Implant biomaterials: A comprehensive review

Implant Body Fracture Due to Fatigue in a Maxillary Implant-Retained Overdenture Treatment

The aim of this study was to determine the causes of fatigue and implant failures in an implant-retained overdenture case. One out of four implants portrayed inadequate osseointegration during healing abutment placement, and one was fractured from the middle to the apical third after 1 year of denture use. Various aspects, such as insufficient cooling while implant socket preparation, incorrect prosthodontic planning, and erroneous design of the denture, were evaluated. Macroscopic and microscopic inspections of the fractured implant body were assessed by scanning electron microscopy (SEM) and optical microscopy. Consequently, metallic fatigue along with secondary cracks and beach marks were evident. It was deduced that the failed and fractured implants depicted substandard osseointegration; thus, they were susceptible to the wear out effect of the occlusal forces. Unfavorable osseointegration caused the fulcrum axis to move apically instead of forming on the neck part of the implant, and micromovements around the fulcrum axis mustered the fracture.

Metal Hypersensitivity in Patients With Failure of Joint Prosthesis Treatment

The objective of this study is to measure lymphocyte responses to metal antigens using MELISA (memory lymphocyte immunostimulation assay) test-modified lymphocyte transformation test (mLTT) and to evaluate metal sensitization in patients with and without the need of prosthetic surgery. This study is a case-control retrospective survey. We retrospectively analyzed all patients from 2013 to 2018 who were referred to the Institute of Dental Medicine, General University Hospital in Prague, and First Faculty of Medicine, Charles University, Prague, either following joint prosthesis-related complications or as a preoperative evaluation concerning metal hypersensitivity. For the control group, we selected healthy adults from our database. A group of 127 patients aged 25-81 years was chosen, 92 of which were female and 35 were male. The patients completed a special questionnaire aimed at information regarding their health status and history of metal exposure. After clinical examination, their peripheral blood samples were taken to perform mLTT. mLTT provided quantitative lymphocyte proliferation measurement, where a stimulation index of >2 indicated metal sensitivity. For statistical analysis, the Fisher's exact test, χ2 test, McNemar's exact test Student's paired t-test were used. By comparison of the study group and control group mLTT results, it can be stated that patients of the study group showed a higher level of lymphocyte reactivity to most of the tested metal antigens (Ag [silver], Cu [copper], Fe [iron], Mo [molybdenum], Pd [palladium], Pt [platinum], Ti [titanium], and Zn [zinc]) and an elevated incidence of metal hypersensitivity to Hg (mercury), Al (aluminum), Au (gold), Co (cobalt), Cr (chromium), Ni (nickel), and Sn (tin). The evaluation of the data obtained from patients in this study confirmed a significant clinical benefit of mLTT in diagnostics of metal hypersensitivity. Our study has revealed that the patients with the need of prosthetic surgery exhibited an elevated lymphocyte response to metal antigens. This result supports a metal-specific adaptive immune response and suggests involvement of metal exposure as a trigger for their health problems. This knowledge could be helpful in effectively enhancing the treatment of patients with need of orthopedic joint prosthesis.

Investigating the interplay between environmental conditioning and nanotopographical cueing on the response of human MG63 osteoblastic cells to titanium nanotubes

Titanium nanotubular surfaces have been extensively studied for their potential use in biomedical implants due to their ability to promote relevant phenomena associated with osseointegration, among other functions. However, despite the large body of literature on the subject, potential synergistic/antagonistic effects resulting from the combined influence of environmental variables and nanotopographical cues remain poorly investigated. Specifically, it is still unclear whether the nanotube-induced variations in cellular activity are preserved across different biochemical contexts. To bridge this gap, this study systematically evaluates the combined influence of nanotopographical cues and environmental factors on human MG63 osteoblastic cells. To this end, we capitalized on a triphasic anodization protocol to create nanostructured surfaces characterized by an average nanotube inner diameter of 25 nm (NT1) and 82 nm (NT2), as well as a two-tiered honeycomb (HC) architecture. A variable glucose content was chosen as the environmental modifier due to its well-known ability to affect specific functions of MG63 cells. Alkaline phosphatase (ALP), viability/metabolic activity and proliferation were quantified to identify the suitable preconditioning window required for dictating a change in behaviour without significantly damaging cells. Successively, a combination of immunofluorescence, colorimetric assays, live cell imaging and western blots quantified viability/metabolic activity and cell proliferation, migration and differentiation as a function of the combined effects exerted by the nanostructured substrates and the glucose content. To achieve a thorough understanding of MG63 cell adaptation and response, a comparative analysis table that includes and systematically cross-analyzes all variables from this study was used for interpretation and discussion of the results. Taken together, we have demonstrated that all surfaces mitigate the negative effects of high glucose. However, nanotubular topographies, particularly NT2, elicit a more beneficial outcome in high glucose in respect to untreated titanium. In addition, while NT1 surfaces are associated with the most stable cellular response across varying glucose levels, the NT2 and HC substrates exhibit the strongest enhancement of cell migration, viability/metabolism and differentiation. Moreover, shorter-term processes such as adhesion and proliferation are favored on untreated titanium, while anodized samples support later-term events. Lastly, the role of anodized surfaces is dominant over the effects of environmental glucose, underscoring the importance of carefully considering nanoscale surface features in the design and development of cell-instructive titanium surfaces.

Preparation and Optimization of a Polyhydroxyoctanoate-Hydroxyapatite Composite Available to Scaffolds in Implantable Devices

Biomaterials represent a distinct class of materials used in various medical applications, such as replicating the shape or function of damaged tissue caused by disease or trauma. The increasing focus on polyhydroxyalkanoate (PHA) research can be attributed to their properties, such as biodegradability, biocompatibility, and bioresorbability. PHAs can be incorporated into polymeric complexes or combined with bioceramics or bioactive substances. Films of PHO-HAp-Curcumin were prepared, and optimization studies were conducted using Design-Expert software (Stat-Ease 360-Trial Version). The effects of independent variables (amount of PHO, HAp, and curcumin) on biodegradability, film thickness, and curcumin release were studied. Statistical modeling revealed significant interactions among the components, with the 2FI and quadratic models providing strong predictive accuracy. The interaction of HAp and PHO amounts (X2X3) has a significant effect on biodegradability (Y1) and film thickness (Y3). For the degree of the cumulative release of curcumin (CDR), there was no significant interaction between the independent variables (curcumin-X1, HAp-X2, and PHO-X3). Optimized film exhibited a maximum desirability of 0.777 with 1 mg of curcumin, 100 mg of HAp, and 172.31 mg of PHO. A morphological analysis of optimized film revealed a rough, particle-rich surface favorable for biomedical use. The findings highlight the promise of PHO-HAp-Curcumin composite films in advancing tissue engineering.

Long-Term Survival of Implants Placed in Earlier Failed Implant Sites

Dental implant therapy is generally successful. However, when such therapy fails, considerations for implant replacement must be carefully considered. The survivability of implants placed into previously implanted sites must be considered. Appraisal of early implant loss versus late implant loss is important in presurgical planning for implant replacement. This review highlights the factors that can impact the success of implant reimplantation.

The Effect of Implant-Associated Factors on the Long-Term Outcomes of Dental Implants

The long-term outcomes of dental implants are influenced by a variety of factors, all of which play critical roles in their stability, functionality, and esthetic appeal. This review focuses on several key characteristics of dental implants that impact their success overtime: dimensional, morphologic, material, osseointegrative, and connective/prosthetic characteristics. This article synthesizes current literature to analyze how these factors influence the long-term success of dental implants, emphasizing the need for a comprehensive approach in implant selection and placement.

Analysis of Tribological and Cytotoxicity Assays of a Biocompatible Mg-Zn-Ca-Pr Alloy

This work covers a Mg-Zn-Ca-Pr alloy fabricated by a novel method of mechanical alloying and spark plasma sintering (SPS). Currently, magnesium alloys used as biomaterials are mostly commercial alloys without consideration of cytotoxicity from the perspective of biosafety. So far, the tribological and cytotoxic properties of Mg-Zn-Ca-Pr alloys have not been investigated. Hence, in the article, the tribological properties, considering wear rate, wear resistance, coefficient of friction, and the roughness of the sintered Mg-Zn-Ca-Pr alloy, are investigated. Cytotoxicity assays have also been carried out. The ball-on-a-disc method is used in the tribological test. Samples before sintering by the SPS method are milled at varying times of 13, 20, and 70 h. Results show that increasing the milling time affects tribology and cytotoxic tests. The longer the milling time, the lower the cell survival rate. The conducted tests reveal cell survival of 90, 82, and 61% for 13, 20, and 70 h, respectively. A reduction of cell viability by over 30% is considered a cytotoxic effect, which was observed only in the 70 h milling-time samples.

