Osseointegration: an update

Dental implant considerations in patients with systemic diseases: An updated comprehensive review

BACKGROUND

Various medical conditions and the drugs used to treat them have been shown to impede or complicate dental implant surgery. It is crucial to carefully monitor the medical status and potential post-operative complications of patients with systemic diseases, particularly elderly patients, to minimize the risk of health complications that may arise.

AIM

The purpose of this study was to review the existing evidence on the viability of dental implants in patients with systemic diseases and to provide practical recommendations to achieve the best possible results in the corresponding patient population.

METHODS

The information for our study was compiled using data from PubMed, Scopus, Web of Science and Google Scholar databases and searched separately for each systemic disease included in our work until October 2023. An additional manual search was also performed to increase the search sensitivity. Only English-language publications were included and assessed according to titles, abstracts and full texts.

RESULTS

In total, 6784 studies were found. After checking for duplicates and full-text availability, screening for the inclusion criteria and manually searching reference lists, 570 articles remained to be considered in this study.

CONCLUSION

In treating patients with systemic conditions, the cost-benefit analysis should consider the patient's quality of life and expected lifespan. The success of dental implants depends heavily on ensuring appropriate maintenance therapy, ideal oral hygiene standards, no smoking and avoiding other risk factors. Indications and contraindications for dental implants in cases of systemic diseases are yet to be more understood; broader and hardcore research needs to be done for a guideline foundation.

An Advanced Human Bone Tissue Culture Model for the Assessment of Implant Osteointegration In Vitro

In the field of biomaterials for prosthetic reconstructive surgery, there is the lack of advanced innovative methods to investigate the potentialities of smart biomaterials before in vivo tests. Despite the complex osteointegration process being difficult to recreate in vitro, this study proposes an advanced in vitro tissue culture model of osteointegration using human bone. Cubic samples of trabecular bone were harvested, as waste material, from hip arthroplasty; inner cylindrical defects were created and assigned to the following groups: (1) empty defects (CTRneg); (2) defects implanted with a cytotoxic copper pin (CTRpos); (3) defects implanted with standard titanium pins (Ti). Tissues were dynamically cultured in mini rotating bioreactors and assessed weekly for viability and sterility. After 8 weeks, immunoenzymatic, microtomographic, histological, and histomorphometric analyses were performed. The model was able to simulate the effects of implantation of the materials, showing a drop in viability in CTR+, while Ti appears to have a trophic effect on bone. MicroCT and a histological analysis supported the results, with signs of matrix and bone deposition at the Ti implant site. Data suggest the reliability of the tested model in recreating the osteointegration process in vitro with the aim of reducing and refining in vivo preclinical models.

Exosomes: A New Hope for Angiogenesis-Mediated Bone Regeneration

Bone is a metabolically dynamic structure that is generally remodeled throughout the lifetime of an individual but often causes problems with increasing age. A key player for bone development and homeostasis, but also under pathological conditions, is the bone vasculature. This complex system of arteries, veins, and capillaries forms distinct structures where each subset of endothelial cells has important functions. Starting with the basic process of angiogenesis and bone-specific blood vessel formation, coupled with initial bone formation, the importance of different vascular structures is highlighted with respect to how these structures are maintained or changed during homeostasis, aging, and pathological conditions. After exemplifying the current knowledge on bone vasculature, this review will move on to exosomes, a novel hotspot of scientific research. Exosomes will be introduced starting from their discovery via current isolation procedures and state-of-the-art characterization to their role in bone vascular development, homeostasis, and bone regeneration and repair while summarizing the underlying signal transduction pathways. With respect to their role in these processes, especially mesenchymal stem cell-derived extracellular vesicles are of interest, which leads to a discussion on patented applications and an update on ongoing clinical trials. Taken together, this review provides an overview of bone vasculature and bone regeneration, with a major focus on how exosomes influence this intricate system, as they might be useful for therapeutic purposes in the near future.

Patient-reported outcome measures and prosthetic events in implant-supported mandibular overdenture patients after immediate versus delayed loading: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Immediately loaded mandibular overdentures are clinically acceptable treatment options that have gained popularity because their use shortens the treatment duration. However, whether the immediate loading of dental implants can match the prosthetic events, satisfaction, and quality of life of delayed loading is still unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to compare the prosthetic events, satisfaction, and quality of life of immediate versus delayed loading implants in patients rehabilitated with mandibular overdentures.

MATERIAL AND METHODS

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered at The International Prospective Register of Systematic Reviews (PROSPERO) (CRD42021258187). Electronic searches were carried out by 2 independent reviewers in the PubMed/MEDLINE, Cochrane Library, and Web of Science databases up to May 2021. Only randomized clinical trials and prospective studies with at least 10 participants that compared immediate versus delayed loading were selected. A meta-analysis was performed by using the RevMan 5 software program for complications and maintenance outcomes.

RESULTS

Seven articles were included in the qualitative analysis, and 4 were included in the quantitative analysis. The meta-analysis demonstrated no significant difference between immediate and delayed loading for prosthetic complications (RR=1.71; 95% CI=0.67-4.37; I2=85%, P=.27) or maintenance (RR=1.92, 95% CI=0.44-8.28; I2=94%, P=.38).

CONCLUSIONS

Although the prosthetic complications and maintenance were more likely to favor the delayed loading group, available evidence showed no statistical difference for prosthetic complications and maintenance between immediate loading and delayed loading in mandibular overdentures.

Early Periprosthetic Femur Fractures After Primary Cementless Total Hip Arthroplasty: High Risk of Periprosthetic Joint Infection and Subsequent Reoperation

BACKGROUND

Periprosthetic femur fracture (PFF) following total hip arthroplasty (THA) is a leading cause of early reoperation. The objective of this study was to compare rates of periprosthetic joint infection (PJI) and reoperation following PFFs occurring early postoperatively to those that occurred late.

METHODS

We retrospectively identified 173 consecutive surgically managed PFFs following primary THA. Cases were categorized as "early" if they occurred within 90 days of THA (n = 117) or "late" if they occurred following the initial 90 days (n = 56). Mean age at time of PFF was 68 years (range, 26 to 96) and 60% were women. Mean body mass index was 29 (range, 16 to 52). Mean follow-up was 2 years (range, 0 to 13). Kaplan-Meier survival analysis estimated cumulative incidences of PJI and reoperation.

RESULTS

Early PFFs had higher 2-year cumulative incidence of PJI (11% versus 0%, P < .001) and reoperation (24% versus 13%, P = .110). Following early PFF, 27 patients required reoperation (ie, 13 for PJI, 5 for instability, 2 for re-fracture, 2 for painful hardware, 2 for non-union, 1 for adverse local tissue reaction, 1 for aseptic loosening, and 1 for leg-length discrepancy). Following late PFF, 5 patients required reoperation (ie, 3 for instability, 1 for re-fracture, and 1 for non-union).

CONCLUSIONS

There are greater incidences of PJIs and overall reoperations following early PFFs compared to late PFFs after THA. In addition to focusing efforts on prevention of early PFFs, surgeons should consider antiseptic interventions to mitigate the increased risk of PJI after treatment of early PFF.

Mechano-driven intervertebral bone bridging via oriented mechanical stimulus in a twist metamaterial cage: An in silico study

Stiffer cages provide sufficient mechanical support but fail to promote bone ingrowth due to stress shielding. It remains challenging for fusion cage to satisfy both bone bridging and mechanical stability. Here we designed a fusion cage based on twist metamaterial for improved bone ingrowth, and proved its superiority to the conventional diagonal-based cage in silico. The fusion process was numerically reproduced via an injury-induced osteogenesis model and the mechano-driven bone remodeling algorithm, and the outcomes fusion effects were evaluated by the morphological features of the newly-formed bone and the biomechanical behaviors of the bone-cage composite. The twist-based cages exhibited oriented bone formation in the depth direction, in comparison to the diagonal-based cages. The axial stiffness of the bone-cage composites with twist-based cages was notably higher than that with diagonal-based cages; meanwhile, the ranges of motion of the twist-based fusion segment were lower. It was concluded that the twist metamaterial cages led to oriented bone ingrowth, superior mechanical stability of the bone-cage composite, and less detrimental impacts on the adjacent bones. More generally, metamaterials with a tunable displacement mode of struts might provide more design freedom in implant designs to offer customized mechanical stimulus for osseointegration.

