Growth changes and orthodontic treatment in a patient with condylolysis

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.

Condylar surface CT value in sagittal plane before and after sagittal split ramus osteotomy

PURPOSE

The purpose of this study was to evaluate the relationship between computed tomography (CT) values of the condylar surface and temporomandibular joint (TMJ) disc position in the sagittal plane before and after sagittal split ramus osteotomy (SSRO) setback surgery, retrospectively.

MATERIALS AND METHODS

The subjects were 75 patients (150 condyles) who underwent bilateral SSRO setback surgery. They were divided into two groups (42 symmetric patients and 33 asymmetric patients). Maximum CT values (pixel values) of five points of the condylar surface and condylar height, length, fossa height, fossa length, and ramus angle in the sagittal plane were measured preoperatively and 1 year postoperatively. Disc position was classified as anterior disc displacement, anterior type, fully covered type, and posterior type, both pre- and postoperatively, using magnetic resonance imaging (MRI).

RESULTS

Postoperative value was significantly higher than preoperative one in CT value of 135° (P = 0.0199) and 180° (0.0363), in the non-deviation side in the asymmetry group. The anterior disc displacement group was significantly larger than those of some other areas pre- and postoperatively in the CT value of 0° point (P < 0.05).

CONCLUSIONS

This study suggested that CT value of the posterior site of the condylar surface could change in the non-deviation side in the asymmetry group after 1 year SSRO, and the condyle with anterior displacement showed high CT value at the anterior site of the condyle before and after surgery.

The incidence of osteoarthritic change on computed tomography of Korean temporomandibular disorder patients diagnosed by RDC/TMD; a retrospective study

Objective Osteoarthritis (OA) of the temporomandibular joint (TMJ) is generally thought to be an age-related disease like those of other joints. This study aims to investigate the incidence of computed tomographic (CT) OA changes in Korean temporomandibular disorder (TMD) patients diagnosed by the Research Diagnostic Criteria for TMD (RDC/TMD). Materials and methods The clinical records and radiographs of 1038 TMD patients (297 men and 741 women with mean age 31.1 ± 17.4 and 34.0 ± 16.2, respectively) diagnosed based on RDC/TMD Axis I in 2010 were reviewed. Results The incidence rate of OA changes in TMD patients is estimated to 27.3%, and higher in women than in men (15.5% in men and 32.0% in women) by 2.3 odds (p < 0.001). It has no correlation with age, showing an almost flat incidence rate throughout the age from the 2nd decade and has no correlation as well with pain or disc displacement diagnosed according to RDC/TMD, while arthrosis/arthritis diagnosis based on RDC/TMD supplemented by plain radiographs shows high risk of OA changes on CT by 38.8 odds (p < 0.05). Conclusions These results imply that the OA changes in young Korean TMD patients are as common as in the old and have no correlation with clinical pain and noise. Considered with high prevalence of TMDs known in the young population, the overall/absolute OA changes in the TMJ can be even higher in the young than in the old population, not like in other joints.

Current status of temporomandibular joint disorders and the therapeutic system derived from a series of biomechanical, histological, and biochemical studies

This article was designed to report the current status of temporomandibular joint disorders (TMDs) and the therapeutic system on the basis of a series of clinical, biomechanical, histological and biochemical studies in our research groups. In particular, we have focused on the association of degenerative changes of articular cartilage in the mandibular condyle and the resultant progressive condylar resorption with mechanical stimuli acting on the condyle during the stomatognathic function. In a clinical aspect, the nature and prevalence of TMDs, association of malocclusion with TMDs, association of condylar position with TMDs, association of craniofacial morphology with TMDs, and influences of TMDs, TMJ-osteoarthritis (TMJ-OA) in particular, were examined. In a biomechanical aspect, the nature of stress distribution in the TMJ from maximum clenching was analyzed with finite element method. In addition, the pattern of stress distribution was examined in association with varying vertical discrepancies of the craniofacial skeleton and friction between the articular disk and condyle. The results demonstrated an induction of large compressive stresses in the anterior and lateral areas on the condyle by the maximum clenching and the subsequent prominent increases in the same areas of the mandibular condyle as the vertical skeletal discrepancy became more prominent. Increase of friction at the articular surface was also indicated as a cause of larger stresses and the relevant disk displacement, which further induced an increase in stresses in the tissues posterior to the disks, indicating an important role of TMJ disks as a stress absorber. In a histological or biological aspect, increase in TMJ loading simulated by vertical skeletal discrepancy, which has already been revealed by the preceding finite element analysis or represented by excessive mouth opening, produced a decrease in the thickness of cartilage layers, an increase in the numbers of chondroblasts and osteoclasts and the subsequent degenerative changes in the condylar cartilage associated with the expression of bone resorption-related factors. In a biochemical or molecular and cellular aspect, excessive mechanical stimuli, irrespective of compressive or tensile stress, induced HA fragmentation, expression of proinflammatory cytokines, an imbalance between matrix metalloproteinases and the tissue inhibitors, all of which are assumed to induce lower resistance to external stimuli and degenerative changes leading to bone and cartilage resorption. Excessive mechanical stimuli also reduced the synthesis of superficial zone protein in chondrocytes, which exerts an important role in the protection of cartilage and bone layers from the degenerative changes. It is also revealed that various cytoskeletal changes induced by mechanical stimuli are transmitted through a stretch-activated or Ca2+channel. Finally, on the basis of the results from a series of studies, it is demonstrated that optimal intra-articular environment can be achieved by splint therapy, if indicated, followed by occlusal reconstruction with orthodontic approach in patients with myalgia of the masticatory muscles, and TMJ internal derangement or anterior disk displacement with or without reduction. It is thus shown that orthodontic treatment is available for the treatment of TMDs and the long-term stability after treatment.

