Role of Stem Cells in Augmenting Dental Implant Osseointegration: A Systematic Review

Bone-Mimetic Osteon Microtopographies on Poly-ε-Caprolactone Enhance the Osteogenic Potential of Human Mesenchymal Stem Cells

The attributes of implant surfaces are pivotal for successful osseointegration. Among surface engineering strategies, microtopography stands out as a promising approach to promote early cellular interactions. This study aims to design and craft a novel biomimetic osteon-like surface modification and to compare its impact on human mesenchymal stem cells (hMSCs) with four established topographies: blank, inverted pyramids, protrusions, and grooves. Poly-ε-caprolactone samples are fabricated using 2-photon-polymerization and soft lithography, prior to analysis via scanning electron microscopy (SEM), water contact angle (WCA), and protein adsorption assays. Additionally, cellular responses including cell attachment, proliferation, morphology, cytoskeletal organization, and osteogenic differentiation potential are evaluated. SEM confirms the successful fabrication of microtopographies, with minimal effect on WCA and protein adsorption. Cell attachment experiments demonstrate a significant increase on the osteon-like structure, being three times higher than on the blank. Proliferation assays indicate a fourfold increase with osteon-like microtopography compared to the blank, while ALP activity is notably elevated with osteon-like microtopography at days 7 (threefold increase over blank) and 14 (fivefold increase over blank). In conclusion, the novel biomimetic osteon-like structure demonstrates favorable responses from hMSCs, suggesting potential for promoting successful implant integration in vivo.

Odontoblasts or odontocytes, expression of stem cells markers and differentiation markers among human adult odontoblasts

Despite that, the odontoblasts of the dental pulp are considered a terminally differentiated type of cell. We were interested in investigating if they express any embryonic, mesenchymal, or neural stem cell markers, along with other differentiation markers they were reported to express previously. Methods: An immunohistochemistry study was performed on wisdom teeth extracted from healthy donors aged between 17 and 19 for dental reasons. Nine markers were tested: c-Myc, SOX2, MCAM, CD73, NCAM1, STRO1, osteocalcin, S100, and Thy1. Results: Odontoblasts expressed the following markers: embryonic stem cell markers SOX2, c-Myc, mesenchymal stem cell marker MCAM, the neural differentiation marker S100, and the osteogenic differentiation marker osteocalcin. Odontoblasts did not express the following markers: mesenchymal stem cell markers CD73, STRO1, Thy1, and neural stem cell marker NCAM1. Conclusion: These findings suggest that odontoblasts' expression of these stem cell markers may enable them to dedifferentiate under certain conditions. Further investigation is needed into whether dental materials could induce such dedifferentiation for functional dentin regeneration.

Biomaterials science and surface engineering strategies for dental peri-implantitis management

Peri-implantitis is a bacterial infection that causes soft tissue inflammatory lesions and alveolar bone resorption, ultimately resulting in implant failure. Dental implants for clinical use barely have antibacterial properties, and bacterial colonization and biofilm formation on the dental implants are major causes of peri-implantitis. Treatment strategies such as mechanical debridement and antibiotic therapy have been used to remove dental plaque. However, it is particularly important to prevent the occurrence of peri-implantitis rather than treatment. Therefore, the current research spot has focused on improving the antibacterial properties of dental implants, such as the construction of specific micro-nano surface texture, the introduction of diverse functional coatings, or the application of materials with intrinsic antibacterial properties. The aforementioned antibacterial surfaces can be incorporated with bioactive molecules, metallic nanoparticles, or other functional components to further enhance the osteogenic properties and accelerate the healing process. In this review, we summarize the recent developments in biomaterial science and the modification strategies applied to dental implants to inhibit biofilm formation and facilitate bone-implant integration. Furthermore, we summarized the obstacles existing in the process of laboratory research to reach the clinic products, and propose corresponding directions for future developments and research perspectives, so that to provide insights into the rational design and construction of dental implants with the aim to balance antibacterial efficacy, biological safety, and osteogenic property.