Effect of metallic materials on magnetic resonance image uniformity: a quantitative experimental study

OBJECTIVE

To assess quantitatively the effect of metallic materials on MR image uniformity using a standardized method.

METHODS

Six types of 1 cm cubic metallic materials (i.e., Au, Ag, Al, Au-Ag-Pd alloy, Ti, and Co-Cr alloy) embedded in a glass phantom filled were examined and compared with no metal condition inserted as a reference. The phantom was scanned five times under each condition using a 1.5-T MR superconducting magnet scanner with an 8-channel phased-array brain coil and head and neck coil. For each examination, the phantom was scanned in three planes: axial, coronal, and sagittal using T1-weighted spin echo (SE) and gradient echo (GRE) sequences in accordance with the American Society for Testing and Materials (ASTM) F2119-07 standard. Image uniformity was assessed using the non-uniformity index (NUI), which was developed by the National Electrical Manufacturers Association (NEMA), as an appropriate standardized measure for investigating magnetic field uniformity.

RESULTS

T1-GRE images with Co-Cr typically elicited the lowest uniformity, followed by T1-GRE images with Ti, while all other metallic materials did not affect image uniformity. In particular, T1-GRE images with Co-Cr showed significantly higher NUI values as far as 6.6 cm at maximum equivalent to 11 slices centering around it in comparison with the measurement uncertainty from images without metallic materials.

CONCLUSION

We found that MR image uniformity was influenced by the scanning sequence and coil type when Co-Cr and Ti were present. It is assumed that the image non-uniformity in Co-Cr and Ti is caused by their high magnetic susceptibility.

Microplasma-Sprayed Titanium and Hydroxyapatite Coatings on Ti6Al4V Alloy: in vitro Biocompatibility and Corrosion Resistance: Part I

This two-part paper investigates the bioactivity and mechanical properties of coatings applied to Ti6Al4V, a common titanium alloy used in endoprosthetic implants. Coatings made from hydroxyapatite (HA) powder and commercially pure titanium (CP-Ti) wires were applied using microplasma spraying. The study focuses on the responses of rat mesenchymal stem cells (MSCs), which are essential for bone healing, to these coatings. Part I shows how adjusting the microplasma spraying process allows coatings with varying porosity and surface roughness to be achieved.

Gallium-doped zirconia coatings modulate microbiological outcomes in dental implant surfaces

Despite the significant recent advances in manufacturing materials supporting advanced dental therapies, peri-implantitis still represents a severe complication in dental implantology. Herein, a sol-gel process is proposed to easily deposit antibacterial zirconia coatings onto bulk zirconia, material, which is becoming very popular for the manufacturing of abutments. The coatings' physicochemical properties were analyzed through x-ray diffraction and scanning electron microscopy-energy-dispersive x-ray spectroscopy investigations, while their stability and wettability were assessed by microscratch testing and static contact angle measurements. Uniform gallium-doped tetragonal zirconia coatings were obtained, featuring optimal mechanical stability and a hydrophilic behavior. The biological investigations pointed out that gallium-doped zirconia coatings: (i) displayed full cytocompatibility toward human gingival fibroblasts; (ii) exhibited significant antimicrobial activity against the Aggregatibacter actinomycetemcomitans pathogen; (iii) were able to preserve the commensal Streptococcus salivarius. Furthermore, the proteomic analyses revealed that the presence of Ga did not impair the normal oral microbiota. Still, interestingly, it decreased by 17% the presence of Fusobacterium nucleatum, a gram-negative, strictly anaerobic bacteria that is naturally present in the gastrointestinal tract. Therefore, this work can provide a valuable starting point for the development of coatings aimed at easily improving zirconia dental implants' performance.

Expression of osteopontin and osteocalcin in Osteoblast cells exposed to a combination of polymethylmethacrylate (PMMA) and hydroxyapatite (HAp): A prospective observational study

The success of implant placement will depend on the ability of the implant material to integrate with the surrounding tissue. Polymethylmethacrylate (PMMA) has been used as an implant material, but it has several fallback properties in its interaction with bone tissue. The addition of hydroxyapatite (HAp) to PMMA is expected to produce reinforced bioceramic polymers with better mechanical and biological properties. The purpose of this study was to evaluate the expression of osteopontin and osteocalcin in cultured osteoblasts when exposed to two implant candidate materials: PMMA-HApGMP, derived from bovine bone and processed under Good Manufacturing Practice by a Tissue Bank, and PMMA-HApBBK, sourced from limestone (CaCO3) and processed by Balai Besar Keramik. Twenty-four fetal rat calvariae osteoblast cell cultures were randomly divided into 6 groups: 7- and 14-day control group, 7 and 14 days PMMA-HApGMP group, 7 and 14 days PMMA-HApBBK group. The expression of osteopontin and osteocalcin was seen by immunocytochemical examination. The results showed that the average expression of osteopontin and osteocalcin in the treatment group on the 7th and 14th days was higher than the control group. The expression of osteopontin and osteocalcin in the PMMA-HApGMP group increased significantly (P < .05) on day 14. The PMMA-HAp combination material can accelerate the process of osteoblast differentiation which is characterized by an increase in osteopontin and osteocalcin which are markers of bone formation. This will support in increasing osseointegration.

Potential role of metal nanoparticles in treatment of peri-implant mucositis and peri-implantitis

Peri-implantitis (PI), a pathological condition associated with plaque, affects the tissues around dental implants. In addition, peri-implant mucositis (PIM) is a precursor to the destructive inflammatory PI and is an inflammation of the soft tissues surrounding the dental implant. It is challenging to eradicate and regulate the PI treatment due to its limited effectiveness. Currently, there is a significant interest in the development and research of additional biocompatible materials to prevent the failure of dental implants. Nanotechnology has the potential to address or develop solutions to the significant challenge of implant failure caused by cytotoxicity and biocompatibility in dentistry. Nanoparticles (NPs) may be used as carriers for the release of medicines, as well as to make implant coatings and supply appropriate materials for implant construction. Furthermore, the bioactivity and therapeutic efficacy of metal NPs in peri-implant diseases (PID) are substantiated by a plethora of in vitro and in vivo studies. Furthermore, the use of silver (Ag), gold (Au), zinc oxide, titanium oxide (TiO2), copper (Cu), and iron oxide NPs as a cure for dental implant infections brought on by bacteria that have become resistant to several medications is the subject of recent dentistry research. Because of their unique shape-dependent features, which enhance bio-physio-chemical functionalization, antibacterial activity, and biocompatibility, metal NPs are employed in dental implants. This study attempted to provide an overview of the application of metal and metal oxide NPs to control and increase the success rate of implants while focusing on the antimicrobial properties of these NPs in the treatment of PID, including PIM and PI. Additionally, the study reviewed the potential benefits and drawbacks of using metal NPs in clinical settings for managing PID, with the goal of advancing future treatment strategies for these conditions.

Randomized Clinical Trial: Bone Bioactive Liquid Improves Implant Stability and Osseointegration

Implant stability can be compromised by factors such as inadequate bone quality and infection, leading to potential implant failure. Ensuring implant stability and longevity is crucial for patient satisfaction and quality of life. In this multicenter, randomized, double-blind clinical trial, we assessed the impact of a bone bioactive liquid (BBL) on the Galaxy TS implant's performance, stability, and osseointegration. We evaluated the impact stability, osseointegration, and pain levels using initial stability quotient (ISQ) measurements, CBCT scans, and pain assessment post-surgery. Surface analysis was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). In vitro studies examined the BBL's effects on dental pulp pluripotent stem cells' (DPPSCs') osteogenesis and inflammation modulation in human macrophages. All implants successfully osseointegrated, as demonstrated by the results of our clinical and histological studies. The BBL-treated implants showed significantly lower pain scores by day 7 (p < 0.00001) and improved stability by day 30 (ISQ > 62.00 ± 0.59, p < 8 × 10-7). By day 60, CBCT scans revealed an increased bone area ratio in BBL-treated implants. AFM images demonstrated the BBL's softening and wettability effect on implant surfaces. Furthermore, the BBL promoted DPPSCs' osteogenesis and modulated inflammatory markers in human primary macrophages. This study presents compelling clinical and biological evidence that BBL treatment improves Galaxy TS implant stability, reduces pain, and enhances bone formation, possibly through surface tension modulation and immunomodulatory effects. This advancement holds promise for enhancing patient outcomes and implant longevity.

