Stem cells and common biomaterials in dentistry: a review study

The role of mesenchymal stem cells-derived from oral and teeth in regenerative and reconstructive medicine

Defects and abnormalities of the skull, jaw, and face tissues due to various physiological problems such as speech, chewing, and swallowing disorders, cause illness and psychological effects with creation of significant public health challenges. Both autograft and allograft reconstruction methods, have different limitations, especially in the complete reconstruction of complex tissues such as sensory and periodontal tissues, which cannot be wholly relied on for treatment. Recently, mesenchymal stem cells (MSCs)-derived from oral and teeth have emerged as a promising alternative way in regenerative and reconstructive medicine. These types of stem cells with the high differentiation potential and self-renewal capabilities include dental pulp stem cells (DPSCs), stem cells from human exfoliated deciduous teeth (SHEDs), periodontal stem cells (PDLSCs) and gum-derived stem cells (GMSCs). These stem cells can be easily collected from accessible and numerous sources, such as extracted molars and milk teeth, with minimal invasiveness, playing pivotal roles in clinical application. This review explains the applications and therapeutic effects of the above-mentioned MSCs-derived from oral and dental tissues. Each of these stem cells, have unique characteristics and used for the treatment of specific abnormalities and defects. In this article, we aims to elucidate the indispensable and pivotal roles of MSCs-derived from the oral and teeth in addressing intractable and complex challenges in restorative and reconstructive medicine.

Stem Cells from Human Exfoliated Deciduous Teeth-Derived Exosomes for the Treatment of Acute Liver Injury and Liver Fibrosis

Mesenchymal stem cells (MSCs) play a crucial role in regenerative medicine due to their regenerative potential. However, traditional MSC-based therapies are hindered by issues such as microvascular obstruction and low cell survival after transplantation. Exosomes derived from MSCs (MSC-Exo) provide a cell-free, nanoscale alternative, mitigating these risks and offering therapeutic potential for liver diseases. Nonetheless, the functional variability of MSCs from different sources complicates their clinical application. Stem cells derived from human exfoliated deciduous teeth (SHED) offer advantages such as ease of procurement and robust proliferative capacity, but their secretome, particularly SHED-Exo, remains underexplored in the context of liver disease therapy. This study analyzed MSC-Exo from various sources via small RNA sequencing to identify differences in microRNA profiles, aiding in the selection of optimal MSC sources for clinical use. SHED-Exo was subsequently tested in an acute liver injury model, showing notable regenerative effects, including enhanced hepatocyte proliferation, macrophage polarization, and reduced inflammation. Despite strong liver-targeting properties, the rapid hepatic clearance of SHED-Exo limits its effectiveness in chronic liver diseases. To address this challenge, a GelMA-based hydrogel was developed for in situ delivery, ensuring sustained release and enhanced antifibrotic efficacy, providing a promising strategy for chronic liver disease management.

Irx1 mechanisms for oral epithelial basal stem cell plasticity during reepithelialization after injury

The oral mucosa undergoes daily insults, and stem cells in the epithelial basal cell layer regenerate gingiva tissue to maintain oral health. The Iroquois Homeobox 1 (IRX1) protein is expressed in the stem cell niches in human/mouse oral epithelium and mesenchyme under homeostasis. We found that Irx1+/- heterozygous (Het) mice have delayed wound closure, delayed morphological changes of regenerated epithelium, and defective keratinocyte proliferation and differentiation during wound healing. RNA-Seq analyses between WT and Irx1+/- mice at 3 days postinjury (dpi) found impaired epithelial migration and decreased keratinocyte-related genes upon injury. IRX1-expressing cells are found in the gingival epithelial basal cell layer, a stem cell niche for gingival maintenance. IRX1-expressing cells are also found in cell niches in the underlying stroma. IRX1 activates SOX9 in the transient amplifying layer to increase cell proliferation, and EGF signaling is activated to induce cell migration. Krt14CreERT lineage tracing experiments reveal defects in the stratification of the Irx1+/- HET mouse oral epithelium. IRX1 is primed at the base of the gingiva in the basal cell layer of the oral epithelium, facilitating rapid and scarless wound healing through activating SOX9 and the EGF signaling pathway.

