Effects of surgical mandibular advancement and rotation on signs and symptoms of temporomandibular disorder: A 2-year follow-up study

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.

Effect of Orthognathic Surgery on Pre-existing Temporomandibular Disorders

The management of patients with pre-existing temporomandibular disorders (TMDs) undergoing orthognathic surgery remains a subject of ongoing debate. This study aimed to profile these individuals and evaluate the correlation between orthognathic surgery and alterations in TMD indicators and symptoms. We conducted a retrospective cohort investigation involving patients with skeletal malocclusion and established TMDs. Variables of interest encompassed the performance of orthognathic surgery, documented TMDs (including temporomandibular joint (TMJ) sounds, TMJ pain, muscle discomfort, and jaw locking), and patients' self-assessments of TMJ and muscle pain using a visual analog scale (VAS). The primary outcome measures focused on changes in TMD indicators and symptoms. Among the study cohort, 73.4% exhibited skeletal class III malocclusion, while 26.6% presented with skeletal class II malocclusion. Notably, patients classified as skeletal class III were significantly younger than their skeletal class II counterparts (mean age: 23.06±5.37 vs. 26.71±7.33; P=0.034). The most prevalent pre-existing TMD complaint was TMJ sounds (65.5%), followed by TMJ pain (39.1%), muscle discomfort (23.4%), and jaw locking (12.5%). Skeletal class II patients were more likely to experience TMJ sounds compared to skeletal class III patients (88.2% vs. 57.4%; P=0.022). Statistically significant improvements were observed in the VAS assessments among class III patients following surgery. A majority of patients with pre-existing TMDs seeking orthognathic surgery exhibited skeletal class III malocclusion and were younger than those with skeletal class II malocclusion. Importantly, orthognathic surgery was associated with positive changes in TMD indicators and symptoms in these patients.

Changes of Temporomandibular Joint Morphology and Symptoms in Class II Malocclusion Patients With Bilateral Sagittal Split Ramous Osteotomy

This study included 46 patients with class II malocclusion ranging in age from 19 to 39 years old treated with bilateral sagittal split ramous osteotomy (BSSRO). Left and right temporomandibular joints (TMJs) of each subject were evaluated independently with cone-beam computed tomography (CBCT) before operation (T1), 1 week after operation (T2), and 1 year after operation (T3) and assessed the effects of orthognathic surgery (OGS) on the temporomandibular joint disease (TMD) symptoms. Temporomandibular joint morphology evaluation included condylar volume, condylar area, cortical bone thickness, depth of the mandibular fossa, fossa thickness, joint nodule angle, joint space, and condyle-fossa relationship, which were calculated by using the Mimics software and 3-matic software. Data were statistically analyzed with SPSS software (P <0.05 means statistically significant). In our study, bilateral TMJs have no difference in T3. Bilateral sagittal split ramous osteotomy had no significant effect on the articular fossa. The condyle volume and surface area decreased from T1 to T3, but the cortical thickness of the bone did not change significantly. More anterior condyle positions in T1 and more posterior in T3.21 patients had at least 1 sign or symptom of TMD in T1 and 27 patients in T3. Four patients who were asymptomatic in T1 developed pain after surgery, 10 developed noises, 12 showed limited mouth opening, and 8 had abnormal opening patterns. It is concluded that more condylar posterior position after BSSRO and the reduction of condyle may be related to the enlargement of anterior space. The number of patients with joint symptoms increased postoperative, and the impact of BSSRO on TMD may be negative.

Evaluation of occlusal function during orthognathic therapy : A prospective clinical trial using a digital registration method

OBJECTIVES

Reduced occlusal function is a main characteristic of orthognathic patients. The present study aimed to investigate the extent of therapy-induced functional improvements in occlusal function using a digital diagnostic method.

METHODS

This prospective clinical study included 41 orthognathic patients (24 women and 17 men, median age 27.26 ± 8.2 years) and 10 control patients (5 women and 5 men, median age 29.8 ± 13.5 years) with neutral skeletal and dental configurations. The patients were divided into classes I, II and III based on their cephalometry. Digital occlusal registrations in habitual occlusion in an upright sitting position were taken before (T1) and after (T2) therapy using the T‑Scan Novus (Tekscan, South Boston, MA, USA) application.