TMJ osteoarthritis/osteoarthrosis and immune system factors in a Japanese sample

OBJECTIVE

To determine whether there is an association between temporomandibular joint (TMJ) osteoarthritis/osteoarthrosis (OA) and immune system factors in a Japanese sample.

MATERIALS AND METHODS

The records of 41 subjects (7 men, aged 22.0 +/- 3.8 years; 34 women, aged 24.8 +/- 6.3 years) and 41 pair-matched controls (7 men, aged 22.1 +/- 2.3 years; 34 women, aged 24.8 +/- 6.4 years) based on age and gender were reviewed. Information on medical history included local or systemic diseases, details on medication type and use, and the presence of allergies and asthma. Dental history questions referred to details regarding past oral injuries. The validity of the hypothesis, defining allergies and asthma as risk factors in OA, was tested by using a logistic regression analysis.

RESULTS

The incidence of allergy was significantly higher in the TMJ OA (P = .008), with a mean odds ratio of 4.125 and a 95% confidence interval of 1.446-11.769.

CONCLUSION

These results suggest that allergy may be a risk factor in association with TMJ OA in this Japanese sample.

Insulin-like growth factor I regulates apoptosis in condylar cartilage

Endogenous insulin-like growth factor-I (IGF-I) is known to affect the growth and development of condylar cartilage. However, the critical effect of IGF-I on cell survival is still unknown. We hypothesized that endogenous IGF-I could regulate the survival of cells of the mandibular condylar cartilage. Mandibular condyles dissected from 12-day-old rats were cultured for 1, 3, and 5 days in medium containing antisense oligodeoxynucleotide (AS-ODN) for IGF-I. Real-time RT-PCR analysis showed that the levels of IGF-I and IGF binding protein (IGFBP)3 mRNAs in the AS-ODN group were significantly decreased. After 3 days' culture, the number of necrotic cells was observed in the undifferentiated mesenchymal cell layer. These cells were TUNEL-positive and confirmed to be apoptotic by electron microscopic observation. Immunoblotting revealed that expression of cleaved caspase3 was increased with AS-ODN. These results may suggest that the cells in the undifferentiated mesenchymal cell layer of the mandibular condyle require IGF-I for survival.

Observation of three cases of temporomandibular joint osteoarthritis and mandibular morphology during adolescence using helical CT

Temporomandibular joint (TMJ) osteoarthritis (OA) is a potential cause of craniofacial deformity. If TMJ OA appears during orthodontic treatment, the mandible usually rotates posteriorly, resulting in an unsatisfactory profile, especially in patients with pre-treatment mandibular retrusion. Although it is important to confirm the kind of TMJ pathosis at the start of orthodontic treatment, the relationship between TMJ OA, condylar remodelling and changes in craniofacial morphology remains unclear because of a lack of longitudinal studies. Elucidating this relationship might allow better prediction of post-treatment craniofacial morphology. In the present case reports, helical computed tomography and cephalometry were used to analyse relationships between the pattern and location of condylar remodelling and the changes in craniofacial morphology in three patients with TMJ OA.

Condylar bony change and self-reported parafunctional habits in prospective orthognathic surgery patients with temporomandibular disorders

OBJECTIVE

The purpose of this study was to investigate the relationship between self-reported parafunctional habits and condylar bony change and disk displacement in orthognathic surgery patients with signs and symptoms of temporomandibular joint disorders.

STUDY DESIGN

This is a cross-sectional retrospective study of pretreatment helical computed tomography scans and questionnaires of 94 female orthognathic surgery patients.