Advancement in therapeutic strategies for immune-mediated oral diseases

BACKGROUND

Immune-mediated diseases are a diverse group of conditions characterized by alteration of cellular homeostasis and inflammation triggered by dysregulation of the normal immune response. Several immune-mediated diseases exhibit oral signs and symptoms. Traditionally, these conditions are treated with corticosteroids or immunosuppressive agents, including azathioprine, cyclophosphamide, and thalidomide. Recent research into the developmental pathways of these diseases has led to the exploration of novel approaches in treatment. This review examines newer treatment modalities for the management of immune-mediated diseases with oral presentations. Topical calcineurin inhibitors (TCIs) such as tacrolimus and pimecrolimus have been employed successfully in managing oral lichen planus and pemphigus vulgaris. Biologic agents, comprising monoclonal antibodies, fusion proteins, and recombinant cytokines, can provide targeted therapy with fewer adverse effects. Neutraceutical agents comprising aloe vera, curcumin, and honey are commonly used in traditional medicine and offer a holistic approach. They may have a place as adjuvants to current standard therapeutic protocols. Photodynamic therapy (PDT) and low-level laser therapy (LLLT) utilize a specific wavelength of light to achieve desired cellular change. While the use of PDT in immune-mediated diseases is contentious, LLLT has shown positive results. Newer therapeutic modalities involve kinase inhibitors, S1P₁ receptor modulators, MSCs, and iRNA providing targeted treatment of specific diseases.

Implant Survival Rate and Prosthetic Complications of OT Equator Retained Maxillary Overdenture: A Cohort Study

(1) Background: The overdenture is a complete denture, an implant-supported prosthesis, that the patient can remove at home for the usual oral hygiene procedures, thanks to a simple and intuitive anchoring system. Clinically, the execution of this rehabilitation for the lower arch is often favored, but when it is necessary to limit the extension of the palate in the upper arch, it can represent the least invasive and economic solution. The aim of the study is to analyze post-loading implant loss for implant-supported prostheses in the edentulous upper jaw. (2) Methods: This retrospective study was carried out on patients who received a superior overdenture on four implants for rehabilitation. A total of 42 patients were included in this study and initially evaluated clinically and radiographically. The follow-up period for patients after delivery of the upper overdenture is between 48 and 72 months. A total of 168 implants were inserted and monitored in this period. Clinical and radiographic tests were carried out on all 168 implants, with constant re-evaluation. (3) Results: The overall implant survival rate is 92.9%, a value that corresponds to those present in the literature in previously published studies. There were few prosthetic complications, mainly the detachment of anterior prosthetic teeth. (4) Conclusions: Most of these complete prostheses, which as antagonist had another previously made overdenture on four or on two implants, achieved excellent success rates in this study at 72 months.

Antibacterial Effects of Curcumin Nanocrystals against Porphyromonas gingivalis Isolated from Patients with Implant Failure

Background. Despite their benefits, dental implants may sometimes fail for a diversity of causes; the most common reasons of failure are infection and bone loss. Porphyromonas gingivalis (P. gingivalis) bacteria show a major role in peri-implantitis infection and dental implant failure. Methods. In this study, the prevalence of P. gingivalis isolated from the gingival crevicular fluid (GCF) of fifteen Iranian patients with implant failure (more than 1/3 of the implant length), who had average oral and dental hygiene and no antibiotic use for at least one month, was determined. Moreover, the antimicrobial effects of curcumin nanocrystals against isolated P. gingivalis were investigated. The collected samples from patients were transferred to a microbiology laboratory to culture. The presence of P. gingivalis in the culture media was confirmed using a trypsin reagent test. An isolate from a patient with the highest colony count was selected to evaluate the antibacterial effects of curcumin nanoparticles. The inhibition zone diameter, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) were determined. Results. Out of fifteen patients, eight (53.33%) were positive for the presence of P. gingivalis. The results of the microbial tests showed that curcumin nanoparticles had an MIC of 6.25 µg/mL and an MBC of 12.5 µg/mL. Conclusions. The use of curcumin nanoparticles may control the bacterial infection around the implant.

The Importance of Correlation between CBCT Analysis of Bone Density and Primary Stability When Choosing the Design of Dental Implants—Ex Vivo Study

This study aims to determine the correlation between the mean value of bone density measured on the CBCT device and the primary stability of dental implants determined by resonant frequency analysis. An experimental study was conducted on a material of animal origin: bovine femur and pig ribs. Two types of implants were used in this study: self-tapping and non-self-tapping of the same dimensions. Results of the experimental study showed a statistically significant correlation between bone density expressed in HU units and the primary stability of self-tapping and non-self- tapping dental implants expressed in ISQ units in bovine femur bones and self-tapping implants and pig rib bones. There was no statistically significant correlation between non-self-tapping dental implants in pig rib bones. Self-tapping and non-self-tapping implants did not show statistical significance in the primary stability in bones of different qualities. The analysis of bone density from CBCT images in the software of the apparatus expressed in HU units can be used to predict the degree of primary stability of self-tapping and non-self-tapping dental implants in bones of densities D1 and D2, and self-tapping dental implants in bones of the lower quality D4.