3D Bioprinting Techniques and Bioinks for Periodontal Tissues Regeneration-A Literature Review

The periodontal tissue is made up of supporting tissues and among its functions, it promotes viscoelastic properties, proprioceptive sensors, and dental anchorage. Its progressive destruction by disease leads to the loss of bone and periodontal ligaments. For this reason, biomaterials are constantly being developed to restore tissue function. Various techniques are being used to promote regenerative dentistry, including 3D bioprinting with bioink formulations. This paper aims to review the different types of bioink formulations and 3D bioprinting techniques used in periodontal tissue regeneration. Different techniques have been formulated, and the addition of different materials into bioinks has been conducted, with the intention of improving the process and creating a bioink that supports cell viability, proliferation, differentiation, and stability for periodontal tissue regeneration.

Scaffold Application for Bone Regeneration with Stem Cells in Dentistry: Literature Review

Bone tissue injuries within oral and dental contexts often present considerable challenges because traditional treatments may not be able to fully restore lost or damaged bone tissue. Novel approaches involving stem cells and targeted 3D scaffolds have been investigated in the search for workable solutions. The use of scaffolds in stem cell-assisted bone regeneration is a crucial component of tissue engineering techniques designed to overcome the drawbacks of traditional bone grafts. This study provides a detailed review of scaffold applications for bone regeneration with stem cells in dentistry. This review focuses on scaffolds and stem cells while covering a broad range of studies explaining bone regeneration in dentistry through the presentation of studies conducted in this field. The role of different stem cells in regenerative medicine is covered in great detail in the reviewed literature. These studies have addressed a wide range of subjects, including the effects of platelet concentrates during dental surgery or specific combinations, such as human dental pulp stem cells with scaffolds for animal model bone regeneration, to promote bone regeneration in animal models. Noting developments, research works consider methods to improve vascularization and explore the use of 3D-printed scaffolds, secretome applications, mesenchymal stem cells, and biomaterials for oral bone tissue regeneration. This thorough assessment outlines possible developments within these crucial regenerative dentistry cycles and provides insights and suggestions for additional study. Furthermore, alternative creative methods for regenerating bone tissue include biophysical stimuli, mechanical stimulation, magnetic field therapy, laser therapy, nutritional supplements and diet, gene therapy, and biomimetic materials. These innovative approaches offer promising avenues for future research and development in the field of bone tissue regeneration in dentistry.

Unlocking the Future: Bioprinting Salivary Glands-From Possibility to Reality

Salivary gland biofabrication represents a promising avenue in regenerative medicine, aiming to address the challenges of salivary gland dysfunction caused by various factors such as autoimmune diseases and radiotherapy. This review examines the current state of bioprinting technology, biomaterials, and tissue engineering strategies in the context of creating functional, implantable salivary gland constructs. Key considerations include achieving vascularization for proper nutrient supply, maintaining cell viability and functionality during printing, and promoting tissue maturation and integration with surrounding tissues. Despite the existing challenges, recent advancements offer significant potential for the development of personalized therapeutic options to treat salivary gland disorders. Continued research and innovation in this field hold the potential to revolutionize the management of salivary gland conditions, improving patient outcomes and quality of life. This systematic review covers publications from 2018 to April 2024 and was conducted on four databases: Google Scholar, PubMed, EBSCOhost, and Web of Science. The key features necessary for the successful creation, implantation and functioning of bioprinted salivary glands are addressed.

The current techniques in dorsal augmentation rhinoplasty: a comprehensive review

BACKGROUND

An essential aspect of rhinoplasty is the enhancement of the nasal dorsal contour by performing dorsal augmentation (DA) rhinoplasty. A wide range of techniques are available for DA as the demand for aesthetic nasal refinement grows. This review aims to provide a comprehensive overview of the current techniques used in DA rhinoplasty.

MAIN BODY

Research articles on DA rhinoplasty techniques were identified through a comprehensive literature search. Scopus, PubMed, and Web of Science were used as electronic databases. Each database was searched for articles published since its inception. DA rhinoplasty techniques were examined in this literature review. Methodological quality was assessed for the selected studies, and data was extracted to examine materials used, surgical approaches, and reported outcomes for each technique. Various DA methods, including autologous grafts and synthetic implants, are examined in-depth in this review. Comparing approaches can help better understand their respective advantages and limitations.

