3D printing for bone regeneration: challenges and opportunities for achieving predictability.

3D printing offers attractive opportunities for large-volume bone regeneration in the oro-dental and craniofacial regions. This is enabled by the development of CAD-CAM technologies that support the design and manufacturing of anatomically accurate meshes and scaffolds. This review describes the main 3D-printing technologies utilized for the fabrication of these patient-matched devices, and reports on their pre-clinical and clinical performance including the occurrence of complications for vertical bone augmentation and craniofacial applications. Furthermore, the regulatory pathway for approval of these devices is discussed, highlighting the main hurdles and obstacles. Finally, the review elaborates on a variety of strategies for increasing bone regeneration capacity and explores the future of 4D bioprinting and biodegradable metal 3D printing.

In Vitro and In Vivo Biological Assessments of 3D-Bioprinted Scaffolds for Dental Applications.

Three-dimensional (3D) bioprinting is a unique combination of technological advances in 3D printing and tissue engineering. It has emerged as a promising approach to address the dilemma in current dental treatments faced by clinicians in order to repair or replace injured and diseased tissues. The exploration of 3D bioprinting technology provides high reproducibility and precise control of the bioink containing the desired cells and biomaterial over the architectural and dimensional features of the scaffolds in fabricating functional tissue constructs that are specific to the patient treatment need. In recent years, the dental applications of different 3D bioprinting techniques, types of novel bioinks, and the types of cells used have been extensively explored. Most of the findings noted significant challenges compared to the non-biological 3D printing approach in constructing the bioscaffolds that mimic native tissues. Hence, this review focuses solely on the implementation of 3D bioprinting techniques and strategies based on cell-laden bioinks. It discusses the in vitro applications of 3D-bioprinted scaffolds on cell viabilities, cell functionalities, differentiation ability, and expression of the markers as well as the in vivo evaluations of the implanted bioscaffolds on the animal models for bone, periodontal, dentin, and pulp tissue regeneration. Finally, it outlines some perspectives for future developments in dental applications.

Sol-Gel Technologies to Obtain Advanced Bioceramics for Dental Therapeutics.

The aim of this work is to review the application of bioceramic materials in the context of current regenerative dentistry therapies, focusing on the latest advances in the synthesis of advanced materials using the sol-gel methodology. Chemical synthesis, processing and therapeutic possibilities are discussed in a structured way, according to the three main types of ceramic materials used in regenerative dentistry: bioactive glasses and glass ceramics, calcium phosphates and calcium silicates. The morphology and chemical composition of these bioceramics play a crucial role in their biological properties and effectiveness in dental therapeutics. The goal is to understand their chemical, surface, mechanical and biological properties better and develop strategies to control their pore structure, shape, size and compositions. Over the past decades, bioceramic materials have provided excellent results in a wide variety of clinical applications related to hard tissue repair and regeneration. Characteristics, such as their similarity to the chemical composition of the mineral phase of bones and teeth, as well as the possibilities offered by the advances in nanotechnology, are driving the development of new biomimetic materials that are required in regenerative dentistry. The sol-gel technique is a method for producing synthetic bioceramics with high purity and homogeneity at the molecular scale and to control the surfaces, interfaces and porosity at the nanometric scale. The intrinsic nanoporosity of materials produced by the sol-gel technique correlates with the high specific surface area, reactivity and bioactivity of advanced bioceramics.

Resorbable magnesium metal membrane for sinus lift procedures: a case series.

BACKGROUND: The purpose of this case series was to demonstrate the use of a magnesium membrane for repairing the perforated membrane in both direct and indirect approaches, as well as its application in instances where there has been a tear of the Schneiderian membrane. CASE PRESENTATION: The case series included four individual cases, each demonstrating the application of a magnesium membrane followed by bone augmentation using a mixture of xenograft and allograft material in the sinus cavity. In the first three cases, rupture of Schneiderian membrane occurred as a result of tooth extraction, positioning of the dental implant, or as a complication during the procedure. In the fourth case, Schneiderian membrane was perforated as a result of the need to aspirate a polyp in the maxillary sinus. In case one, 10 mm of newly formed bone is visible four months after graft placement. Other cases showed between 15 and 20 mm of newly formed alveolar bone. No residual magnesium membrane was seen on clinical inspection. The vertical and horizontal augmentations proved stable and the dental implants were placed in the previously grafted sites. CONCLUSION: Within the limitations of this case series, postoperative clinical examination, and panoramic and CBCT images demonstrated that resorbable magnesium membrane is a viable material for sinus lift and Schneiderian membrane repair. The case series showed successful healing and formation of new alveolar bone with separation of the oral cavity and maxillary sinus in four patients.

