Present and Theoretical Applications of Poly-Ether-Ether-Ketone (PEEK) in Orthodontics: A Scoping Review

A bioactive and anti-bacterial nano-sized zirconium phosphate/GO (nZrP/GO) composite: Potential use as a coating for dental implants?

OBJECTIVE

Dental implants fabricated from titanium have several limitations and therefore, alternative materials that fulfil the criteria of successful dental implant (bioactivity and anti-bacterial activity) need to be considered. Polyether ether ketone (PEEK) has been suggested to replace titanium implants. However, this material needs surface modification to meet the appropriate criteria. A nano-sized zirconium phosphate/GO (nZrP/GO) composite coating was prepared to improve PEEK's biological qualities.

METHODS

Polished and cleaned PEEK discs were coated with the composite of nZrP doped with 1.25 wt% GO by the soft-template method. To analyze the composite coating, X-ray, atomic force microscopy, and field emission scanning electron microscopy-energy dispersive spectroscopy were used. The adhesion of the coating to PEEK was measured by adhesive tape test. By measuring the optical contact angle, the coated and non-coated samples' differences in wettability were evaluated. Antimicrobial activity was evaluated against S. aureus and E. coli and cytotoxicity tested employing gingival fibroblasts and osteoblast-like cells.

RESULTS

The nZrP/GO composite coating was 23.45 µm thick, was irregular and attached strongly to the PEEK surface. Following coating, the water contact angle dropped to 34° and surface roughness to 13 nm. The coating reduced the count of bacteria two-fold and was non-cytotoxic to mammalian osteoblast-like cells and fibroblasts. A precipitation of nano-calcium-deficient apatite was observed on the surface of the nZrP/GO coating following a 28-day immersion in SBF.

SIGNIFICANCE

PEEK-coated with nZr/GO coating is a good candidate as dental implant.

Failed Orthodontic PEEK Retainer: A Scanning Electron Microscopy Analysis and a Possible Failure Mechanism in a Case Report

This study presents a scanning electron microscopy analysis of a failed PEEK retainer in an orthodontic patient. After 15 months of use, the patient reported a gap opening between teeth 41 and 42. The PEEK retainer was removed and sent for electron microscope analysis. To investigate the failure, scanning electron microscopy was employed to assess the microstructure and composition of the retainer at various magnifications. These findings suggest that the failure of the PEEK retainer was multifaceted, implicating factors such as material defects, manufacturing flaws, inadequate design, environmental factors, and patient-related factors. In conclusion, this scanning electron microscopy analysis offers valuable insights into the failure mechanisms of PEEK retainers in orthodontic applications. Further research is necessary to explore preventive strategies and optimize the design and fabrication of PEEK retainers, minimizing the occurrence of failures in orthodontic practice.

Assessing color stability of orthodontic esthetic wires in different staining solutions

BACKGROUND

Esthetic orthodontic wires are preferred for their ease to fit in with natural tooth color, but their susceptibility to staining in the oral environment poses a concern. Various Coatings such as Teflon and Epoxy aim to enhance appearance and biocompatibility but may still result in discoloration. Understanding the color stability of these wires under different staining conditions is crucial for a better and enhanced treatment plan.

OBJECTIVE

This study intended to assess the color stability of esthetic orthodontic wires under various staining solutions that are often used in daily life.

METHOD

Color changes of Teflon and Epoxy-coated esthetic orthodontic wires were meticulously measured at baseline, 7, 14, and 21-day intervals utilizing the precise CIE Lab* color measurement system. A total of thirty-two samples of wires from each brand were prepared (n= 8/group) and immersed in staining solutions (coffee, tea, cola, and saffron). The color change within and between the groups was statistically evaluated (p< 0.05).

RESULTS

Significant variations in color stability were observed across different staining solutions. Saffron emerged as the most potent agent, inducing the most pronounced color changes, whereas cola demonstrated the least impact. Furthermore, Epoxy-coated wires consistently exhibited superior color stability compared to their Teflon-coated counterparts across all staining solutions and time intervals.