Femtosecond Laser Irradiation to Zirconia Prior to Calcium Phosphate Coating Enhances Osteointegration of Zirconia in Rabbits

Calcium phosphate (CaP) coating of zirconia and zirconia-based implants is challenging, due to their chemical instability and susceptibility to thermal and mechanical impacts. A 3 mol% yttrium-stabilized tetragonal zirconia polycrystal was subjected to femtosecond laser (FsL) irradiation to form micro- and submicron surface architectures, prior to CaP coating using pulsed laser deposition (PLD) and low-temperature solution processing. Untreated zirconia, CaP-coated zirconia, and FsL-irradiated and CaP-coated zirconia were implanted in proximal tibial metaphyses of male Japanese white rabbits for four weeks. Radiographical analysis, push-out test, alizarin red staining, and histomorphometric analysis demonstrated a much improved bone-bonding ability of FsL-irradiated and CaP-coated zirconia over CaP-coated zirconia without FsL irradiation and untreated zirconia. The failure strength of the FsL-irradiated and CaP-coated zirconia in the push-out test was 6.2-13.1-times higher than that of the CaP-coated zirconia without FsL irradiation and untreated zirconia. Moreover, the adhesion strength between the bone and FsL-irradiated and CaP-coated zirconia was as high as that inducing host bone fracture in the push-out tests. The increased bone-bonding ability was attributed to the micro-/submicron surface architectures that enhanced osteoblastic differentiation and mechanical interlocking, leading to improved osteointegration. FsL irradiation followed by CaP coating could be useful for improving the osteointegration of cement-less zirconia-based joints and zirconia dental implants.

Demographic characteristics influencing the stem subsidence in total hip arthroplasty: an imaging study

INTRODUCTION

The present study evaluated whether patient demographic characteristics influence the subsidence of the stem in total hip arthroplasty (THA). The following characteristics were evaluated: age, height, weight, and sex. The association between the time elapsed from the THA implantation and the amount of stem subsidence was also investigated.

METHODS

The records of patients who underwent THA in the period between 2016 and 2023 were accessed. All patients underwent two-staged bilateral THA using cementless DePuy collarless Corail (DePuy Synthes, Raynham, MA, USA) stems. The following parameters were measured and compared to assess stem subsidence: distance from the proximal femur at the stem bone interface and the medial apex of the regular triangle built within the trochanter minor (point A); distance from the medial apex of the regular triangle built within the trochanter minor and the distal portion of the femoral stem (point B).

RESULTS

Overall, 294 patients were included. 62% (182 of 294 patients) were women. 45% (134 of 296 THAs) were on the right side. The mean age was 64.9 ± 10.4 years. The mean BMI was 28.3 ± 5.1 kg/m2. The mean length of the follow-up was 14.4 ± 11.0 months. The mean subsidence in point A was 2.1 mm (P < 0.0001), and that in point B was 3.1 mm (P < 0.0001). There was evidence of a weak positive association between patient weight (P < 0.0001), age (P = 0.03), follow-up (P = 0.002) and the amount of stem subsidence. Patient height did not demonstrate any association with the amount of stem subsidence (P = 0.07). There was no difference in stem subsidence between women and men (P = 0.9).

CONCLUSION

Stem subsidence in THA using cementless DePuy collarless Corail implants is approximately 2.6 mm after 14.4 months. Greater patient weight, age, and longer time elapsed from THA implantation were associated with greater stem subsidence. Patient height and sex did not demonstrate any influence on the amount of stem subsidence. These results must be considered in light of the limitations of the present study.

Nano-topography and functionalization with the synthetic peptoid GN2-Npm9 as a strategy for antibacterial and biocompatible titanium implants

In recent years, antimicrobial peptides (AMPs) have attracted great interest in scientific research, especially for biomedical applications such as drug delivery and orthopedic applications. Since they are readily degradable in the physiological environment, scientific research has recently been trying to make AMPs more stable. Peptoids are synthetic N-substituted glycine oligomers that mimic the structure of peptides. They have a structure that does not allow proteolytic degradation, which makes them more stable while maintaining microbial activity. This structure also brings many advantages to the molecule, such as greater diversity and specificity, making it more suitable for biological applications. For the first time, a synthesized peptoid (GN2-Npm9) was used to functionalize a nanometric chemically pre-treated (CT) titanium surface for bone-contact implant applications. A preliminary characterization of the functionalized surfaces was performed using the contact angle measurements and zeta potential titration curves. These preliminary analyses confirmed the presence of the peptoid and its adsorption on CT. The functionalized surface had a hydrophilic behaviour (contact angle = 30°) but the hydrophobic tryptophan-like residues were also exposed. An electrostatic interaction between the lysine residue of GN2-Npm9 and the surface allowed a chemisorption mechanism. The biological characterization of the CT_GN2-Nmp9 surfaces demonstrated the ability to prevent surface colonization and biofilm formation by the pathogens Escherichia coli and Staphylococcus epidermidis thus showing a broad-range activity. The cytocompatibility was confirmed by human mesenchymal stem cells. Finally, a bacteria-cells co-culture model was applied to demonstrate the selective bioactivity of the CT_GN2-Nmp9 surface that was able to preserve colonizing cells adhered to the device surface from bacterial infection.

Impact of 3D imaging techniques and virtual patients on the accuracy of planning and surgical placement of dental implants: A systematic review

Aim

The integration of advanced technologies, including three-dimensional (3D) imaging modalities and virtual simulations, has significantly influenced contemporary approaches to preoperative planning in implant dentistry. Through a meticulous analysis of relevant studies, this review synthesizes findings related to accuracy outcomes in implant placement facilitated by 3D imaging in virtual patients.

Methods

A comprehensive literature search was conducted across relevant databases to identify relevant studies published to date. The inclusion criteria were studies utilizing 3D imaging techniques, virtual patients, and those focusing on the accuracy of dental implant planning and surgical placement. The selected studies were critically appraised for their methodological quality.

Results

After a rigorous analysis, 21 relevant articles were included out of 3021 articles. This study demonstrates the versatility and applicability of these technologies in both in vitro and in vivo settings. Integrating Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM), cone bean computed tomography (CBCT), and advanced 3D reconstruction methodologies showcases a trend toward enhanced precision in implant planning and placement. Notably, the evaluation parameters varied, encompassing distances, discrepancies, and deviations in the implant placement. The ongoing integration of systems such as dynamic navigation systems, augmented reality, and sophisticated software platforms shows a promising trajectory for the continued refinement of virtual reality applications in dental implantology, providing valuable insights for future research and clinical implementation. Moreover, using stereolithographic surgical guides, virtual planning with CBCT data, and 3D-printed templates consistently demonstrates enhanced precision in dental implant placement compared to traditional methods.

Conclusion

The synthesis of the available evidence underscores the substantial positive impact of 3D imaging techniques and virtual patients on dental implant planning and surgical placement accuracy. Utilizing these technologies contributes to a more personalized and precise approach that enhances overall treatment outcomes. Future research directions and potential refinements to the application of these technologies in clinical practice should be discussed.

Biomedical Applications of Titanium Alloys: A Comprehensive Review

Titanium alloys have emerged as the most successful metallic material to ever be applied in the field of biomedical engineering. This comprehensive review covers the history of titanium in medicine, the properties of titanium and its alloys, the production technologies used to produce biomedical implants, and the most common uses for titanium and its alloys, ranging from orthopedic implants to dental prosthetics and cardiovascular devices. At the core of this success lies the combination of machinability, mechanical strength, biocompatibility, and corrosion resistance. This unique combination of useful traits has positioned titanium alloys as an indispensable material for biomedical engineering applications, enabling safer, more durable, and more efficient treatments for patients affected by various kinds of pathologies. This review takes an in-depth journey into the inherent properties that define titanium alloys and which of them are advantageous for biomedical use. It explores their production techniques and the fabrication methodologies that are utilized to machine them into their final shape. The biomedical applications of titanium alloys are then categorized and described in detail, focusing on which specific advantages titanium alloys are present when compared to other materials. This review not only captures the current state of the art, but also explores the future possibilities and limitations of titanium alloys applied in the biomedical field.

How Can Imbalance in Oral Microbiota and Immune Response Lead to Dental Implant Problems?

Dental implantology is one of the most dynamically developing fields of dentistry, which, despite developing clinical knowledge and new technologies, is still associated with many complications that may lead to the loss of the implant or the development of the disease, including peri-implantitis. One of the reasons for this condition may be the fact that dental implants cannot yield a proper osseointegration process due to the development of oral microbiota dysbiosis and the accompanying inflammation caused by immunological imbalance. This study aims to present current knowledge as to the impact of oral microflora dysbiosis and deregulation of the immune system on the course of failures observed in dental implantology. Evidence points to a strong correlation between these biological disturbances and implant complications, often stemming from improper osseointegration, pathogenic biofilms on implants, as well as an exacerbated inflammatory response. Technological enhancements in implant design may mitigate pathogen colonization and inflammation, underscoring implant success rates.