Biosynthesis and Response of Zinc Oxide Nanoparticles against Periimplantitis Triggering Pathogens

Periimplantitis due to pathogenic bacteria is considered as a major cause for dental implants failures. Biogenic zinc oxide nanoparticles (ZnPs) are known to inhibit periimplantitis triggering pathogens. The current investigation intended to perform ZnPs biosynthesis and evaluation against periimplantitis triggering bacteria. The current study involved ZnPs biosynthesis using Andrographis paniculata leaves aqueous extract (APLAE), followed by optimization, stability, characterization, and in vitro evaluation against periimplantitis triggering bacteria. The experimental results indicated the success of ZnPs biosynthesis based on the optimization of zinc acetate (1.5 g), plant extract (5 mL), pH 12, and temperature (25 °C), and using the stability study (absorbance between 365-370 nm) and characterization data exhibiting broad and shifted bands (in FTIR spectrum), the size was found to be below 98.61 nm (determined by FESEM and XRD spectra) and 71.54% zinc was observed in the EDX spectrum. Biogenic ZnPs exhibited a high inhibitory activity against periimplantitis-triggering pathogens (E. coli and S. aureus). Based on the experimental results, the present study concludes that biogenic ZnPs possess a high inhibitory potential against periimplantitis-triggering bacteria, and it is established that the biosynthesis of ZnPs using APLAE is a useful method.

Bone Augmentation for Implant Placement: Recent Advances

There are various advancements in biomaterials and methods for bone augmentation. This article aims to review the recent advances in bone augmentation for dental implants. Relevant articles on bone augmentation for dental implants were searched in PubMed/Medline, Scopus, Google Scholar, and Science Direct published in English literature published between January 1996 and March 2021. Relevant studies on bone grafts for dental implants were included and critically analyzed in this review. Various biomaterials can be used to augment bone for implant placement. Each graft procedure has advantages and disadvantages in each clinical application and needs to choose the graft material with a high success rate and less morbidity.

Titanium dioxide dental implants surfaces related oxidative stress in bone remodeling: a systematic review

Background

Titanium dioxide dental implants have a controversial effect on reactive oxygen species (ROS) production. ROS is necessary for cellular signal transmission and proper metabolism, but also has the ability to cause cell death as well as DNA, RNA, and proteins damage by excessive oxidative stress. This study aimed to systematically review the effect of titanium dioxide dental implant-induced oxidative stress and its role on the osteogenesis-angiogenesis coupling in bone remodeling.

Methods

This systematic review was performed conforming to preferred reporting items for systematic review and meta-analysis (PRISMA) model. Four different databases (PubMed, Science Direct, Scopus and Medline databases) as well as manual searching were adopted. Relevant studies from January 2000 till September 2021 were retrieved. Critical Appraisal Skills Programme (CASP) was used to assess the quality of the selected studies.

Results

Out of 755 articles, only 14 which met the eligibility criteria were included. Six studies found that titanium dioxide nanotube (TNT) reduced oxidative stress and promoted osteoblastic activity through its effect on Wnt, mitogen-activated protein kinase (MAPK) and forkhead box protein O1 (FoxO1) signaling pathways. On the other hand, three studies confirmed that titanium dioxide nanoparticles (TiO₂NPs) induce oxidative stress, reduce ostegenesis and impair antioxidant defense system as a significant negative correlation was found between decreased SIR3 protein level and increased superoxide (O₂ ^•-). Moreover, five studies proved that titanium implant alloy enhances the generation of ROS and induces cytotoxicity of osteoblast cells via its effect on NOX pathway.

Conclusion

TiO₂NPs stimulate a wide array of oxidative stress related pathways. Scientific evidence are in favor to support the use of TiO₂ nanotube-coated titanium implants to reduce oxidative stress and promote osteogenesis in bone remodeling. To validate the cellular and molecular cross talk in bone remodeling of the present review, well-controlled clinical trials with a large sample size are required.