Validation of Low Cost Patient Specific Implant Design Using Finite Element Analysis (FEA) for Reconstruction of Segmental Mandibular Defects: A Case Report and Literature Review

Introduction

Mandibular continuity defects can cause functional and cosmetic deformities affecting a patient's quality of life. Reconstruction of such defects can be intricate even for the most seasoned maxillofacial surgeons. Reconstruction plates were the standard of care in the past, followed by a secondary reconstruction using autogenous grafts.

Materials and methods

Novel technological upgrades like customized computer-designed patient-specific implants (PSIs) have overtaken these stock reconstruction plates to enhance the aesthetics and address the individual clinical situation. Affirmation of the above plate design using biomechanical analysis can further improve the efficacy of PSIs.

Discussion

The present case report describes a novel combination of an autogenous graft and a low-cost patient-specific implant with the prosthesis design validated using finite element analysis. The authors have also reviewed the biomechanical evaluation of PSIs design and its uses in treating mandibular continuity defects.

Conclusion

Use of FEA helped to inspect the potential weakness and stress distribution through out the implant due to this there was no sign of hardware failure.

A Conservative Technique for Fractured Implant Abutment Screw Retrieval on an Internal Connection Implant: Proof of Concept

Broken screw removal from the implant connection is a common but challenging process. Several proposed methods and technical solutions may result in unsuccessful removal; thus, a novel, more conservative, risk-free method is proposed as a first attempt. The proposal is to use a silicon restoration holder to be twisted counterclockwise on the dried surface of the broken fragment inside the implant connection. This method, within the limitations of a minimal case series, yielded 100% results; however, despite previous attempts with less conservative techniques, this approach showed no efficacy. This article aims to promote the use of silicon restoration holders as a minimally invasive first attempt at broken screw retrieval treatment before considering other options.

Precise surface engineering: Leveraging chemical vapor deposition for enhanced biocompatibility and durability in biomedical implants

Biomedical implants have revolutionized modern medicine, providing diverse treatment options for various medical conditions. Ensuring the long-term success of certain materials used in various applications requires careful consideration of their ability to interact with biological systems and withstand harsh biological conditions. Optimizing surface properties is crucial for successfully integrating biomedical implants into the human body, ensuring biocompatibility, durability, and functionality. Chemical Vapor Deposition (CVD) has become a crucial technology in surface engineering, offering a precise technique for applying thin films with customized properties. This article provides a comprehensive study of surface engineering for biomedical implants, specifically emphasizing the CVD coating technique. By carefully manipulating chemical reactions in the vapor phase, CVD allows for the creation of coatings that enhance wear resistance, minimize friction, and improve biocompatibility. This review also explores the underlying principles of CVD, the various process parameters involved, and the subsequent enhancements in implant performance. Using case studies and experimental findings, it showcases the ability of CVD to greatly enhance the durability and effectiveness of biomedical implants.

Electrically conductive coatings in tissue engineering

Recent interest in tissue engineering (TE) has focused on electrically conductive biomaterials. This has been inspired by the characteristics of the cells' microenvironment where signalling is supported by electrical stimulation. Numerous studies have demonstrated the positive influence of electrical stimulation on cell excitation to proliferate, differentiate, and deposit extracellular matrix. Even without external electrical stimulation, research shows that electrically active scaffolds can improve tissue regeneration capacity. Tissues like bone, muscle, and neural contain electrically excitable cells that respond to electrical cues provided by implanted biomaterials. To introduce an electrical pathway, TE scaffolds can incorporate conductive polymers, metallic nanoparticles, and ceramic nanostructures. However, these materials often do not meet implantation criteria, such as maintaining mechanical durability and degradation characteristics, making them unsuitable as scaffold matrices. Instead, depositing conductive layers on TE scaffolds has shown promise as an efficient alternative to creating electrically conductive structures. A stratified scaffold with an electroactive surface synergistically excites the cells through active top-pathway, with/without electrical stimulation, providing an ideal matrix for cell growth, proliferation, and tissue deposition. Additionally, these conductive coatings can be enriched with bioactive or pharmaceutical components to enhance the scaffold's biomedical performance. This review covers recent developments in electrically active biomedical coatings for TE. The physicochemical and biological properties of conductive coating materials, including polymers (polypyrrole, polyaniline and PEDOT:PSS), metallic nanoparticles (gold, silver) and inorganic (ceramic) particles (carbon nanotubes, graphene-based materials and Mxenes) are examined. Each section explores the conductive coatings' deposition techniques, deposition parameters, conductivity ranges, deposit morphology, cell responses, and toxicity levels in detail. Furthermore, the applications of these conductive layers, primarily in bone, muscle, and neural TE are considered, and findings from in vitro and in vivo investigations are presented. STATEMENT OF SIGNIFICANCE: Tissue engineering (TE) scaffolds are crucial for human tissue replacement and acceleration of healing. Neural, muscle, bone, and skin tissues have electrically excitable cells, and their regeneration can be enhanced by electrically conductive scaffolds. However, standalone conductive materials often fall short for TE applications. An effective approach involves coating scaffolds with a conductive layer, finely tuning surface properties while leveraging the scaffold's innate biological and physical support. Further enhancement is achieved by modifying the conductive layer with pharmaceutical components. This review explores the under-reviewed topic of conductive coatings in tissue engineering, introducing conductive biomaterial coatings and analyzing their biological interactions. It provides insights into enhancing scaffold functionality for tissue regeneration, bridging a critical gap in current literature.

In Vivo Assessment of a Triple Periodic Minimal Surface Based Biomimmetic Gyroid as an Implant Material in a Rabbit Tibia Model

Biomimetic approaches to implant construction are a rising frontier in implantology. Triple Periodic Minimal Surface (TPMS)-based additively manufactured gyroid structures offer a mean curvature of zero, rendering this structure an ideal porous architecture. Previous studies have demonstrated the ability of these structures to effectively mimic the mechanical cues required for optimal implant construction. The porous nature of gyroid materials enhances bone ingrowth, thereby improving implant stability within the body. This enhancement is attributed to the increased surface area of the gyroid structure, which is approximately 185% higher than that of a dense material of the same form factor. This larger surface area allows for enhanced cellular attachment and nutrient circulation facilitated by the porous channels. This study aims to evaluate the biological performance of a gyroid-based Ti6Al-4V implant material compared to a dense alloy counterpart. Cellular viability was assessed using the lactate dehydrogenase (LDH) assay, which demonstrated that the gyroid surface allowed marginally higher viability than dense material. The in vivo integration was studied over 6 weeks using a rabbit tibia model and characterized using X-ray, micro-CT, and histopathological examination. With a metal volume of 8.1%, the gyroid exhibited a bone volume/total volume (BV/TV) ratio of 9.6%, which is 11-fold higher than that of dense metal (0.8%). Histological assessments revealed neovascularization, in-bone growth, and the presence of a Haversian system in the gyroid structure, hinting at superior osteointegration.

Application of PVD coatings in medical implantology for enhanced performance, biocompatibility, and quality of life

Physical vapor deposition (PVD) coating is a versatile and well-liked method for depositing thin films of materials onto surfaces in a range of industries. Due to their numerous functional and aesthetic benefits, PVD coatings are beneficial in several applications, from electronics and optics to automotive and medical equipment. PVD coating technology dramatically improves the effectiveness and quality of medical implants. PVD-coated medical implants improve osseointegration, lower wear and friction, increase corrosion resistance, and have antibacterial properties, which lead to better patient outcomes, fewer complications, and overall higher quality of life for people who need implantable medical devices. The essential concepts of PVD coating and the numerous deposition techniques and materials used are covered at the study's outset. The specific uses of PVD-coated medical implants are then highlighted, including those for orthopedic and dental implants and cardiovascular and neurosurgical devices. The review also emphasizes the critical contribution of PVD coatings to reducing wear and friction, improving corrosion resistance, augmenting biocompatibility, enhancing osseointegration, and aesthetic appeal. The challenges and prospects of PVD coating technologies were further addressed in this article. This review is invaluable for academics, doctors, and businesspeople interested in the beneficial combination of PVD coating and medical implantology.