CONCLUSION

A wealth of techniques is available for DA rhinoplasty, each with advantages. Patients' nasal anatomy, desired outcomes, and potential risks must be considered by surgeons when determining their surgical approach. DA methods continue to evolve rapidly, creating a need for a thorough understanding of the current landscape to make informed decisions.

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.

The effect of photobiomodulation therapy in common maxillofacial injuries: Current status

The use of photobiomodulation therapy (PBMT) may be used for treating trauma to the maxillofacial region. The effects of PBMT on maxillofacial injuries were discussed in this review article. The electronic databases Pubmed, Scopus, and Web of Science were thoroughly searched. This review included in vitro, in vivo, and clinical studies describing how PBMT can be used in maxillofacial tissue engineering and regenerative medicine. Some studies suggest that PBMT may offer a promising therapy for traumatic maxillofacial injuries because it can stimulate the differentiation and proliferation of various cells, including dental pulp cells and mesenchymal stem cells, enhancing bone regeneration and osseointegration. PBMT reduces pain and swelling after oral surgery and tooth extraction in human and animal models of maxillofacial injuries. Patients with temporomandibular disorders also benefit from PBMT in terms of reduced inflammation and symptoms. PBMT still has some limitations, such as the need for standardizing parameters. PBMT must also be evaluated further in randomized controlled trials in various maxillofacial injuries. As a result, PBMT offers a safe and noninvasive treatment option for patients suffering from traumatic maxillofacial injuries. PBMT still requires further research to establish its efficacy in clinical practice and determine the optimal parameters.

Mesenchymal Stromal Cells Derived from Dental Tissues: Immunomodulatory Properties and Clinical Potential

Mesenchymal stem/stromal cells (MSCs) are multipotent cells located in different areas of the human body. The oral cavity is considered a potential source of MSCs because they have been identified in several dental tissues (D-MSCs). Clinical trials in which cells from these sources were used have shown that they are effective and safe as treatments for tissue regeneration. Importantly, immunoregulatory capacity has been observed in all of these populations; however, this function may vary among the different types of MSCs. Since this property is of clinical interest for cell therapy protocols, it is relevant to analyze the differences in immunoregulatory capacity, as well as the mechanisms used by each type of MSC. Interestingly, D-MSCs are the most suitable source for regenerating mineralized tissues in the oral region. Furthermore, the clinical potential of D-MSCs is supported due to their adequate capacity for proliferation, migration, and differentiation. There is also evidence for their potential application in protocols against autoimmune diseases and other inflammatory conditions due to their immunosuppressive capacity. Therefore, in this review, the immunoregulatory mechanisms identified at the preclinical level in combination with the different types of MSCs found in dental tissues are described, in addition to a description of the clinical trials in which MSCs from these sources have been applied.

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.

[Advances in Molecular Regulatory Mechanisms of Jaw Repair and Reconstruction]

Jawbone injuries resulting from trauma, diseases, and surgical resections are commonly seen in clinical practice, necessitating precise and effective strategies for repair and reconstruction to restore both function and aesthetics. The precise and effective repair and the reconstruction of jawbone injuries pose a significant challenge in the field of oral and maxillofacial surgery, owing to the unique biomechanical characteristics and physiological functions of the jawbone. The natural repair process following jawbone injuries involves stages such as hematoma formation, inflammatory response, ossification, and bone remodeling. Bone morphogenetic proteins (BMPs), transforming growth factor beta (TGF-β), vascular endothelial growth factor (VEGF), and other growth factors play crucial roles in promoting jawbone regeneration. Cytokines such as interleukins and tumor necrosis factor play dual roles in regulating inflammatory response and bone repair. In recent years, significant progress in molecular biology research has been made in the field of jawbone repair and reconstruction. Tissue engineering technologies, including stem cell therapy, bioactive scaffolds, and growth factor delivery systems, have found important applications in jawbone repair. However, the intricate molecular regulatory mechanisms involved in the complex jawbone repair and reconstruction methods are not fully understood and still require further research. Future research directions will be focused on the precise control of these molecular processes and the development of more efficient combination therapeutic strategies to promote the effective and functional reconstruction of the jawbone. This review aims to examine the latest findings on the molecular regulatory mechanisms of the repair and reconstruction of jawbone injuries and the therapeutic strategies. The conclusions drawn in this article provide a molecular-level understanding of the repair of jawbone injuries and highlight potential directions for future research.

