scholarly journals Trueness of Fit of Biphasic Transversely Isotropic Parameters Model in the Porcine Temporomandibular Joint Disc and Mandibular Condylar Cartilage and Regional Dependence

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Adam R. Chin ◽  
Alejandro J. Almarza

Abstract Temporomandibular joint (TMJ) disorders (TMDs) are not well understood and the mechanical differences between the regions of the mandibular condylar cartilage (MCC) and the TMJ disc have not been thoroughly compared. As of now, there are no commercially available regenerative therapies for the TMJ. Elucidating the mechanical properties of these two structures of the articulating joint will help future efforts in developing tissue engineering treatments of the TMJ. In this study, we evaluate the compressive properties of the porcine disc and mandibular condylar cartilage by performing unconfined compression at 10% strain with 4.5%/min strain rate. Punches (4 mm biopsy) from both tissues were taken from five different regions of both the MCC and TMJ: anterior, posterior, lateral, medial, and central. Previously, theoretical models of compression in the porcine tissue did not fit the whole ramp-relaxation behavior. Thus, the data stress–relaxation was fitted to the biphasic transversely isotropic model, for both the TMJ disc and cartilage. From the results found in the disc, it was found that the posterior region had the highest values in multiple viscoelastic parameters when compared to the other regions. The mandibular condylar cartilage was only found to be significantly different in the transverse modulus between the posterior and lateral regions. Both the TMJ disc and MCC had similar magnitudes of values (for the modulus and other corresponding compressive properties) and behavior under this testing modality.

Author(s):  
Catherine K. Hagandora ◽  
Alejandro J. Almarza

The temporomandibular joint (TMJ) is a synovial, bilateral joint formed by the articulation of the condyle of the mandible and the articular eminence and glenoid fossa of the temporal bone. The articulating tissues of the joint include the TMJ disc and the mandibular condylar cartilage (MCC). It is estimated that 10 million Americans are affected by TMJ disorders (TMDs), a term encompassing a variety of conditions which result in positional or structural abnormalities in the joint. [1] Characterization of the properties of the articulating tissues of the joint is a necessary prequel to understanding the process of pathogenesis as well as tissue engineering suitable constructs for replacement of damaged joint fibrocartilage. Furthermore, the current literature lacks a one-to-one comparison of the regional compressive behavior of the goat MCC to the TMJ disc.


2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Vincent P. Willard ◽  
Kerem N. Kalpakci ◽  
Andrew J. Reimer ◽  
Kyriacos A. Athanasiou

Understanding structure-function relationships in the temporomandibular joint (TMJ) disc is a critical first step toward creating functional tissue replacements for the large population of patients suffering from TMJ disc disorders. While many of these relationships have been identified for the collagenous fraction of the disc, this same understanding is lacking for the next most abundant extracellular matrix component, sulfated glycosaminoglycans (GAGs). Though GAGs are known to play a major role in maintaining compressive integrity in GAG-rich tissues such as articular cartilage, their role in fibrocartilaginous tissues in which GAGs are much less abundant is not clearly defined. Therefore, this study investigates the contribution of GAGs to the regional viscoelastic compressive properties of the temporomandibular joint (TMJ) disc. Chondroitinase ABC (C-ABC) was used to deplete GAGs in five different disc regions, and the time course for >95% GAG removal was defined. The compressive properties of GAG depleted regional specimens were then compared to non-treated controls using an unconfined compression stress-relaxation test. Additionally, treated and non-treated specimens were assayed biochemically and histologically to confirm GAG removal. Compared to untreated controls, the only regions affected by GAG removal in terms of biomechanical properties were in the intermediate zone, the most GAG-rich portion of the disc. Without GAGs, all intermediate zone regions showed decreased tissue viscosity, and the intermediate zone lateral region also showed a 12.5% decrease in modulus of relaxation. However, in the anterior and posterior band regions, no change in compressive properties was observed following GAG depletion, though these regions showed the highest compressive properties overall. Although GAGs are not the major extracellular matrix molecule of the TMJ disc, they are responsible for some of the viscoelastic compressive properties of the tissue. Furthermore, the mechanical role of sulfated GAGs in the disc varies regionally in the tissue, and GAG abundance does not always correlate with higher compressive properties. Overall, this study found that sulfated GAGs are important to TMJ disc mechanics in the intermediate zone, an important finding for establishing design characteristics for future tissue engineering efforts.


Cartilage ◽  
2020 ◽  
pp. 194760352096256
Author(s):  
Paige S. Woods ◽  
Alyssa A. Morin ◽  
Po-Jung Chen ◽  
Sarah Mahonski ◽  
Liping Xiao ◽  
...  

