at the end of treatment (T1), 2years postoperatively (T2) and 5years postoperatively (T3) were collected and reconstructed for 3-dimensional (3D) qualitative analyse. At the end of the surgical-orthodontic treatment (26months), good function and good aesthetics were achieved. The qualitative and comparative analysis of the superimpositions and the cuts made on the CBCT at T0, T1, T2, T3 showed a physiological remodelling and adaptation of the condyles.

[Three-dimensional assessment of positional changes of the mandibular condyles following orthognathic surgery]

THE AIM THE STUDY

This study aims to assess the postoperative condylar displacement after orthognathic surgery using three-dimensional analysis of computed tomography.

MATERIAL AND METHODS

This retrospective study included 64 condyles from 32 patients with skeletal Class II (Group 1, n=16) and III (Group 2, n=16) deformities. All patients underwent a bimaxillary surgery. The three-dimensional CT images were evaluated to assess condylar displacement.

RESULTS

The condyle exhibited mainly superior and lateral torque immediately after surgery. Posterior displaced condyles were found in two cases in group 1 (Class II malocclusion).

CONCLUSION

The present study found the condyle displacement that can be mistaken as posterior displacement of condyle in analysis of sagittal sections of CT scans.

Nonsurgical orthodontic correction of facial asymmetry by condylar remodeling and mandibular repositioning following occlusal cant correction with microimplants: a case report

Recently, the demand for correcting facial asymmetry has been increasing, even when the extent of asymmetry is small. This case report describes nonsurgical orthodontic treatment for facial asymmetry in a 13-year-old female patient, facilitated by moving the deviant mandible to the nondeviated side after correcting for relevant dental compensation using microimplants. Mandibular repositioning was attempted using intermaxillary elastics between the microimplants placed into each jaw and guided by resin that was bonded on the maxillary first molar of the deviated side. To enhance mandibular movement, correction of the transverse occlusal cant and buccolingual inclination of the teeth were also performed. After 65 months of gradual treatment, facial symmetry, with favorable occlusion and jaw function, was achieved. These satisfactory results, including a well-balanced face and good occlusal interdigitation, were well maintained at the 53-month follow-up. Direct and functional forces applied against deviant functional forces can reduce facial asymmetry by differential growth or modeling of the condyle.

Three-Dimensional Quantitative Assessment of Condylar Displacement and Adaptive Remodeling in Asymmetrical Mandibular Prognathism Patients After Sagittal Split Ramus Osteotomy

This study was performed to evaluate the condylar displacement and associated condylar remodeling in class III patients following mandibular setback surgery via sagittal split ramus osteotomy (SSRO). The sample comprised of 26 condyles of 13 subjects (mean age of 21.2±2.6 y). We evaluated patients with mandibular prognathism and facial asymmetry who had undergone SSRO for mandibular setback at Korea University Hospital between January 2016 and December 2018. Three-dimensional segmentation of the mandibular condyles was done using the initial cone-beam computed tomography scan and scan taken 12 months postoperatively or later. Quantitative assessments of the 3-dimensional condylar displacement from T0 to T1 and bony remodeling of 8 regions of the condylar head were performed. The correlation between the condylar displacement and condylar head remodeling on the deviated (D) and nondeviated (ND) sides was analyzed. Significant correlations between condylar displacement and surface remodeling were observed in both D and ND condyles. The anteroposterior condylar displacement was significantly different between the D and ND sides (P=0.007). There was no significant difference in condylar remodeling between the 2 sides. Condylar displacement and adaptive remodeling after SSRO varied greatly among individuals. Compared with displacement in the ND condyle, displacement in the D condyle has a greater association with condylar remodeling in both D and ND condyles. There is no significant difference in condylar head remodeling between D and ND condyles.

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.

Comparison of short-term condylar positional changes in mandibular prognathism after surgery-first approach: Symmetric setback versus asymmetric setback

The aim of this study was to compare how the displacement of the mandibular condyle changed after symmetric or asymmetric mandibular setback surgery using the surgery-first approach (SFA). Patients who underwent mandibular setback surgery using the SFA were selected and divided into a symmetry group (n = 18) with differences of less than 2 mm between the right and left setback, and an asymmetry group (n = 18) with a difference of greater than 2 mm. Cone-beam computed tomography (CBCT)-generated cephalograms were obtained after three-dimensional superimposition of CBCT images taken before surgery (T0), within one week after surgery (T1), and seven months after surgery (T2). The condylar positions were measured. Condylar positional changes according to time were compared between the two groups and correlation analysis was performed. There were significant positional changes in mandibular condyles over time in both groups. However, most of these changes returned to their initial state. In the asymmetry group, there was a greater internal rotation of the mandibular condyle on the lesser setback side. The correlation analysis results revealed that only the setback difference was associated with rotational displacement of the condyle on the lesser setback side at two time points (T1-T0, T2-T0). In the SFA, significant condylar displacement occurred immediately after both symmetric and asymmetric mandibular setback surgery, and the right/left difference in mandibular setback showed a significant positive correlation with rotational displacement. Although more significant rotational displacement of the mandibular condyle was observed after asymmetric mandibular setback surgery, the amount was not large enough to be clinically significant.