An Insight into the Role of Marine Biopolymer Alginate in Endodontics: A Review.

Alginate is a natural marine biopolymer that has been widely used in biomedical applications, but research on its use as an endodontic material is still sparse in the literature. This pioneer review aims to summarize the emerging roles of alginate and to outline its prospective applications as a core biomaterial in endodontics. Ten electronic databases and five textbooks were used to perform a search of English-language literature on the use of alginate in endodontics published between January 1980 and June 2022. The risk of bias (RoB) of each included study was assessed using the Office of Health Assessment and Translation (OHAT) tool. Subsequently, studies were categorized into three tiers to represent the overall risk. Qualitative analysis was performed, and the articles were sorted into different thematic categories. An initial search yielded a total of 1491 articles, but only 13 articles were chosen. For most domains, all the studies were rated with 'probably low' or 'definitely low' RoB, except for domains 2 and 6. All included studies fall in the Tier 1 category and were either in vitro, in vivo, or ex vivo. Four thematic categories were identified: endodontic regeneration, intracanal medicament, filing material, and chelating agent. Based on the available evidence, alginate has emerged as a cell carrier and scaffold in regenerative endodontics, a microcapsule delivery system for intracanal medicaments, a chelating agent reinforcing material, and a root canal sealer. More well-designed experiments and clinical trials are needed to warrant the promising advent of this hydrogel-based biomaterial.

Mesenchymal Stem Cells Based Treatment in Dental Medicine: A Narrative Review.

Application of mesenchymal stem cells (MSC) in regenerative therapeutic procedures is becoming an increasingly important topic in medicine. Since the first isolation of dental tissue-derived MSC, there has been an intense investigation on the characteristics and potentials of these cells in regenerative dentistry. Their multidifferentiation potential, self-renewal capacity, and easy accessibility give them a key role in stem cell-based therapy. So far, several different dental stem cell types have been discovered and their potential usage is found in most of the major dental medicine branches. These cells are also researched in multiple fields of medicine for the treatment of degenerative and inflammatory diseases. In this review, we summarized dental MSC sources and analyzed their treatment modalities with particular emphasis on temporomandibular joint osteoarthritis (TMJ OA).

Clinical Perspectives of Non-Coding RNA in Oral Inflammatory Diseases and Neuropathic Pain: A Narrative Review.

Non-coding RNAs (ncRNAs) represent a research hotspot by playing a key role in epigenetic and transcriptional regulation of diverse biological functions and due to their involvement in different diseases, including oral inflammatory diseases. Based on ncRNAs' suitability for salivary biomarkers and their involvement in neuropathic pain and tissue regeneration signaling pathways, the present narrative review aims to highlight the potential clinical applications of ncRNAs in oral inflammatory diseases, with an emphasis on salivary diagnostics, regenerative dentistry, and precision medicine for neuropathic orofacial pain.

Fabrication and In Vitro Characterization of Novel Hydroxyapatite Scaffolds 3D Printed Using Polyvinyl Alcohol as a Thermoplastic Binder.

