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Special Issue "Biocompatible Materials Investigated with Optical Methods"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: 20 February 2023 | Viewed by 9304

Special Issue Editor

Prof. Dr. Virgil-Florin Duma
E-Mail Website
Guest Editor
1. 3OM Optomechatronics Group, Faculty of Engineering, Aurel Vlaicu University of Arad, 310130 Arad, Romania
2. Doctoral School, Polytechnic University of Timisoara, 300006 Timisoara, Romania
Interests: optomechatronics; laser systems; imaging techniques; optical coherence tomography (OCT); measuring systems; optical metrology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Biocompatible and bioactive materials are essential for various fields of tissue engineering. Hard tissue such as bone or teeth, as well as soft tissue such as skin, muscles, and ligament are targeted by the development of scaffolds of different types. Their characterization often targets trade-offs between contradictory properties (e.g. porosity and mechanical resistance for bone replacement scaffolds). The results of several assessment methods must be therefore correlated in order to design and optimize biomaterials. On the other hand, both in vitro and in vivo investigations are required, the latter after implementing the biomaterials. Optical techniques such as optical coherence tomography (OCT) have the capability to perform non-invasive, real time, quantitative assessments of biomaterials and tissue, but a wide range of methods are utilized for such investigations, that include but are not limited to optical and laser scanning microscopy (including for the gold standard of histological evaluations), fluorescence, spectrometry, X-rays investigations (including micro-CT), scanning electron microscopy, as well as mechanical testing.

The aim of this Special Issue is to bring together such optical and non-optical methods for in vitro and/or in vivo characterizations of biocompatible materials. Of special interest are hot topics such as OCT, as well as emerging techniques, but also the correlation of a range of methods (as mentioned above) to design, test, optimize, or assess after implementation biomaterials, as well as corresponding tissue. Development and testing of dedicated systems and probes, as well as image and data processing to optimize biomaterials assessments are also encouraged.

Prof. Dr.-habil. Virgil-Florin Duma
Guest Editor

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Keywords

  • biomaterials
  • biocompatibility
  • optical methods
  • biophotonics
  • biomedical imaging
  • optical coherence tomography (OCT)
  • optical microscopy
  • confocal microscopy
  • X-rays investigations
  • data/image processing

Published Papers (7 papers)

