Surface modification of zirconia with polydopamine to enhance fibroblast response and decrease bacterial activity in vitro : A potential technique for soft tissue engineering applications

Nano-Based Approaches in Surface Modifications of Dental Implants: A Literature Review

Rehabilitation of fully or partially edentulous patients with dental implants represents one of the most frequently used surgical procedures. The work of Branemark, who observed that a piece of titanium embedded in rabbit bone became firmly attached and difficult to remove, introduced the concept of osseointegration and revolutionized modern dentistry. Since then, an ever-growing need for improved implant materials towards enhanced material-tissue integration has emerged. There is a strong belief that nanoscale materials will produce a superior generation of implants with high efficiency, low cost, and high volume. The aim of this review is to explore the contribution of nanomaterials in implantology. A variety of nanomaterials have been proposed as potential candidates for implant surface customization. They can have inherent antibacterial properties, provide enhanced conditions for osseointegration, or act as reservoirs for biomolecules and drugs. Titania nanotubes alone or in combination with biological agents or drugs are used for enhanced tissue integration in dental implants. Regarding immunomodulation and in order to avoid implant rejection, titania nanotubes, graphene, and biopolymers have successfully been utilized, sometimes loaded with anti-inflammatory agents and extracellular vesicles. Peri-implantitis prevention can be achieved through the inherent antibacterial properties of metal nanoparticles and chitosan or hybrid coatings bearing antibiotic substances. For improved corrosion resistance various materials have been explored. However, even though these modifications have shown promising results, future research is necessary to assess their clinical behavior in humans and proceed to widespread commercialization.

Photothermal modulation of gingival fibroblasts via polydopamine-coated zirconia: A novel approach for promoting peri-implant soft tissue integration

Achieving robust soft tissue integration around dental implants is crucial for long-term clinical success, as it forms a protective biological seal against bacterial invasion. However, the soft tissue attachment to implants is relatively deficient compared to natural teeth, particularly in the connective tissue region lacking sufficient gingival fibroblasts and collagen fiber alignment. This study proposed an innovative strategy to enhance peri‑implant soft tissue integration by modulating gingival fibroblast behavior via photothermal conversion. Zirconia surfaces were coated with polydopamine (PDA), a melanin-like polymer exhibiting near-infrared (NIR) absorption for photothermal conversion. Under NIR irradiation, the PDA coating enabled mild hyperthermia (42-43 °C) on the zirconia surface. Remarkably, this mild photothermal stimulation significantly promoted human gingival fibroblast proliferation, adhesion, and collagen production compared to unmodified zirconia in vitro. By utilizing the photothermal properties of PDA coatings to modulate cellular behaviors beneficial for connective tissue formation, this approach provides a promising avenue to achieve improved soft tissue integration and long-term stability of dental implants. The findings highlight the innovative potential of combining biomaterial surface engineering with photothermal therapy for applications in implant dentistry.

Biofabrication of biomimetic undulating microtopography at the dermal-epidermal junction and its effects on the growth and differentiation of epidermal cells

The undulating microtopography located at the junction of the dermis and epidermis of the native skin is called rete ridges (RRs), which plays an important role in enhancing keratinocyte function, improving skin structure and stability, and providing three-dimensional (3D) microenvironment for skin cells. Despite some progress in recent years, most currently designed and manufactured tissue-engineered skin models still cannot replicate the RRs, resulting in a lack of biological signals in the manufactured skin models. In this study, a composite manufacturing method including electrospinning, 3D printing, and functional coating was developed to produce the epidermal models with RRs. Polycaprolactone (PCL) nanofibers were firstly electrospun to mimic the extracellular matrix environment and be responsible for cell attachment. PCL microfibers were then printed onto top of the PCL nanofibers layer by 3D printing to quickly prepare undulating microtopography and finally the entire structures were dip-coated with gelatin hydrogel to form a functional coating layer. The morphology, chemical composition, and structural properties of the fabricated models were studied. The results proved that the multi-process composite fabricated models were suitable for skin tissue engineering. Live and dead staining, cell counting kit-8 (CCK-8) as well as histology (haematoxylin and eosin (HE) methodology) and immunofluorescence (primary and secondary antibodies combination assay) were used to investigate the viability, metabolic activity, and differentiation of skin cells forin vitroculturing.In vitroresults showed that each model had high cell viability, good proliferation, and the expression of differentiation marker. It was worth noting that the sizes of the RRs affected the cell growth status of the epidermal models. In addition, the unique undulation characteristics of the epidermal-dermal junction can be reproduced in the developed epidermal models. Overall, thesein vitrohuman epidermal models can provide valuable reference for skin transplantation, screening and safety evaluation of drugs and cosmetics.

New insights on collagen structural organization and spatial distribution around dental implants: a comparison between machined and laser-treated surfaces

BACKGROUND

One of the main factors for the osseointegration of dental implants is the development of an adequate soft tissue barrier, mainly composed by collagen, which protects the implant from bacterial development. The structural features of the peri-implant collagen are influenced by the implant components and, in particular, by the type of the surface. In the clinical practice, healing abutments are characterized by smooth surfaces, named machined. Recently, a new laser technique, Synthegra, has been developed to obtain a topography-controlled surface with micrometric regular pores that seems reducing the risk of peri-implantitis. Based on this background, this study aims investigating the structural organization and spatial distribution of collagen surrounding healing abutments characterized by laser-treated and machined surfaces.

METHODS

Gingiva portions surrounding custom-made healing abutments (HA), characterized by alternated laser-treated and machined surfaces, were collected and analyzed by combining Fourier Transform InfraRed Imaging (FTIRI) spectroscopy, a non-invasive and high-resolution bidimensional analytical technique, with histological and multivariate analyses.

RESULTS

Masson's trichrome staining, specific for collagen, highlighted a massive presence of collagen in all the analyzed samples, evidencing a surface-related spatial distribution. The nature of collagen, investigated by the FTIRI spectroscopy, appeared more abundant close to the laser-treated surface, with a perpendicular disposition of the bundles respect to the HA; conversely, a parallel distribution was observed around the machined surface. A different secondary structure was also found, with a higher amount of triple helices and a lower quantity of random coils in collagen close to the laser treated surfaces.

CONCLUSIONS

FTIRI spectroscopy demonstrates that the use of a laser treated transmucosal surface can improve the morphological organization of the peri-implant collagen, which presents a distribution more similar to that of natural teeth.

TRIAL REGISTRATION

This trial is registered with ClinicalTrials.gov Identifier: (Registration Number: NCT05754970). Registered 06/03/2023, retrospectively registered, https://clinicaltrials.gov/show/NCT05754970 .

Biological effects of gamma-ray sterilization on 3 mol% yttria-stabilized tetragonal zirconia polycrystal: An in vitro study

STATEMENT OF PROBLEM

Selecting the sterilization method is important because sterilization can alter the surface chemistry of implant materials, including zirconia, and influence their cellular biocompatibility. Studies on the biological effects of sterilization on implant materials are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the biocompatibility of gamma-ray irradiated 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) compared with unirradiated titanium, 3Y-TZP, and pure gold.