Zirconia Dental Implant Designs and Surface Modifications: A Narrative Review

Titanium currently has a well-established position as the gold standard for manufacturing dental implants; however, it is not free of flaws. Mentions of possible soft-tissue discoloration, corrosion, and possible allergic reactions have led to the development of zirconia dental implants. Various techniques for the surface modification of titanium have been applied to increase titanium implants' ability to osseointegrate. Similarly, to achieve the best possible results, zirconia dental implants have also had their surface modified to promote proper healing and satisfactory long-term results. Despite zirconium oxide being a ceramic material, not simply a metal, there have been mentions of it being susceptible to corrosion too. In this article, we aim to review the literature available on zirconia implants, the available techniques for the surface modification of zirconia, and the effects of these techniques on zirconia's biological properties. Zirconia's biocompatibility and ability to osseointegrate appears unquestionably good. Despite some of its mechanical properties being, factually, inferior to those of titanium, the benefits seem to outweigh the drawbacks. Zirconia implants show very good success rates in clinical research. This is partially due to available methods of surface treatment, including nanotopography alterations, which allow for improved wettability, bone-to-implant contact, and osteointegration in general.

Osseointegrative and antimicrobial properties of graphene oxide nano coated dental implants: A systematic review

Introduction

Osseointegration stands as a pivotal concept within the realm of dental implants, signifying the intricate process through which a dental implant integrates with the adjoining bone tissue. Graphene oxide (GO) has been shown to promote osseointegration, the process by which the implant fuses with the surrounding bone. The objective of this study was to assess the osseointegrative and antimicrobial properties of GO nano coated dental implants.

Methods

A systematic search was conducted using electronic databases (e.g., PubMed, Scopus, Web of Science) to identify relevant studies published. Inclusion criteria encompassed studies that evaluated the effects of GO nano coating on osseointegrative and antimicrobial characteristics of dental implants. Studies not written in English and published before 2012 were excluded.

Results

The initial search yielded a total of 127 potential studies, of which six met the inclusion criteria and five were included in the review. These studies provided data on GO nano coated dental implants and their osseointegrative and antimicrobial properties. All the included studies showed moderate risk of bias. None of the studies provided information related to sample size calculation or sampling technique.

Discussion

The findings from the included studies demonstrated that GO nano coating had a positive impact on osseointegrative properties of dental implants. Enhanced bone-implant contact and increased bone density were observed in animals and humans receiving GO nano coated implants. Furthermore, the antimicrobial properties of GO nano coating were found to inhibit bacterial colonization and biofilm formation on the implant surface, reducing the risk of implant-associated infections.

Conclusion

The findings indicate that GO nano coating holds promise in enhancing the success rate and longevity of dental implants. However, more studies with larger sample sizes, are needed to further strengthen the evidence and determine the long-term effects of GO nano coated dental implants.

Allergic reaction of poly-ether-ether-ketone versus titanium implants: A posttest-only control group design experimental study using a rabbit model

PURPOSE

The aim of this study was to determine clinically and genetically the allergic effects of titanium and poly-ether-ether-ketone (PEEK) implants following loading in rabbit tibias.

MATERIALS AND METHODS

This study included 18 white New Zealand male rabbits (n = 18) divided evenly into three groups: control, titanium (Ti), and PEEK (P). Clinically, the allergenic effect of titanium and PEEK was investigated by detecting the effect on lymph nodes. Furthermore, RT-PCR and ELISA were used to detect the expression of certain genes IL-6, TNF-α, OPG, RANKL, and RUNX-2 through both types of implants.

RESULTS

Our findings demonstrated that titanium implants induced enlarged lymph nodes, which PEEK did not. Overall, RT-PCR and ELISA techniques revealed that Ti implants had higher expression of the inflammatory genes IL-6 and TNF-α. Ti had the highest expression in OPG findings, while PEEK had the lowest. RANKL expression was highest in the control group and lowest in the PEEK group. RUNX-2 is the highest for the control group and the lowest for the titanium group.

CONCLUSION

Although titanium implants elicited greater allergy responses than PEEK implants, titanium has the highest expression of bone formation genes and the lowest expression of bone resorption genes, making it preferable to PEEK.

Macrophages as a Source and Target of GDF-15

Growth differentiation factor 15 (GDF-15) is a multifunctional cytokine that belongs to the transforming growth factor-beta (TGF-β) superfamily. GDF-15 is involved in immune tolerance and is elevated in several acute and chronic stress conditions, often correlating with disease severity and patient prognosis in cancer172 and metabolic and cardiovascular disorders. Despite these clinical associations, the molecular mechanisms orchestrating its effects remain to be elucidated. The effects of GDF-15 are pleiotropic but cell-specific and dependent on the microenvironment. While GDF-15 expression can be stimulated by inflammatory mediators, its predominant effects were reported as anti-inflammatory and pro-fibrotic. The role of GDF-15 in the macrophage system has been increasingly investigated in recent years. Macrophages produce high levels of GDF-15 during oxidative and lysosomal stress, which can lead to fibrogenesis and angiogenesis at the tissue level. At the same time, macrophages can respond to GDF-15 by switching their phenotype to a tolerogenic one. Several GDF-15-based therapies are under development, including GDF-15 analogs/mimetics and GDF-15-targeting monoclonal antibodies. In this review, we summarize the major physiological and pathological contexts in which GDF-15 interacts with macrophages. We also discuss the major challenges and future perspectives in the therapeutic translation of GDF-15.

The effect of different implant-abutment types and heights on screw loosening in cases with increased crown height space

OBJECTIVES

The stability of the abutment screw is pivotal for successful implant-supported restorations, yet screw loosening remains a common complication, leading to compromised function and potential implant failure. This study aims to evaluate the effect of different implant-abutment types and heights on screw loosening in cases with increased crown height space (CHS).

MATERIALS AND METHODS

In this in vitro study, a total of 64 abutments in eight distinct groups based on their type and height were evaluated. These groups included stock, cast, and milled abutments with heights of 4 mm (groups S4, C4, and M4), 7 mm (groups S7, C7, and M7), and 10 mm (groups C10 and M10). Removal torque loss (RTL) was assessed both before and after subjecting the abutments to dynamic cyclic loading. Additionally, the differences between initial RTL and RTL following cyclic loading were analyzed for each group (p < .05).

RESULTS

The C10 group demonstrated the highest RTL, whereas the S4 group exhibited the lowest initial RTL percentage (p < .05). Furthermore, the study established significant variations in RTL percentages and the discrepancies between initial and postcyclic loading RTL across different abutment groups (p < .05). Additionally, both abutment types and heights were found to significantly influence the RTL percentage (p < .05).

CONCLUSION

The type and height of the implant abutment affected screw loosening, and in an increased CHS of 12 mm, using a stock abutment with a postheight of 4 mm can be effective in minimizing screw loosening.

Comprehensive Evaluation of Novel Biomaterials for Dental Implant Surfaces: An In Vitro Comparative Study

BACKGROUND

Dental implantology is continually evolving in its quest to discover new biomaterials to improve dental implant success rates. The study explored the potential of innovative biomaterials for dental implant surfaces, including titanium-zirconium (Ti-Zr) alloy, hydroxyapatite-coated titanium (HA-Ti), and porous polyetheretherketone (PEEK), in comparison to conventional commercially pure titanium (CP Ti).

MATERIALS AND METHODS

A total of 186 samples were harvested for the analysis. Biomaterials were thoroughly evaluated in terms of surface topography, chemical composition, biocompatibility, mechanical properties, osseointegration performance, and bacterial adhesion. Study methods and techniques included scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), cell culture variants, tensile tests, hardness measurements, histological analysis, and microbiological testing.

RESULTS

Surface topography examination showed significant disparities between the biomaterials: Ti-Zr had a better roughness of 1.23 μm, while HA-Ti demonstrated a smoother surface at 0.98 μm. Chemical composition evaluation indicated the presence of a Ti-Zr alloy in Ti-Zr, calcium-phosphorus richness in HA-Ti, and high titanium amounts in CP Ti. The mechanical properties assessment showed that Ti-Zr and CP Ti had good tensile strengths of 750 MPa and 320 HV. In addition, bacterial adhesion tests showed low propensities for Ti-Zr and HA-Ti at 1200 and 800 cfu/cm2, respectively.

