Improved Mechanical Properties and Bioactivity of Silicate Based Bioceramics Reinforced Poly(ether-ether-ketone) Nanocomposites for Prosthetic Dental Implantology

Prospectives and challenges of nano-tailored biomaterials-assisted biological molecules delivery for tissue engineering purposes

Nano carriers have gained more attention for their possible medical and technological applications. Tailored nanomaterials can transport medications efficiently to targeted areas and allow for sustained medication discharge, reducing undesirable toxicities while boosting curative effectiveness. Nonetheless, transitioning nanomedicines from experimental to therapeutic applications has proven difficult, so different pharmaceutical incorporation approaches in nano scaffolds are discussed. Then numerous types of nanobiomaterials implemented as carriers and their manufacturing techniques are explored. This article is also supported by various applications of nanobiomaterials in the biomedical field.

Biomimetic Coatings in Implant Dentistry: A Quick Update

Biomimetic dental implants are regarded as one of the recent clinical advancements in implant surface modification. Coatings with varying thicknesses and roughness may affect the dental implant surface's chemical inertness, cell adhesion, and antibacterial characteristics. Different surface coatings and mechanical surface changes have been studied to improve osseointegration and decrease peri-implantitis. The surface medication increases surface energy, leading to enhanced cell proliferation and growth factors, and, consequently, to a rise in the osseointegration process. This review provides a comprehensive update on the numerous biomimetic coatings used to improve the surface characteristics of dental implants and their applications in two main categories: coating to improve osseointegration, including the hydroxyapatite layer and nanocomposites, growth factors (BMPs, PDGF, FGF), and extracellular matrix (collagen, elastin, fibronectin, chondroitin sulfate, hyaluronan, and other proteoglycans), and coatings for anti-bacterial performance, covering drug-coated dental implants (antibiotic, statin, and bisphosphonate), antimicrobial peptide coating (GL13K and human beta defensins), polysaccharide antibacterial coatings (natural chitosan and its coupling agents) and metal elements (silver, zinc, and copper).

Strength and bioactivity of PEEK composites containing multiwalled carbon nanotubes and bioactive glass

Polyetheretherketone (PEEK) polymer is a widely accepted implantable biomaterial in the biomedical field. However, PEEK has a low elastic modulus (E-modulus) as well as a bio-inert nature which is not conductive to rapid bone cell attachment, hence, producing delayed or weak bone-implant integration. Multiwalled carbon nanotubes (MWCNTs) represent one of the strongest known materials that could be added to a polymer to improve its mechanical properties. Bioactive glasses (BGs) can form hydroxyapatite deposits on their surfaces and form a tight bond with the bone, thus, their incorporation into the PEEK matrix may improve its bioactivity.

METHODS

Eight groups were formulated according to the type and percentage of modification of PEEK by MWCNTs and BGs. Group 1: Pure PEEK (P), Group 2: P + 3% MWCNTs (PC3), Group 3: P + 5% MWCNTs (PC5), Group 4: P + 5% BGs (PG5), Group 5: P + 10% BGs (PG10), Group 6: P + 3% MWCNTs + 5% BGs (PC3G5), Group 7: P + 3% MWCNTs + 10% BGs (PC3G10), and Group 8: P + 5% MWCNTs + 5% BGs (PC5G5). Characterization of the vacuum-pressed PEEK and PEEK composite specimens was done using FE-SEM, EDS, FT-IR and TF-XRD. Three-point load test was done to obtain the flexural strength (F.S) and the E-modulus of the specimens. Wettability was determined by measuring the contact angle with distilled water. In-vitro bioactivity was determined after immersion of specimens in simulated body fluid (SBF). Moreover, the effect of the specimens on osteoblastic cell viability was evaluated.

RESULTS

Three-point load test results have shown an improvement in both F.S. and E-modulus for groups PC5, PC3G5 and PC5G5. The lowest contact angle was obtained for group PC5G5 followed by the PC3G10 group. All specimens containing BGs showed the formation of hydroxyapatite-like deposits after their immersion in SBF, as well as an improvement in osteoblastic cell viability compared to PEEK.