This paper presents a proof-of-concept study on the biocolonization of 3D-printed hydroxyapatite scaffolds with mesenchymal stem cells (MSCs). Three-dimensional (3D) printed biomimetic bone structure made of calcium deficient hydroxyapatite (CDHA) intended as a future bone graft was made from newly developed composite material for FDM printing. The biopolymer polyvinyl alcohol serves in this material as a thermoplastic binder for 3D molding of the printed object with a passive function and is completely removed during sintering. The study presents the material, the process of fused deposition modeling (FDM) of CDHA scaffolds, and its post-processing at three temperatures (1200, 1300, and 1400 °C), as well it evaluates the cytotoxicity and biocompatibility of scaffolds with MTT and LDH release assays after 14 days. The study also includes a morphological evaluation of cellular colonization with scanning electron microscopy (SEM) in two different filament orientations (rectilinear and gyroid). The results of the MTT assay showed that the tested material was not toxic, and cells were preserved in both orientations, with most cells present on the material fired at 1300 °C. Results of the LDH release assay showed a slight increase in LDH leakage from all samples. Visual evaluation of SEM confirmed the ideal post-processing temperature of the 3D-printed FDM framework for samples fired at 1300 °C and 1400 °C, with a porosity of 0.3 mm between filaments. In conclusion, the presented fabrication and colonization of CDHA scaffolds have great potential to be used in the tissue engineering of bones.

Chitosan-Based Scaffold for Mineralized Tissues Regeneration.

Conventional bone grafting procedures used to treat bone defects have several limitations. An important aspect of bone tissue engineering is developing novel bone substitute biomaterials for bone grafts to repair orthopedic defects. Considerable attention has been given to chitosan, a natural biopolymer primarily extracted from crustacean shells, which offers desirable characteristics, such as being biocompatible, biodegradable, and osteoconductive. This review presents an overview of the chitosan-based biomaterials for bone tissue engineering (BTE). It covers the basic knowledge of chitosan in terms of biomaterials, the traditional and novel strategies of the chitosan scaffold fabrication process, and their advantages and disadvantages. Furthermore, this paper integrates the relevant contributions in giving a brief insight into the recent research development of chitosan-based scaffolds and their limitations in BTE. The last part of the review discusses the next-generation smart chitosan-based scaffold and current applications in regenerative dentistry and future directions in the field of mineralized tissue regeneration.

The role of nanohydroxyapatite on the morphological, physical, and biological properties of chitosan nanofibers.

OBJECTIVES: This study aimed to evaluate the effects of nanohydroxyapatite (nHAp) particles on the morphological, chemical, physical, and biological properties of chitosan electrospun nanofibers. MATERIALS AND METHODS: nHAp particles with a 1.67 Ca/P ratio were synthesized via the aqueous precipitation method, incorporated into chitosan polymer solution (0.5 wt%), and electrospun into nHAp-loaded fibers (ChHa fibers). Neat chitosan fibers (nHAp-free, Ch fibers) were used as the control. The electrospun fiber mats were characterized using morphological, topographical, chemical, thermal, and a range of biological (antibacterial, antibiofilm, cell viability, and alkaline phosphatase [ALP] activity) analyses. Data were analyzed using ANOVA and Tukey's test (α = 0.05). RESULTS: ChHa fibers demonstrated a bead-like morphology, with thinner (331 ± 110 nm) and smoother (Ra = 2.9 ± 0.3 µm) distribution as compared to the control fibers. Despite showing similar cell viability and ALP activity to Ch fibers, the ChHa fibers demonstrated greater antibacterial potential against most tested bacteria (except for P. intermedia), and higher antibiofilm activity against P. gingivalis biofilm. CONCLUSIONS: The incorporation of nHAp particles did not jeopardize the overall morphology, topography, physical, and biological characteristics of the chitosan nanofibers. CLINICAL RELEVANCE: The combination of nHAp particles with chitosan can be used to engineer bioactive, electrospun composite nanofibers with potential applications in regenerative dentistry.

Platform technologies for regenerative endodontics from multifunctional biomaterials to tooth-on-a-chip strategies.