RESULTS

Class II and III patients showed a significantly less efficient occlusal pattern than the untreated controls regarding total antagonism (p < 0.001), time of occlusion (p = 0.004), occlusal asymmetry (p = 0.001), anterior antagonism (p < 0.001) and posterior antagonism (p < 0.001). After therapy, the occlusal pattern increased in both therapy groups, where class III patients became indistinguishable from the controls, and class II patients differed only in posterior antagonism (p = 0.035).

CONCLUSIONS

The digital occlusal registration method proved to be a useful diagnostic tool and provided new insights into therapeutic effects in orthognathic patients. By precisely adjusting the occlusal function, masticatory performance improved significantly.

CLINICAL RELEVANCE

Severe malocclusion leads to a significantly lower masticatory performance for patients, which can be improved by orthognathic therapy and captured by digital occlusal registration.

Relationship between Changes in Condylar Morphology and Masticatory Muscle Volume after Skeletal Class II Surgery

The treatment of dentofacial deformities generally includes orthognathic surgery in which mandibular condyle changes following surgery are a common cause of relapse. This study investigated the changes in the mandibular condyle and related muscles to identify the factors that affected the changes in the mandibular condyle after orthognathic surgery in skeletal class II patients. This research studied 60 joints in 30 patients with skeletal class II dentofacial deformities who received surgical orthodontic treatment, including bilateral sagittal split ramus osteotomy, and underwent computed tomography before and after orthodontic treatment. The mandibular condyle, masseter, and medial pterygoid muscles were reconstructed and measured in 3D. Condylar positional and morphology changes, masseter and medial pterygoid muscle volume, temporomandibular joint (TMJ) pain, and distal segment movement were analyzed. The study observed that both the masseter and medial pterygoid muscle volumes decreased with statistical significance. The changes in the horizontal direction were positively correlated with the amount of movement. The findings indicated that mandibular condyle changes were significantly affected by the movement of the distal segment, the medial pterygoid muscle volume, and the direction of the distal segment, which influenced the treatment's long-term stability after orthognathic surgery.

The effect of orthognathic surgery on temporomandibular disorder

This study aimed to evaluate the difference in prevalence of temporomandibular disorder (TMD) before and after orthognathic surgery (OGS), particularly in patients with mandibular asymmetry. A prospective cohort study of patients undergoing corrective orthognathic surgery was conducted. Pre-operative and post-operative (3 months, 6 months and 1 year) TMD assessment were performed according to the Diagnostic Criteria for TMD (DC/TMD) protocol. 64 patients were included in the study. Overall, there was a significant reduction of 26.5% in TMD prevalence from 60.9% pre-operatively to 34.4% 1-year post-operatively (p = 0.003). In all, 37.5% of patients had their TMD condition treated, 50% had no change in their symptoms while 12.5% experienced a worsening of their symptoms. No significant difference in terms of change in TMJ status was observed among the different ramus procedures, the type and magnitude of mandibular movement, skeletal class, and presence of mandibular asymmetry. In conclusion, it appears that corrective orthognathic surgery for dentofacial deformities might provide a secondary benefit of treating TMD. However, surgeons have to be aware that a small percentage of patients might experience a deterioration of their TMD condition, and that those who were previously asymptomatic may develop TMD symptoms after surgery.

Postsurgical Stability of Temporomandibular Joint of Skeletal Class III Patients Treated with 2-Jaw Orthognathic Surgery via Computer-Aided Three-Dimensional Simulation and Navigation in Orthognathic Surgery (CASNOS)

Objective

The aim of this study is to clarify the postsurgical stability of temporomandibular joints in skeletal class III patients treated with 2-jaw orthognathic surgery which was performed utilizing computer-aided three-dimensional simulation and navigation in orthognathic surgery (CASNOS) protocol.

Materials and Methods

23 consecutive nongrowing skeletal class III patients with mandibular prognathism associated with maxillary retrognathism treated with 2-jaw orthognathic surgery between 2018 and 2019 were enrolled in this study. The surgery was planned according to the standardized protocol of CASNOS (computer-aided three-dimensional simulation and navigation in orthognathic surgery). Computed tomography (CT) scans were performed in all patients 3 weeks presurgically and 6 months postsurgically. ITKSNAP and 3D Slicer software were used to reconstruct three-dimensional facial skeletal images, to carry out image segmentation, and to superimpose and quantify the TMJ position changes before and after surgery. Amount of displacement of the most medial and lateral points of the condyles and the change of intercondylar angles were measured to evaluate the postsurgical stability of TMJ.