CONCLUSION

This study underlines the significance for orthodontists to consider staining agents' possible effects on orthodontic wires into account when selecting the orthodontic wires. The findings suggest that Epoxy-coated wires hold promise in mitigating discoloration issues during orthodontic therapy.

Graphene loaded into dental polymers as reinforcement of mechanical properties: A systematic review

Graphene compounds are incorporated into polymers in order to improve their mechanical properties and in dentistry this modification favors the clinical performance of these materials. The aim of this review was to evaluate graphene compounds, their concentrations, and their effect on mechanical properties as flexural, tensile, and compressive strength and hardness of polymethylmethacrylate (PMMA) and polyether-ether-ketone (PEEK) for dental application. The search was carried out in two steps in PubMed/Medline, Embase, Scopus, and Web of Science databases. The eligibility criteria included studies that incorporated pure graphene compounds into dental polymers and evaluated their mechanical properties. Were found 4984 results, of which 11 articles were included in this review. Graphene compounds: graphene oxide (GO), reduced graphene oxide (rGO), and graphene nanoplatelets (GNP) were incorporated into PMMA and PEEK, in concentrations ranging from 0.1 to 10 wt%. Concentrations lower than 0.75 wt% of GO in PMMA and 1 wt% of GNP in PEEK resulted in increased flexural, tensile, compression strength, and hardness of these polymers. It was concluded that the incorporation of graphene compounds in low concentrations increases dental polymers' mechanical properties.

Direct 3D-Printed Orthodontic Retainers. A Systematic Review

Three-dimensional (3D) printing technology has shed light on many fields in medicine and dentistry, including orthodontics. Direct 3D-printed prosthetics, implants or surgical devices are well-documented. The fabrication of orthodontic retainers using CAD technology and additive manufacturing is an emerging trend but the available data are scarce. The research approach of the present review included keywords in Medline, Scopus, Cochrane Library and Google Scholar up to December 2022. The searching process concluded with five studies eligible for our project. Three of them investigated directly 3D-printed clear retainers in vitro. The other two studies investigated directly 3D-printed fixed retainers. Among them, one study was in vitro and the second was a prospective clinical trial. Directly 3D-printed retainers can be evolved over time as a good alternative to all the conventional materials for retention. Devices that are 3D-printed are more time and cost efficient, offer more comfortable procedures for both practitioners and patients and the materials used in additive manufacturing can solve aesthetic problems, periodontal issues or problems with the interference of these materials with magnetic resonance imaging (MRI). More well-designed prospective clinical trials are necessary for more evaluable results.

PEEK for Oral Applications: Recent Advances in Mechanical and Adhesive Properties

Polyetheretherketone (PEEK) is a thermoplastic material widely used in engineering applications due to its good biomechanical properties and high temperature stability. Compared to traditional metal and ceramic dental materials, PEEK dental implants exhibit less stress shielding, thus better matching the mechanical properties of bone. As a promising medical material, PEEK can be used as implant abutments, removable and fixed prostheses, and maxillofacial prostheses. It can be blended with materials such as fibers and ceramics to improve its mechanical strength for better clinical dental applications. Compared to conventional pressed and CAD/CAM milling fabrication, 3D-printed PEEK exhibits excellent flexural and tensile strength and parameters such as printing temperature and speed can affect its mechanical properties. However, the bioinert nature of PEEK can make adhesive bonding difficult. The bond strength can be improved by roughening or introducing functional groups on the PEEK surface by sandblasting, acid etching, plasma treatment, laser treatment, and adhesive systems. This paper provides a comprehensive overview of the research progress on the mechanical properties of PEEK for dental applications in the context of specific applications, composites, and their preparation processes. In addition, the research on the adhesive properties of PEEK over the past few years is highlighted. Thus, this review aims to build a conceptual and practical toolkit for the study of the mechanical and adhesive properties of PEEK materials. More importantly, it provides a rationale and a general new basis for the application of PEEK in the dental field.