OBJECTIVES: The aim of this review is to highlight recent progress in the field of biomaterials-mediated dental pulp tissue engineering. Specifically, we aim to underscore the critical design criteria of biomaterial platforms that are advantageous for pulp tissue engineering, discuss models for preclinical evaluation, and present new and innovative multifunctional strategies that hold promise for clinical translation. MATERIALS AND METHODS: The current article is a comprehensive overview of recent progress over the last 5 years. In detail, we surveyed the literature in regenerative pulp biology, including novel biologic and biomaterials approaches, and those that combined multiple strategies, towards more clinically relevant models. PubMed searches were performed using the keywords: "regenerative dentistry," "dental pulp regeneration," "regenerative endodontics," and "dental pulp therapy." RESULTS: Significant contributions to the field of regenerative dentistry have been made in the last 5 years, as evidenced by a significant body of publications. We chose exemplary studies that we believe are progressive towards clinically translatable solutions. We close this review with an outlook towards the future of pulp regeneration strategies and their clinical translation. CONCLUSIONS: Current clinical treatments lack functional and predictable pulp regeneration and are more focused on the treatment of the consequences of pulp exposure, rather than the restoration of healthy dental pulp. CLINICAL RELEVANCE: Clinically, there is great demand for bioinspired biomaterial strategies that are safe, efficacious, and easy to use, and clinicians are eager for their clinical translation. In particular, we place emphasis on strategies that combine favorable angiogenesis, mineralization, and functional tissue formation, while limiting immune reaction, risk of microbial infection, and pulp necrosis.

Mesenchimal stem cells in oral medicine: an overview.

This review aims to address the procedures and indications, required for the application of the mesenchymal stem cells treatment strategy of regenerative dentistry. Mesenchymal stem cells have rarely been used in this field; conversely, experience from other clinical fields and basic research seems to recommend the suitability of this scope of application. We reviewed 31 out of 206 articles on Web of Science, Scopus, PubMed, etc. The main purpose of this paper is a short review of the literature evaluating the application of stem cells in regenerative dentistry, their ability to get a multilineage differentiation and to introduce a safe and useful alternative way of harvesting and selection. The most common derivation of stem cells used for regenerative dentistry is from the adipose tissue. There are conditions in which the levy adipose cannot be easily achieved, or where large amounts of injectables are not needed. For this purpose, the possibility of selecting stromal stem cells directly from the lax subcutaneous connective tissue preferably of the head region would allow a technical simplification and a greater homology in tissues. .

[Growing of murine tooth in situ by homotopic transplantation of embryonic germ]. / Vyrashchivanie zuba myshi in situ metodom gomotopicheskoi transplantatsii émbrional'nogo zachatka.

Tissue engineering offers to restore the lost tooth using a biological analogue grown from the tooth germ. These technologies provide long-term cultivation of the germ in bioreactor in vitro. The subsequent transfer and growth of the in vitro grown tooth in the jaw is hampered by difficulty of integration of the new tooth with the host tissue. We suggested that growing tooth by homotopic transplantation in situ, that is, immediately in the jaw passing the in vitro stage will help to solve these problems. The aim of the work was to test the hypothesis. The principal possibility of transfer of the tooth germ directly into the jaw and cultivation in situ eliminating the stage in vitro is shown. The results showed a good integration of the grown teeth with the jaw without signs of inflammation and with the appearance of blood vessels in the pulp. At the same time, the results also showed the necessity to improve the preparation of tooth germs for transplantation and surgical procedures.

The Chemistry and Biological Activities of Mimosine: A Review.

Mimosine [ß-[N-(3-hydroxy-4-oxypyridyl)]-α-aminopropionic acid] is a non-protein amino acid found in the members of Mimosoideae family. There are a considerable number of reports available on the chemistry, methods for estimation, biosynthesis, regulation, and degradation of this secondary metabolite. On the other hand, over the past years of active research, mimosine has been found to have various biological activities such as anti-cancer, antiinflammation, anti-fibrosis, anti-influenza, anti-virus, herbicidal and insecticidal activities, and others. Mimosine is a leading compound of interest for use in the development of RAC/CDC42-activated kinase 1 (PAK1)-specific inhibitors for the treatment of various diseases/disorders, because PAK1 is not essential for the growth of normal cells. Interestingly, the new roles of mimosine in malignant glioma treatment, regenerative dentistry, and phytoremediation are being emerged. These identified properties indicate an exciting future for this amino acid. The present review is focused on the chemistry and recognized biological activities of mimosine in an attempt to draw a link between these two characteristics. Copyright © 2016 John Wiley & Sons, Ltd.