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Research

Article
Electrostatic Analysis of Bioactivity of Ti-6Al-4V Hydrophilic Surface with Laser Textured Micro-Square Convexes
Materials 2022, 15(22), 7942; https://doi.org/10.3390/ma15227942 - 10 Nov 2022
Viewed by 415
Abstract
At solid-liquid interfaces, charged particles within the electric double layer (EDL) are acted on by the electrostatic force, which may affect cell absorption and surface wettability. In this study, a model of the electrostatic force and surface tension of textured surfaces was presented. [...] Read more.
At solid-liquid interfaces, charged particles within the electric double layer (EDL) are acted on by the electrostatic force, which may affect cell absorption and surface wettability. In this study, a model of the electrostatic force and surface tension of textured surfaces was presented. Then, the growth and adhesion of Murine osteoblasts (MC3T3-E1) cells on laser-ablated micro-square-textured Ti-6Al-4V surfaces were studied to demonstrate the use of a laser-processed texture to effectively improve bioactivity. Three different micro-square-textured hydrophilic surfaces, presenting lower contact angles of 19°, 22.5°, and 31.75° compared with that of a smooth surface (56.5°), were fabricated using a fiber-optic laser. Cellular morphology and initial cell attachment were analyzed by field emission scanning electron microscopy (SEM) and fluorescence microscopy, respectively. The results show that the electrostatic force not only made the textured surface more hydrophilic but also made the cells tend to adhere to the edges and corners of the protruding convexes. Cell morphology analysis also showed that cells would prefer to grow at the edges and corners of each micro-square convex protrusion. The laser-treated surfaces were more conducive to rapid cell growth and adhesion, and cells were preferentially attached on the hydrophilic-textured surfaces. Electrostatic force may be an important factor in effectively improving the bioactivity of Ti-6Al-4V surfaces, and the presence of more surface grooves would be more conducive to improving the bioactivity of cells. Full article
(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)
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Article
Impact of Dentistry Materials on Chemical Remineralisation/Infiltration versus Salivary Remineralisation of Enamel—In Vitro Study
Materials 2022, 15(20), 7258; https://doi.org/10.3390/ma15207258 - 17 Oct 2022
Viewed by 744
Abstract
The aim of this study is to evaluate salivary remineralisation versus chemical remineralisation/infiltration of enamel, using different dentistry materials. The enamel changes were studied using confocal laser scanning microscopy (CLSM), and the depth of lesions and demineralisation/remineralisation/infiltration percentage were calculated. Additionally, the macro [...] Read more.
The aim of this study is to evaluate salivary remineralisation versus chemical remineralisation/infiltration of enamel, using different dentistry materials. The enamel changes were studied using confocal laser scanning microscopy (CLSM), and the depth of lesions and demineralisation/remineralisation/infiltration percentage were calculated. Additionally, the macro elemental composition of the teeth was performed using atomic absorption spectroscopy (AAS). Two studies were performed: (i) demineralisation of enamel in 3% citric acid and infiltration treatment with infiltration resin (Icon, DMG), remineralisation with Fluor Protector (Ivoclar Vivadent) and artificial saliva pH 8; and (ii) enamel demineralisation in saliva at pH 3 and remineralisation at salivary pH 8. The results showed that, firstly, for the remineralisation of demineralised enamel samples, Fluor Protector (Ivoclar Vivadent) was very effective for medium demineralised lesions followed by saliva remineralisation. In cases of deep demineralisation lesions where fluoride could not penetrate, low viscosity resin (Icon, DMG, Hamburg) effectively infiltrated to stop the demineralisation process. Secondly, remineralisation in salivary conditions needed supplementary study over a longer period, to analyse the habits, diet and nutrition of patients in detail. Finally, demineralisation/remineralisation processes were found to influence the macro elemental composition of enamel demineralisation, with natural saliva proving to be less aggressive in terms of decreasing Ca and Mg content. Full article
(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)
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Article
Ceramic Scaffolds for Bone Augmentation: Design and Characterization with SEM and Confocal Microscopy
Materials 2022, 15(14), 4899; https://doi.org/10.3390/ma15144899 - 14 Jul 2022
Cited by 1 | Viewed by 699
Abstract
Bone scaffolds must fulfil numerous and sometimes contradictory characteristics: biocompatibility, bioactivity, high porosity, and appropriate mechanical strength. To tackle some of these issues, this study has several aims for the development of such scaffolds for dentistry applications: (i) to utilize appropriate materials (ceramics [...] Read more.
Bone scaffolds must fulfil numerous and sometimes contradictory characteristics: biocompatibility, bioactivity, high porosity, and appropriate mechanical strength. To tackle some of these issues, this study has several aims for the development of such scaffolds for dentistry applications: (i) to utilize appropriate materials (ceramics and sponges) and to introduce a novel, potentially performant ceramic material; (ii) to characterize the obtained scaffolds by using a range of methods; (iii) to compare and to correlate the assessment results with the scope to validate them reciprocally. There are two commercially available dental ceramics (i.e., Ceramco iC Natural Enamel (E) and Ceramco iC Natural Dentine (D), (DeguDent GmbH, Hanau-Wolfgang, Deutschland)) that are considered, as well as a new-developed porcelain (ceramic C). To obtain porous structures of scaffolds, each ceramic is introduced in two different sponges: a denser one, green (G) and a less dense one, blue (B). A total of 60 samples are manufactured and divided in six study groups, obtained by combining the above materials: GE, BE, GD, BD, GC, and BC (where the first letter represents the sponge type and the second one the utilized ceramic). Several methods are applied to characterize their chemical composition, as well as their macro- and micro-porosity: X-ray Diffraction (XRD), apparent porosity measurements, scanning electronic microscopy (SEM), and confocal microscopy (CM). The latter two methods image the inner (porous) and the outer/cortical (denser) areas of the samples. The results show a good porosity (i.e., dimensions and uniformity of pores) of around 65% for the final group BC, with satisfactory values of around 51% for BD and GC. A certain correlation is made between SEM, CM, and the apparent porosity results. The biocompatibility of the new ceramic C is demonstrated. Finally, a necessary trade-off is made with the mechanical strength of the obtained scaffolds, which was also evaluated. From this point of view, Group BD has the highest compressive strength of around 4 MPa, while Group BC comes second, with around 2 MPa. This trade-off between porosity and mechanical strength suggests a choice between Groups BC and BD, which are the best with regard to the porosity and mechanical strength criterium, respectively. Full article