CONCLUSION

PC3G10, PC3G5 and PG10, groups are promising for the fabrication of patient-specific implants that can be used in low-stress-bearing areas.

The Toothbrushing Effects on Surface Properties and Color Stability of CAD/CAM and Pressable Ceramic Fixed Restorations-An In Vitro Study

Pressable ceramic restorations have been introduced and investigated, and found comparable to CAD/CAM ceramic in terms of mechanical properties; however, the effect of toothbrushing on the pressable ceramic has not been thoroughly investigated. The objective of the current study was to assess the effect of artificial toothbrushing simulation on the surface roughness, microhardness, and color stability of different ceramic materials. Three lithium disilicate-based ceramics (IPS Emax CAD [EC], IPS Emax Press [EP]; (Ivoclar Vivadent AG), and LiSi Press [LP] (GC Corp, Tokyo, Japan)) were examined. For each ceramic material, eight bar-shaped specimens were prepared and subjected to 10,000 brushing cycles. Surface roughness, microhardness, and color stability (∆E) were measured before and after brushing. Scanning electron microscopy (SEM) was used for surface profile analysis. The results were analyzed using one-way ANOVA, Tukey's post hoc test, and paired sample t-test α = 0.05. The findings revealed a non-significant decrease in the surface roughness of EC, EP, and LP groups (p > 0.05), and both LP and EP have the lowest surface roughness values (0.64 ± 0.13, 0.64 ± 0.08 µm) after brushing, respectively. Toothbrushing showed a decrease in the microhardness of the three groups: EC and LP, p < 0.001; EP, p = 0.012). EP showed the lowest hardness value after brushing (862.45 ± 273.83). No significant changes (∆E) were observed in all groups (p > 0.05); however, the EC group was found to be considerably affected by color changes, in comparison to the EC and LP groups. Toothbrushing had no effect on surface roughness and color stability of all tested materials, but it decreased the microhardness. Material type, surface treatments, and glazing of ceramic materials contributed to the surface changes in the ceramic materials, necessitating further investigations in terms of the toothbrushing effect with different glazing as variables.

Bioceramics in Endodontics: Updates and Future Perspectives

Bioceramics, with excellent bioactivity and biocompatibility, have been widely used in dentistry, particularly in endodontics. Mineral trioxide aggregate (MTA) is the most widely used bioceramic in endodontics. Recently, many new bioceramics have been developed, showing good potential for the treatment of endodontic diseases. This paper reviews the characteristics of bioceramics and their applications in various clinical endodontic situations, including root-end filling, root canal therapy, vital pulp therapy, apexification/regenerative endodontic treatment, perforation repair, and root defect repair. Relevant literature published from 1993 to 2023 was searched by keywords in PubMed and Web of Science. Current evidence supports the predictable outcome of MTA in the treatment of endodontic diseases. Although novel bioceramics such as Biodentine, EndoSequence, and calcium-enriched mixtures have shown promising clinical outcomes, more well-controlled clinical trials are still needed to provide high-level evidence for their application in endodontics. In addition, to better tackle the clinical challenges in endodontics, efforts are needed to improve the bioactivity of bioceramics, particularly to enhance their antimicrobial activity and mechanical properties and reduce their setting time and solubility.

Additive manufacturing technologies in the oral implant clinic: A review of current applications and progress

Additive manufacturing (AM) technologies can enable the direct fabrication of customized physical objects with complex shapes, based on computer-aided design models. This technology is changing the digital manufacturing industry and has become a subject of considerable interest in digital implant dentistry. Personalized dentistry implant treatments for individual patients can be achieved through Additive manufacturing. Herein, we review the applications of Additive manufacturing technologies in oral implantology, including implant surgery, and implant and restoration products, such as surgical guides for implantation, custom titanium meshes for bone augmentation, personalized or non-personalized dental implants, custom trays, implant casts, and implant-support frameworks, among others. In addition, this review also focuses on Additive manufacturing technologies commonly used in oral implantology. Stereolithography, digital light processing, and fused deposition modeling are often used to construct surgical guides and implant casts, whereas direct metal laser sintering, selective laser melting, and electron beam melting can be applied to fabricate dental implants, personalized titanium meshes, and denture frameworks. Moreover, it is sometimes required to combine Additive manufacturing technology with milling and other cutting and finishing techniques to ensure that the product is suitable for its final application.