Development of reduced volume endosseous cuspid tooth implant using topology optimization by SIMP technique for improved osseointegration

The article aims to design and develop a topology-optimized endosseous cuspid tooth implant of the maxilla region. The manuscript presents a numerical analysis of the resulting von Mises stresses and effective strain resulting in the topology-optimized implant with occlusal loading of 110 N. Solid Isotropic Material with Penalization (SIMP) method is employed for topology optimization and four different models, namely model-1, model-2, model-3, and model-4, are developed based on volume reduction rates of 8%, 16%, 24%, and 32%, respectively. FEA results highlight that the maximum stress and strain in the screw increases with volume reduction rates. The comparative analyses of the resulting stresses in the compact and cancellous bone along with the strain in the screw led to the conclusion that model-1, model-2, and model-3 resulted in moderate stresses on compact and cancellous bone compared to the original model of the implant. However, the screw and bones are subjected to maximum stress and strain in the model-4. The study concludes that model-2, with 16% reduced volume and 14.2% reduced mass as compared to the original implant, may be considered as the optimized design of the model. The resulting model offers a significant reduction in the weight and volume with a minor increase in effective stress and strain without negatively impacting the functionality and bio-mechanical performance of the implant. The optimized dental implant prototype is also fabricated as a proof of concept by the Fused Deposition Modelling process.

Surface Functionalization of Poly(lactic acid) via Deposition of Hydroxyapatite Monolayers for Biomedical Applications

The surface modification of poly(lactic acid) (PLA) using hydroxyapatite (HAP) particles via Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) approaches has been reported. The HAP monolayer was characterized at the air/water interface and deposited on three-dimensional (3D) printed poly(lactic acid). The deposition of HAP particles using the LS approach led to a larger surface coverage in comparison to the LB method, which produces a less uniform coating because of the aggregation of the particles. After the transfer of HAP on the PLA surface, the wettability values remained within the desired range. The presence of HAP on the surface of the polymer altered the topography and roughness in the nanoscale, as evidenced by the atomic force microscopy (AFM) images. This effect can be beneficial for the osteointegration of polymeric implants at an early stage, as well as for the reduction of the adherence of the microbial biofilm. Overall, the results suggest that the LS technique could be a promising approach for surface modification of PLA by hydroxyapatite with respective advantages in the biomedical field.

Biocompatibility Testing for Implants: A Novel Tool for Selection and Characterization

This review article dives into the complex world of biocompatibility testing: chemical, mechanical, and biological characterization, including many elements of biocompatibility, such as definitions, descriptive examples, and the practical settings. The focus extends to evaluating standard documents obtained from reliable organizations; with a particular focus on open-source information, including FDA-USA, ISO 10933 series, and TÜV SÜD. We found a significant gap in this field: biomaterial scientists and those involved in the realm of medical device development in general, and implants in particular, lack access to a tool that reorganizes the process of selecting the appropriate biocompatibility test for the implant being examined. This work progressed through two key phases that aimed to provide a solution to this gap. A straightforward "yes or no" flowchart was initially developed to guide biocompatibility testing decisions based on the previously accumulated information. Subsequently, the Python code was employed, generating a framework through targeted questions. This work reshapes biocompatibility evaluation, bridging theory and practical implementation. An integrated approach via a flowchart and the Python code empowers stakeholders to navigate biocompatibility testing effortlessly. To conclude, researchers are now better equipped for a safer, more effective implant development, propelling the field towards improved patient care and innovative progress.

Stress-strain and fatigue life numerical evaluation of two different dental implants considering isotropic and anisotropic human jaw

Dental prostheses are currently a valid solution for replacing potential missing tooth or edentulism clinical condition. Nevertheless, the oral cavity is a dynamic and complex system: occlusal loads, external agents, or other unpleasant events can impact on implants functionality and stability causing a future revision surgery. One of the failure origins is certainly the dynamic loading originated from daily oral activities like eating, chewing, and so on. The aim of this paper was to evaluate, by a numerical analysis based on Finite Elements Method (FEM), and to discuss in a comparative way, firstly, the stress-strain of two different adopted dental implants and, subsequently, their fatigue life according to common standard of calculations. For this investigation, the jawbone was modeled accounting for either isotropic or anisotropic behavior. It was composed of cortical and cancellous regions, considering it completely osseointegrated with the implants. The impact of implants' fixture design, loading conditions, and their effect on the mandible bone was finally investigated, on the basis of the achieved numerical results. Lastly, the life cycle of the investigated implants was estimated according to the well-established theories of Goodman, Soderberg, and Gerber by exploiting the outcomes obtained by the numerical simulations, providing interesting conclusions useful in the dental practice.

Improving dental implant stability by optimizing thread design: Simultaneous application of finite element method and data mining approach

STATEMENT OF PROBLEM

Lack of knowledge regarding the optimal design of thread configuration in dental implants, which can offer a satisfactory level of stability in the implant-bone construct, is a significant challenge in the field of dental biomechanics.

PURPOSE

The purpose of this finite element analysis study was to identify the optimal thread design by investigating the effects of thread parameters such as thread depth (TD), thread width (TW), and thread pitch (TP), as well as upper (α) and lower (β) thread angles, on the maximum principal stress in cancellous and cortical bone, maximum von Mises stress in the dental implant, and maximum shear stress at the implant-bone interface.

MATERIAL AND METHODS

A finite element model of an alveolar bone segment with a dental implant was developed. The Latin hypercube sampling method was used to generate a dataset of virtual experiments, which were analyzed by using the decision tree method to identify suitable thread designs that minimize mechanical stimuli. Additionally, the effectiveness of thread parameters on stress levels in the bone, implant, and their interface were assessed.

RESULTS

The results of this study, verified by comparison with previous literature, indicated that TD, TW, and upper thread angle were the most effective parameters in promoting implant stability.

CONCLUSIONS

By analyzing the decision trees, optimum ranges for all the thread parameters were determined as follows: 0.25 Collapse

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Affiliation(s)

Masoud Arabbeiki Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
Mohammad Reza Niroomand Department of Mechanical Engineering, Payame Noor University, Tehran, Iran.
Gholamreza Rouhi Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran

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Manufacture of titanium alloy materials with bioactive sandblasted surfaces and evaluation of osseointegration properties

Titanium alloys are some of the most important orthopedic implant materials currently available. However, their lack of bioactivity and osteoinductivity limits their osseointegration properties, resulting in suboptimal osseointegration between titanium alloy materials and bone interfaces. In this study, we used a novel sandblasting surface modification process to manufacture titanium alloy materials with bioactive sandblasted surfaces and systematically characterized their surface morphology and physicochemical properties. We also analyzed and evaluated the osseointegration between titanium alloy materials with bioactive sandblasted surfaces and bone interfaces by in vitro experiments with co-culture of osteoblasts and in vivo experiments with a rabbit model. In our in vitro experiments, the proliferation, differentiation, and mineralization of the osteoblasts on the surfaces of the materials with bioactive sandblasted surfaces were better than those in the control group. In addition, our in vivo experiments showed that the titanium alloy materials with bioactive sandblasted surfaces were able to promote the growth of trabecular bone on their surfaces compared to controls. These results indicate that the novel titanium alloy material with bioactive sandblasted surface has satisfactory bioactivity and osteoinductivity and exhibit good osseointegration properties, resulting in improved osseointegration between the material and bone interface. This work lays a foundation for subsequent clinical application research into titanium alloy materials with bioactive sandblasted surfaces.

Enhanced human periodontal ligament stem cell viability and osteogenic differentiation on two implant materials: An experimental in vitro study

Background: Surface roughness of dental implants impacts the survival of adult periodontal stem cells and rate of differentiation. This research was conducted to test how human periodontal ligament stem cells behaved on yttria stabilized tetragonal zirconia polycrystals and polyetheretherketone (PEEK) discs with different surface topographies. Methods: Discs roughening was prepared by sandblasting. Stem cells were cultivated on zirconia discs with a polished surface, PEEK discs with a polished surface, sandblasted zirconia discs and sandblasted PEEK discs. Cells viability was assessed after 24, 48, 72 hours. Scanning electron microscopy was used to examine the adherence and attachment of cells. Osteoblastic differentiation capacity was studied by checking the mineralization clusters development through alizarin red S staining and alkaline phosphatase assay. ANOVA and the Tukey post hoc test were used for the statistical analysis. Results: Polished PEEK discs showed lower cell viability, whereas roughened sandblasted zirconia and PEEK discs showed the highest proliferation rates and cell viability percent. The osteogenic differentiation was enhanced for rough surfaces in comparison to polished surfaces. Sandblasted zirconia and PEEK discs showed a markedly increased mineralized nodule development and ALP enzyme activity compared to the polished surface and control. Conclusions: Micro- topographies creation on the PEEK implant surface enhances stem cell attachment, viability, and osteogenic differentiation.