Results

A total amount of 23 skeletal class III patients (female : male = 12 : 11) with age ranged from 20.3 to 33.5 years (mean: 24.39 ± 4.8 years old) underwent Le Fort I maxillary advancement and BSSO setback of the mandible. The surgical outcome revealed the satisfactory correction of their skeletal deformities. The mean displacement of the right most lateral condylar point (RL-RL′) was 1.04 ± 0.42 mm and the mean displacement of the left most lateral condylar point (LL-LL′) was 1.19 ± 0.41 mm. The mean displacement of the right most medial condylar point (RM-RM′) was 1.03 ± 0.39 mm and the left most medial condylar point (LM-LM′) was 0.96 ± 0.39 mm. The mean intercondylar angle was 161.61 ± 5.08° presurgically and 159.28 ± 4.92° postsurgically.

Conclusion

The postsurgical position of TM joint condyles in our study only presented a mild change with all the landmark displacement within a range of 1.2 mm. This indicates the bimaxillary orthognathic surgery via 3D CASNOS protocol can achieve a desired and stable result of TMJ position in treating skeletal class III adult patients with retrognathic maxilla and prognathic mandible.

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

BACKGROUND

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

REGISTRATION NUMBER

CRD42020198088.

The Effect of Orthognathic Surgery on Temporomandibular Joint Function and Symptoms: What are the Risk Factors? A Longitudinal Analysis of 375 Patients

PURPOSE

The effects of orthognathic surgery (OGS) on the temporomandibular joint (TMJ) are still controversial. Based on a high-volume uniform collective, the function and clinical symptoms of the TMJ and the dysfunction index (Di) by Helkimo were evaluated prior and up to 2 years after OGS.

METHODS

A longitudinal cohort study was performed between 2006 and 2016. A comprehensive examination focusing on TMJ function, temporomandibular disorder (TMD) symptoms, and the Di had been performed preopertaively (T0) and postoperatively at 6 weeks (T1), 6 months (T2), 1 year (T3), and 2 years (T4). The predictor variables used were sex, age, skeletal class, type of surgery, and amount of dysfunction or number of TMD complaints before treatment. The outcome of this study was TMD symptoms and the Di. Descriptive and bivariate statistics were computed, and the significance level was set at P < .05.

RESULTS

The sample consisted of 375 patients (247 women, 128 men, mean age 28.1 ± 9.4 years), 269 with skeletal Class II (71.7%) and 106 with skeletal Class III (28.3%) treated with sagittal split osteotomy bilateral sagittal split osteotomy (n = 173) or Le Fort I and bilateral sagittal split osteotomy (n = 202). Severe signs of dysfunction (Di 2/3) were seen in 5.9% of the patients before OGS and in 2.1% of the patients 2 years after OGS. The difference in Di (Di0/1 and Di2/3) between T0 and T1/T2 was statistically significant (P = .028; P = .011, respectively). TMD symptoms were significantly reduced 2 years after OGS (P = .028). Female gender (P = .013), skeletal Class II (P < .001), and counterclockwise rotation (P < .001) were the only risk factors significantly associated with the occurrence of TMD at T1.

CONCLUSIONS

The results of this study suggest that in most cases TMD symptoms can be significantly reduced and only a few can be induced with OGS. No risk factors were found for long-term effects on the TMJ.

The relationship between neurosensory disturbance of the inferior alveolar nerve and the lingual split pattern after sagittal split osteotomy

OBJECTIVE

The aim of this study was to evaluate the relationship between neurosensory disturbance (NSD) and the different types of bilateral sagittal split osteotomy (BSSO) lingual fracture created.

STUDY DESIGN

The study group consisted of 45 patients with mandibular deformities (90 sides; 14 males and 31 females). Computed tomography (CT) scans were obtained preoperatively and 1 week postoperatively. All patients were divided into lingual fracture line groups on the basis of their postoperative scans. NSD was tested preoperatively and 1, 3, and 12 months postoperatively by using a sensory touch Semmes-Weinstein (SW) test and the 2-point discrimination (TPD) test.

RESULTS

Patients were divided into 2 groups on the basis of their lingual fracture lines after mandibular BSSO; among the 45 patients, 39 sides (43.3%) had short-splits, and 51 sides (56.7%) had long-splits. The short-split group was less affected at all tested times, and the difference between the 2 groups was significant 1 month postoperatively on TPD test but not at other times on the both tests.

CONCLUSIONS

The split type did not affect the NSD incidence at 3 and 12 months postoperatively.