Advanced functional polymers for regenerative and therapeutic dentistry.

Use of ceramics and polymers continues to dominate clinical procedures in modern dentistry. Polymers have provided the basis for adhesives, tissue void fillers, and artificial replacements for whole teeth. They have been remarkably effective in the clinic at restoration of major dental functions after damage or loss of teeth. With the rapid development of polymer science, dental materials science has significantly lagged behind in harnessing these advanced polymer products. What they offer is new and unique properties superior to traditional polymers and crucially a range of properties that more closely match natural biomaterials. Therefore, we should pursue more vigorously the benefits of advanced polymers in dentistry. In this review, we highlight how the latest generation of advanced polymers will enhance the application of materials in the dental clinic using numerous promising examples. Polymers have a broad range of applications in modern dentistry. Some major applications are to construct frameworks that mimic the precise structure of tissues, to restore tooth organ function, and to deliver bioactive agents to influence cell behavior from the inside. The future of polymers in dentistry must include all these new enhancements to increase biological and clinical effectiveness beyond what can be achieved with traditional biomaterials.

Calcium silicate/calcium phosphate biphasic cements for vital pulp therapy: chemical-physical properties and human pulp cells response.

OBJECTIVES: The aim was to test the properties of experimental calcium silicate/calcium phosphate biphasic cements with hydraulic properties designed for vital pulp therapy as direct pulp cap and pulpotomy. METHODS: CaSi-αTCP and CaSi-DCDP were tested for ion-releasing ability, solubility, water sorption, porosity, ability to nucleate calcium phosphates, and odontoblastic differentiation­alkaline phosphatase (ALP) and osteocalcin (OCN) upregulation­of primary human dental pulp cells (HDPCs). RESULTS: The materials showed high Ca and OH release, high open pore volume and apparent porosity, and a pronounced ability to nucleate calcium phosphates on their surface. HDPCs treated with CaSi-αTCP showed a strong upregulation of ALP and OCN genes, namely a tenfold increase for OCN and a threefold increase for ALP compared to the control cells. Conversely, CaSi-DCDP induced a pronounced OCN gene upregulation but had no effect on ALP gene regulation. CONCLUSIONS: Both cements showed high biointeractivity (release of Ca and OH ions) correlated with their marked ability to nucleate calcium phosphates. CaSi-αTCP cement proved to be a potent inducer of ALP and OCN genes as characteristic markers of mineralization processes normally poorly expressed by HDPCs. CLINICAL RELEVANCE: Calcium silicate/calcium phosphate cements appear to be attractive new materials for vital pulp therapy as they may provide odontogenic/dentinogenic chemical signals for pulp regeneration and healing, and dentin formation in regenerative endodontics.

Three-dimensional eco-friendly bacterial nanocellulose (BNC) scaffold for regenerative dentistry: Characterization, cytocompatibility and differentiation potential.

OBJECTIVE: Regenerative dentistry (RD) is an innovative strategy for treating necrotic teeth and regenerating damaged dental tissue. Biocompatible materials are pivotal for the advancement of RD, and the rising interest in environmental sustainability drives exploration of sustainable materials for dentistry. Bacterial nanocellulose (BNC) has emerged as a promising eco-friendly option and this study aims to assess BNC's suitability as scaffolds for regenerative dentistry applications. METHODS: Different in vitro methods have been utilized to characterize the properties of BNC scaffolds in regenerative dentistry, such as scanning electron microscopy (SEM) to analyse surface property and porosity, as well as examining their absorption behaviour using phosphate-buffered saline and bovine serum. Dental pulp stem cell (DPSCs) attachment, viability, and proliferation were evaluated using SEM, live and dead, and tetrazolium reduction assays. The odontogenic potential of the scaffold was evaluated using Alizarin Red staining and qPCR (14 and 21 days). RESULTS: Scanning electron microscopy (SEM) images and ethanol displacement method demonstrated the porous architecture of the BNC scaffold with an average porosity of 70.02 ± 4.74% and 50.26 ± 1.43% respectively. The scaffold absorbed 2846.54 ± 258.95 of BSA and 1648.63 ± 50.37% PBS after immersion in solution for 1 h, following pseudo first and second order kinetics. The biocompatibility assay indicated that cell density increased with time and that the scaffold was appropriate for cell adhesion and migration. Moreover, the BNC led to significantly higher mineralization and odontogenic expression compared to the control (BNC in conditioned media). SIGNIFICANCE: BNC showed fast adsorption of bovine serum, allowed DPSC attachment, migration, and odontogenic differentiation. This suggests its suitability as a biocompatible scaffold for triggering in situ mineralized tissue regeneration for regenerative dental applications.