Design modification of surgical drill bit for final osteotomy site preparation towards improved bone-implant contact

Implant stability significantly impacts accelerated osseointegration, leading to faster patient recovery. Both primary and secondary stability necessitates superior bone-implant contact influenced by the surgical tool required to prepare the final osteotomy site. Besides, excessive shearing and frictional forces generate heat causing local tissue necrosis. Hence, surgical procedure necessitates proper irrigation with water to minimize heat generation. Notably, the water irrigation system removes bone chips and osseous coagulums, which may help accelerate osseointegration and improve bone-implant contact. The inferior bone-implant contact and thermal necrosis at the osteotomy site are primarily responsible for poor osseointegration and eventual failure. Therefore, optimizing tool geometry is key to minimizing shear force, heat generation, and necrosis during final osteotomy site preparation. The present study explores modified drilling tool geometry, especially cutting edge for osteotomy site preparation. The mathematical modeling is used to find out ideal cutting-edge geometry that facilitates drilling under relatively less operational force (0.55-5.24 N) and torque (98.8-154.5 N-mm) with a significant reduction (28.78%-30.87%) in heat generation. Twenty-three conceivable designs were obtained using the mathematical model; however, only three have shown promising results in static structural FEM platforms. These drill bits are designed for the final drilling operation and need to be carried out during the final osteotomy site preparation.

The Effects of Statins on Bone Formation Around Implants Placed in Animal Bones: A Systematic Review and Meta-Analysis

Background

Implants are preferred for replacement of missing teeth by the clinicians as well as the patients. Lesser alveolar bone density doesn't preclude any individual for choosing this option but warrants for extra caution. Preclinical studies have explored the osteoinductive potential of statins, but results should be analyzed vigorously before implementing them in humans. There is no meta-analysis to document effect of statins on bone formation around implants in osteoporotic animals.

Methods and material

PubMed, Embase and Cochrane were searched for studies investigating the effect of statins on bone implant contact (BIC %), bone mineral density (BMD %) and bone volume (BV %) around implants at 2, 4 and 12 weeks. Meta-analysis was performed on subgroups with osteoporotic animals which were administered statins through different routes.

Results

Quantitative data from 12 studies showed favorable effect of statins on bone around implants. Positive difference was observed at 4 weeks in BIC (parenteral [SMD = 4.33 (2.89, 5.77); I 2 = 3%)], BMD (local [SMD = 1.33 (0.51, 2.15); I 2 = 0%] and BV (local [SMD = 1.58 (0.76, 2.40); I 2 = 0%]. BIC [SMD = 1.40 (0.89, 1.90); I 2 = 0%] and BV [SMD = 3.91 (2.33, 5.50); I 2 = 43%] were higher in experimental group after 12 weeks of oral administration.

Conclusions

Statins can be investigated as potential bone graft materials to increase the predictability of osseointegration especially in osteoporotic individuals. Future research should focus to reproduce homogeneous data and conclusive recommendations which can be applied in clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12663-023-01873-z.

Surface Coatings of Dental Implants: A Review

Replacement of missing teeth is possible using biocompatible devices such as endosseous implants. This study aims to analyze and recognize the best characteristics of different implant surfaces that ensure good peri-implant tissue healing and thus clinical success over time. The present review was performed on the recent literature concerning endosseous implants made of titanium, a material most frequently used because of its mechanical, physical, and chemical characteristics. Thanks to its low bioactivity, titanium exhibits slow osseointegration. Implant surfaces are treated so that cells do not reject the surface as a foreign material and accept it as fully biocompatible. Analysis of different types of implant surface coatings was performed in order to identify ideal surfaces that improve osseointegration, epithelial attachment to the implant site, and overall peri-implant health. This study shows that the implant surface, with different adhesion, proliferation, and spreading capabilities of osteoblastic and epithelial cells, influences the cells involved in anchorage. Implant surfaces must have antibacterial capabilities to prevent peri-implant disease. Research still needs to improve implant material to minimize clinical failure.

Zinc (Zn) Doping by Hydrothermal and Alkaline Heat-Treatment Methods on Titania Nanotube Arrays for Enhanced Antibacterial Activity

Titanium (Ti) is a popular biomaterial for orthopedic implant applications due to its superior mechanical properties such as corrosion resistance and low modulus of elasticity. However, around 10% of these implants fail annually due to bacterial infection and poor osseointegration, resulting in severe pain and suffering for the patients. To improve their performance, nanoscale surface modification approaches and doping of trace elements on the surfaces can be utilized which may help in improving cell adhesion for better osseointegration while reducing bacterial infection. In this work, at first, titania (TiO₂) nanotube arrays (NT) were fabricated on commercially available pure Ti surfaces via anodization. Then zinc (Zn) doping was conducted following two distinct methods: hydrothermal and alkaline heat treatment. Scanning electron microscopic (SEM) images of the prepared surfaces revealed unique surface morphologies, while energy dispersive X-ray spectroscopy (EDS) revealed Zn distribution on the surfaces. Contact angle measurements indicated that NT surfaces were superhydrophilic. X-ray photoelectron spectroscopy (XPS) provided the relative amount of Zn on the surfaces and indicated that hydrothermally treated surfaces had more Zn compared to the alkaline heat-treated surfaces. X-ray crystallography (XRD) and nanoindentation techniques provided the crystal structure and mechanical properties of the surfaces. While testing with adipose-derived stem cells (ADSC), the surfaces showed no apparent cytotoxicity to the cells. Finally, bacteria adhesion and morphology were evaluated on the surfaces after 6 h and 24 h of incubation. From the results, it was confirmed that NT surfaces doped with Zn drastically reduced bacteria adhesion compared to the Ti control. Zn-doped NT surfaces thus offer a potential platform for orthopedic implant application.

Guided Bone Regeneration Effects on Bone Quantity and Outcomes of Dental Implants in Patients With Insufficient Bone Support: A Single-Center Observational Study

Background Guided bone regeneration (GBR) is used to influence on stabilization of dental implants in patients with insufficient bone quantity and anatomical problems. But many studies using GBR resulted in divergent results according to the efficiency of new bone quantity formation and implant survival. This research aimed to study the effects of GBR on the increase of bone quantity and short-term stabilization of dental implants in patients with insufficient bone support. Methodology The study included 26 patients that underwent the procedure for 40 dental implants from September 2020 to September 2021. In each case, the vertical bone support was intraoperatively measured, through the MEDIDENT Italia paradontal millimetric probe (Medident Italia, Carpi, Italy). The vertical bone defect was considered when the mean vertical depth between the abutment junction and the marginal bone was greater than 1mm up to 8mm. In the group with the presence of the vertical bone defect, GBR technique was used during the procedure of dental implants realized with synthetic bone graft, resorbable membrane, and platelet-rich fibrin (PRF), and the group was considered the study (GBR) group. The group of patients with no vertical bone defects (less than 1mm) and no need for any GBR technique use was considered the control (no-GBR) group. The bone support was evaluated again intraoperatively after six months in both groups when the healing abutments were positioned. The vertical bone defect for each group in baseline and after six months is presented as mean±SD and compared using a t-test. A t-test for Equality of Means was used to calculate the mean depth difference (MDD) between baseline and six months values in each group (GBR and no-GBR) and also between both groups. P-value ≤ 0.05 is considered statistically significant. Results Overall 40 dental implants were placed, 20 of them were included in the GBR group and 20 in the no-GBR group. In the GBR group, a statistically significant greater mean vertical bone defect in baseline (day 1), compared to the no-GBR group was found (-4.46±2.76 vs -0.27±0.22; MDD = -4.19 [-5.44 to -2.94] p<0.001). At six months of follow-up in the GBR group, a new bone around the implant was formed, presenting a significantly lower bone defect compared to the baseline measure (-0.39±0.43 vs -4.46±2.76; MDD = -4.07 mm [-5.37 to -2.78] p<0.001). In six months, no statistically significant difference between GBR and no-GBR group in bone support was found (-0.39±0.43 vs -0.27±0.22; MDD = -0.19 [-0.40 to -0.03] p=0.10). In each group, only one implant failure was observed. Conclusions The use of GBR showed an important reduction of vertical depth defect between healing abutment and marginal bone predisposing similar short-term stability and survival of dental implants. The use of GBR techniques could be essential in the stabilization of dental implants in patients with insufficient bone support.