CONCLUSION

Ti-Zr and HA-Ti performed better than the other biomaterials in surface topography and mechanical properties and against bacterial adhesion. This study emphasizes that multi-parameter analysis is critical for clinical decision-making, allowing for the selection of the currently available biomaterial, which could be conducive to the long-term success of the implant.

The geometry of photopolymerized topography influences neurite pathfinding by directing growth cone morphology and migration

Objective. Cochlear implants provide auditory perception to those with severe to profound sensorineural hearing loss: however, the quality of sound perceived by users does not approximate natural hearing. This limitation is due in part to the large physical gap between the stimulating electrodes and their target neurons. Therefore, directing the controlled outgrowth of processes from spiral ganglion neurons (SGNs) into close proximity to the electrode array could provide significantly increased hearing function.Approach.For this objective to be properly designed and implemented, the ability and limits of SGN neurites to be guided must first be determined. In this work, we engineer precise topographical microfeatures with angle turn challenges of various geometries to study SGN pathfinding and use live imaging to better understand how neurite growth is guided by these cues.Main Results.We find that the geometry of the angled microfeatures determines the ability of neurites to navigate the angled microfeature turns. SGN neurite pathfinding fidelity is increased by 20%-70% through minor increases in microfeature amplitude (depth) and by 25% if the angle of the patterned turn is made obtuse. Further, we see that dorsal root ganglion neuron growth cones change their morphology and migration to become more elongated within microfeatures. Our observations also indicate complexities in studying neurite turning. First, as the growth cone pathfinds in response to the various cues, the associated neurite often reorients across the angle topographical microfeatures. Additionally, neurite branching is observed in response to topographical guidance cues, most frequently when turning decisions are most uncertain.Significance.Overall, the multi-angle channel micropatterned substrate is a versatile and efficient system to assess neurite turning and pathfinding in response to topographical cues. These findings represent fundamental principles of neurite pathfinding that will be essential to consider for the design of 3D systems aiming to guide neurite growthin vivo.

Radiopacity Enhancements in Polymeric Implant Biomaterials: A Comprehensive Literature Review

Polymers as biomaterials possess favorable properties, which include corrosion resistance, light weight, biocompatibility, ease of processing, low cost, and an ability to be easily tailored to meet specific applications. However, their inherent low X-ray attenuation, resulting from the low atomic numbers of their constituent elements, i.e., hydrogen (1), carbon (6), nitrogen (7), and oxygen (8), makes them difficult to visualize radiographically. Imparting radiopacity to radiolucent polymeric implants is necessary to enable noninvasive evaluation of implantable medical devices using conventional imaging methods. Numerous studies have undertaken this by blending various polymers with contrast agents consisting of heavy elements. The selection of an appropriate contrast agent is important, primarily to ensure that it does not cause detrimental effects to the relevant mechanical and physical properties of the polymer depending upon the intended application. Furthermore, its biocompatibility with adjacent tissues and its excretion from the body require thorough evaluation. We aimed to summarize the current knowledge on contrast agents incorporated into synthetic polymers in the context of implantable medical devices. While a single review was found that discussed radiopacity in polymeric biomaterials, the publication is outdated and does not address contemporary polymers employed in implant applications. Our review provides an up-to-date overview of contrast agents incorporated into synthetic medical polymers, encompassing both temporary and permanent implants. We expect that our results will significantly inform and guide the strategic selection of contrast agents, considering the specific requirements of implantable polymeric medical devices.

Surface Topography, Microbial Adhesion, and Immune Responses in Silicone Mammary Implant-Associated Capsular Fibrosis

Breast cancer is the most common cancer in women globally, often necessitating mastectomy and subsequent breast reconstruction. Silicone mammary implants (SMIs) play a pivotal role in breast reconstruction, yet their interaction with the host immune system and microbiome remains poorly understood. This study investigates the impact of SMI surface topography on host antimicrobial responses, wound proteome dynamics, and microbial colonization. Biological samples were collected from ten human patients undergoing breast reconstruction with SMIs. Mass spectrometry profiles were analyzed for acute and chronic wound proteomes, revealing a nuanced interplay between topography and antimicrobial response proteins. 16S rRNA sequencing assessed microbiome dynamics, unveiling topography-specific variations in microbial composition. Surface topography alterations influenced wound proteome composition. Microbiome analysis revealed heightened diversity around rougher SMIs, emphasizing topography-dependent microbial invasion. In vitro experiments confirmed staphylococcal adhesion, growth, and biofilm formation on SMI surfaces, with increased texture correlating positively with bacterial colonization. This comprehensive investigation highlights the intricate interplay between SMI topography, wound proteome dynamics, and microbial transmission. The findings contribute to understanding host-microbe interactions on SMI surfaces, essential for optimizing clinical applications and minimizing complications in breast reconstruction.

Chemical multiscale robotics for bacterial biofilm treatment

A biofilm constitutes a bacterial community encased in a sticky matrix of extracellular polymeric substances. These intricate microbial communities adhere to various host surfaces such as hard and soft tissues as well as indwelling medical devices. These microbial aggregates form a robust matrix of extracellular polymeric substances (EPSs), leading to the majority of human infections. Such infections tend to exhibit high resistance to treatment, often progressing into chronic states. The matrix of EPS protects bacteria from a hostile environment and prevents the penetration of antibacterial agents. Modern robots at nano, micro, and millimeter scales are highly attractive candidates for biomedical applications due to their diverse functionalities, such as navigating in confined spaces and targeted multitasking. In this tutorial review, we describe key milestones in the strategies developed for the removal and eradication of biofilms using robots of different sizes and shapes. It can be seen that robots at different scales are useful and effective tools for treating bacterial biofilms, thus preventing persistent infections, the loss of costly implanted medical devices, and additional costs associated with hospitalization and therapies.

Mechanobiology of Dental Pulp Cells

The dental pulp is the inner part of the tooth responsible for properly functioning during its lifespan. Apart from the very big biological heterogeneity of dental cells, tooth microenvironments differ a lot in the context of mechanical properties-ranging from 5.5 kPa for dental pulp to around 100 GPa for dentin and enamel. This physical heterogeneity and complexity plays a key role in tooth physiology and in turn, is a great target for a variety of therapeutic approaches. First of all, physical mechanisms are crucial for the pain propagation process from the tooth surface to the nerves inside the dental pulp. On the other hand, the modulation of the physical environment affects the functioning of dental pulp cells and thus is important for regenerative medicine. In the present review, we describe the physiological significance of biomechanical processes in the physiology and pathology of dental pulp. Moreover, we couple those phenomena with recent advances in the fields of bioengineering and pharmacology aiming to control the functioning of dental pulp cells, reduce pain, and enhance the differentiation of dental cells into desired lineages. The reviewed literature shows great progress in the topic of bioengineering of dental pulp-although mainly in vitro. Apart from a few positions, it leaves a gap for necessary filling with studies providing the mechanisms of the mechanical control of dental pulp functioning in vivo.

Enhanced antibacterial activity and superior biocompatibility of cobalt-deposited titanium discs for possible use in implant dentistry

The clinical success of implants depends on rapid osseointegration, and new materials are being developed considering the increasing demand. Considering cobalt (Co) antibacterial characteristics, we developed Co-deposited titanium (Ti) using direct current (DC) sputtering and investigated it as a new material for implant dentistry. The material was characterized using atomic absorption spectroscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The material's surface topography, roughness, surface wettability, and hardness were also analyzed. The Co thin film (Ti-Co15) showed excellent antibacterial effects against microbes implicated in peri-implantitis. Furthermore, Ti-Co15 was compatible and favored the attachment and spreading of MG-63 cells. The alkaline phosphatase and calcium mineralization activities of MG-63 cells cultured on Ti-Co15 remained unaltered compared to Ti. These data correlated well with the time-dependent expression of ALP, RUNX-2, and BMP-2 genes involved in osteogenesis. The results demonstrate that Co-deposited Ti could be a promising material in implant dentistry.

Investigation on bacterial capture and antibacterial properties of acid-treated Ti surface

OBJECTIVES

Utilizing Ti and Ti alloys as dental materials established a huge spurt in the field of dentistry. Since implantation is an invasive procedure that involves tissue penetration, infection control is mandatory for increasing the success rate of the implant treatment. In this study, we aimed to assess the impact of the surface physicochemical properties of acid-treated Ti on microorganisms specifically bacteria.