MATERIAL AND METHODS

Disk-shaped specimens each of commercially pure grade 4 titanium, 3Y-TZP, gamma-rayed 3Y-TZP, and pure gold were prepared and evaluated for osteogenic potential by using a clonal murine cell line of immature osteoblasts derived from mice (MC3T3-E1 cells). The surface topography (n=3), chemical analysis of the disks (n=3), and cell morphology cultured on these surfaces were examined using scanning electron microscopy, confocal laser scanning microscopy, and energy dispersive spectroscopy. Cellular biocompatibility was analyzed for 1 and 3 days after seeding. Cell adhesion and spreading were evaluated using confocal laser scanning microscopy (n=3). Cell proliferation was evaluated using methyl thiazolyl tetrazolium assay (n=3). Kruskal-Wallis and Bonferroni corrections were used to evaluate the statistical significance of the intergroup differences (α=.05).

RESULTS

Gamma-ray sterilization of 3Y-TZP showed significantly higher surface roughness compared with titanium and gold (P<.002). On day 1, the proliferation and adhesion of MC3T3-E1 cells cultured on gamma-rayed 3Y-TZP were significantly higher than those cultured on gold (P<.05); however, cell spreading was significantly lower than that of titanium on days 1 and 3 (P<.05). On day 3, cell proliferation of gamma-rayed 3Y-TZP was significantly lower than that of unirradiated 3Y-TZP (P<.05). Cell adhesion of gamma-rayed 3Y-TZP was slightly lower than that of zirconia and titanium but without significant difference (P>.05).

CONCLUSIONS

Gamma-rayed zirconia exhibited increased surface roughness compared with titanium and significantly decreased bioactivity compared with titanium and zirconia. The use of gamma-ray sterilization on zirconia is not promising regarding biocompatibility, and the effect of this sterilization method on implant materials warrants further investigation.

Assessment of Polydopamine to Reduce Streptococcus mutans Adhesion to a Dental Polymer

Bacterial adhesion to the surface of materials is the first step in biofilm formation, which will lead to conditions that may compromise the health status of patients. Recently, polydopamine (PDA) has been proposed as an antibacterial material. Therefore, the objective of the current work was to assess and compare the adhesion of Streptococcus mutans to the surface of poly(methyl methacrylate) (PMMA) discs that were modified using PDA following a biomimetic approach versus smooth PDA-coated PMMA surfaces. In addition, an assessment of the growth inhibition by PDA was performed. PMMA discs were manufactured and polished; soft lithography, using the topography from the Crocosmia aurea leaf, was used to modify their surface. PDA was used to smooth-coat PMMA discs by dip-coating. The growth inhibition was measured using an inhibition halo. The surfaces were characterized by means of atomic force microscopy (AFM), the contact angle (CA), and Fourier-transform infrared spectroscopy (FTIR). Polydopamine exhibited a significant antibacterial effect when used directly on the S. mutans planktonic cells, but such an effect was not as strong when modifying the PMMA surfaces. These results open the possibility of using polydopamine to reduce the adhesion and growth of S. mutans, which might have important consequences in the dental field.

The integration of peri-implant soft tissues around zirconia abutments: Challenges and strategies

Stable soft tissue integration around the implant abutment attenuates pathogen penetration, protects underlying bone tissue, prevents peri-implantitis and is essential in maintaining long-term implant stability. The desire for "metal free" and "aesthetic restoration" has favored zirconia over titanium abutments, especially for implant restorations in the anterior region and for patients with thin gingival biotype. Soft tissue attachment to the zirconia abutment surface remains a challenge. A comprehensive review of advances in zirconia surface treatment (micro-design) and structural design (macro-design) affecting soft tissue attachment is presented and strategies and research directions are discussed. Soft tissue models for abutment research are described. Guidelines for development of zirconia abutment surfaces that promote soft tissue integration and evidence-based references to inform clinical choice of abutment structure and postoperative maintenance are presented.

Instantaneous Inactivation of Herpes Simplex Virus by Silicon Nitride Bioceramics

Hydrolytic reactions taking place at the surface of a silicon nitride (Si3N4) bioceramic were found to induce instantaneous inactivation of Human herpesvirus 1 (HHV-1, also known as Herpes simplex virus 1 or HSV-1). Si3N4 is a non-oxide ceramic compound with strong antibacterial and antiviral properties that has been proven safe for human cells. HSV-1 is a double-stranded DNA virus that infects a variety of host tissues through a lytic and latent cycle. Real-time reverse transcription (RT)-polymerase chain reaction (PCR) tests of HSV-1 DNA after instantaneous contact with Si3N4 showed that ammonia and its nitrogen radical byproducts, produced upon Si3N4 hydrolysis, directly reacted with viral proteins and fragmented the virus DNA, irreversibly damaging its structure. A comparison carried out upon testing HSV-1 against ZrO2 particles under identical experimental conditions showed a significantly weaker (but not null) antiviral effect, which was attributed to oxygen radical influence. The results of this study extend the effectiveness of Si3N4's antiviral properties beyond their previously proven efficacy against a large variety of single-stranded enveloped and non-enveloped RNA viruses. Possible applications include the development of antiviral creams or gels and oral rinses to exploit an extremely efficient, localized, and instantaneous viral reduction by means of a safe and more effective alternative to conventional antiviral creams. Upon incorporating a minor fraction of micrometric Si3N4 particles into polymeric matrices, antiherpetic devices could be fabricated, which would effectively impede viral reactivation and enable high local effectiveness for extended periods of time.

Fetuin-A adsorption to tunable polydimethylsiloxane and subsequent macrophage response

Surface modifications can be applied to biomaterials to alter the various surface properties that influence protein-material interactions and the cellular response. The plasma protein fetuin-A has been found to adsorb to many biomaterials but details of its interactions with polydimethylsiloxane (PDMS) and roles in regulating the immune response are not clear. Here, PDMS modifications are achieved by altering the ratio of PDMS formulations to control elastic modulus, and by coating PDMS with polydopamine (PDA) to attach fetuin-A. Surface characterization confirmed that altering the PDMS formulation changed the elastic modulus without affecting surface wetting properties. Surface roughness was measured using atomic force microscopy and surface chemistry was determined using X-ray photoelectron spectroscopy, with only minor changes detected on the softest samples. PDA deposition on PDMS was confirmed and contact angle measurements demonstrated an increase in hydrophilicity. Fetuin-A adsorption was influenced by the PDMS formulations, adsorption changed in a competitive plasma environment, and PDA was able to immobilize the greatest amount of fetuin-A. The inflammatory effects of fetuin-A were investigated, and data suggests that the elastic modulus influences cytokine secretion from macrophages at certain timepoints, a result likely due to varied protein amounts and orientations/conformations in response to material stiffness. The addition of a PDA layer demonstrated the potentially cytokine mitigating effect upon fetuin-A immobilization when compared to unmodified PDMS samples. The results provide new insight into the interactions of fetuin-A with PDMS and PDA, and the potential immune regulatory properties of fetuin-A modified materials.