Advances in Regenerative Dentistry Approaches: An Update.

Regenerative dentistry is a rapidly evolving field in dentistry, which has been driven by advancements in biomedical engineering research and the rising treatment expectations and demands that exceed the scope of conventional approaches. Tissue engineering, the foundation of regenerative dentistry, mainly focuses on 3 key components: stem cells, bioactive molecules, and scaffolds. Dental tissue-derived stem cells are especially significant in this regard due to their remarkable properties. Regenerative techniques have provided novel approaches to many conventional treatment strategies in various disciplines of dentistry. For instance, regenerative endodontic procedures such as pulp revascularisation have provided an alternative approach to conventional root canal treatment. In addition, conventional surgical and nonsurgical periodontal treatment is being taken over by modified approaches of guided tissue regeneration with the aid of 3-dimensional bioprinting and computer-aided design, which has revolutionised oral and maxillofacial tissue engineering. This review presents a concise overview of the latest treatment strategies that have emerged into clinical practice, potential future technologies, and the role of dental tissue-derived stem cells in regenerative dentistry.

In Vitro Characterization of Reversine-Treated Gingival Fibroblasts and Their Safety Evaluation after In Vivo Transplantation.

Reversine is a purine derivative that has been investigated with regard to its biological effects, such as its anticancer properties and, mostly, its ability to induce the dedifferentiation of adult cells, increasing their plasticity. The obtained dedifferentiated cells have a high potential for use in regenerative procedures, such as regenerative dentistry (RD). Instead of replacing the lost or damaged oral tissues with synthetic materials, RD uses stem cells combined with matrices and an appropriate microenvironment to achieve tissue regeneration. However, the currently available stem cell sources present limitations, thus restricting the potential of RD. Based on this problem, new sources of stem cells are fundamental. This work aims to characterize mouse gingival fibroblasts (GFs) after dedifferentiation with reversine. Different administration protocols were tested, and the cells obtained were evaluated regarding their cell metabolism, protein and DNA contents, cell cycle changes, morphology, cell death, genotoxicity, and acquisition of stem cell characteristics. Additionally, their teratoma potential was evaluated after in vivo transplantation. Reversine caused toxicity at higher concentrations, with decreased cell metabolic activity and protein content. The cells obtained displayed polyploidy, a cycle arrest in the G2/M phase, and showed an enlarged size. Additionally, apoptosis and genotoxicity were found at higher reversine concentrations. A subpopulation of the GFs possessed stem properties, as supported by the increased expression of CD90, CD105, and TERT, the existence of a CD106+ population, and their trilineage differentiation capacity. The dedifferentiated cells did not induce teratoma formation. The extensive characterization performed shows that significant functional, morphological, and genetic changes occur during the dedifferentiation process. The dedifferentiated cells have some stem-like characteristics, which are of interest for RD.

Success in Tooth Bud Regeneration: A Short Communication.

INTRODUCTION: Tooth caries and loss are frequent clinical diseases in dentistry. Tissue engineering is a new therapeutic choice for the complete biological regeneration of pulpal and dental tissues in regenerative dentistry. The aim of this study was to establish a protocol for in situ regeneration of a dental bud in the extracted socket. METHODS: The current study examined tooth bud regeneration with dental pulp stem cells induced by a dentin derivative signal in a rabbit's jaw. RESULT: A tooth bud was regenerated; the morphology and structure of it were typical, and it was post-Bell stage. CONCLUSIONS: In our study, a real tooth bud was formed in the post-Bell stage with complete morphologic and biological features. However, the application of this method for tooth regeneration in humans necessitates further research.