METHODS

After investigating the surface morphology and characteristics of acid-treated and untreated Ti sheets, we evaluated their potential to capture Escherichia coli (E. coli.) as well as the latter's survival on the surface of both types of sheets. Finally, we assessed the efficiency of the antibacterial properties exhibited by Ti against the oral microflora.

RESULTS

SEM images revealed surface roughening of the acid-treated Ti represented by significantly irregular shape. Moreover, the acid-treated Ti exhibited remarkable hydrophobicity. A quantitative evaluation confirmed that acid-treated Ti has higher bacterial capture and antibacterial properties than untreated Ti. Further experiments showed similar effects of both types of Ti not only on E. coli but also on oral microflora.

SIGNIFICANCE

Results suggest that acid treatment of Ti surface is a potent technique for enhancing the antibacterial properties of Ti-derived materials.

Comparative analysis of energy transfer mechanisms for neural implants

As neural implant technologies advance rapidly, a nuanced understanding of their powering mechanisms becomes indispensable, especially given the long-term biocompatibility risks like oxidative stress and inflammation, which can be aggravated by recurrent surgeries, including battery replacements. This review delves into a comprehensive analysis, starting with biocompatibility considerations for both energy storage units and transfer methods. The review focuses on four main mechanisms for powering neural implants: Electromagnetic, Acoustic, Optical, and Direct Connection to the Body. Among these, Electromagnetic Methods include techniques such as Near-Field Communication (RF). Acoustic methods using high-frequency ultrasound offer advantages in power transmission efficiency and multi-node interrogation capabilities. Optical methods, although still in early development, show promising energy transmission efficiencies using Near-Infrared (NIR) light while avoiding electromagnetic interference. Direct connections, while efficient, pose substantial safety risks, including infection and micromotion disturbances within neural tissue. The review employs key metrics such as specific absorption rate (SAR) and energy transfer efficiency for a nuanced evaluation of these methods. It also discusses recent innovations like the Sectored-Multi Ring Ultrasonic Transducer (S-MRUT), Stentrode, and Neural Dust. Ultimately, this review aims to help researchers, clinicians, and engineers better understand the challenges of and potentially create new solutions for powering neural implants.

Exploring Advanced Functionalities of Carbon Fiber-Graded PEEK Composites as Bone Fixation Plates Using Finite Element Analysis

This study aims to address the challenges associated with conventional metallic bone fixation plates in biomechanical applications, such as stainless steel and titanium alloys, including stress shielding, allergic reactions, corrosion resistance, and interference with medical imaging. The use of materials with a low elastic modulus is regarded as an effective approach to overcome these problems. In this study, the impact of different types of chopped carbon fiber-reinforced polyether ether ketone (CCF/PEEK) functionally graded material (FGM) bone plates on stress shielding under static and instantaneous dynamic loading was explored using finite element analysis (FEA). The FGM bone plate models were established using ABAQUS and the user's subroutine USDFLD and VUSDFLD, and each model was established with an equivalent overall elastic modulus and distinctive distributions. The results revealed that all FGM bone plates exhibited lower stress shielding effects compared to metal bone plates. Particularly, the FGM plate with an elastic modulus gradually increased from the centre to both sides and provided maximum stress stimulation and the most uniform stress distribution within the fractured area. These findings offer crucial insights for designing implantable medical devices that possess enhanced mechanical adaptability.

Cellular Senescence Program is Sensitive to Physical Differences in Polymeric Tissue Scaffolds

A typical cellular senescence program involves exposing cells to DNA-damaging agents such as ionization radiation or chemotherapeutic drugs, which cause multipronged changes, including increased cell size and volume, the onset of enhanced oxidative stress, and inflammation. In the present study, we examined if the senescence onset decision is sensitive to the design, porosity, and architecture of the substrate. To address this, we generated a library of polymeric scaffolds widely used in tissue engineering of varied stiffness, architecture, and porosity. Using irradiated A549 lung cancer cells, we examined the differences between cellular responses in these 3D scaffold systems and observed that senescence onset is equally diminished. When compared to the two-dimensional (2D) culture formats, there were profound changes in cell size and senescence induction in three-dimensional (3D) scaffolds. We further establish that these observed differences in the senescence state can be attributed to the altered cell spreading and cellular interactions on these substrates. This study elucidates the role of scaffold architecture in the cellular senescence program.

Systemic allergic contact dermatitis to palladium, platinum, and titanium: mechanisms, clinical manifestations, prevalence, and therapeutic approaches

Contact dermatitis (CD) is an inflammatory skin disease of eczema that is elicited by chemicals or metal ions that have toxic effects without eliciting a T-cell response (contact elicitation) or by small reactive chemicals that modify proteins and induce innate and adaptive immune responses (contact allergens). The clinical condition is characterized by localized skin rash, pruritus, redness, swelling, and lesions, which are mainly detected by patch tests and lymphocyte stimulation. Heavy metals such as palladium (Pd), platinum (Pt), and titanium (Ti) are ubiquitous in our environment. These heavy metals have shown CD effects as allergic agents. Immunological responses result from the interaction of cytokines and T cells. Occupational metal CD accounts for most cases of work-related cutaneous disorders. In this systematic review, the allergic effects of heavy metals, including Pd, Pt, and Ti, and the mechanisms, clinical manifestations, prevalence, and therapeutic approaches are discussed in detail. Furthermore, the therapeutic approaches introduced to treat CD, including corticosteroids, topical calcineurin inhibitors, systemic immunosuppressive agents, phototherapy, and antihistamines, can be effective in the treatment of these diseases in the future. Ultimately, the insights identified could lead to improved therapeutic and diagnostic pathways.

Comparative study of hydroxyapatite synthesized using Schiff base and wet chemical precipitation methods

Hydroxyapatite (HAp) exists as an inorganic and crystalline composition present in bones and dental enamel, and hence can be utilized as a direct element or as part of the composition of biomaterials and implants for dental and orthopaedic applications. Listed below are a few synthesis techniques for HAp that are listed in the literature: solid-state and mechano-chemical methods (dry methods), wet chemical precipitation and sol-gel methods (wet methods), and combustion and pyrolysis methods (high-temperature processes). Nevertheless, there are new and more productive techniques that result in HAp with a regulated morphology, such as the Schiff base method, which, on reaction with calcium and phosphate precursors, forms chelating complexes to produce HAp nuclei. This research paper presents the comparison in characteristics between HAp synthesized using Schiff base (HAp-SB), wet chemical precipitation (HAp-WC) methods, and commercial HAp (HAp-CM) in their powdered and pelleted form. The average size of HAp-WC particles in the spherical form was found to be 603 nm ± 176, HAp-SB were found to have rod-like morphology, which is very similar to human bone-like HAp, with an average length and width of 1522 nm ± 759 and 400 nm ± 112, respectively, and HAp-CM were found to have spherical morphology with dimensions of 52 nm ± 25. Biological studies show that cell viability of HAp-SB pellet (202.01% ± 8.16) seemed to have higher cell proliferation properties than HAp-WC pellet (145.7% ± 5.11) and HAp-CM pellet (71.53% ± 3.61) due to its higher aspect ratio, and hence higher surface area for the cells to adhere. In a detailed study, it is observed that both techniques had their advantages, and there were no significant disadvantages observed.

Understanding the Complexities of Cast Post Retention: A Comprehensive Review of Influential Factors

This comprehensive review delves into the intricate landscape of cast post retention in restorative dentistry, encompassing historical perspectives, contemporary techniques, and future directions. Examining factors ranging from tooth-related considerations to prosthesis-related dynamics, the review provides a detailed analysis of clinical techniques, including step-by-step procedures, common challenges, and innovative advancements. Technological breakthroughs, such as digital impressions, computer-aided design and computer-aided manufacturing (CAD/CAM) technology, three-dimensional (3D) printing, and finite element analysis, are explored for their transformative impact on precision and customization. The discussion extends to the promising future of cast post retention, emphasising emerging materials, the integration of artificial intelligence in treatment planning, and patient-specific approaches. Implications for clinical practice underscore the importance of individualised treatment planning and the adoption of advanced technologies. Recommendations for future research advocate for comprehensive long-term clinical studies, investigations into AI-driven treatment planning, and a focus on patient outcomes and satisfaction. This review consolidates existing knowledge and anticipates a future marked by enhanced precision, individualised care, and improved long-term success in cast post-retained restorations.