Applications of photothermally mediated nanohybrids for white spot lesions in orthodontics

In orthodontic treatment, cariogenic bacteria in the oral cavity are the main cause of enamel white spot lesions (WSLs). Therefore, to effectively prevent and treat WSLs, it is crucial to inhibit the cariogenic bacterial activity while promoting the remineralization of demineralized tooth enamel. However, fluoride preparations commonly used for the prevention and treatment of WSLs can induce dental fluorosis if ingested in excess, and their remineralization effect is limited by the residual hydroxyapatite (HAp) content and salivary Ca²⁺ and PO₄^3- levels. In this study, we propose a strategy (CMCS/ACP@PDA) for antibacterial and remineralization of WSLs by a nanohybrid of carboxymethyl chitosan (CMCS)-stabilized amorphous calcium phosphate (ACP) loaded polydopamine nanoparticles (PDA NPs) based on biomimetic remineralization techniques and biocompatible near-infrared (NIR) photoactivation therapy. The nanohybrid utilizes the excellent photothermal conversion ability of polydopamine for antimicrobial purposes, while CMCS with its own positive and negative charges (-NH₃⁺ and -COO^-) acts as a biomimetic mineralizing agent to stabilize ACP, supplemented with abundant Ca²⁺ and PO₄^3- for remineralization of demineralized enamel. The results showed that CMCS/ACP@PDA could effectively inhibit the adhesion of cariogenic Streptococcus mutants (S. mutants) with high bactericidal rates. In addition, the remineralization of demineralized enamel by nanohybrid was more effective after 7 days of in vitro mineralization. This study provides a theoretical and experimental basis for the use of CMCS/ACP@PDA nanohybrid materials as potential materials against WSLs.

Surface modifications of zirconia with plasma pretreatment and polydopamine coating to enhance the bond strength and durability between zirconia and titanium

The aim of this study was to assess the shear bond strength and durability between plasma-pretreated and polydopamine (PDA)-coated zirconia and titanium. Four groups were prepared according to the different surface treatments (untreated ZrO₂, plasma-pretreated ZrO₂, PDA-coated ZrO₂, and plasma-pretreated and PDA-coated ZrO₂ (PP+PDA-ZrO₂). The surface topography and roughness, contact angle, and elemental analysis of the coatings of the four groups were investigated, and the bond strength and durability of the specimens were evaluated based on shear bond strength and thermocycle tests. Physical and chemical characterization results confirmed that PDA coatings can be successfully formed on zirconia substrates. The roughness and hydrophilicity were significantly higher in the PP+PDA-ZrO₂ group_, which demonstrated better shear bond strength and durability between zirconia and titanium. The plasma pretreatment of zirconia substrates can enhance the stability of the PDA coating layer, and hybrid surface modifications can provide several bonding advantages for clinical use.

Enhanced Antibacterial Effect on Zirconia Implant Abutment by Silver Linear-Beam Ion Implantation

Peri-implant lesions, such as peri-implant mucositis and peri-implantitis, are bacterial-derived diseases that happen around dental implants, compromising the long-term stability and esthetics of implant restoration. Here, we report a surface-modification method on zirconia implant abutment using silver linear-beam ion implantation to reduce the bacterial growth around the implant site, thereby decreasing the prevalence of peri-implant lesions. The surface characteristics of zirconia after ion implantation was evaluated using energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and a contact-angle device. The antibacterial properties of implanted zirconia were evaluated using Streptococcus mutans and Porphyromonas gingivalis. The biocompatibility of the material surface was evaluated using human gingival fibroblasts. Our study shows that the zirconia surface was successfully modified with silver nanoparticles by using the ion-implantation method. The surface modification remained stable, and the silver-ion elution was below 1 ppm after one-month of storage. The modified surface can effectively eliminate bacterial growth, while the normal gingiva's cell growth is not interfered with. The results of the study demonstrate that a silver-ion-implanted zirconia surface possesses good antibacterial properties and good biocompatibility. The surface modification using silver-ion implantation is a promising method for future usage.

Biomaterials and Clinical Applications of Customized Healing Abutment-A Narrative Review

Customized healing abutments have been introduced in clinical practice along with implant surgery to preserve or create natural-appearing hard and soft tissue around the implant. This provides the benefits of reducing the overall treatment time by eliminating the second stage and reducing the elapsed time of the fabrication of the final prostheses. This article aims to review the types and properties of materials used for the fabrication of customized healing abutments and their clinical applications. Articles published in English on customized healing abutments were searched in Google Scholar, PubMed/MEDLINE, ScienceDirect, and the Scopus databases up to August 2022. The relevant articles were selected and included in this literature review. Customized healing abutments can be fabricated from materials available for dental implants, including PEEK, PMMA, zirconia, resin composite, and titanium. All the materials can be used following both immediate and delayed implant placement. Each material provides different mechanical and biological properties that influence the peri-implant tissues. In conclusion, the studies have demonstrated promising outcomes for all the materials. However, further investigation comparing the effects of each material on peri-implant soft and hard tissues is required.

Mussel-inspired polydopamine decorated alginate dialdehyde-gelatin 3D printed scaffolds for bone tissue engineering application

This study utilized extrusion-based 3D printing technology to fabricate calcium-cross-linked alginate dialdehyde-gelatin scaffolds for bone regeneration. The surface of polymeric constructs was modified with mussel-derived polydopamine (PDA) in order to induce biomineralization, increase hydrophilicity, and enhance cell interactions. Microscopic observations revealed that the PDA layer homogeneously coated the surface and did not appear to induce any distinct change in the microstructure of the scaffolds. The PDA-functionalized scaffolds were more mechanically stable (compression strength of 0.69 ± 0.02 MPa) and hydrophilic (contact angle of 26) than non-modified scaffolds. PDA-decorated ADA-GEL scaffolds demonstrated greater durability. As result of the 18-days immersion in simulated body fluid solution, the PDA-coated scaffolds showed satisfactory biomineralization. Based on theoretical energy analysis, it was shown that the scaffolds coated with PDA interact spontaneously with osteocalcin and osteomodulin (binding energy values of −35.95 kJ mol⁻¹ and −46.39 kJ mol⁻¹, respectively), resulting in the formation of a protein layer on the surface, suggesting applications in bone repair. PDA-coated ADA-GEL scaffolds are capable of supporting osteosarcoma MG-63 cell adhesion, viability (140.18% after 7 days), and proliferation. In addition to increased alkaline phosphatase secretion, osteoimage intensity also increased, indicating that the scaffolds could potentially induce bone regeneration. As a consequence, the present results confirm that 3D printed PDA-coated scaffolds constitute an intriguing novel approach for bone tissue engineering.