Prevention of Nasal Ala Pressure Injuries With Use of Hydroactive Dressings in Patients With Nasotracheal Intubation of Orthognathic Surgery: A Randomized Controlled Trial

PURPOSE

To compare a hydroactive dressing to an adhesive tape standard of care in the prevention of nasal ala pressure injuries associated with nasotracheal intubation during orthognathic surgery.

DESIGN

Randomized controlled trial.

SUBJECTS AND SETTING

The study took place in a tertiary hospital of stomatology in China. Patients undergoing general anesthesia with nasotracheal intubation during orthognathic surgical procedures were invited to participate.

METHODS

Participants were divided into 2 groups: in the experimental group, a hydroactive dressing was applied to the nasal ala before the surgical procedures; the control group received standard prevention with a type of tape. Skin assessments were performed on the wards up to 72 hours after the procedures. Demographic information and potential contributing factors associated the development of nasal ala pressure injuries were collected from patients' electronic medical records. Pressure injury development was staged using National Pressure Injury Advisory staging guidelines. Pressure injury incidence was compared between groups using the χ test and odds ratio.

RESULTS

The sample comprised 450 participants, 225 in each group. The incidence of nasal ala pressure injuries development was 14.222% and 4.444% in the 2 groups, respectively (P = .000). The odds ratio was 3.565 (95% confidence interval, 1.707-7.443).

CONCLUSIONS

The study findings indicate that the incidence of pressure injuries of nasal ala skin protected by hydroactive dressings was lower than the standard preventive method. Hydroactive dressings should be considered as a prevention method to reduce device-related skin injuries associated with nasotracheal intubation.

Mandibular condyle displacements after orthognathic surgery-an overview of quantitative studies

The repositioning of bone segments during orthognathic surgeries often results in mandibular condyle positional changes and can also affect jaw muscles, soft tissues and the temporomandibular joint (TMJ). Condylar displacements are considered as one of the factors of bone remodeling and further skeletal relapse. The quantitative approach is commonly used in comparative analyses and evaluations of the relationships between examined factors. The aim of this study is the overview of the current literature including quantitative analysis in the research of mandibular condyle positional changes as a consequence of orthognathic surgeries. Thirty articles were included in the overview. Most of the articles present a comparative and evaluative analysis of treatment results concerning different surgical approaches, fixation methods or types of skeletal defects. The correlation between condylar displacements and bone remodeling, skeletal relapse and TMJ dysfunctions were considered. The most frequently repeated study variables were: short-term changes, Class III malocclusion, yaw rotation, 3D cephalometry measurements. Quantitative data might be useful in the evaluation of patterns and range of condylar displacements for specific treatment conditions. Available literature concerning the analysed topic is characterized by great heterogeneity with regards to the purpose and methodologies of the studies. More systematic approaches and long-term considerations are needed in future research.

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.

Straight Locking Miniplate Technique Achieves Submillimeter Accuracy of Condylar Positional Change During Bimaxillary Orthognathic Surgery for Patients With Skeletal Class III Malocclusion

PURPOSE

The straight locking miniplate (SLM) technique is a straightforward method to accurately reposition the maxilla during bimaxillary orthognathic surgery. The present study evaluated the accuracy of the SLM technique in maintaining the condylar position during surgery without the use of a cutting guide.

PATIENTS AND METHODS

The present prospective, single-center study was conducted at Yokohama City University between 2016 and 2017 and included patients with skeletal Class III malocclusion. The patients were divided into 2 groups according to the fixation method used for the mandibular segments. The mandibular segments were fixed with miniplates either manually (manual group) or using the SLM technique (SLM group). Computed tomography was performed before and 3 days after surgery to compare the condylar position. The bodily and rotational movements of the condyle were analyzed.

RESULTS

The subjects were 18 Japanese patients (36 condyles) who had undergone bilateral set back surgery with Le Fort I osteotomy. The amount of bodily movements in the manual and SLM groups were 1.44 and 0.62 mm, respectively. The degree of rotational movement in the sagittal plane in the manual and SLM groups was 3.33° and 0.23°, respectively. The bodily and rotational movements in the SLM group were significantly smaller than those in the manual group (P < .05 and P < .01, respectively).

CONCLUSIONS

These results suggest that use of the SLM technique reduces the risk of condylar positional changes to less than 1 mm during orthognathic surgery without the use of any complex devices or a cutting guide.