The Sympathetic Nervous System in Dental Implantology

The sympathetic nervous system plays a vital role in various regulatory mechanisms. These include the well-known fight-or-flight response but also, for example, the processing of external stressors. In addition to many other tissues, the sympathetic nervous system influences bone metabolism. This effect could be highly relevant concerning osseointegration, which is responsible for the long-term success of dental implants. Accordingly, this review aims to summarize the current literature on this topic and to reveal future research perspectives. One in vitro study showed differences in mRNA expression of adrenoceptors cultured on implant surfaces. In vivo, sympathectomy impaired osseointegration in mice, while electrical stimulation of the sympathetic nerves promoted it. As expected, the beta-blocker propranolol improves histological implant parameters and micro-CT measurements. Overall, the present data are considered heterogeneous. However, the available publications reveal the potential for future research and development in dental implantology, which helps to introduce new therapeutic strategies and identify risk factors for dental implant failure.

Analysis of Bone Density and Bone Morphometry by Periapical Radiographs in Dental Implant Osseointegration Process

Objective. This research aimed to analyze the differences in bone density and bone morphometry by periapical implant radiography in the dental implant osseointegration stages. Methods. This experimental research uses 12 periapical radiographs of tibial bones from a New Zealand white rabbit (Oryctolagus cuniculus). The analysis was performed on day 3, 14, and 28 of the osseointegration stages with density, trabecular thickness (Tb.Th.), trabecular separation (Tb.Sp.), and trabecular number (Tb.N.) as parameters. The implant used is a titanium alloy and coated by SA (sunblasted with alumina acid) of 4 mm in diameter and 7 mm in length. The radiographic assessment of the osseointegration process is obtained with the region of interest (ROI) segmentation results. Additionally, each ROI was analyzed for bone density and morphometry using the open-source ImageJ software with the BoneJ plugin. The significant difference was evaluated by analysis of variance (F-test) with $p<0.05$ and nonparametric Kruskal–Wallis test with $p<0.05$ . Results. Analysis of the osseointegration images of dental implants at day 3, 14, and 28 with the periapical X-ray modality shows significant differences ( $p<0.05$ ) in the parameters measuring density and trabecular thickness (Tb.Th.). In the variables of trabecular separation (Tb.Sp.) and number (Tb.N.) ( $p>0.05$ ), there is no significant difference. Conclusion. Based on the results, density and trabecular thickness (Tb.Th.) showed a significant difference between healing times. However, trabecular separation (Tb.Sp.) and trabecular number (Tb.N.) showed no difference in healing time.

Dental Implants and Implant Coatings: A Focus on Their Toxicity and Safety

Dental implants are medical devices that are surgically inserted into the patient's jawbone by an orthodontist to act as roots of missing teeth. After the implantation, the maxilla or mandible integrates with the surface of the dental implant. This process, called "osseointegration," is an important period to ensure the long-term use of dental implants and prevent implant failures. Metal implants are the most used implant materials. However, they have disadvantages such as corrosion, metal ion release from metal implant surfaces and associated toxicity. To avoid these adverse effects and improve osseointegration, alternative dental implant materials such as ceramics, polymers, composites, and novel surface modification technologies have been developed. The safety of these materials are also of concern for toxicologists. This review will give general information about dental implant materials, osseointegration and successful implantation process. Moreover, we will focus on the new surface coatings materials for of dental implants and their toxicity and safety concerns will be discussed.

Type-A Gelatin-Based Hydrogel Infiltration and Degradation in Titanium Foams as a Potential Method for Localised Drug Delivery

A gelatin-based hydrogel was infiltrated and degraded-released in two different titanium foams with porosities of 30 and 60 vol.% (Ti30 and Ti60 foams) and fabricated by the space holder technique to evaluate its potential to act as an innovative, alternative, and localised method to introduce both active pharmaceutical ingredients, such as antibiotics and non-steroidal anti-inflammatory drugs, and growth factors, such as morphogens, required after bone-tissue replacement surgeries. In addition, the kinetic behaviour was studied for both infiltration and degradation-release processes. A higher infiltration rate was observed in the Ti60 foam. The maximum infiltration hydrogel was achieved for the Ti30 and Ti60 foams after 120 min and 75 min, respectively. Further, both processes followed a Lucas-Washburn theoretical behaviour, typical for the infiltration of a fluid by capillarity in porous channels. Regarding the subsequent degradation-release process, both systems showed similar exponential degradation performance, with the full release from Ti60 foam (80 min), versus 45 min for Ti30, due to the greater interconnected porosity open to the surface of the Ti60 foam in comparison with the Ti30 foam. In addition, the optimal biocompatibility of the hydrogel was confirmed, with the total absence of cytotoxicity and the promotion of cell growth in the fibroblast cells evaluated.

Impact of implant thread design on insertion torque and osseointegration: a preclinical model

BACKGROUND

Successful osseointegration of endosteal dental implants has been attributed to implant design, including the macro-, micro- and nano- geometric properties. Based on current literature pertaining to implant design, the resultant cellular and bone healing response is unknown when the thread thickness of the implants is increased, resulting in an increased contact area in implants designed with healing chambers. The aim of this study was to evaluate the effect of two implant designs with different thread profiles on the osseointegration parameters and implant stability at 3- and 6-weeks in vivo using a well-established preclinical dog model.

MATERIAL AND METHODS

A total of 48 type V Ti alloy implants were divided in two groups according to their thread design (D1= +0.1x/mm and D2= +0.15x/mm) and placed in an interpolated fashion into the radii of six beagles. Insertion torque was measured at time of placement, radii were extracted for histological processing following 3- and 6-week healing intervals. Histologic and histomorphometric analyses were performed in terms of bone to implant contact (%BIC) and bone area fraction occupancy within implant threads (%BAFO). Statistical analyses were performed through a linear mixed model with fixed factors of time and implant thread design.

RESULTS

Surface roughness analysis demonstrated no significant differences in Sa and Sq between D1 and D2 implant designs, which confirmed that both implant designs were homogenous except for their respective thread profiles. For insertion torque, statistically significant lower values were recorded for D1 in comparison to D2 (59.6 ± 11.1 and 78.9 ± 10.1 N⋅cm, respectively). Furthermore, there were no significant differences with respect to histological analysis and histomorphometric parameters, between D1 and D2 at both time points.

CONCLUSIONS

Both thread profiles presented equivalent potential to successfully osseointegrate in the osteotomies, with D2 yielding higher mechanical retention upon placement without detrimental bone resorption.

FEATURES OF BONE REMODELING AROUND SURFACE-MODIFIED TITANIUM AND TANTALUM IMPLANTS

OBJECTIVE

The aim: To study the osseointegrative properties of titanium and tantalum implants with different surface structures in animal experiments.

PATIENTS AND METHODS

Materials and methods: The histological and morphometric study was carried out on 60 male white rats after titanium implants with different surface structures made by 3D printed technology were inserted in the distal femur bone: presented by the multilayered layers of interlacing pores of 300 microns (series 1); rough (> 2 microns) (series 2); and tantalum implants with 300 microns pores and 80% porosity (series 3) as control material.

RESULTS

Results: On the 30 days we found statistically significant differences in the bone-implant contact rate between the 2nd experiment series (44.77 ± 1.86)% and 1st (59.91 ± 2.86)% (p=0.000047) and 3rd (53.89 ± 2.11)% (р=0.000065), on the 90 days between the 2nd experiment series (51.26 ± 2.7)% and 1st (66.84 ± 2.63)% (p=0.000187) and 3rd (70.35 ± 4.32)% (p=0.000349). There was a difference between the indices of the bone-implant volume at day 90 between the 1st (48.43 ± 2.2)% and 2nd (36.88 ± 2.56)% series (p=0.000919), between the 2nd and 3rd series (51.2 ± 3.06)% (p=0.000107). There were no significant differences between the studied indices in the 1st and 3rd series of the experiment.

CONCLUSION

Conclusions: Titanium implants with multilayered interlaced pore layers of 300 microns and tantalum with 300 microns pore size and 80% porosity may be promising. Rough-surface titanium also has osseointegrative qualities, but they are lower compared to other materials.