Objective Employ an automated indentation technique, using a commercially available machine, to assess the effect of fibroblast growth factor 2 (FGF2) expression on structural stiffness over the surface of both murine femoral articular cartilage (AC) and temporomandibular joint (TMJ) mandibular condylar cartilage (MCC). Design Experiments were performed using 3-month-old female homozygote Fgf2KO mice with wild type (WT) littermates. After euthanization, isolated mandibles and hindlimbs were either processed for histology or subjected to automated indentation on a Biomomentum Mach-1 v500csst with a 3-axis motion controller in a phosphate buffered saline bath using a 0.3 mm spherical tip indenter. The effect of indentation depth on normal force was characterized, then structural stiffness was calculated and mapped at multiple positions on the AC and MCC. Results Automated indentation of the AC and TMJ MCC was successfully completed and was able to demonstrate both regional variation in structural stiffness and differences between WT and Fgf2KO mice. Structural stiffness values for Fgf2KO AC were significantly smaller than WT at both the medial/anterior ( P < 0.05) and medial/posterior ( P < 0.05) positions. Global Fgf2KO also lead to a decrease in MCC thickness of the TMJ compared with WT ( P < 0.05) and increased structural stiffness values for Fgf2KO at both the posterior and anterior location ( P < 0.05). Conclusions Automated indentation spatially resolved differences in structural stiffness between WT and Fgf2KO tissue, demonstrating FGF2 expression affects femoral AC and TMJ MCC. This quantitative method will provide a valuable approach for functional characterization of cartilage tissues in murine models relevant to knee joint and TMJ health and disease.


2018 ◽  
Vol 10 (446) ◽  
pp. eaaq1802 ◽  
Author(s):  
Natalia Vapniarsky ◽  
Le W. Huwe ◽  
Boaz Arzi ◽  
Meghan K. Houghton ◽  
Mark E. Wong ◽  
...  

Treatments for temporomandibular joint (TMJ) disc thinning and perforation, conditions prevalent in TMJ pathologies, are palliative but not reparative. To address this, scaffold-free tissue-engineered implants were created using allogeneic, passaged costal chondrocytes. A combination of compressive and bioactive stimulation regimens produced implants with mechanical properties akin to those of the native disc. Efficacy in repairing disc thinning was examined in minipigs. Compared to empty controls, treatment with tissue-engineered implants restored disc integrity by inducing 4.4 times more complete defect closure, formed 3.4-fold stiffer repair tissue, and promoted 3.2-fold stiffer intralaminar fusion. The osteoarthritis score (indicative of degenerative changes) of the untreated group was 3.0-fold of the implant-treated group. This tissue engineering strategy paves the way for developing tissue-engineered implants as clinical treatments for TMJ disc thinning.


Author(s):  
Edward D. Bonnevie ◽  
Laura Barito ◽  
Matthew Aldridge ◽  
Liyun Wang ◽  
David L. Burris ◽  
...  

Temporomandibular joint (TMJ), the only diarthrodial joint in human head, is composed of two articulating bones covered by cartilage with an extra disc between the two cartilage surfaces. The rotation and gliding motions of TMJ allow us to talk, chew, and yawn. Dislocation of the disc or degeneration of the cartilage can severely ruin the congruity and integrality of TMJ and further leads to TMJ disorders (TMD). Histology studies showed that the composition and structure of condylar cartilage do not resemble any other fibrocartilages [1], our recent study also found that the condylar cartilage is much softer than cartilage in other joints [2]. The condyle is fully covered by the disc, which glides on the condyle cartilage during daily activities [3]. Little is known about the frictional coefficients of these cartilaginous tissues in TMJ. In this study, using a novel custom-built tribometer, we propose to investigate: 1) the frictional coefficients of condylar cartilage and disc at five different regions, and 2) the dependency of frictional coefficient on sliding speed and loading magnitude.


2019 ◽  
Vol 1 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Yi-Shu Liu ◽  
Adrian U-Jin Yap ◽  
Jie Lei ◽  
Kai-Yuan Fu

Background: The causes of mandibular condylar hypoplasia can be congenital or acquired in nature. Cited local causes of acquired hypoplasia include trauma, infection and irradiation. We report a case of hypoplastic condyle that was attributed to temporomandibular joint (TMJ) disc displacement without reduction (DDwoR). Clinical Presentation: A 16-year-old male presented with restricted mouth opening and right TMJ pain for 6 months. He was subsequently diagnosed with DDwoR. Conservative treatment comprising self-care and moist-heat therapy was administered and he was followed for 27 months without any further interventions. During this period, transitions from “normal” morphology to condylar flattening / erosion, and eventually a re-modeled smaller “normal” right TMJ were observed. Conclusion: The present case provided initial support that DDwoR could be a plausible cause of condylar hypoplasia in adolescents / young adults.


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