Biomaterials Recycling: A Promising Pathway to Sustainability

Biomaterials undergo a transformative journey, from their origin as renewable resources to the manufacturing plants where they are processed and stored, until they fulfill their intended therapeutic or diagnostic purposes and become medical waste. However, during this life cycle, biomaterials can be susceptible to contamination and subsequent degradation through various mechanisms such as hydro-mechanical, thermal, or biochemical processes in water, soil, or air. These factors raise significant concerns regarding biological safety. Additional complexities arise from the potential amalgamation of biomaterials with other materials, either of the same kind or different types. Use of biomaterials influences their porosity, surface chemistry, and structural strength, and these factors affect biomaterials' reusability. Given the multitude of materials, processing parameters, sustainability requirements, and the limitation of natural resources, the recycling of biomaterials becomes necessary. Unfortunately, this topic has received limited attention thus far. In this context, this perspective provides a brief overview, analysis, and classification of reports on biomaterials recycling, aiming to initiate a discussion on this frequently overlooked subject. We highlight the challenges related to energy consumption and environmental pollution. However, the lack of established protocols and reporting on biomaterials recycling prevents a comprehensive understanding of these challenges and potential solutions. Nevertheless, addressing these issues can lead to more efficient resource use and reduced environmental impact in the field of biomaterials.

Development and material characteristics of glaucoma surgical implants

BACKGROUND

Glaucoma is the leading cause of irreversible blindness worldwide. The reduction of intraocular pressure has proved to be the only factor which can be modified in the treatment, and surgical management is one of the important methods for the treatment of glaucoma patients.

MAIN TEXT

In order to increase aqueous humor outflow and further reduce intraocular pressure, various drainage implants have been designed and applied in clinical practice. From initial Molteno, Baerveldt and Ahmed glaucoma implants to the Ahmed ClearPath device, Paul glaucoma implant, EX-PRESS and the eyeWatch implant, to iStent, Hydrus, XEN, PreserFlo, Cypass, SOLX Gold Shunt, etc., glaucoma surgical implants are currently undergoing a massive transformation on their structures and performances. Multitudinous materials have been used to produce these implants, from original silicone and porous polyethylene, to gelatin, stainless steel, SIBS, titanium, nitinol and even 24-carat gold. Moreover, the material geometry, size, rigidity, biocompatibility and mechanism (valved versus nonvalved) among these implants are markedly different. In this review, we discussed the development and material characteristics of both conventional glaucoma drainage devices and more recent implants, such as the eyeWatch and the new minimally invasive glaucoma surgery (MIGS) devices.

CONCLUSIONS

Although different in design and materials, these delicate glaucoma surgical implants have widely expanded the glaucoma surgical methods, and improved the success rate and safety of glaucoma surgery significantly. However, all of these glaucoma surgical implants have various limitations and should be used for different glaucoma patients at different conditions.

Malignant Neoplasms Arising in the Cardiac Pacemaker Cavity: A Systematic Review

Cancer is the abnormal proliferation of physiologically inadequate cells. Studies have identified the cardiac pacemaker pocket as a site of rare neoplasms. To evaluate the clinical outcomes, treatment, prognosis, and individualized management of tumors originating in the cardiac pacemaker pocket, a systematic review was conducted using case reports and case series available in the PubMed/Medline, Science Direct, Cochrane Central, LILACS, and Scientific Electronic Library Online (Scielo) databases. Pacemaker pocket tumors affected patients with a mean age of 72.9 years, with a higher incidence in males (76.9%, n = 10). The average time for neoplasm development was 4.4 years (54.07 months). The most prevalent model was Medtronic (38.4%, n = 5), with titanium (83.3%) being the most common metal composition. Chemotherapy was the most performed procedure among patients (38.4%), followed by radiation therapy (38.4%) and surgical tumor resection (30.7%). Six analyzed cases (46.1%) resulted in death, and four patients (30.7%) achieved a cure. Patients with pacemakers should be routinely evaluated for the occurrence of malignant tumors at the site of device implantation.

The geometry of photopolymerized topography influences neurite pathfinding by directing growth cone morphology and migration

Cochlear implants (CIs) provide auditory perception to those with profound sensorineural hearing loss: however, the quality of sound perceived by a CI user does not approximate natural hearing. This limitation is due in part to the large physical gap between the stimulating electrodes and their target neurons. Therefore, directing the controlled outgrowth of processes from spiral ganglion neurons (SGNs) into close proximity to the electrode array could provide significantly increased hearing function. For this objective to be properly designed and implemented, the ability and limits of SGN neurites to be guided must first be determined. In this work, we engineered precise topographical microfeatures with angle turn challenges of various geometries to study SGN pathfinding. Additionally, we analyze sensory neurite growth in response to topographically patterned substrates and use live imaging to better understand how neurite growth is guided by these cues. In assessing the ability of neurites to sense and turn in response to topographical cues, we find that the geometry of the angled microfeatures determines the ability of neurites to navigate the angled microfeature turns. SGN neurite pathfinding fidelity can be increased by 20-70% through minor increases in microfeature amplitude (depth) and by 25% if the angle of the patterned turn is made more obtuse. Further, by using engineered topographies and live imaging of dorsal root ganglion neurons (DRGNs), we see that DRGN growth cones change their morphology and migration to become more elongated within microfeatures. However, our observations also indicate complexities in studying neurite turning. First, as the growth cone pathfinds in response to the various cues, the associated neurite often reorients across the angle topographical microfeatures. This reorientation is likely related to the tension the neurite shaft experiences when the growth cone elongates in the microfeature around a turn. Additionally, neurite branching is observed in response to topographical guidance cues, most frequently when turning decisions are most uncertain. Overall, the multi-angle channel micropatterned substrate is a versatile and efficient system to assess SGN neurite turning and pathfinding in response to topographical cues. These findings represent fundamental principles of neurite pathfinding that will be essential to consider for the design of 3D systems aiming to guide neurite growth in vivo.

Factors Influencing Properties of Spider Silk Coatings and Their Interactions within a Biological Environment

Biomaterials are an indispensable part of biomedical research. However, although many materials display suitable application-specific properties, they provide only poor biocompatibility when implanted into a human/animal body leading to inflammation and rejection reactions. Coatings made of spider silk proteins are promising alternatives for various applications since they are biocompatible, non-toxic and anti-inflammatory. Nevertheless, the biological response toward a spider silk coating cannot be generalized. The properties of spider silk coatings are influenced by many factors, including silk source, solvent, the substrate to be coated, pre- and post-treatments and the processing technique. All these factors consequently affect the biological response of the environment and the putative application of the appropriate silk coating. Here, we summarize recently identified factors to be considered before spider silk processing as well as physicochemical characterization methods. Furthermore, we highlight important results of biological evaluations to emphasize the importance of adjustability and adaption to a specific application. Finally, we provide an experimental matrix of parameters to be considered for a specific application and a guided biological response as exemplarily tested with two different fibroblast cell lines.

Properties of SiCN Films Relevant to Dental Implant Applications

The application of surface coatings is a popular technique to improve the performance of materials used for medical and dental implants. Ternary silicon carbon nitride (SiCN), obtained by introducing nitrogen into SiC, has attracted significant interest due to its potential advantages. This study investigated the properties of SiCN films deposited via PECVD for dental implant coatings. Chemical composition, optical, and tribological properties were analyzed by adjusting the gas flow rates of NH3, CH4, and SiH4. The results indicated that an increase in the NH3 flow rate led to higher deposition rates, scaling from 5.7 nm/min at an NH3 flow rate of 2 sccm to 7 nm/min at an NH3 flow rate of 8 sccm. Concurrently, the formation of N-Si bonds was observed. The films with a higher nitrogen content exhibited lower refractive indices, diminishing from 2.5 to 2.3 as the NH3 flow rate increased from 2 sccm to 8 sccm. The contact angle of SiCN films had minimal differences, while the corrosion rate was dependent on the pH of the environment. These findings contribute to a better understanding of the properties and potential applications of SiCN films for use in dental implants.

Surface modifications of biomaterials in different applied fields

Biomaterial implantation into the human body plays a key role in the medical field and biological applications. Increasing the life expectancy of biomaterial implants, reducing the rejection reaction inside the human body and reducing the risk of infection are the problems in this field that need to be solved urgently. The surface modification of biomaterials can change the original physical, chemical and biological properties and improve the function of materials. This review focuses on the application of surface modification techniques in various fields of biomaterials reported in the past few years. The surface modification techniques include film and coating synthesis, covalent grafting, self-assembled monolayers (SAMs), plasma surface modification and other strategies. First, a brief introduction to these surface modification techniques for biomaterials is given. Subsequently, the review focuses on how these techniques change the properties of biomaterials, and evaluates the effects of modification on the cytocompatibility, antibacterial, antifouling and surface hydrophobic properties of biomaterials. In addition, the implications for the design of biomaterials with different functions are discussed. Finally, based on this review, it is expected that the biomaterials have development prospects in the medical field.