Use of CGF in Oral and Implant Surgery: From Laboratory Evidence to Clinical Evaluation

Edentulism is the condition of having lost natural teeth, and has serious social, psychological, and emotional consequences. The need for implant services in edentulous patients has dramatically increased during the last decades. In this study, the effects of concentrated growth factor (CGF), an autologous blood-derived biomaterial, in improving the process of osseointegration of dental implants have been evaluated. Here, permeation of dental implants with CGF has been obtained by using a Round up device. These CGF-coated dental implants retained a complex internal structure capable of releasing growth factors (VEGF, TGF-β1, and BMP-2) and matrix metalloproteinases (MMP-2 and MMP-9) over time. The CGF-permeated implants induced the osteogenic differentiation of human bone marrow stem cells (hBMSC) as confirmed by matrix mineralization and the expression of osteogenic differentiation markers. Moreover, CGF provided dental implants with a biocompatible and biologically active surface that significantly improved adhesion of endothelial cells on CGF-coated implants compared to control implants (without CGF). Finally, data obtained from surgical interventions with CGF-permeated dental implants presented better results in terms of optimal osseointegration and reduced post-surgical complications. These data, taken together, highlight new and interesting perspectives in the use of CGF in the dental implantology field to improve osseointegration and promote the healing process.

Evolution of implants and advancements for osseointegration: A narrative review

Since ancient times, reduction and internal fixation has been applied to restore skeletal integrity. Despite advances in the understanding of fracture healing, the risk of complication such as implant loosening or implant-related infection still depicts a challenging complication. Nowadays, a great deal of research is devoted to unreveal the impact of implant surface modifications on osteogenic processes to enhance bone consolidation and osseointegration. This narrative review is aimed to (1) show the evolution and already achieved milestones of implant optimization, and (2) to outline the key factors that contribute to an enhanced osseointegration. Different physical and chemical roughening techniques are currently applied in various studies. Surface patterning on the nanoscale has been found to be an essential factor for the biological response, achievable by e.g. anodisation or laser texturing. Besides surface roughening, also different coating methods are vastly investigated. Next to metal or inorganic compounds as coating material, a variety of biomolecules is currently studied for their osteosupportive capacities. Osseointegration can be improved by surface modification on the micro and nanoscale. Bioactive agents can further improve the osseointegration potential. Used agents at the moment are e.g. inorganic compounds, growth factors (BMPs and non-BMPs) and antiresorptive drugs. The advancement in research on new implant generations therefore aims at actively supporting osseointegration processing.

Multifunctional exosomes derived from bone marrow stem cells for fulfilled osseointegration

Bone marrow mesenchymal stem cells (BMSCs) have self-renewal, multi-directional differentiation potential, and immune regulation function and are widely used for de novo bone formation. However, the wide variation in individual amplification, the potential risk of cancer cell contamination, and the need for culture time significantly limit their widespread use clinically. Alternatively, numerous studies have shown that exosomes secreted by BMSCs in the nanoscale can also affect the functionality of endothelial cells (angiogenesis), macrophages (immunomodulation), and osteoblasts/osteoclasts (osteogenesis), which is a highly promising therapy for osseointegration with pronounced advantages (e.g., safety, high efficiency, and no ethical restrictions). The review aims to summarize the multifaceted effect of BMSCs-derived exosomes on osseointegration and provide reference and basis for rapid and qualified osseointegration.

Diagnosis and Detection of Subtle Aseptic Loosening in Total Hip Arthroplasty

Aseptic loosening is a common cause of revision total hip arthroplasty (rTHA), and with the rising number of primary THAs, revisions for aseptic loosening represent a significant burden for arthroplasty surgeons. Aseptic loosening remains a diagnostic and management challenge. Loosening can occur as a result of inadequate initial fixation, mechanical loss of fixation over time, or a biological loss of fixation over time. However, in most cases, etiology is multifactorial, involving all 3 factors. The diagnosis of aseptic loosening involves a careful history, focused clinical exam, and thorough evaluation of imaging using several diagnostic modalities. The careful evaluation of serial radiographs remains the cornerstone of diagnosis with additional input from advanced imaging modalities such as FDG-PET, DEXA, MRI, and several others, each offering unique advantages and disadvantages. In certain patients, history and physical exam might be the only initial obvious signs of loosening, and thus, unexplained continuous pain augmented by imaging findings serves as an indication for revision surgery.

Tamoxifen improves homeostasis in the peri-implant bone remodeling of osseointegrated titanium implants

BACKGROUND

The purpose of this preclinical study was to evaluate the influence of tamoxifen (TAM) on the peri-implant bone remodeling of osseointegrated titanium implants in ovariectomized female rats.

MATERIALS AND METHODS

Seventy-two female rats underwent bilateral ovariectomy 20 weeks before implants placement. One titanium implant was inserted in each tibia of the animals. Six weeks following the implant surgery, animals were randomly divided into two experimental groups (n = 36), which received either saline solution (SS) or tamoxifen citrate (TAM) via gavage until euthanasia. Euthanasia was performed at 30, 60, and 90 days after the first gavage. Assessments of bone to implant contact (BIC), bone ingrowth percentage (BIN), morphological description of cellular and tissue reactions, immunohistochemistry for the detection of bone morphogenetic protein 2/4 (BMP2/4), runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN) and tartrate-resistant acid phosphatase (TRAP), and bone chemical composition through scanning electron microscopy with energy-dispersive x-ray spectroscopy were performed.

RESULTS

Tamoxifen group presented higher BIC, higher BIN, higher RUNX-2 and OCN, lower TRAP-positive cells/mm2 , and no differences regarding BMP-2/4 positive cells/mm2 than SS group in all periods. TAM group also showed higher Ca/P rate than SS group.

CONCLUSION

Tamoxifen enhanced the remodeling of the bone surrounding titanium implants in ovariectomized rats.

Polymer–Metal Composite Healthcare Materials: From Nano to Device Scale

Metals have been investigated as biomaterials for a wide range of medical applications. At nanoscale, some metals, such as gold nanoparticles, exhibit plasmonics, which have motivated researchers’ focus on biosensor development. At the device level, some metals, such as titanium, exhibit good physical properties, which could allow them to act as biomedical implants for physical support. Despite these attractive features, the non-specific delivery of metallic nanoparticles and poor tissue–device compatibility have greatly limited their performance. This review aims to illustrate the interplay between polymers and metals, and to highlight the pivotal role of polymer–metal composite/nanocomposite healthcare materials in different biomedical applications. Here, we revisit the recent plasmonic engineered platforms for biomolecules detection in cell-free samples and highlight updated nanocomposite design for (1) intracellular RNA detection, (2) photothermal therapy, and (3) nanomedicine for neurodegenerative diseases, as selected significant live cell–interactive biomedical applications. At the device scale, the rational design of polymer–metallic medical devices is of importance for dental and cardiovascular implantation to overcome the poor physical load transfer between tissues and devices, as well as implant compatibility under a dynamic fluidic environment, respectively. Finally, we conclude the treatment of these innovative polymer–metal biomedical composite designs and provide a future perspective on the aforementioned research areas.

Mineralizing Coating on 3D Printed Scaffolds for the Promotion of Osseointegration

Design and fabrication of implants that can perform better than autologous bone grafts remain an unmet challenge for the hard tissue regeneration in craniomaxillofacial applications. Here, we report an integrated approach combining additive manufacturing with supramolecular chemistry to develop acellular mineralizing 3D printed scaffolds for hard tissue regeneration. Our approach relies on an elastin-like recombinamer (ELR) coating designed to trigger and guide the growth of ordered apatite on the surface of 3D printed nylon scaffolds. Three test samples including a) uncoated nylon scaffolds (referred to as "Uncoated"), b) ELR coated scaffolds (referred to as "ELR only"), and c) ELR coated and in vitro mineralized scaffolds (referred to as "Pre-mineralized") were prepared and tested for in vitro and in vivo performance. All test samples supported normal human immortalized mesenchymal stem cell adhesion, growth, and differentiation with enhanced cell proliferation observed in the "Pre-mineralized" samples. Using a rabbit calvarial in vivo model, 'Pre-mineralized' scaffolds also exhibited higher bone ingrowth into scaffold pores and cavities with higher tissue-implant integration. However, the coated scaffolds ("ELR only" and "Pre-mineralized") did not exhibit significantly more new bone formation compared to "Uncoated" scaffolds. Overall, the mineralizing coating offers an opportunity to enhance integration of 3D printed bone implants. However, there is a need to further decipher and tune their immunologic response to develop truly osteoinductive/conductive surfaces.

