Page 267 - IJB-9-5

International Journal of Bioprinting

which affects 9.8% of the adult and elderly population [2,3] . as seed cells, and inoculate them with bioactive additives
Among the complicated etiological factors of TMJ on biodegradable scaffolds to form artificial grafts, which
osteoarthritis, the fundamental cause is assumed to be the are transplanted into the cartilage defect . Degradation
[11]
excessive mechanical loading on the healthy or impaired of the scaffold material occurs simultaneously with cell
articular fibrocartilage, which may result from mandibular proliferation and cartilage matrix secretion, resulting in the
asymmetry, severe malocclusion, and muscle overuse . formation of new cartilage and local anatomical structures.
[4]
Locally, the excessive mechanical loading would lead to However, the complex heterogeneous structures of the
both displacement and impairment of the TMJ disc and TMJ disc and mandibular condyle pose great challenges
progressive osteochondral defects of the mandibular to the fabrication of biomimetic tissue structures based
condyle , with flattening and erosion of the articular on traditional scaffold-based strategies. Notably, three-
[5]
surface as the typical morphologic changes on the cone dimensional (3D) printing has emerged in recent years
beam computed tomography . The typical pathological as a promising technique, which allows precise control
[6]
change in the fibrocartilage tissue in the early phase of of the internal structure and dimensional parameters
TMJ osteoarthritis is chondrocyte apoptosis or necrosis, of scaffolds to fabricate bionic scaffolds for articular
along with the overexpression of inflammatory cytokines cartilage regeneration . Unfortunately, in some reviews
[12]
in the synovial fluid of patients . As TMJ osteoarthritis on TMJ regenerative medicine, the content related to
[7]
progresses, patients may exhibit orofacial pain, mouth- 3D-printed scaffolds for TMJ tissue regeneration was very
opening limitation, and joint clicking sound as common limited and thus did not fully present the great potential
clinical symptoms, affecting swallowing, speaking, and of 3D-printed scaffolds [13,14] . On the other hand, several
other orofacial activities . reviews focusing on 3D printing technology in various
[7]
Treatment alternatives for TMJ osteoarthritis are cartilage tissue-engineering fields, such as knee joint,
primarily divided into non-surgical and surgical options, meniscus, intervertebral disc, ear and nose, etc., have been
depending on the severity of the case . For TMJ osteoarthritis published recently, while reviews on 3D-printed scaffolds
[2]
[12,15-18]
patients with mild pain and clicking sounds, conservative for TMJ fibrocartilage regeneration are lacking .
treatment, such as arthrocentesis with/without hyaluronic With the increasing popularity of 3D printing techniques
acid injection, occlusal splints, and non-steroidal anti- in tissue engineering and regenerative medicine, the great
inflammatory drugs, aiming to relieve pain and pathological potential of 3D-printed scaffolds for TMJ fibrocartilage
progress is recommended . When local inflammation has regeneration should not be ignored. Therefore, in this
[7]
severely impaired most of the TMJ anatomical structure review, we will briefly introduce some popular 3D printing
and caused intractable pain, surgical intervention would techniques and a scaffold design framework, and then
be the priority treatment option. Functional restoration summarize the research progress of 3D-printed scaffolds
of the TMJ can be achieved by joint replacement using for TMJ fibrocartilage regeneration, followed by some
an autologous bone, such as costochondral grafts and free current challenges and emerging tissue-engineering
fibula flaps, or an artificial joint . Autologous cartilage strategies, which are potential approaches to improve the
[8]
transplantation, on the other hand, would pose additional performance of 3D-printed scaffolds.
lesions and risk of complications at the donor site.
Allogeneic cartilage transplantation avoids the donor site 2. 3D printing techniques for cartilage
lesion but has limited application due to the risk of immune tissue engineering
rejection . Regarding the long-term treatment effects of The initial step in the 3D printing process to achieve
[9]
TMJ prosthesis, postoperative complications, such as metal articular cartilage regeneration is to scan the biological
particulation leading to osteolysis, have been reported, and tissue or organ with computed tomography and magnetic
therefore, patients treated by TMJ prosthesis have to take resonance imaging and build 3D models based on
the risk of revision surgery . Considering that the need the acquired data of the tissue characteristics. Then,
[10]
for physiological reconstruction of TMJ condyle and disc appropriate biomaterials are adopted to fabricate scaffolds
remains unmet based on the existing treatment regimen, using 3D printing techniques. Seed cells are cultured
cartilage tissue engineering has garnered increasing with specific bioactive factors (BFs) and then seeded into
attention as a promising alternative for TMJ fibrocartilage the 3D-printed scaffolds to enhance their performance.
defects.
Another strategy is to fabricate the bioink consisting of
With progressive achievements in biomaterials and seed cells, BFs, and scaffold materials . A 3D bioprinter
[19]
regenerative medicine, cartilage tissue engineering has under the control of computer can convert the obtained
been increasingly explored. The primary process of cartilage data into a 3D-printed scaffold using bioink. Subsequently,
tissue engineering is to select one or some specific cells in vitro culture will accelerate the maturation and promote

Volume 9 Issue 5 (2023) 259 https://doi.org/10.18063/ijb.761