RESULTS

Condylar bony change, unilaterally or bilaterally, was found in 56.4% of the subjects, or 43.6% of the joints. Disk displacement, unilaterally or bilaterally, was seen in 59.6% of the subjects, or 45.7% of the joints. Bruxism and clenching was significantly associated with condylar bony change and disk displacement. Subjects with 3 or more parafunctional habits showed a significantly higher rate of bilateral condylar bony change.

CONCLUSION

Our results suggest that bruxism and clenching might be related to deterioration of the temporomandibular joint and that the greater the number of parafunctional habits a subject has, the higher the risk of condylar bony change.

A case of anterior open bite developing during adolescence

Imaging studies have reported on the relationship between temporomandibular joint (TMJ) degeneration and facial deformity. These studies have suggested that mandibular growth is affected by TMJ degeneration, resulting in altered skeletal structure as mandibular retrusion. However, there are very few longitudinal case reports on TMJ osteoarthrosis (OA). Progressive open bite occurred in an adolescent patient with TMJ OA. Cephalometric analysis showed a downward and backward rotated mandible, and a labial inclination of the upper incisor. Magnetic resonance imaging showed internal derangement without reduction and erosion in the right and the left condyles. Although the cause of open bite is unclear in this case, tongue thrusting, and internal derangements in the temporomandibular joint were suspected as causes of the open bite.

Condylar remodelling and resorption after Le Fort I and bimaxillary osteotomies in patients with anterior open bite. A clinical and radiological study

A sample of 259 patients with vertical maxillary hyperplasia, mandibular hypoplasia and anterior vertical open bite, collected from three different institutions, was analysed regarding temporomandibular joint (TMJ) sounds, condylar remodelling, and condylar resorption. All patients underwent Le Fort I osteotomies, and bilateral sagittal split advancement osteotomies were performed in 117 patients. Intraosseous wire fixation was used in 149 and rigid internal fixation in 110 patients. Cephalometric and orthopantomographic radiographs were available before surgery, immediately after surgery, one year postoperatively and at the latest follow up. The mean follow up was 69 months (range 20-210 months). The number of patients with TMJ sounds decreased from 38% to 31%. At the latest follow up 23.6% of the patients showed condylar remodelling, 7.7% unilateral condylar resorption and 7.7% bilateral condylar resorption. Condylar contours, as assessed on orthopantomographic radiographs, were classified as five different types. Condyles with preexisting radiological signs of osteoarthrosis or having a posterior inclination were at high risk for progressive resorption. Female patients with severe anterior open bite, high mandibular plane angle and a low posterior-to-anterior facial height ratio, who underwent a bimaxillary osteotomy, were prone to condylar resorption. Bone loss was predominantly found at the anterior site of the condyle. The incidence of condylar resorption was significantly higher after bimaxillary osteotomies (23%) than after only Le Fort I intrusion osteotomies (9%). Avoidance of intermaxillary fixation by using rigid internal fixation tended to reduce condylar changes, in particular in patients who underwent only a Le Fort I osteotomy. Rigid internal fixation in bimaxillary osteotomies resulted in condylar remodelling in 30% and progressive condylar resorption in 19% of the patients. Condylar changes were not significantly different after using either miniplate osteosynthesis or positional screws in bilateral sagittal split osteotomy procedures.

A comparison of surgery and orthodontics in "borderline" adults with Class II, division 1 malocclusions

From a pool of 108 former patients, discriminant analysis was used to identify a homogeneous borderline prognostic subgroup of 27 adult orthodontic and 26 adult surgical Class II patients who, before treatment, were similar with respect to the characteristics on which the orthodontic/surgical decision appears to have been based. The fact that some had been treated orthodontically, whereas others had been treated surgically, was taken as empirical evidence that the patients in this stratum were equally susceptible to the two treatments and that the actual choice was largely a function of whose office they happened to contact. The former orthodontic patients were recalled an average of 7.1 years after treatment, the former surgical patients, 4.7 years after surgery. Each subject was evaluated with respect to skeletal and dental stability, profile esthetics, and temporomandibular function. Although there were dramatic differences in the nature of the correction (dental versus skeletal), both groups of patients generally thought that their profiles had been improved by treatment. As judged by data generated from visual analogue scales, the mean difference between the orthodontic and surgical patients' evaluations of their treatments was small and nonsignificant. Moreover, the "borderline" Class II orthodontic and surgical patients showed no significant differences in craniomandibular function and incisor stability. There was, however, one profound difference between treatments: 3 of the 26 surgical patients underwent extensive relapse, probably as a result of condylar resorption. From the standpoint of estimated probabilities and utilities for the various outcomes, the present results imply that orthodontics would be the better choice for the borderline adult Class II patient, whereas surgery would be appropriate for the more severely affected patient.