TMJ related short-term outcomes comparing two different osteosynthesis techniques for bilateral sagittal split osteotomy

OBJECTIVES

Bilateral sagittal split osteotomy (BSSO) is a morpho-functional surgery and post-surgical osteosynthesis may influence temporomandibular joint (TMJ) health. Our objective was to evaluate temporomandibular disorders (TMD) and TMJ symptoms after orthognathic surgery according to the type of osteosynthesis used in a population of patients with dentofacial deformities.

MATERIALS AND METHODS

One hundred and eighty-three consecutive patients undergoing orthodontic and maxillofacial surgery treatment for correction of their malocclusion were recruited for a two-year period at Lille University Hospital. All patients had at least a mandibular BSSO using Epker's technique. Each patient was examined before and one year after orthognathic surgery. We compared osteosynthesis by miniplates fixed with monocortical screws (n=42) and the hybrid fixation with bicortical retro-molar screws used with miniplates (n=141). TMJ health was assessed by monitoring TMD signs and symptoms according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and scores obtained from the "Jaw Pain Function" questionnaire.

RESULTS

There was no significant difference in pre-operative and one year post-operative RDC/TMD assessments (p≥0.91) or JPF score (p≥0.29) between the two types of osteosynthesis.

CONCLUSION

There was no difference in TMJ health between the two techniques of osteosynthesis after BSSO.

CLINICAL RELEVANCE

In our experience the hybrid technique fixation affords many advantages and does not influence postoperative TMD compared with osteosynthesis by miniplates.

Evaluation of temporomandibular joint function after orthognathic surgery using a jaw tracker

OBJECTIVE

It has been reported that temporomandibular joint (TMJ) function after orthognathic surgery differs from normal patients. Dysfunction of the joints occurs often even in the general public, with an incidence in the range of 20%-25%. Population-based studies among adults report that approximately 10%-15% have symptoms of pain and 5% of them had a perceived need for treatment. To date, no studies have reported on the evaluation of TMJ function after orthognathic surgery through the use of four-dimensional jaw tracking.

DESIGN AND SETTING

This study evaluated TMJ function using such a device and information from a TMJ questionnaire. Sixteen orthognathic surgery patients and 17 controls were included in this study. Four-dimensional jaw tracking information was obtained using the SiCAT JMT device. Clinical signs and jaw function were evaluated.

RESULTS

Within the limitations of the study, the following results were seen using the SICAT JMT+ jaw tracking device: (1) no significant differences were found in any of the millimetric measurements between the surgery patients and controls; (2) no significant difference was found in subjective reported symptoms of pain, clicking, crepitation, locking, stiffness, headaches and migraines between the groups; and (3)there was a significant difference in the popping of the joints for surgery and non-surgery groups.

CONCLUSION

Jaw tracking did not detect significant differences in jaw function, but some clinical symptoms were present.

Temporomandibular disorders in Class II malocclusion patients after surgical mandibular advancement treatment as compared to non-treated patients

BACKGROUND

Severe malocclusions may cause functional and aesthetic problems and symptoms of temporomandibular disorders (TMD). Studies have investigated association between malocclusions and TMDs and shown controversial findings.

OBJECTIVE

Purpose of this investigation was to examine the prevalence of TMD sub-diagnoses, using Diagnostic Criteria for the TMD (DC/TMD), in patients with Class II malocclusion and retrognathic mandible who had undergone mandibular advancement surgery 4-8 years previously, and to compare their frequencies with non-treated patients with a similar pre-existing condition.

METHODS

Study cohort comprised 151 patients who had orthognathic treatment due to mandibular retrognathia in 2007-2011. Seventy-seven (51%) participated in the study (Group 1). Group 2 comprised 22 patients who were planned for orthognathic treatment but had not started their treatment. Patients filled in the Finnish version of the DC/TMD Symptom Questionnaire and were examined using to the DC/TMD Axis I. DC/TMD Symptom Questionnaire were inquired by phone from 24 of the 74 patients who did not participate in the study.

RESULTS

Results showed that Group 2 had more myalgia (13% vs 50%, P < 0.001) and arthralgia (18% vs 65%, P < 0.001) sub-diagnoses than Group 1. A tendency was noted that Group 2 had more pain-related TMD symptoms than Group 1. No differences were found between Groups 1 and 3 in gender and age distribution or frequency TMD symptoms.

CONCLUSION

Prevalence of especially pain-related TMD diagnoses was higher in Group 2 compared to Group 1, thus indicating a possible beneficial effect of this treatment for TMD.

