Effect of TMJ disc position on condylar bone remodeling after arthroscopic disc repositioning surgery

3D model construction and biomechanical analysis of temporomandibular joint disc perforation based on arthrography

OBJECTIVES

Disc perforation (DP) is a severe type of temporomandibular joint (TMJ) disorder. Arthrography-assisted CBCT can visually detect the location and size of DPs. This study aims to use imaging modeling software to construct a three-dimensional (3D) visual model of DP, simulating its biomechanical impact on the TMJ to provide a scientific basis for diagnosis and treatment.

MATERIALS AND METHODS

TMJ imaging data were obtained through arthrography and CBCT scans. Imaging modeling software was used to reconstruct and measure the DICOM files in 3D. The model was imported into biomechanical analysis software to simulate the static occlusal state of the mandibular muscles on the TMJ. The effects of DP on the mechanical properties of the TMJ were assessed via von Mises stress and total deformation analysis.

RESULTS

(1) The maximum von Mises stress (MVMS) on the affected side of the disc was significantly greater than that on the unaffected side. This stress was negatively correlated with the height of the condylar head and positively correlated with the perforation volume. (2) The maximum total deformation (MTD) of the affected side's disc was significantly greater and negatively correlated with the condylar head height. (3) The MVMS of the condyle was markedly greater on the affected side than on the unaffected side.

CONCLUSION

(1) DPs may increase stress on bilateral TMJs, with the affected side experiencing significantly greater stress. (2) A larger perforation volume can result in greater stress on the affected side's disc. (3) The height of the affected condylar head can have an adverse effect on the stress and deformation of bilateral TMJs.

CLINICAL RELEVANCE

TMJ arthrography can assist clinicians in accurately determining the location, morphology, and size of the disc perforation, enabling early diagnosis and intervention to prevent further enlargement. Additionally, the restoration and protection of the condylar head height contribute to maintaining the stability of the intra-articular stresses within the TMJ.

Synergistic effects of estrogen deficiency and articular disk derangement on condylar bone loss

OBJECTIVES

Temporomandibular joint osteoarthritis (TMJ-OA) with condylar resorption is a multifactorial condition involving hormonal imbalance and articular disk dysfunction, often leading to severe TMJ degeneration. This study investigated the combined effects of estrogen deficiency and anterior articular disk derangement (ADD) on condylar bone resorption in a mouse model.

METHODS

Female C57BL/6J mice underwent ovariectomy (OVX) to induce estrogen deficiency and ADD was surgically induced for stress. The animals were divided into the control, OVX, ADD, and OVX + ADD groups. Microcomputed tomography and histological analyses were conducted to evaluate condylar bone structure, trabecular architecture, and osteoclast activity.

RESULTS

OVX and ADD caused significant condylar bone loss, characterized by reduced bone volume per tissue volume (BV/TV) and abnormal trabecular architecture. The OVX + ADD group exhibited exacerbated bone resorption, with decreased BV/TV and increased trabecular separation compared to OVX or ADD alone. Histological analyses revealed increased osteoclast activity in the OVX + ADD group, suggesting a synergistic effect of estrogen deficiency and ADD on condylar degradation.

CONCLUSION

Estrogen deficiency amplifies the bone-resorptive and inflammatory effects of ADD, accelerates temporomandibular joint (TMJ) degeneration, and underscores the interplay between hormone imbalance and articular disk dysfunction in the pathophysiology of TMJ-OA. There is a need for integrated treatment strategies, such as effective hormone replacement therapy and articular disk repositioning, to effectively manage temporomandibular joint disorders, particularly in postmenopausal women or those with hormonal imbalances. Further research is required to elucidate these molecular pathways and evaluate long-term therapeutic interventions.

Characteristics of Temporomandibular Joint Osteoarthritis Patients With Condylar Erosion: A Retrospective Cross-Sectional Study

BACKGROUND

Condylar erosion (CE) may indicate an active progressive stage of temporomandibular joint osteoarthritis (TMJOA), but no studies have analysed the characteristics of this population.

OBJECTIVE

This cross-sectional study analysed the characteristics of TMJOA patients with CE.

METHODS

A total of 267 patients were included. The severity of CE of all joints was evaluated using cone beam computed tomography (CBCT) and scored using a four-point rating scale (0-III). Patients were categorised into mild (grade I), moderate (grade II) and severe (grade III) groups. Demographic and clinical characteristics were summarised and stratified by age and erosion severity. Univariate and multivariate logistic regression analyses were performed based on the assignment of the variables.

RESULTS

The proportion of patients under 30 years old is much higher than other age groups. Compared to adults (≥ 20 years old), a higher proportion of adolescent patients (10-19 years old) choose orthodontics department for their first consultation (p < 0.01). And adolescent patients have a higher proportion of temporomandibular joint (TMJ) noise (p < 0.05) and a lower proportion of arthralgia (p < 0.001). Significant differences exist in CE severity between adolescents and adults (p < 0.001). The severe group had the youngest patients (p < 0.05) and the highest proportion of mandibular deviation and abnormal postural habits.

CONCLUSIONS

Patients under 30 years of age constitute a significant proportion of TMJOA cases with CE. Compared to adults, adolescent patients have more severe CE and less arthralgia. Due to obvious dental and maxillofacial deformities and milder TMJ symptoms, adolescent patients may not be aware that they have TMJ disease, potentially leading to delayed treatment.

Arthroscopic reduction and rigid fixation of the anteriorly displaced temporomandibular joint disc without reduction using titanium screw: a case series

OBJECTIVES

To evaluate the effectiveness of arthroscopic reduction and rigid fixation (ARRF) using a suture-free titanium screw as a treatment approach to temporomandibular joint's (TMJ) anterior disc displacement without reduction (ADDwoR) and assess its impact on clinical outcomes, including improvements in symptoms related to TMJ disorders.

MATERIALS AND METHODS

A series of twenty patients presented to the Department of Orthognathic and Temporomandibular Surgery at West China Hospital of Stomatology between September 2022 and January 2023, complaining of symptoms such as pain, clicking, and limited mouth opening. Standard magnetic resonance image (MRI) imaging T1 and T2 sequences in both sagittal and coronal views study with closed and maximal open mouth positions were taken preoperatively to assess the disc's position, integrity, and shape. Also, cone-beam computed tomography (CBCT) scans images to find any degenerative changes and evaluate the condylar bone's features and volume. Additionally, the clinical examination assesses limited oral opening, mechanical pain, and the presence of any noises such as clicking and crepitus. All cases were treated under general anesthesia using the arthroscopic release, reduction, and rigid fixation of the TMJ's ADDwoR to establish a normal disc-condyle relationship and to restore the functional position.

RESULTS

Patients' symptoms, such as pain and mouth opening, improved significantly following the arthroscopic treatment. Postoperative MRI and CBCT imaging follow-up conducted at 6 months demonstrated the stable position of the reduced TMJ disc and the fixation screw. Notably, none of the patients exhibited signs of relapse during this follow-up period.

CONCLUSION

Overall, the ARRF of TMJ's ADDwoR using a suture-free titanium screw proved to be safe and provides satisfactory results, in addition to the several advantages of using suture-free titanium screws, such as biocompatibility, strong fixation, and durability. However, it is a technically demanding procedure requiring extensive, long-term training.

CLINICAL RELEVANCE

ARRF using a cost-effective fixation titanium screw to treat ADDwoR emerges as a clinically effective minimally invasive approach.