Advancing dental implants: Bioactive and therapeutic modifications of zirconia

Zirconium-based implants have gained popularity in the dental implant field owing to their corrosion resistance and biocompatibility, attributed to the formation of a native zirconia (ZrO₂) film. However, enhanced bioactivity and local therapy from such implants are desirable to enable the earlier establishment and improved long-term maintenance of implant integration, especially in compromised patient conditions. As a result, surface modification of zirconium-based implants have been performed using various physical, chemical and biological techniques at the macro-, micro-, and nano-scales. In this extensive review, we discuss and detail the development of Zr implants covering the spectrum from past and present advancements to future perspectives, arriving at the next generation of highly bioactive and therapeutic nano-engineered Zr-based implants. The review provides in-depth knowledge of the bioactive/therapeutic value of surface modification of Zr implants in dental implant applications focusing on clinical translation.

Novel Titanium Nanospike Structure Using Low-Energy Helium Ion Bombardment for the Transgingival Part of a Dental Implant

AIM(S)

The aim of the study was to fabricate a nanospike surface on a titanium alloy surface using a newly established method of low-energy helium ion bombardment. Various methods to achieve nanospike formation on titanium have been introduced recently, and their antibacterial properties have been mainly investigated with respect to Escherichia coli and Staphylococcus aureus. Oral pathogens such as Porphyromonas gingivalis play an important role in the development of peri-implantitis. For that reason, the antibacterial properties of the novel, nanostructured titanium surface against P. gingivalis were assessed, and a possible effect on the viability of gingival fibroblasts was evaluated.

MATERIALS AND METHODS

Helium sputtering was employed for developing titanium surfaces with nanospikes of 500 nm (ND) in height; commercially available smooth-machined (MD) and sandblasted and acid-etched titanium disks (SLA) were used as controls. Surface structure characterization was performed through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Following incubation with P. gingivalis, antibacterial properties were determined via conventional culturing and SEM. Additionally, the viability of human gingival fibroblasts (HGFs) was tested through MTT assay, and cell morphology was assessed through SEM.

RESULTS

SEM images confirmed the successful establishment of a nanospike surface with required heights, albeit with heterogeneity. AFM images of the 500 nm nanospike surface revealed that the roughness is dominated by large-scale hills and valleys. For frame sizes of 5 × 5 μm and smaller, the average roughness is dominated by the height of the titanium spikes. ND successfully induces dysmorphisms within P. gingivalis cultures following the incubation period, while conventional culturing reveals a 17% and 20% reduction for ND compared to MD and SLA, respectively. Moreover, the nanospike surfaces did not affect the viability of human growth fibroblasts despite their sharp surface.

CONCLUSION(S)

This study successfully developed a novel titanium-nanospike-based structuration technique for titanium surfaces. In addition, the nanospikes did not hinder gingival fibroblast viability. Enhanced antimicrobial effects for such a novel nanospike-based resurfacing technique can be achieved through further optimizations for nanospike spacing and height parameters.

Design of a Superhydrophobic Strain Sensor with a Multilayer Structure for Human Motion Monitoring

A flexible strain sensor is of significant importance in wearable electronics since it can help monitor the physical signals from the human body. Among various strain sensors, the polyurethane (PU)-based ones have received widespread attention owing to their excellent toughness, large working range, and nice gas permeability. However, the hydrophobicity of these sensors is not good enough, which may affect their use life and sensitivity. In this work, a high-performance strain sensor composed of PU, reduced graphene oxide (rGO), polydopamine (PDA), and 1H,1H,2H,2H-perfluorodecane-thiol (PFDT) was designed and prepared. The results revealed that this PU/rGO/PDA/PFDT device possessed good superhydrophobicity with a water contact angle of 153.3°, a wide working strain range of 590%, and an outstanding gauge factor as high as 221 simultaneously. Because of these above advantages, the sensor worked effectively in detecting both subtle and large human movements (such as joint motion, finger motion, and vocal cord vibration) even in a high humidity environment. This strain sensor with high sensitivity, wide working range, and suitable modulus may have great potential in the field of flexible and wearable electronics in the near future.

Polydopamine nanospheres coated with bovine serum albumin permit enhanced cell differentiation: fundamental mechanism and practical application for protein coating formation

Protein coating is a strategy for modifying and improving the surface functional properties of nanomaterials. However, the underlying mechanism behind protein coating formation, which is essential for its practical applications, remains largely unknown. Herein, we investigate the fundamental molecular mechanism of protein coating formation. Polydopamine nanospheres (PDANS) coated with bovine serum albumin (BSA) are examined in this study due to their wide biomedical potential. Our results demonstrate that BSAs can flexibly bind to PDANS and maintain their structural dynamicity. Our findings unveil that regular structure formation arises from BSAs lateral interactions via electrostatic forces. Notably, the protein coating modified PDANS surface enhances cell adhesion and proliferation as well as osteogenic differentiation. Such an enhancement is attributed to complementary surface properties provided by the dynamic PDANS-BSA complex and regular structure caused by BSA-BSA interactions in protein coating formation. This study provides a fundamental understanding of the molecular mechanism of protein coating formation, which facilitates the further development of functional protein-coated nanomaterials and guides the bioengineering decision making for biomedical applications, especially in bone tissue engineering.

Surface Modifications for Zirconia Dental Implants: A Review

Zirconia-based bioceramic is a potential material for dental implants developed and introduced in dentistry 30 years ago. However, some limitations still exist for zirconia implants caused by several factors, such as manufacturing difficulties, low-temperature degradation (LTD), long-term stability, and clinical experience. Several studies validated that some subtle changes on the zirconia surface might significantly impact its mechanical properties and osseointegration. Thus, attention was paid to the effect of surface modification of zirconia implants. This review generally summarizes the surface modifications of zirconia implants to date classified as physical treatment, chemical treatment, and surface coating, aiming to give an overall perspective based on the current situation. In conclusion, surface modification is an effective and essential method for zirconia implant application. However, before clinical use, we need more knowledge about these modification methods.

Effect of zirconia surface modification using dopamine polymerisation on the shear bond strength of resin cement

This study evaluated the influence of polydopamine treatment on the surface properties and bond strength of yttria-stabilised tetragonal zirconia polycrystal (Y-TZP). Sixty-three zirconia blocks (10 × 10 × 2 mm) were randomly divided into three groups defined by surface treatment: (i) control group (C), (ii) grit-blasted with 110 μm alumina particles (GB), and (iii) polydopamine (PDA) coating. The surfaces of specimens subjected to different treatments were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and water contact angle measurements. After the surface treatments, the specimens were cemented to resin composite cylinders. After bonding, the shear bond strength of the ceramic to the resin was measured, and the failure mode of each specimen was analysed using a stereomicroscope. The results indicated that the shear bond strength is highest for the GB treatment and lowest for the controls. However, the difference between groups GB and PDA was not statistically significant. In the control group, adhesive failure was predominant, whereas in the treatment groups, mixed mode failure was predominant. The pre-treatment of Y-TZP ceramic with the polydopamine coating might improve the bond strength of the resin cement to the zirconia ceramic.