Orthognathic Surgery as a Treatment for Temporomandibular Disorders

Well-controlled clinical trials supporting orthognathic surgery as the primary management for temporomandibular disorders (TMDs) are lacking. Most published studies lack an adequate experimental design to minimize biases. Studies that did minimize some biases do support an overall reduction in the frequency of TMD signs and symptoms in some Class III and Class II patients who had orthognathic surgery. However, Class II correction with counter-clockwise rotation of the mandible increased TMD. Individual variability precludes the ability to predict TMD outcome after surgery. Irreversible therapies such as orthognathic surgery should not be primary treatments in the management or prevention of TMDs.

Does fixation method affects temporomandibular joints after mandibular advancement?

PURPOSE

Sagittal split ramus osteotomy (SSRO) is a standard procedure in which miniplates and screws are used to achieve stabilization. Although the titanium plate and screw fixation system is stable, resorbable fixation systems are also used. There is currently no consensus on the ideal fixation technique for SSRO procedures and its effect on the condyle. We aimed to evaluate the stress distribution on temporomandibular joints (TMJ).

METHODS

A 3D finite element model of a hemimandible was designed and 5 mm advancement was simulated on a computer model. Four different fixation techniques were applied: inverted-L shaped bicortical screws, L-shaped bicortical screws, miniplate with monocortical screws, and miniplate with monocortical screws and bicortical screw. Computer models were prepared twice for resorbable and titanium material. Load of 600N and muscle forces were applied. In the finite element analysis, computer models simulated and analyzed stress distribution of bone, fixation materials and condyle.

RESULTS

Bicortical screws increase the total stress on TMJ, and the stress is located more on the posterior part than the anterior. Miniplates decrease the stress, and the forces are located more on the anterior aspect of the TMJ.

CONCLUSION

According to our analysis, the use of bicortical screws increases the stress amount on the condyle. For the patients with a tendency toward temporomandibular disorders, using miniplate fixation techniques may decrease the forces around the condyle. These findings should be useful for oral surgeons when deciding on the most appropriate fixation technique in patients with a tendency toward temporomandibular joint disorders.

Assessment of occlusion with the T-Scan system in patients undergoing orthognathic surgery

Dental occlusion varies among individuals, and achieving correct physiological occlusion after osteotomy is essential for the complex functioning of the stomatognathic system. The T-Scan system records the centre of force, first contact, maximum bite force, and maximum intercuspation. The aim of the present study was to investigate the usefulness and consistency of T-Scan in assessing occlusion before and after orthognathic surgery. Occlusal information was evaluated for 30 healthy adults with normal occlusion and 40 patients undergoing orthognathic surgery. T-Scan had a high degree of reliability for consecutive measurements (Pearson correlation, r = 0.98). For most parameters, occlusal distribution was better after surgery than before surgery. More teeth contributed to occlusion at maximum intercuspation after surgery than before surgery (14 vs. 10). In addition, the difference in the posterior force distribution was reduced after surgery (17.6 ± 13.8 vs. 22.7 ± 21.4 before surgery), indicating better occlusal force distribution after surgery. The maximum percentage force on teeth (p = 0.004) and the number of teeth contributing to occlusion (p < 0.001) also differed significantly. Thus, T-Scan is good for assessing occlusal discrepancies and can be used to portray the pre- and post-operative occlusal contact distribution during treatment planning and follow-up.

Experiencing your own orthognathic surgery: a personal case report

There has been much research on minimizing the side effects of orthognathic surgery. However, there are very few doctors and researchers who themselves have undergone this surgery. This case report describes the findings of a maxillofacial surgeon who underwent combined orthodontic and orthognathic treatment for correction of Class II malocclusion. In March 2012, the surgeon was referred to an orthodontist, and an orthodontic examination revealed a Class II, division 2, malocclusion with a traumatic palatal bite and attrition of the lower front teeth. The patient underwent alignment of the upper and lower arches, followed by a bilateral sagittal split osteotomy. During this treatment, he made many interesting observations and learned much as a patient, which can have implications in improving the outcomes and quality of care for patients receiving such treatment. Thus, this case report aims to provide a critical perspective of the surgical procedure and treatment from the viewpoint of a maxillofacial surgeon who himself experienced the surgery as a patient.

