Pulp health and calcific healing of a complicated crown–root fracture with additional root fracture in a maxillary incisor: A case report

BACKGROUND Complicated crown–root fracture (CRF) involves severe injury to the crown, root,and pulp, and may be accompanied by multiple root fractures. The loss of a toothhas lifelong consequences for children and teenagers, but the maintenance of pulphealth and the calcific healing of multiple root fractures are rarely reported in theliterature.CASE SUMMARY This case reports healing of a permanent tooth with complicated crown–root andadditional root fractures, in which pulp health was maintained. A 10-year-old girlfell and fractured the root of her maxillary left central incisor at the cervical level.After the coronal fragment was repositioned, the tooth was splinted until thetooth was no longer mobile, 2 years later. Eight years after treatment, the toothhas remained asymptomatic with vital pulp and localized gingival overgrowth.Cone-beam computed tomography revealed not only calcified healing of the CRFbut also spontaneous healing in an additional undiagnosed root fracture. Thefracture line on the enamel could not be healed by hard tissue and formed agroove in the cervical crown. It was speculated that the groove was related to thelocalized gingival overgrowth.CONCLUSION This case provides a clinical perspective of the treatment of a tooth with acomplicated CRF and an additional root fracture.

Strategies of functionalized GelMA-based bioinks for bone regeneration:Recent advances and future perspectives

Gelatin methacryloyl(GelMA)hydrogels is a widely used bioink because of its good biological properties and tunable physicochemical properties,which has been widely used in a variety of tissue engineering and tissue regeneration.However,pure GelMA is limited by the weak mechanical strength and the lack of continuous osteogenic induction environment,which is difficult to meet the needs of bone repair.Moreover,GelMA hydrogels are unable to respond to complex stimuli and therefore are unable to adapt to physiological and pathological microenvironments.This review focused on the functionalization strategies of GelMA hydrogel based bioinks for bone regeneration.The synthesis process of GelMA hydrogel was described in details,and various functional methods to meet the requirements of bone regeneration,including mechanical strength,porosity,vascularization,osteogenic differentiation,and immunoregulation for patient specific repair,etc.In addition,the response strategies of smart GelMA-based bioinks to external physical stimulation and internal pathological microenvironment stimulation,as well as the functionalization strategies of GelMA hydrogel to achieve both disease treatment and bone regeneration in the presence of various common diseases(such as inflammation,infection,tumor)are also briefly reviewed.Finally,we emphasized the current challenges and possible exploration directions of GelMA-based bioinks for bone regeneration.

Breakthrough of extracellular vesicles in pathogenesis, diagnosis and treatment of osteoarthritis

Osteoarthritis(OA)is a highly prevalent whole-joint disease that causes disability and pain and affects a patient’s quality of life.However,currently,there is a lack of effective early diagnosis and treatment.Although stem cells can promote cartilage repair and treat OA,problems such as immune rejection and tumorigenicity persist.Extracellular vesicles(EVs)can transmit genetic information from donor cells and mediate intercellular communication,which is considered a functional paracrine factor of stem cells.Increasing evidences suggest that EVs may play an essential and complex role in the pathogenesis,diagnosis,and treatment of OA.Here,we introduced the role of EVs in OA progression by influencing inflammation,metabolism,and aging.Next,we discussed EVs from the blood,synovial fluid,and joint-related cells for diagnosis.Moreover,we outlined the potential of modified and unmodified EVs and their combination with biomaterials for OA therapy.Finally,we discuss the deficiencies and put forward the prospects and challenges related to the application of EVs in the field of OA.

Three-dimensional bioprinting biphasic multicellular living scaffold facilitates osteochondral defect regeneration

Due to tissue lineage variances and the anisotropic physiological character-istics,regenerating complex osteochondral tissues(cartilage and subchondral bone)remains a great challenge,which is primarily due to the distinct requirements for cartilage and subchondral bone regeneration.For cartilage regeneration,a significant amount of newly generated chondrocytes is required while maintaining their phenotype.Conversely,bone regeneration necessitates inducing stem cells to differentiate into osteoblasts.Additionally,the construction of the osteochondral interface is crucial.In this study,we fabricated a biphasic multicellular bioprinted scaffold mimicking natural osteochondral tissue employing three-dimensional(3D)bioprinting technol-ogy.Briefly,gelatin-methacryloyl(GelMA)loaded with articular chondrocytes and bone marrow mesenchymal stem cells(ACs/BMSCs),serving as the cartilage layer,preserved the phenotype of ACs and promoted the differentia-tion of BMSCs into chondrocytes through the interaction between ACs and BMSCs,thereby facilitating cartilage regeneration.GelMA/strontium-substituted xonotlite(Sr-CSH)loaded with BMSCs,serving as the subchondral bone layer,regulated the differentiation of BMSCs into osteoblasts and enhanced the secretion of cartilage matrix by ACs in the cartilage layer through the slow release of bioactive ions from Sr-CSH.Additionally,GelMA,serving as the matrix material,contributed to the reconstruction of the osteochondral interface.Ultimately,this biphasic multicellular bioprinted scaffold demonstrated satisfactory simultaneous regeneration of osteochondral defects.In this study,a promising strategy for the application of 3D bioprinting technology in complex tissue regeneration was proposed.