Improved response of human gingival fibroblasts to titanium coated with micro-/nano-structured tantalum

OBJECTIVES

This study aims to evaluate the ability of tantalum-coated titanium to improve human gingival fibroblasts' adhesion, viability, proliferation, migration performance, and the potential molecular mechanisms.

MATERIALS AND METHODS

Titanium plates were divided into two groups: (1) no coating (Ti, control), (2) Tantalum-coated titanium (Ta-coated Ti). All samples were characterized by scanning electronic microscopy, surface roughness, and hydrophilicity. Fibroblasts' performance were analyzed by attached cell number at 1 h, 4 h, and 24 h, morphology at 1 h and 4 h, viability at 1 day, 3 days, 5 days, and 7 days, recovery after wounding at 6 h, 12 h, and 24 h. RT-PCR, western blot were applied to detect attachment-related genes' expression and protein synthesis at 4 h and 24 h. Student's t test was used for statistical analysis.

RESULTS

Tantalum-coated titanium demonstrates a layer of homogeneously distributed nano-grains with mean diameter of 25.98 (± 14.75) nm. It was found that after tantalum deposition, human gingival fibroblasts (HGFs) adhesion, viability, proliferation, and migration were promoted in comparison to the control group. An upregulated level of Integrin β1 and FAK signaling was also detected, which might be the underlying mechanism.

CONCLUSION

In the present study, adhesion, viability, proliferation, migration of human gingival fibroblasts are promoted on tantalum-coated titanium, upregulated integrin β1 and FAK might contribute to its superior performance, indicating tantalum coating can be applied in transmucosal part of dental implant.

CLINICAL SIGNIFICANCE

Tantalum deposition on titanium surfaces can promote human gingival fibroblast adhesion, accordingly forming a well-organized soft tissue sealing and may contribute to a successful osseointegration.

Peptidic biofunctionalization of laser patterned dental zirconia: A biochemical-topographical approach

A dual approach employing peptidic biofunctionalization and laser micro-patterns on dental zirconia was explored, with the aim of providing a flexible tool to improve tissue integration of restorations. Direct laser interference patterning with a femtosecond Ti:Sapphire laser was employed, and two periodic grooved patterns were produced with a periodicity of 3 and 10 μm. A platform containing the cell-adhesive RGD and the osteogenic DWIVA peptides was used to functionalize the grooved surfaces. Topography and surface damage were characterized by confocal laser scanning (CLSM), scanning electron and scanning transmission electron microscopy techniques. The surface patterns exhibited a high homogeneity and subsurface damage was found in the form of nano-cracks and nano-pores, at the bottom of the valleys. Accelerated tests in water steam were carried out to assess hydrothermal degradation resistance, which slightly decreased after the laser treatment. Interestingly, the detrimental effects of the laser modification were reverted by a post-laser thermal treatment. The attachment of the molecule was verified trough fluorescence CLSM and X-ray photoelectron spectroscopy. Finally, the biological properties of the surfaces were studied in human mesenchymal stem cells. Cell adhesion, morphology, migration and differentiation were investigated. Cells on grooved surfaces displayed an elongated morphology and aligned along the patterns. On these surfaces, migration was greatly enhanced along the grooves, but also highly restricted in the perpendicular direction as compared to flat specimens. After biofunctionalization, cell number and cell area increased and well-developed cell cytoskeletons were observed. However, no effects on cell migration were found for the peptidic platform. Although some osteogenic potential was found in specimens grooved with a periodicity of 10 μm, the largest effects were observed from the biomolecule, which favored upregulation of several genes related to osteoblastic differentiation in all the surfaces.

Orchestrating soft tissue integration at the transmucosal region of titanium implants

Osseointegration at the bone-implant interface and soft tissue integration (STI) at the trans-mucosal region are crucial for the long-term success of dental implants, especially in compromised patient conditions. The STI quality of conventional smooth and bio-inert titanium-based implants is inferior to that of natural tissue (i.e. teeth), and hence various surface modifications have been suggested. This review article compares and contrasts the various modification strategies (physical, chemical and biological) utilized to enhance STI of Ti implants. It also details the STI challenges associated with conventional Ti-based implants, current surface modification strategies and cutting-edge nano-engineering solutions. The topographical, biological and therapeutic advances achievable via electrochemically anodized Ti implants with TiO₂ nanotubes/nanopores are highlighted. Finally, the status and future directions of such nano-engineered implants is discussed, with emphasis on bridging the gap between research and clinical translation.

Laser surface texturing of zirconia-based ceramics for dental applications: A review

Laser surface texturing is widely explored for modifying the surface topography of various materials and thereby tuning their optical, tribological, biological, and other surface properties. In dentistry, improved osseointegration has been observed with laser textured titanium dental implants in clinical trials. Due to several limitations of titanium materials, dental implants made of zirconia-based ceramics are now considered as one of the best alternatives. Laser surface texturing of zirconia dental implants is therefore attracting increasing attention. However, due to the brittle nature of zirconia, as well as the metastable tetragonal ZrO₂ phase, laser texturing in the case of zirconia is more challenging than in the case of titanium. Understanding these challenges requires different fields of expertise, including laser engineering, materials science, and dentistry. Even though much progress was made within each field of expertise, a comprehensive analysis of all the related factors is still missing. This review paper provides thus an overview of the common challenges and current status on the use of lasers for surface texturing of zirconia-based ceramics for dental applications, including texturing of zirconia implants for improving osseointegration, texturing of zirconia abutments for reducing peri-implant inflammation, and texturing of zirconia restorations for improving restoration retention by bonding.

Race to invade: Understanding soft tissue integration at the transmucosal region of titanium dental implants

OBJECTIVES

The success of a dental implant system not only depends on appropriate osseointegration at the bone-implant interface, but also on robust soft-tissue integration (STI)/muco-integration at the transmucosal region. However, numerous studies have reported that the STI quality of conventional smooth and bio-inert titanium-based transmucosal components is significantly inferior to that of natural teeth, which may compromise the long-term success of implant restorations. In this review article, we discuss the structural and histological characteristics of peri-implant tissues; compare the roles of various cells residing in the transmucosal region and explore the material-based challenges that must be addressed to achieve early establishment and long-term maintenance of STI.

METHODS

This extensive review article critically compares and contrasts the findings from articles published in the domain of 'soft-tissue integration around Ti dental implants'.

