Research Spotlight

Revilla-León, M., Fountain, J., Piedra-Cascón, W., Özcan, M. and Zandinejad, A. (2021). “Workflow of a fiber-reinforced composite fixed dental prosthesis by using a 4-piece additive manufactured silicone index: A dental technique.” J Prosthet Dent 125(4): 569-575.

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A digital workflow for fabricating a fiber-reinforced composite prosthesis is described. A facial scanner and an intraoral scanner were used to gather records, and dental and open-source software programs were used to elaborate a diagnostic waxing and design a 4-piece additively manufactured clear silicone index. Advantages of the index design included precise translation of the diagnostic waxing, optimal composite resin stratification, and minimal clinical time.

Piedra-Cascón, W., Mostafavi, D., Ruiz-de-Gopegui, J., Pérez-Pevida, E., Robles-Cantero, D. and Revilla-León, M. (2021). “Fabricating a dual-material, vat-polymerized, additively manufactured static implant surgical guide: A dental technique.” J Prosthet Dent Mar 11;S0022-3913(21)00078-0. [Epub ahead of print].

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Protocols with static computer-aided implant placement provide more tangible clinical advantages than conventional implant placement methods. A technique to manufacture a dual-material implant surgical guide by using a vat-polymerization printer is described. The implant surgical guide combined a resilient intaglio and hard exterior surface. The technique should minimize the clinical adjustments needed to ensure fit and improve patient comfort.

Li, Q., Hu, Z., Liang, Y., Xu, C., Hong, Y. and Liu, X. (2021). “Multifunctional peptide-conjugated nanocarriers for pulp regeneration in a full-length human tooth root.” Acta Biomater Apr 1;S1742-7061(21)00209-9. [Epub ahead of print].

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Dental pulp is a highly vascularized tissue, situated in an inextensible environment surrounded by rigid dentinal walls. The pulp receives its blood supply solely from the small apical foramen of a tooth root. Due to the unique anatomy that controls nutrition supply, regeneration of pulp tissue in a full-length tooth root has long been a challenge in regenerative endodontics. In this study, we designed and synthesized a multifunctional peptide-conjugated, pH-sensitive, non-viral gene vector for fast revascularization and pulp regeneration in a full-length human tooth root. The multifunctional peptide was designed to have distinctive features, including a cell-penetrating peptide to enhance cellular uptake, a nuclear localization signal peptide to assist in the translocation of an angiogenic gene into the nucleus, and a fluorescent tryptophan residue to visualize and quantify the transfection efficiency. Furthermore, a pH-sensitive dimethylmaleic anhydride (DMA) was integrated with the multifunctional peptide to enhance the transfected gene complex to escape from endosomes/lysosomes after internalization. In vitro experiments showed that the multifunctional non-viral gene vector significantly increased internalization and gene transfection efficiency as well as reduced cytotoxicity. After dental pulp stem cells (DPSCs) were transfected with the multifunctional gene vector/pVEGF complexes, the expression of VEGF from the DPSCs was upregulated for more than eight folds, which in turn greatly enhanced endothelial cell migration and vascular-like tube formation. Six weeks after implantation, the VEGF-transfected DPSCs accelerated new blood vessel formation and the regenerated pulp tissue occupied most of the area in the canal of a full-length human tooth root. The multifunctional peptide conjugated non-viral gene delivery is a safe and effective approach for regenerative endodontics. STATEMENT OF SIGNIFICANCE: Pulp regeneration in a full-length tooth root canal has long been a challenge in regenerative endodontics. This is due to the unique root anatomy that allows the blood supply of the tooth root only from a small apical foramen (< 1 mm), leading to a severe barrier for revascularization during pulp regeneration. In this work, we designed a multifunctional peptide-conjugated, pH-sensitive, non-viral gene vector to address this challenge. Our work shows that the peptide-conjugated system was an excellent carrier for fast revascularization and pulp tissue regeneration in a full-length toot root. This study will interest the multidisciplinary readership in gene delivery, biomaterials, and dental/craniofacial tissue engineering community.

Chang, B. and Liu, X. (2021). “Osteon: Structure, Turnover, and Regeneration.” Tissue Eng Part B Rev Mar 8. [Epub ahead of print].

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Bone is composed of dense and solid cortical bone and honeycomb-like trabecular bone. Although cortical bone provides the majority of mechanical strength for a bone, there are few studies focusing on cortical bone repair or regeneration. Osteons (the Haversian system) form structural and functional units of cortical bone. In recent years, emerging evidences have shown that the osteon structure (including osteocytes, lamellae, lacunocanalicular network, and Haversian canals) plays critical roles in bone mechanics and turnover. Therefore, reconstruction of the osteon structure is crucial for cortical bone regeneration. This article provides a systematic summary of recent advances in osteons, including the structure, function, turnover, and regenerative strategies. First, the hierarchical structure of osteons is illustrated and the critical functions of osteons in bone dynamics are introduced. Next, the modeling and remodeling processes of osteons at a cellular level and the turnover of osteons in response to mechanical loading and aging are emphasized. Furthermore, several bioengineering approaches that were recently developed to recapitulate the osteon structure are highlighted. Impact statement This review provides a comprehensive summary of recent advances in osteons, especially the roles in bone formation, remodeling, and regeneration. Besides introducing the hierarchical structure and critical functions of osteons, we elucidate the modeling and remodeling of osteons at a cellular level. Specifically, we highlight the bioengineering approaches that were recently developed to mimic the hierarchical structure of osteons. We expect that this review will provide informative insights and attract increasing attentions in orthopedic community, shedding light on cortical bone regeneration in the future.

Aminoshariae, A., Azarpazhooh, A., Diogenes, A.R., Fouad, A.F., Glickman, G.N., Kishen, A., Letra, A.M., Levin, L., Roda, R.S., Setzer, F.C., Tay, F.R. and Hargreaves, K.M. (2021). “Insights into the May 2021 issue of the JOE.” J Endod Mar 26;S0099-2399(21)00199-0. [Epub ahead of print].

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Welcome to the May 2021 issue of the Journal of Endodontics (JOE). Here we share some of our favorite articles that are published in this issue of the journal. We hope you look forward to reading these and other articles in JOE. [No abstract]