Attachment and proliferation of human gingival fibroblasts seeded on barrier membranes using Wharton's jelly-derived stem cells conditioned medium: An in vitro study

The effect of Wharton's jelly mesenchymal stem cells conditioned medium (WJMSCs-CM) and zinc oxide nanoparticles (ZnO-NPs) on cultured human gingival fibroblasts on various barrier membranes was investigated in this study. In this study, human gingival fibroblasts were prepared and cultured on three membranes: collagen membrane, acellular dermal matrix (ADM) with ZnO-NPs, and ADM without ZnO-NPs. WJMSCs-CM was given to the testing groups, while control groups received the same membranes without WJMSCs-CM. Following 48 and 72 h, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tests were performed to assess cell survival. Cell proliferation on the membranes was also evaluated using 4',6-diamidino-2-phenylindole (DAPI) staining after 48 and 72 h. Field emission scanning electron microscopy was used to determine membrane surface structure and cell adhesion. Nanoparticles were also subjected to an energy-dispersive x-ray analysis to identify their chemical structure. Two-way analysis of variance was used to conduct the statistical analysis. The p-value ≤.05 was considered significant. When ADM-ZnO-NPs were combined with CM, fibroblast viability, and adhesion significantly differed from ADM-ZnO-NPs alone. DAPI results confirmed cell proliferation in all six groups on both experiment days. The abundance and concentrated distribution of cells during cell proliferation were found in CM-containing membranes, specifically the ADM-ZnO-NPs membrane, demonstrating the improved biocompatibility of the ADM-ZnO-NPs membrane for cell proliferation. The other groups did not significantly differ from one another. WJMSCs-CM positively affected the viability and proliferation of gingival fibroblasts, but only marginally. Under certain conditions, ZnO-NPs below a specific concentration increased the biocompatibility of the membranes.

CXC chemokine receptor 4 (CXCR4) blockade in cancer treatment

CXC chemokine receptor type 4 (CXCR4) is a member of the G protein-coupled receptors (GPCRs) superfamily and is specific for CXC chemokine ligand 12 (CXCL12, also known as SDF-1), which makes CXCL12/CXCR4 axis. CXCR4 interacts with its ligand, triggering downstream signaling pathways that influence cell proliferation chemotaxis, migration, and gene expression. The interaction also regulates physiological processes, including hematopoiesis, organogenesis, and tissue repair. Multiple evidence revealed that CXCL12/CXCR4 axis is implicated in several pathways involved in carcinogenesis and plays a key role in tumor growth, survival, angiogenesis, metastasis, and therapeutic resistance. Several CXCR4-targeting compounds have been discovered and used for preclinical and clinical cancer therapy, most of which have shown promising anti-tumor activity. In this review, we summarized the physiological signaling of the CXCL12/CXCR4 axis and described the role of this axis in tumor progression, and focused on the potential therapeutic options and strategies to block CXCR4.

The effects of Kinesio tapes on facial swelling following bimaxillary orthognathic surgery in the supraclavicular region

BACKGROUND

Several osteotomies are required for orthognathic surgery to reposition the jaws correctly. This study aimed to evaluate whether Kinesiotaping can reduce swelling, pain, and trismus following orthognathic surgery of the facial skull.

MATERIALS AND METHODS

The present study consists of two phases. In the split-mouth phase, 16 skeletal class III patients underwent Bimax Orthognathic surgery, and Kinesiological tape (KT) was applied on one half of the face. In the prospective case-control phase, 30 patients were divided into two groups. Kinesio tape was applied on both sides of the face of the Kinesio group, and pressure dressing and ice therapy were used for the second group. The tape was parallel to the lower border of the mandible along its entire length, tangent to the labial commissure area on the studied side. The tape was placed in place for 5 days. Edema was evaluated by measuring the distance from the menton to the lower edge of the tragus. The maximum mouth-opening trismus was evaluated, and the VAS index was used to evaluate pain.