RESULTS

Histological characteristics, including poorer epithelial attachment and absence of direct collagen-implant/abutment integration, are responsible for the inferior STI strength around dental implants/abutments. Furthermore, various cellular functions during STI establishment and maturation at the abutment-mucosa interface must be modulated to achieve early STI. Moreover, we discuss and detail the challenges of achieving robust STI, including the presence of oral bacterial milieu, as well as material and corrosion related issues. Finally, research challenges towards achieving and maintaining robust STI are discussed, targeting the future directions to enhance the long-term survival of implant restorations.

SIGNIFICANCE

Based on its histological characteristics, STI on current implant/abutment surfaces is suboptimal compared to the periodontal attachment found at teeth, making implants potentially more susceptible to disease initiation and progression. To obtain stable STI at the trasmucosal region, it is essential for future studies to design customized implant systems, with enhanced surface bioactivity and tailorable therapeutic capacity, which can improve the long-term success of implant restorations, especially in compromised conditions.

Recent Advances in a Polydopamine-Mediated Antimicrobial Adhesion System

The drug resistance developed by bacteria during antibiotic treatment has been a call to action for researchers and scientists across the globe, as bacteria and fungi develop ever increasing resistance to current drugs. Innovative antimicrobial/antibacterial materials and coatings to combat such infections have become a priority, as many infections are caused by indwelling implants (e.g., catheters) as well as improving postsurgical function and outcomes. Pathogenic microorganisms that can exist either in planktonic form or as biofilms in water-carrying pipelines are one of the sources responsible for causing water-borne infections. To combat this, researchers have developed nanotextured surfaces with bactericidal properties mirroring the topographical features of some natural antibacterial materials. Protein-based adhesives, secreted by marine mussels, contain a catecholic amino acid, 3,4-dihydroxyphenylalanine (DOPA), which, in the presence of lysine amino acid, empowers with the ability to anchor them to various surfaces in both wet and saline habitats. Inspired by these features, a novel coating material derived from a catechol derivative, dopamine, known as polydopamine (PDA), has been designed and developed with the ability to adhere to almost all kinds of substrates. Looking at the immense potential of PDA, this review article offers an overview of the recent growth in the field of PDA and its derivatives, especially focusing the promising applications as antibacterial nanocoatings and discussing various antimicrobial mechanisms including reactive oxygen species-mediated antimicrobial properties.

Surface modification of a three-dimensional polycaprolactone scaffold by polydopamine, biomineralization, and BMP-2 immobilization for potential bone tissue applications

Three-dimensional (3D) bioprinting is a free-form fabrication technique enabling fine feature control for tissue engineering applications. Especially, 3D scaffolds capable of supporting cell attachment, proliferation, and osteogenic differentiation are a prerequisite for bone tissue regeneration. Herein, we elaborated this approach to produce a 3D polycaprolactone (PCL) scaffold with long-term osteogenic activity. Specifically, we coated polydopamine (PDA) on 3D PCL scaffolds, subsequently deposited hydroxyapatite (HA) nanoparticles via biomimetic mineralization, and finally immobilized bone morphogenetic protein-2 (BMP-2). Material properties were characterized and compared with various 3D scaffolds, including PCL, PDA-coated PCL (PCL/PDA), and PDA-coated and HA-deposited PCL (PCL/PDA/HA). In vitro cell culture studies with osteoblasts revealed that the PCL/PDA/HA scaffolds immobilized with BMP-2 showed long-term retention of BMP-2 (for up to 21 days) and significantly increased osteoblast proliferation and osteogenic differentiation, as evidenced by metabolic activity, alkaline phosphatase activity, and calcium deposition. We believe that this multifunctional osteogenic 3D scaffold will be useful for bone tissue engineering applications.

Peri-implant soft tissue integration in humans - influence of materials: A study protocol for a randomised controlled trial and a pilot study results

Background

Recently, there has been a growing interest in mucointegration as the formation of an early and long-standing soft tissue barrier seems essential for both the initial healing and long-term implant survival.

Aim

To develop an experimental method to characterize the mucointegration of different transgingival materials (titanium (Ti), polyetheretherketone (PEEK), polymethylmethacrylate (PMMA), zirconia (Zi), polymer infiltrated ceramic network (PICN), cobalt-chrome (Co–Cr), and lithium disilicate (LD)) in a human model.

Methods

The study is designed as a multi-part randomized controlled clinical trial. Ninety bone level Straumann implants will randomly receive an experimental, custom-made abutment to allow for the removal of the abutment together with the surrounding soft tissues using a punch biopsy device at 8 weeks of healing (10 per material). The specimens will be further processed for non‐decalcified histology, followed by histomorphometric analysis. The same protocol will be used for additional 90 implants-abutments, but during harvesting, soft tissues will be separated from the abutment and processed for immunohistochemistry in order to study tissue inflammation and vascularization, while the abutments will undergo SEM analysis. Additionally, in vitro analyses, including SEM and profilometry, will be performed in order to characterize surface topography of all experimental materials.

Conclusion

The limited number of pilot samples presented herein indicate that the use of custom-made abutments in humans is a reproducible method to study peri-implant soft tissue integration. This further intensifies the rationale to compare different abutment materials, used as transgingival components in daily practice, under the same conditions.

Harnessing biomolecules for bioinspired dental biomaterials

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.

Fluoro-functionalized stationary phases for electrochromatographic separation of organic fluorides

Fluorous affinity means remarkably specific interaction between highly organic fluorides. This work aims to explore the potential of fluoro-functionalized stationary phase for the separation of organic fluorides by means of fluorous-fluorous interaction. Here, by using the Michael addition strategy between 1H,1H,2H,2H-perfluorodecanethiol (PFDT) and polydopamine (PD), a novel fluoro-functionalized stationary phase was synthesized for open-tubular capillary electrochromatography (OT-CEC). The PFDT@PD was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray Photoelectron Spectrometer (XPS). The PFDT@PD@capillary exhibited outstanding separation performance towards neutral compounds (such as alkylbenzenes and chlorobenzenes) and organic fluorides (such as fluorobenzenes and perfluoroalkyl methacrylates etc.) with high resolution and high separation efficiency by hydrophobic interaction and fluorous-fluorous interaction. In addition, the column shows good stability and reproducibility. The relative standard deviations (RSDs) of the retention time for intra-day (n = 5) and inter-day (n = 3) runs and between columns (n = 3) are less than 0.39%, 1.22% and 3.87%, respectively. This novel type of fluoro-functionalized stationary phase represents a great application potential in organic fluorides separation field.