Effects of Two Protocols of Low-Level Laser Therapy on the Proliferation and Differentiation of Human Dental Pulp Stem Cells on Sandblasted Titanium Discs: An In Vitro Study

Introduction: Stem cell activities have different effects on tissue response and its outcomes. Low-level laser therapy (LLLT) can be considered a trigger to modify stem cell activities. The objective of the present experimental investigation was to study the effects of two protocols of LLLT on the proliferation and differentiation of human dental pulp stem cells (hDPSCs) cultured on sandblasted titanium discs. Methods: Cells obtained from human dental pulp were seeded/cultured on titanium discs and were set in 2 main groups: (i) Radiated cells using the gallium-aluminium-arsenide (GaAlAs) diode laser at a continuous wavelength of 808 nm at 3 J/cm² for 12 sec or 5 J/cm² for 20 seconds, and (ii) Non-irradiated cells serving as control groups. The impact of LLLTs on hDPSC-proliferation and viability was investigated using the MTT assay after 24, 72 and 96 hours. The alkaline phosphatase activity was studied with p-nitrophenylphosphate after 14 and 28 days. The ability of hDPSCs to express osteocalcin was investigated using real-time polymerase chain reaction after 28 days, while their attachment was observed under a scanning electron microscope (SEM) after 14 and 28 days. Results: Our study showed that LLLTs caused maximum cell proliferation in 96 hours (P<0.001) with 3 J/cm² resulting in a higher proliferation rate. The highest activity of alkaline phosphatase and osteocalcin expression was observed in the laser radiation groups after 28 days. Conclusion: The outcomes of the current study showed that cultured hDPSCs on sandblasted titanium discs had a tendency towards increased cellular activity in response to LLLTs. Thus, LLLTs could regulate the activities of hDPSCs on bone repair surrounding the sandblasted titanium discs.

Automatic computation of bone defective volume from tomographic images

One of the most difficult aims of modern biomaterial science is predicting the shape and volume of a bone defect and adjusting the implementation of a bone substitute. Prior to implantation, practitioners must carefully identify the architecture and volume of the defective bone to be filled. This information is often accessed via imaging techniques. The defective bone is frequently confused with its surroundings and the image background. The use of conventional segmentation for the selection and isolation of the cavity to be filled proves to be difficult. In this work, a defect in a dead bone is created and then imaged with the microtomography technique (343 cuts generated). The goal is to separate the defect's shape and volume from both the bone and the background image. An adaptive morphological operation technique was employed to complete these tasks. The proposed method allows for exact segmentation and calculation of the volume of the cavity to be filled. Using several calculated phantoms, the approach is subjectively and quantitatively evaluated: Compared to the high error value of the conventional method, the error value of the proposed one has no bearing on the overall data. The method's accuracy was also confirmed by comparing the calculated volume of the bone defect (0.91 cm3) and the volume of prepared calcium phosphate cement paste necessary for its filling (0.87 cm3). To challenge the method even further, another direct application on a mandibular bone is realized with an advanced number of cuts (1236 cuts). The result of this application proved that the proposed algorithm overcomes the performance of the classical approaches of segmentation with a gain of 2 min on average. A comparison study between the proposed method and other classical segmentation approaches is also presented. The effectiveness of the method is proved by the various reports and metrics generated. The automated procedure can be beneficial in implantology for realizing and guiding surgical acts, as well as in computer-aided scaffolding techniques.

Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti6Al4V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti6Al4V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3×with 1 ×PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure.

Mesh Ti6Al4V Material Manufactured by Selective Laser Melting (SLM) as a Promising Intervertebral Fusion Cage

Intervertebral cages made of Ti6Al4V alloy show excellent osteoconductivity, but also higher stiffness, compared to commonly used polyether-ether-ketone (PEEK) materials, that may lead to a stress-shielding effect and implant subsidence. In this study, a metallic intervertebral fusion cage, with improved mechanical behavior, was manufactured by the introduction of a three-dimensional (3D) mesh structure to Ti6Al4V material, using an additive manufacturing method. Then, the mechanical and biological properties of the following were compared: (1) PEEK, with a solid structure, (2) 3D-printed Ti6Al4V, with a solid structure, and (3) 3D-printed Ti6Al4V, with a mesh structure. A load-induced subsidence test demonstrated that the 3D-printed mesh Ti6Al4V cage had significantly lower tendency (by 15%) to subside compared to the PEEK implant. Biological assessment of the samples proved that all tested materials were biocompatible. However, both titanium samples (solid and mesh) were characterized by significantly higher bioactivity, osteoconductivity, and mineralization ability, compared to PEEK. Moreover, osteoblasts revealed stronger adhesion to the surface of the Ti6Al4V samples compared to PEEK material. Thus, it was clearly shown that the 3D-printed mesh Ti6Al4V cage possesses all the features for optimal spinal implant, since it carries low risk of implant subsidence and provides good osseointegration at the bone-implant interface.

Effects of Titanium Implant Surface Topology on Bone Cell Attachment and Proliferation in vitro

Purpose

Titanium is commonly used for implants because of its corrosion resistance and osseointegration capability. It is well known that surface topology affects the response of bone tissue towards implants. In vivo studies have shown that in weeks or months, bone tissue bonds more efficiently to titanium implants with rough surfaces compared to smooth surfaces. In addition, stimulating early endosseous integration increases the long-term stability of bone-implants and hence their clinical outcome. Here, we evaluated the response of human MG-63 osteoblast-like cells to flat and solid, compared to rough and porous surface topologies in vitro 1–6 days post seeding. We compared the morphology, proliferation, and attachment of cells onto three smooth surfaces: tissue culture (TC) plastic or microscope cover glasses, machined polyether-ether-ketone (PEEK), and machined solid titanium, to cells on a highly porous (average R_a 22.94 μm) plasma-sprayed titanium surface (composite Ti-PEEK spine implants).

Methods

We used immuno-fluorescence (IF) and scanning electron microscopy (SEM), as well as Live/Dead and WST-1 cell proliferation assays.

Results

SEM analyses confirmed the rough topology of the titanium implant surface, compared to the smooth surface of PEEK, solid titanium, TC plastic and cover glasses. In addition, SEM analyses revealed that MG-63 cells seeded onto smooth surfaces (solid titanium, PEEK) adopted a flat, planar morphology, while cells on the rough titanium surface adopted an elongated morphology with numerous filopodial and lamellipodial extensions interacting with the substrate. Finally, IF analyses of focal adhesions (vinculin, focal adhesion kinase), as well as proliferation assays indicate that MG-63 cells adhere less and proliferate at a slower rate on the rough than on a smooth titanium surface.

Conclusion

These observations suggest that bone-forming osteoblasts adhere less strongly and proliferate slower on rough compared to smooth titanium surfaces, likely promoting cell differentiation, which is in agreement with other porous implant materials.

How to Prevent Aseptic Loosening in Cementless Arthroplasty: A Review

Aseptic loosening is the main late postoperative complication of cementless total hip arthroplasties (THAs), leading to pain and functional impairment. This article aims to update the orthopedic surgeon on the various methods by which the aseptic loosening rate can be reduced. We performed a systematic review by searching the PubMed database for hip aseptic loosening. We included meta-analysis, randomized controlled trials, reviews, and systematic reviews in the last 10 years, which provided information on techniques that can prevent aseptic loosening in total hip arthroplasty. From a total of 3205 articles identified, 69 articles (2%) met the inclusion criteria, leading to a total of 36 recommendations. A lot of research has been conducted in terms of septic loosening in the last decade. Currently, we have various techniques by which we can reduce the rate of aseptic loosening. Nevertheless, further randomized clinical trials are needed to expand the recommendations for aseptic loosening prevention.

Chemically modified mRNA beyond COVID-19: Potential preventive and therapeutic applications for targeting chronic diseases

Chemically modified mRNA represents a unique, efficient, and straightforward approach to produce a class of biopharmaceutical agents. It has been already approved as a vaccination-based method for targeting SARS-CoV-2 virus. The COVID-19 pandemic has highlighted the prospect of synthetic modified mRNA to efficiently and safely combat various diseases. Recently, various optimization advances have been adopted to overcome the limitations associated with conventional gene therapeutics leading to wide-ranging applications in different disease conditions. This review sheds light on emerging directions of chemically modified mRNAs to prevent and treat widespread chronic diseases, including metabolic disorders, cancer vaccination and immunotherapy, musculoskeletal disorders, respiratory conditions, cardiovascular diseases, and liver diseases.