Tests of Dental Properties of Composite Materials Containing Nanohybrid Filler

Complex composite materials are used in many areas of dentistry. Initially, chemically hardened materials were also used, and in this group nanohybrid composites are highly valued. They are often used today, mainly for the direct reconstruction of damaged hard tooth tissue materials for rebuilding damaged tissues using indirect adhesive techniques. The research was conducted to determine the mechanical properties of materials with nanofillers. The article focuses on methods of important test methods for dental prosthetics: resilience, abrasion, wear test, impact strength, hardness, SEM, and chemical analysis. As part of this work, five different series of hybrid composites with nano-fillers were tested. The mechanical properties of composites, such as compressive strength, microhardness, flexural strength, and modulus of elasticity, depend mainly on the type, particle size, and amount of filler introduced. The obtained test results showed that the type and amount of nanofiller have a significant influence on the mechanical and tribological properties. The introduction of nanofillers allowed us to obtain higher mechanical properties compared to classic materials discussed by other researchers. The study observed a change in vibrations in the IR spectrum, which allowed a comparison of the organic structures of the studied preparations.

Calcium Silicate Whiskers-Enforced Poly(Ether-Ether-Ketone) Composites with Improved Mechanical Properties and Biological Activities for Bearing Bone Reconstruction

Poly (ether-ether-ketone) (PEEK) displays promising potential application in bone tissue repair and orthopedic surgery due to its good biocompatibility and chemical stability. However, the bio-inertness and poor mechanical strength of PEEK greatly limit its application in load-bearing bones. In this study, calcium silicate whiskers (CSws) are synthesized and then compounded with PEEK to fabricate the PEEK/CSw composites with excellent mechanical properties, biological activity. Compared with PEEK, the PEEK/CSw composites exhibited higher hydrophilicity and ability to deposit hydroxyapatite on the surface. CSws are evenly dispersed in the PEEK matrix at 10 wt% content and the mechanical strength of the PEEK/CSw composite is ≈96.9 ± 2.4 MPa, 136.3 ± 2.4 MPa, and 266.0 ± 3.2 MPa, corresponding to tensile strength, compressive strength, and bending strength, respectively, which is 20%, 18%, and 52% higher than that of pure PEEK. The composites improve the adhesion, proliferation, and osteogenic differentiation of BMSCs. Furthermore, PEEK/CSw composite remarkably improves bone formation and osteointegration, which has higher bone repair capacity than PEEK. These results demonstrate that the PEEK/CSw scaffolds display superior abilities to integrate with the host bone and promising potential in the field of load bearing bone repair.

Preparation and Characterization of a Polyetherketoneketone/Hydroxyapatite Hybrid for Dental Applications

Here, we developed a new synthetic method for the production of a new class of polymeric inorganic hybrid biomaterial that has potential for dental implant applications and, in general, other orthopedic applications owing to its excellent mechanical properties and biomechanical compatibility. The new hybrid biomaterial is a composite consisting of polyetherketoneketone (PEKK) and hydroxyapatite (HA). This hybrid material boasts several unique features, including its high HA loading (up to 50 wt%), which is close to that of natural human bone; the homogeneous HA distribution in the PEKK matrix without phase separation; and the fact that the addition of HA has no effect on the molecular weight of PEKK. Nanoindentation analysis was used to investigate the mechanical properties of the composite, and its nano/microstructure variations were investigated through a structural model developed here. Through nanoindentation technology, the newly developed PEKK/HA hybrid biomaterial has an indentation modulus of 12.1 ± 2.5 GPa and a hardness of 0.42 ± 0.09 GPa, which are comparable with those of human bone. Overall, the new PEKK/HA biomaterial exhibits excellent biomechanical compatibility and shows great promise for application to dental and orthopedic devices.