RESULTS

There was evidence of swelling reduction after KT; within the same study, differences between the left and right sides as well as for the same side were statistically significant (p < 0.001). As a result of tapping lymphatic Kinesio tape on the affected area, tension was reduced, and lymphatic circulation was restored. Blood and lymph microcirculation was improved, enabling the body to heal itself.

CONCLUSION

Kinesio tape reduced swelling after orthognathic surgery in a positive way. As a simple, non-traumatic, economical method, Kinesio taping seems promising.

In Vitro and In Vivo Evaluation of a Polycaprolactone (PCL)/Polylactic-Co-Glycolic Acid (PLGA) (80:20) Scaffold for Improved Treatment of Chondral (Cartilage) Injuries

Articular cartilage is a specialized tissue that provides a smooth surface for joint movement and load transmission. Unfortunately, it has limited regenerative capacity. Tissue engineering, combining different cell types, scaffolds, growth factors, and physical stimulation has become an alternative for repairing and regenerating articular cartilage. Dental Follicle Mesenchymal Stem Cells (DFMSCs) are attractive candidates for cartilage tissue engineering because of their ability to differentiate into chondrocytes, on the other hand, the polymers blend like Polycaprolactone (PCL) and Poly Lactic-co-Glycolic Acid (PLGA) have shown promise given their mechanical properties and biocompatibility. In this work, the physicochemical properties of polymer blends were evaluated by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM) and were positive for both techniques. The DFMSCs demonstrated stemness by flow cytometry. The scaffold showed to be a non-toxic effect when we evaluated it with Alamar blue, and the samples were analyzed using SEM and phalloidin staining to evaluate cell adhesion to the scaffold. The synthesis of glycosaminoglycans was positive on the construct in vitro. Finally, the PCL/PLGA scaffold showed a better repair capacity than two commercial compounds, when tested in a chondral defect rat model. These results suggest that the PCL/PLGA (80:20) scaffold may be suitable for applications in the tissue engineering of articular hyaline cartilage.

Effect of inter-dental abutment distance on the impression accuracy of digital and conventional methods

This study aimed to examine the effect of inter-dental abutment distance on the accuracy of digital and conventional impression methods. Five maxillary and mandibular models were prepared with different inter-dental abutment distances. Digital scans were obtained using an extraoral laboratory scanner as reference data. Each group was scanned 8 times using the intra-oral scanner for the digital method. For the conventional impression method, 8 additional silicone impression material was used to generate the stone casts from each group. Then casts were scanned. In the next step, stereolithography (STL) data was exported from the scans. The STL files were super-imposed on the reference scans using 3shape dental designer software to make the measurement. Kolmogorov-Smirnoff was used to determine if the data were normally distributed. In the digital impression method, as the abutment distance increased, the accuracy decreased. Various inter-dental abutment distances in digital groups showed significant differences (p=0.016) in impression accuracy, while the difference among conventional groups was not statistically significant (p=0.822). In the digital method, the mean inter-dental abutment between the 4-5 and 3-7 groups, 4-6 and 3-7 groups had a significant difference (p<0.05). However, the conventional method revealed no significant differences (p>0.05) between groups. In conclusion, when the inter-dental abutment distance exists and is surrounded by soft tissue, the possibility of error in the digital impression method is higher than in the conventional impression method.

Bioprinting and biomaterials for dental alveolar tissue regeneration

Three dimensional (3D) bioprinting is a powerful tool, that was recently applied to tissue engineering. This technique allows the precise deposition of cells encapsulated in supportive bioinks to fabricate complex scaffolds, which are used to repair targeted tissues. Here, we review the recent developments in the application of 3D bioprinting to dental tissue engineering. These tissues, including teeth, periodontal ligament, alveolar bones, and dental pulp, present cell types and mechanical properties with great heterogeneity, which is challenging to reproduce in vitro. After highlighting the different bioprinting methods used in regenerative dentistry, we reviewed the great variety of bioink formulations and their effects on cells, which have been established to support the development of these tissues. We discussed the different advances achieved in the fabrication of each dental tissue to provide an overview of the current state of the methods. We conclude with the remaining challenges and future needs.