Randomized controlled study on effect of concentrated growth factors on crestal bone levels and peri-implant bone density in dental implants

Introduction:

Modern dentistry aims to restore the comfort and health of the stomatognathic system. Dental implants have emerged as a promising option for this purpose. Concentrated growth factors (CGFs) have been suggested to enhance the healing of bone grafts and enhance the integration of implants into the bone. Growth factors are proteins which regulate the complex process of wound healing. They play an important role in cell migration, cell proliferation, and angiogenesis in the tissue regeneration phase. CGF was first developed by Sacco in 2006. It can be used as a barrier membrane to accelerate soft-tissue healing. CGF does not require any chemical or anticoagulants, and hence, it is free from viral transmission diseases. Crestal bone levels, peri-implant bone density, bleeding, probing depth, mobility, occlusion factors, restoration adequacy, radiographic images, oral hygiene, and patient health status are some of the important parameters for determining longevity of success rates in implant dentistry. This study will assess the peri-implant bone density and crestal bone levels with and without the use of CGF.

Aim:

To evaluate the effect of CGFs on peri-implant bone density and in the preservation of crestal bone levels around dental implants.

Materials and Methods:

Sampling procedure: Random selection of population (Sealed envelope method)

Number of groups: Two-Control group (Group 1) and Experimental group (Group 2)

Sample size: 20

For Group 2, implants were placed with CGF. For Group 1, implants were placed without CGF. The peri-implant bone density and bone levels were measured by Digora and signora software.

Results:

The mean crestal bone loss on the mesial aspect of implants placed in Group 2 is 0.294 mm and Group 1 is 0.345 mm, and the mean crestal bone loss on the distal aspect of implants placed in Group 2 is 0.320 mm and in Group 1 is 0.331 mm. There are no many significant differences on mesial and distal aspects around implants between the two groups Intragroup comparison of bone density values in Group 1 shows the mean difference from baseline to 1 month is 0.6, and after three and 6 months periods are 1.1 and 1.1, respectively, which indicates not much significant improvement in bone density values in Group 1. Intergroup comparison shows a significant difference between both the groups starting from as early as the 1^st month.

Conclusion:

The results of this study indicate that CGF is significantly better in the regeneration of bone around the implants when comparing with nonCGF groups. Although CGF showed improvement in bone formation, there are no many differences in crestal bone level changes on mesial and distal sides of the implants between the two groups.

Bioprinting of biomimetic self-organised cartilage with a supporting joint fixation device

Despite sustained efforts, engineering truly biomimetic articular cartilage (AC) via traditional top-down approaches remains challenging. Emerging biofabrication strategies, from 3D bioprinting to scaffold-free approaches that leverage principles of cellular self-organisation, are generating significant interest in the field of cartilage tissue engineering as a means of developing biomimetic tissue analoguesin vitro.Although such strategies have advanced the quality of engineered cartilage, recapitulation of many key structural features of native AC, in particular a collagen network mimicking the tissue's 'Benninghoff arcade', remains elusive. Additionally, a complete solution to fixating engineered cartilagesin situwithin damaged synovial joints has yet to be identified. This study sought to address both of these key challenges by engineering biomimetic AC within a device designed to anchor the tissue within a synovial joint defect. We first designed and fabricated a fixation device capable of anchoring engineered cartilage into the subchondral bone. Next, we developed a strategy for inkjet printing porcine mesenchymal stem/stromal cells (MSCs) into this supporting fixation device, which was also designed to provide instructive cues to direct the self-organisation of MSC condensations towards a stratified engineered AC. We found that a higher starting cell-density supported the development of a more zonally defined collagen network within the engineered tissue. Dynamic culture was implemented to further enhance the quality of this engineered tissue, resulting in an approximate 3 fold increase in glycosaminoglycan and collagen accumulation. Ultimately this strategy supported the development of AC that exhibited near-native levels of glycosaminoglycan accumulation (>5% WW), as well as a biomimetic collagen network organisation with a perpendicular to a parallel fibre arrangement (relative to the tissue surface) from the deep to superficial zones via arcading fibres within the middle zone of the engineered tissue. Collectively, this work demonstrates the successful convergence of novel biofabrication methods, bioprinting strategies and culture regimes to engineer a hybrid implant suited to resurfacing AC defects.

Towards an agent-based model to simulate osseointegration in powder-bed 3D printed implant-like structures

The orthopedic industry is still searching for an efficient way to replace bone loss due to surgical procedures such as arthroplasty and limb-sparing surgery. Additive manufacturing (AM) presents an opportunity to manufacture affordable patient-specific implants. Optimization of the implant-bone interface to maximize osseointegration (bone ingrowth) has not been appropriately addressed. Mechanobiological models, suited to predict mechanical adaptation of bone, cannot be used to predict osseointegration inside implants as the implant is not exposed to any mechanical loading until it is fully accepted by the host body. Biological models relying on partial differential equations based on continuum approximation are not well-suited to predict the discrete phenomenon of osseointegration. This study proposes an agent-based modeling (ABM) approach for representing the osseointegration process for orthopedic implants produced by powder-bed additive manufacturing processes. Agent-Based Modeling (ABM) is a cellular automata based discrete computing technique that uses rule-based mathematics derived from experimental studies to simulate evolutionary phenomena. In this paper, osseointegration inside a hexagonal closed packing of AM powder particles is modeled using ABM. Cellular agents such as pre-osteoblasts and osteoblasts are realistically modeled as cubic cells. The proposed model underpredicts osseointegration at early stages but predicts osseointegration at around 21 days with sufficient accuracy when compared to the in vitro test conducted by Xue et al. in 2007.

Comparative Analysis of Stress and Deformation between One-Fenced and Three-Fenced Dental Implants Using Finite Element Analysis

Finite element analysis (FEA) has always been an important tool in studying the influences of stress and deformation due to various loads on implants to the surrounding jaws. This study assessed the influence of two different types of dental implant model on stress dissipation in adjoining jaws and on the implant itself by utilizing FEA. This analysis aimed to examine the effects of increasing the number of fences along the implant and to compare the resulting stress distribution and deformation with surrounding bones. When a vertical force of 100 N was applied, the largest displacements found in the three-fenced and single-fenced models were 1.7469 and 2.5267, respectively, showing a drop of 30.8623%. The maximum stress found in the three-fenced and one-fenced models was 13.518 and 22.365 MPa, respectively, showing a drop of 39.557%. Moreover, when an oblique force at 35° was applied, a significant increase in deformation and stress was observed. However, the three-fenced model still had less stress and deformation compared with the single-fenced model. The FEA results suggested that as the number of fences increases, the stress dissipation increases, whereas deformation decreases considerably.

Influence of surface modification of titanium implants on improving osseointegration: An in vitro study

STATEMENT OF PROBLEM

The effect of aging and the surface treatment of implants on osseointegration needs to be evaluated.

PURPOSE

The purpose of this in vitro study was to evaluate the effects of aging and the surface treatment of titanium with ultraviolet (UV) radiation and fibroblast growth factor (FGF) on hydrophilicity and cell growth and thus on osseointegration.

MATERIAL AND METHODS

A total of 28 specimens were divided into 2 groups to measure hydrophilicity (n=14) and cell growth (n=14). Each group was further divided into 4 groups according to surface modification. These include the control group (CG) (nascent specimens), aged group (AG) (nascent specimens aged for 4 weeks), photofunctionalized group (PG) (aged specimens UV-A treated), and mimed group (MG) (aged specimens UV-A and FGF2 treated). The PG and MG specimens were treated with UV-A light for 40 minutes. The biomimetic surface modification was performed for MG. Hydrophilicity was measured by using the contact angle in relation to the surface of titanium disks with the help of a drop shape analyzing device (KRUSS), and cell growth was measured by calculating the number of stem cells per cm² with the help of a scanning electron microscope (SEM). The data obtained were subjected to statistical analysis with a statistical software program (α=.05).

RESULTS

The lowest contact angle values were found in PG (13.52 ±0.90 degrees) and the highest in AG (70.54 ±1.72 degrees). The highest number of cells per cm² (2880 ±99.33) were found for MG, and the lowest number of cells per cm² (760 ±9.17) for AG.

CONCLUSIONS

Aging decreased the hydrophilicity and cell adhesion, migration, and growth on the titanium surface. UV treatment improved the hydrophilicity, cell adhesion, migration, and growth for both CG and AG. FGF2 treatment increased the cell adhesion, migration, and growth for CG, AG, and PG.