Polydopamine-on-liposomes: stable nanoformulations, uniform coatings and superior antifouling performance

Polydopamine (PDA), a mussel-inspired synthetic polymer, affords biocompatible and antifouling coatings on a variety of surfaces. However, the traditional protocol of preparing PDA by polymerizing dopamine (DA) under basic conditions yields physically-unstable and non-uniform coatings that are prone to delamination and exhibit compromised antifouling performance in vivo. Here, we show that the high local pH in the vicinity of vesicular self-assemblies formed by a series of acetal-based cationic amphiphiles can be exploited to conveniently polymerise DA under physiological conditions in a gradual manner without requiring any external oxidant. Two of the four PDA-liposome nanoformulations viz. PDA-L1 and PDA-L2 turned out to be highly stable physically and resisted precipitation for more than a month while the other two formulations (PDA-L3 and PDA-L4) were less stable and formed visible precipitates with time. Further, the PDA-liposome formulations had significantly improved haemocompatibility compared to that of pristine liposomes. PDA-L1 formed highly uniform, nanostructured coatings on implants like catheter, cotton and bandages that did not delaminate even after a week of continuous incubation in simulated body fluid, or on exposure to pH change and presence of proteolytic enzymes. The PDA-L1 coated catheter implants resisted biofouling by both Gram-positive and Gram-negative bacteria in vitro and also had superior in vivo performance in mice vis-à-vis the implants coated with traditional base-polymerised PDA formulation (BP-PDA). Thus, these novel liposomal PDA nanoformulations significantly improve the practical utility of PDA-based coatings for antimicrobial applications.

Enhanced Antimicrobial Activity of Biofunctionalized Zirconia Nanoparticles

The effective interactions of nanomaterials with biological constituents play a significant role in enhancing their biomedicinal properties. These interactions can be efficiently enhanced by altering the surface properties of nanomaterials. In this study, we demonstrate the method of altering the surface properties of ZrO2 nanoparticles (NPs) to enhance their antimicrobial properties. To do this, the surfaces of the ZrO2 NPs prepared using a solvothermal method is functionalized with glutamic acid, which is an α-amino acid containing both COO- and NH4 + ions. The binding of glutamic acid (GA) on the surface of ZrO2 was confirmed by UV-visible and Fourier transform infrared spectroscopies, whereas the phase and morphology of resulting GA-functionalized ZrO2 (GA-ZrO2) was identified by X-ray diffraction and transmission electron microscopy. GA stabilization has altered the surface charges of the ZrO2, which enhanced the dispersion qualities of NPs in aqueous media. The as-prepared GA-ZrO2 NPs were evaluated for their antibacterial properties toward four strains of oral bacteria, namely, Rothia mucilaginosa, Rothia dentocariosa, Streptococcus mitis, and Streptococcus mutans. GA-ZrO2 exhibited increased antimicrobial activities compared with pristine ZrO2. This improved activity can be attributed to the alteration of surface charges of ZrO2 with GA. Consequently, the dispersion properties of GA-ZrO2 in the aqueous solution have increased considerably, which may have enhanced the interactions between the nanomaterial and bacteria.

Biofunctionalization of zirconia with cell-adhesion peptides via polydopamine crosslinking for soft tissue engineering: effects on the biological behaviors of human gingival fibroblasts and oral bacteria

Rapid soft tissue integration is essential for long-term dental implant success. Zirconia is increasingly used as an abutment material owing to its excellent aesthetic properties and biocompatibility; however, it is bioinert, and tissue integration is poor. We developed a feasible surface modification method, exploiting the reactivity of polydopamine (PDA) films to immobilize cell-adhesion peptides (Arg-Gly-Asp, RGD) onto zirconia abutment surfaces. Further, we evaluated the effect thereof on human gingival fibroblast (HGF) behavior and oral bacterial adhesion, which influence the peri-implant soft tissue seal. HGF responses to linear KGGRGDSP and cyclic RGDfK sequences were compared. PDA deposition and covalent coupling of RGD were verified by X-ray photoelectron spectroscopy and fluorescence microscopy. The biological behaviors of HGFs on the modified zirconia; i.e., adhesion, spreading, proliferation, gene and protein expression, were elucidated. Biofunctionalization of zirconia with the adhesion peptides significantly enhanced the biological activities of HGFs. Cyclic RGD induced slightly improved cell attachment, spreading, and proliferation, but similar cell differentiation when compared to linear RGD peptides. To assess their antimicrobial properties, the different substrates were exposed to cultures of the early colonizer Streptococcus mutans or the periodontal pathogen Porphyromonas gingivalis, and bacterial adhesion was evaluated by scanning electron microscopy and live/dead staining. PDA and PDA-RGD coatings decreased zirconia surface colonization by both bacterial species to similar extents. Thus, PDA-RGD-functionalized zirconia modulates specific HGF responses, while maintaining the antimicrobial activity of the PDA coating. The selective bio-interaction pattern of this surface modification holds great promise for improving soft-tissue integration around zirconia abutments in clinical applications.

Biofunctionalization of zirconia with cell-adhesion peptides via polydopamine and its effect on HGFs/bacterial adhesion for enhanced soft tissue seal.

Influences of sodium tantalite submicro-particles in polyetheretherketone based composites on behaviors of rBMSCs/HGE-1 cells for dental application

Dental implanted materials require excellent mechanical properties, biocompatibility as well as integration with bone tissue and gingival tissue to achieve early loading and long-term stability. In this study, cubic shape sodium tantalite (ST) submicro-particles with the size of around 180 nm were synthesized by a hydrothermal method, and ST/polyetheretherketone (PEEK) composites (TPC) with ST content of 20 w% (TPC20) and 40 w% (TPC40) were prepared by melting blend. The results showed that the compressive strength, thermal properties, surface roughness, hydrophilicity and surface energy as well as adsorption of proteins on TPC40 were also significantly enhanced compared with TPC20 and PEEK. Moreover, the responses (adhesion and proliferation as well as differentiation) of rat bone marrow mesenchymal stem cells (rBMSCs), and responses (adhesion, and proliferation) of human gingival epithelial (HGE-1) cells to TPC40 were significantly promoted compared with TPC20 and PEEK. The results demonstrated that ST content in TPC had remarkable effects on the surface properties, which played key roles in stimulating the responses of both rBMSCs and HGE-1 cells. TPC40 with increased surface properties and excellent cytocompatibility might have great potential as an implanted material for dental application.

Regulating the Behavior of Human Gingival Fibroblasts by sp2 Domains in Reduced Graphene Oxide

Long-term function of dental implants relies on not only stable osseointegration but also strong soft tissue-sealing ability. Ideal soft tissue sealing around implants is an effective protective barrier between the external environment and alveolar bone, preventing the invasion of bacteria that is considered as a vital trigger of irreversible marginal bone loss. Carbon-based materials have been reported to be beneficial to soft tissue sealing, which can be regulated through the hybridization type of carbon atoms (sp² or sp³), but its internal mechanism is still not clear. In this work, graphene oxide with both sp²- and sp³-hybridized carbons was electrophoretic deposited on titanium and reduced to regulate the hybridization type of carbon atoms to investigate its effect and possible mechanism on human gingival fibroblasts (HGFs). X-ray photoelectron spectroscopy and Raman mapping test show the increase of sp² domain content and the decrease of their size after reduction. Through computer simulation, the possible mechanism of the decrease of sp² domain size was proposed. In vitro studies disclose that the HGFs exhibit higher proliferation rate, better adhesion, and migration ability with the increase of sp² domains and the decrease of their sizes. It may be due to the amount and size of sp² domains that synergistically regulate the amount and properties of adsorbed proteins, thereby influencing the cellular behaviors of HGFs. Our results may offer a different perspective on material designing and academic research to enhance the soft tissue integration of implants.