The effect of common dental fixtures on treatment planning and delivery for head and neck intensity modulated proton therapy

PURPOSE

Proton treatment plan perturbation by common dental fixtures such as amalgams (Am) and porcelain-fused-to-metal (PFM) crowns has, to date, been uncharacterized. Previous studies have been conducted to determine the physical effect of these materials within the beam path for single spots, but their effects on complex treatment plans and clinical anatomy have not yet been quantified. The present manuscript aims to study the effect of Am and PFM fixtures on proton treatment planning in a clinical setting.

METHODS

An anthropomorphic phantom with removable tongue, maxilla, and mandible modules was simulated on a clinical computed tomography (CT) scanner. Spare maxilla modules were modified to include either a 1.5 mm depth central groove occlusal amalgam (Am) or a porcelain-fused-to-metal (PFM) crown, implanted on the first right molar. Modified tongue modules were 3D printed to accommodate several axial or sagittal oriented pieces of EBT-3 film. Clinically representative spot-scanning proton plans were generated in Eclipse v.15.6 using the proton convolution superposition (PCS) algorithm v.15.6.06 using a multi-field optimization (MFO) technique with the goal of delivering a uniform 54 Gy dose to a clinical target volume (CTV) typical of a base-of-tongue (BoT) treatment. A typical geometric beam arrangement of two anterior oblique (AO) beams and a posterior beam was employed. Plans optimized without any material overrides were delivered to the phantom A) without implants; B) with Am fixture; or C) with PFM crown. Plans were also reoptimized and delivered with inclusion of material overrides to equate relative stopping power of the fixture with that of a previously measured result.

RESULTS

Plans exhibit slightly greater dose weight towards AO beams. The optimizer accounted for inclusion of fixture overrides by increasing beam weights to the beam closest to the implant. Film measurements exhibited cold spots directly within the beam path through the fixture in plans with and without overridden materials. Cold spots were somewhat mitigated in plans including overridden materials in the structure set but were not entirely eliminated. Cold spots associated with Am and PFM fixtures were quantified at 17% and 14% for plans without overrides, respectively, and 11% and 9% with using Monte Carlo simulation. Compared with film measurements and Monte Carlo simulation, the treatment planning system underestimates the dose shadowing effect in plans including material overrides.

CONCLUSIONS

Dental fixtures create a dose shadowing effect directly in line with the beam path through the material. This cold spot is partially mitigated by overriding the material to measured relative stopping powers. Due to uncertainties in modeling perturbation through the fixture, the magnitude of the cold spot is underestimated using the institutional TPS when compared to measurement and MC simulation.

Polyacrylamide-based hydrogel coatings improve biocompatibility of implanted pump devices

The introduction of transcutaneous and subcutaneous implants and devices into the human body instigates fouling and foreign body responses (FBRs) that limit their functional lifetimes. Polymer coatings are a promising solution to improve the biocompatibility of such implants, with potential to enhance in vivo device performance and prolong device lifetime. Here we sought to develop novel materials for use as coatings on subcutaneously implanted devices to reduce the FBR and local tissue inflammation in comparison to gold standard materials such as poly(ethylene glycol) and polyzwitterions. We prepared a library of polyacrylamide-based copolymer hydrogels, which were selected from materials previously shown to exhibit remarkable antifouling properties with blood and plasma, and implanted them into the subcutaneous space of mice to evaluate their biocompatibility over the course of 1 month. The top performing polyacrylamide-based copolymer hydrogel material, comprising a 50:50 mixture of N-(2-hydroxyethyl)acrylamide (HEAm) and N-(3-methoxypropyl)acrylamide (MPAm), exhibited significantly better biocompatibility and lower tissue inflammation than gold standard materials. Moreover, when applied to polydimethylsiloxane disks or silicon catheters as a thin coating (45 ± 1 μm), this leading copolymer hydrogel coating significantly improved implant biocompatibility. Using a rat model of insulin-deficient diabetes, we showed that insulin pumps fitted with HEAm-co-MPAm hydrogel-coated insulin infusion catheters exhibited improved biocompatibility and extended functional lifetime over pumps fitted with industry standard catheters. These polyacrylamide-based copolymer hydrogel coatings have the potential to improve device function and lifetime, thereby reducing the burden of disease management for people regularly using implanted devices.

Influence of Surface Texturing on the Dry Tribological Properties of Polymers in Medical Devices

There is a constant need to improve patient comfort and product performance associated with the use of medical devices. Efforts to optimise the tribological characteristics of medical devices usually involve modifying existing devices without compromising their main design features and functionality. This article constitutes a state-of-the-art review of the influence of dry friction on polymeric components used in medical devices, including those having microscale surface features. Surface tribology and contact interactions are discussed, along with alternative forms of surface texturing. Evident gaps in the literature, and areas warranting future research are highlighted; these include friction involving polymer Vs polymer surfaces, information regarding which topologies and feature spacings provide the best performing textured surfaces, and design guidelines that would assist manufacturers to minimise or maximise friction under non-lubricated conditions.

Micro-CT Evaluation of Microgaps at Implant-Abutment Connection

The assessment of microgaps at the implant-abutment interface is an important factor that may influence clinical success. Thus, the aim of this study was to evaluate the size of microgaps between prefabricated and customised abutments (Astra Tech, Dentsply, York, PA, USA; Apollo Implants Components, Pabianice, Poland) mounted on a standard implant. The measurement of the microgap was performed using micro-computed tomography (MCT). Due to 15-degree rotation of samples, 24 microsections were obtained. Scans were performed at four levels established at the interface between the abutment and the implant neck. Moreover, the volume of the microgap was evaluated. The size of the microgap at all measured levels varied from 0.1 to 3.7 µm for Astra and from 0.1 to 4.9 µm for Apollo (p > 0.05). Moreover, 90% of the Astra specimens and 70% of the Apollo specimens did not exhibit any microgaps. The highest mean values of microgap size for both groups were detected at the lowest portion of the abutment (p > 0.05). Additionally, the average microgap volume was greater for Apollo than for Astra (p > 0.05). It can be concluded that most samples did not exhibit any microgaps. Furthermore, the linear and volumetric dimensions of microgaps observed at the interface between Apollo or Astra abutments and Astra implants were comparable. Additionally, all tested components presented microgaps (if any) that were clinically acceptable. However, the microgap size of the Apollo abutment was higher and more variable than that of the Astra one.

Preparation and characterization of different micro/nano structures on the surface of bredigite scaffolds

The preparation of controllable micro/nano structures on the surface of the bredigite scaffold is expected to exhibit the same support and osteoconductive capabilities as living bone. However, the hydrophobicity of the white calciμm silicate scaffold surface restricts the adhesion and spreading of osteoblasts. Furthermore, during the degradation process of the bredigite scaffold, the release of Ca2+ results in an alkaline environment around the scaffold, which inhibits the growth of osteoblasts. In this study, the three-dimensional geometry of the Primitive surface in the three-periodic minimal surface with an average curvature of 0 was used as the basis for the scaffold unit cell, and a white hydroxyapatite scaffold was fabricated via photopolymerization-based 3D printing. Nanoparticles, microparticles, and micro-sheet structures with thicknesses of 6 μm, 24 μm, and 42 μm, respectively, were prepared on the surface of the porous scaffold through a hydrothermal reaction. The results of the study indicate that the micro/nano surface did not affect the morphology and mineralization ability of the macroporous scaffold. However, the transition from hydrophobic to hydrophilic resulted in a rougher surface and an increase in compressive strength from 45 to 59-86 MPa, while the adhesion of the micro/nano structures enhanced the scaffold's ductility. In addition, after 8 days of degradation, the pH of the degradation solution decreased from 8.6 to around 7.6, which is more suitable for cell growth in the hμman body. However, there were issues of slow degradation and high P element concentration in the degradation solution for the microscale layer group during the degradation process, so the nanoparticle and microparticle group scaffolds could provide effective support and a suitable environment for bone tissue repair.