TMJ response to mandibular advancement surgery: an overview of risk factors

Objective

In order to understand the conflicting information on temporomandibular joint (TMJ) pathophysiologic responses after mandibular advancement surgery, an overview of the literature was proposed with a focus on certain risk factors.

Methods

A literature search was carried out in the Cochrane, PubMed, Scopus and Web of Science databases in the period from January 1980 through March 2013. Various combinations of keywords related to TMJ changes [disc displacement, arthralgia, condylar resorption (CR)] and aspects of surgical intervention (fixation technique, amount of advancement) were used. A hand search of these papers was also carried out to identify additional articles.

Results

A total of 148 articles were considered for this overview and, although methodological troubles were common, this review identified relevant findings which the practitioner can take into consideration during treatment planning: 1- Surgery was unable to influence TMJ with preexisting displaced disc and crepitus; 2- Clicking and arthralgia were not predictable after surgery, although there was greater likelihood of improvement rather than deterioration; 3- The amount of mandibular advancement and counterclockwise rotation, and the rigidity of the fixation technique seemed to influence TMJ position and health; 4- The risk of CR increased, especially in identified high-risk cases.

Conclusions

Young adult females with mandibular retrognathism and increased mandibular plane angle are susceptible to painful TMJ, and are subject to less improvement after surgery and prone to CR. Furthermore, thorough evidenced-based studies are required to understand the response of the TMJ after mandibular advancement surgery.

[Relations between orthognathic surgery and temporomandibular disorders: a systematic review]

A painful and dysfunctional temporomandibular joint can be associated with a musculoskeletal anomaly. The multifactorial character of the etiology is now recognized. Among the etiologies, the role of orthognathic surgery is still debated. The analysis of the literature from 2000 to 2011 reveals for most authors a decrease in the frequency and intensity of signs and symptoms after surgery, especially pain and clicking. Risk factors may influence post-surgical results. Studies on patient risk factors such as age, sex, type of dysmorphia are inconclusive. Surgical techniques and the procedure used may have an influence on the development of post-surgical clinical signs and symptoms of temporomandibular disorders.

CBCT-based predictability of attachment of the neurovascular bundle to the proximal segment of the mandible during sagittal split osteotomy

Injury to the inferior alveolar nerve (IAN) during surgery is an important complication of bilateral sagittal split osteotomy. With cone beam computed tomography, the course of the nerve and its relationship to the surrounding structures can be assessed in three dimensions. This study aims to determine whether tomography can predict attachment of the neurovascular bundle to the proximal segment of the mandible during sagittal split osteotomy (SSO). Bilateral linear measurements were taken on cross-sectional tomography images. During osteotomy, it was noted for each patient whether the neurovascular bundle was attached to the proximal segment during the split. If attached, a bone-cutting instrument or a blunt instrument was needed to free the nerve. The nerve was attached at more than one-third of operation sites (170 sites). Of these, over 65% of attached nerves (108 sites) required a bone-cutting intervention to free them from the mandible. After correcting for confounding factors, the linear distances from the buccal cortical margin of the IAN canal to the inner and outer buccal cortical margins of the mandible were important predictors of whether the IAN will be attached to the proximal segment of the mandible during SSO.

3D analysis of condylar position after sagittal split osteotomy of the mandible in mono- and bimaxillary orthognathic surgery - a methodology study in 18 patients

OBJECTIVES

This study analyzes the condylar position with intercondylar distance and angle after sagittal split osteotomy in mono- and bimaxillary orthognathic surgery applying cone-beam computed tomography (CBCT) images before and after surgery.

MATERIALS AND METHODS

Data of 18 patients, ten males (mean age 28 years) and eight females (mean age 26 years) undergoing the described surgery between 2008 and 2009 were analyzed. CBCT scans were performed with the KaVo 3DeXam (KaVo, Biberach/ Riß, Germany) (identical with the iCAT scan device) before and after surgery. The exported DICOM data were analyzed with ImageJ morphometry software. Patients were also asked about TMJ problems. The two-tailed t test was used and significance was set at a p value less than p = 0.05.

RESULTS

There was no significant difference between the pre- and postoperative distances between condylar centers (mean difference: 1 mm) (p = 0.69) and intercondylar angle (mean difference: 6.6°) (p = 0.27).

CONCLUSIONS

CBCT is a novel imaging technique appropriate for detailed and three-dimensional analysis of the condylar position in orthognathic surgery. Available freeware analysis software can be applied for metrical measurements. Our cases showed no significant changes of condylar position immediately after surgery without intraoperative condylar fixation.