Influence of bio-aging on corrosion behavior of different implant materials

BACKGROUND

Dental implants and abutments are exposed to challenging oral environment. Corrosion of these materials can affect the overall performance of titanium implants.

PURPOSE

To investigate the effects of biofilm-induced bio-aging on corrosion behavior of different implant materials surface.

MATERIALS AND METHODS

Commercial polished titanium (Polish), sand-blasted, large grit, acid-etched surface treated titanium (SLA), microarc oxidation (MAO), and hydroxyapatite (HA) coated titanium were bio-aged with saliva biofilm for 30 days. Titanium surfaces topography, chemical composition, roughness, and water contact angle changes were evaluated. In addition, human gingival fibroblasts (HGFs) adhesion, Streptococcus sanguinis (S. sanguinis) biofilm formation were determined.

RESULTS

Surface topography, roughness, and chemical composition have no significant changes for all groups after bio-aging (P > .05). Water contact angle of bio-aged SLA was greatly increased (P < .05). While other groups showed no sign of change (P > .05). Adhesion and proliferation of HGFs on the bio-aged SLA titanium surfaces were decreased (P < .05), but increased on bio-aged Polish and HA titanium (P < .05). S. sanguinis biofilm viability was promoted with bio-aging in HA group (P < .05).

CONCLUSIONS

Biological characteristics of Polish, SLA, and HA titanium surfaces were influenced by bio-aging. While MAO group was relatively resistant to saliva biofilm bio-aging.

Novel laser textured surface designs for improved zirconia implants performance

The development of new surface designs to enhance the integration process between surgically placed implants and biological tissues remains a challenge for the scientific community. In this way and trying to overcome this issue, in this work, laser technology was explored to produce novel textures on the surface of green zirconia compacts produced by cold pressing technique. Two strategies regarding line design (8 and 16 lines design) and different laser parameters (laser power and number of laser passages) were explored to assess their influence on geometry and depth of created textures. The produced textures were evaluated with Scanning Electron Microscopy (SEM) and it was observed that well-defined textured surfaces with regular geometric features (cavities or pillars) were obtained by laser combining different strategies lines design and parameters. The potential of proposed textures was also evaluated regarding surface wettability, friction performance (static and dynamic coefficient of friction evolution) against bone, aging resistance and flexural strength. Results demonstrated that all the produced textures display a super hydrophilic or hydrophilic behavior. Regarding the friction behavior, it was experimentally observed a high initial static coefficient of friction (COF) for all produced textures. Concerning the aging resistance, all the textured surfaces revealed a low monoclinic content, less than 25% after 5 h of hydrothermal aging. The flexural strength results showed that the mechanical resistance of zirconia was not significantly compromised with the laser action. Based on the obtained results, it is possible to prove that the processing route used for manufacturing the new and different surface designs (cold pressing technique followed by laser texturing) showed to be particularly effective for the production of zirconia implants with customized surface designs according to the properties required in a specific application. These new surface designs besides to enhance the surface wettability and also to improve the fixation at the initial moment of the implantation, do not significantly compromise the resistance to aging and the mechanical performance of zirconia. Hence, a positive impact on the long-term performance of the zirconia implants may be expected with the proposed novel laser textured surface designs.

Direct Laser Interference Patterning of Bioceramics: A Short Review

Bioceramics are a great alternative to use in implants due to their excellent biocompatibility and good mechanical properties. Depending on their composition, bioceramics can be classified into bioinert and bioactive, which relate to their interaction with the surrounding living tissue. Surface morphology also has great influence on the implant biological behavior. Controlled texturing can improve osseointegration and reduce biofilm formation. Among the techniques to produce nano- and micropatterns, laser texturing has shown promising results due to its excellent accuracy and reproducibility. In this work, the use of laser techniques to improve surface morphology of biomaterials is reviewed, focusing on the application of direct laser interference patterning (DLIP) technique in bioceramics.

The responses of human gingival fibroblasts to magnesium-doped titanium

The titanium (Ti) implant is widely used in implant dentistry; yet peri-implantitis has always been one of the most common and serious complications. Here, we demonstrated that magnesium-doping would be an effective way of enhancing the integration between implant surfaces and gingival tissues, which is critical to peri-implant health. The magnesium (2.76-6.35 at %) was immobilized onto the titanium substrate by a magnesium plasma immersion ion implantation (Mg-PIII) technique. Mg-PIII treatments did not alter surface topographies of the original titanium substrate but improved its hydrophilicity. The in vitro study including cell viability, adhesion, proliferation, migration, and real-time polymerase chain reaction assays disclosed improved adhesion, proliferation, migration, and extracellular matrix remodeling abilities of human gingival fibroblasts (HGFs) on the magnesium-doped titanium. The results of western blot suggested that the Mg-modified titanium induced the phosphorylation of AKT through the activation of PI3K. Our results revealed that magnesium-doping would potentially enhance soft tissue sealings by promoting cellular functions of HGFs in a dose-dependent manner, boding well for its applications on surfaces of implant necks in early peri-implant soft tissue integrations.

Gene-Loaded Nanoparticle-Coated Sutures Provide Effective Gene Delivery to Enhance Tendon Healing

How to accelerate tendon healing remains a clinical challenge. In this study, a suture carrying nanoparticle/pEGFP-basic fibroblast growth factor (bFGF) and pEGFP-vascular endothelial growth factor A (VEGFA) complexes was developed to transfer the growth factor genes into injured tendon tissues to promote healing. Polydopamine-modified sutures can uniformly and tightly absorb nanoparticle/plasmid complexes. After tendon tissues were sutured, the nanoparticle/plasmid complexes still existed on the suture surface. Further, we found that the nanoparticle/plasmid complexes delivered into tendon tissues could diffuse from sutures to tendon tissues and effectively transfect genes into tendon cells, significantly increasing the expression of growth factors in tendon tissues. Finally, biomechanical tests showed that nanoparticle/pEGFP-bFGF and pEGFP-VEGFA complex-coated sutures could significantly increase the ultimate strengths of repaired tendons, especially at 4 weeks after operation. Two kinds of nanoparticle/plasmid complex-coated sutures significantly increased flexor tendon healing strength by 3.7 times for Ethilon and 5.8 times for PDS II, respectively, compared with the corresponding unmodified sutures. In the flexor tendon injury model, at 6 weeks after surgery, compared with the control suture, the nanoparticle/plasmid complex-coated sutures can significantly increase the gliding excursions of the tendon and inhibit the formation of adhesion. These results indicate that this nanoparticle/plasmid complex-coated suture is a promising tool for the treatment of injured tendons.