(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)
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Article
Scanning Distance Influence on the Intraoral Scanning Accuracy—An In Vitro Study
Materials 2022, 15(9), 3061; https://doi.org/10.3390/ma15093061 - 22 Apr 2022
Cited by 4 | Viewed by 969
Abstract
Intraoral scanners (IOS) have reached a point where their impact in the dental office cannot be denied. The distance between the tip of the IOS and the preparation may have implications on the accuracy of the digital model. The objective of this study [...] Read more.
Intraoral scanners (IOS) have reached a point where their impact in the dental office cannot be denied. The distance between the tip of the IOS and the preparation may have implications on the accuracy of the digital model. The objective of this study was to evaluate the differences in accuracy between digital impressions in the scenario of different scanning distances. Twenty consecutive scans were performed at five predetermined distances: 5 mm, 10 mm, 15 mm, 20 mm and 23 mm by a single operator. The scanning distance of 10 mm displayed the best accuracy with an overall trueness value of 23.05 μm and precision value of 4.2 μm. The drawn conclusion was that increased scanning distances can decrease the accuracy of a digital impression. Full article
(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)
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Article
Novel Biocompatible Zr-Based Alloy with Low Young’s Modulus and Magnetic Susceptibility for Biomedical Implants
Materials 2020, 13(22), 5130; https://doi.org/10.3390/ma13225130 - 13 Nov 2020
Cited by 4 | Viewed by 1066
Abstract
The microstructure, mechanical properties, magnetic susceptibility, electrochemical corrosion performance, in vitro cell compatibility and blood consistency of Zr-16Nb-xTi (x = 0, 4, 8, 12 and 16 wt.%) materials were investigated as potential materials for biomedical implants. X-ray diffraction (XRD) and Transmission electron microscopy [...] Read more.
The microstructure, mechanical properties, magnetic susceptibility, electrochemical corrosion performance, in vitro cell compatibility and blood consistency of Zr-16Nb-xTi (x = 0, 4, 8, 12 and 16 wt.%) materials were investigated as potential materials for biomedical implants. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) analyses revealed the secondary phase martensite α’ formed during the quenching process. The phase composition contained metastable β and martensite α’, resulting from Ti addition. These phase constitutions were the main causes of a low Young’s modulus and magnetic susceptibility. The in vitro cytocompatibility analysis illustrated that the MG63 cells maintained high activity (from 91% to 97%) after culturing in Zr-16Nb-xTi extraction media for 12 days due to the high internal biocompatibility of Zr, Nb and Ti elements, as well as the optimal corrosion resistance of Zr-16Nb-xTi. On the basis of Inductively coupled plasma optical emission spectrometry (ICP-OES) ion release studies, the concentration of Zr, Nb and Ti was noted to reach the equipment detective limit of 0.001 mg/L, which was much lower than pure Ti. With respect to the corrosion behavior in Hank’s solution, Zr-16Nb-16Ti displayed superior properties, possessing the lowest corrosion current density and widest passivation region, attributed to the addition of Ti. The blood compatibility test illustrated that the Zr-16Nb-xTi materials were nonhemolytic, and the platelets maintained a spherical shape, with no aggregation or activation on Zr-16Nb-xTi. Overall, Ti addition has obvious effects on the developed Zr-16Nb-xTi alloys, and Zr-16Nb-4Ti exhibited low magnetic susceptibility, low modulus, good biocompatibility and proper corrosion properties, demonstrating the potential of use as implant biomaterials. Full article
(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)
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Article
Dental Diagnosis and Treatment Assessments: Between X-rays Radiography and Optical Coherence Tomography
Materials 2020, 13(21), 4825; https://doi.org/10.3390/ma13214825 - 28 Oct 2020
Cited by 20 | Viewed by 2204
Abstract
A correct diagnosis in dental medicine is typically provided only after clinical and radiological evaluations. They are also required for treatment assessments. The aim of this study is to establish the boundaries from which a modern, although established, imaging technique, Optical Coherence Tomography [...] Read more.
A correct diagnosis in dental medicine is typically provided only after clinical and radiological evaluations. They are also required for treatment assessments. The aim of this study is to establish the boundaries from which a modern, although established, imaging technique, Optical Coherence Tomography (OCT), is more suitable than the common X-ray radiography to assess dental issues and treatments. The most common methods for daily-basis clinical imaging are utilized in this study for extracted teeth (but also for other dental samples and materials), i.e., panoramic, intraoral radiography, and three-dimensional (3D) cone beam computed tomography (CBCT). The advantages of using OCT as an imaging method in dentistry are discussed, with a focus on its superior image resolution. Drawbacks related to its limited penetration depth and Field-of-View (FOV) are pointed out. High-quality radiological investigations are performed, measurements are done, and data collected. The same teeth and samples are also imaged (mostly) with an in-house developed Swept Source (SS)-OCT system, Master-Slave enhanced. Some of the OCT investigations employed two other in-house developed OCT systems, Spectral Domain (SD) and Time Domain (TD). Dedicated toolbars from Romexis software (Planmeca, Helsinki, Finland) are used to perform measurements using both radiography and OCT. Clinical conclusions are drawn from the investigations. Upsides and downsides of the two medical imaging techniques are concluded for each type of considered diagnosis. For treatment assessments, it is concluded that OCT is more appropriate than radiography in all applications, except bone-related investigations and periodontitis that demand data from higher-penetration depths than possible with the current level of OCT technology. Full article
(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)
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Article
Dental Adhesive Interfaces Reinforced with Magnetic Nanoparticles: Evaluation and Modeling with Micro-CT versus Optical Microscopy
Materials 2020, 13(18), 3908; https://doi.org/10.3390/ma13183908 - 04 Sep 2020
Cited by 10 | Viewed by 2081
Abstract
Dental adhesives are used in a wide range of applications, including to place direct composite restorations in frontal or posterior teeth. One of the most frequent causes for the failure of composite resin restorations is microleakages. The first aim of this work is [...] Read more.
Dental adhesives are used in a wide range of applications, including to place direct composite restorations in frontal or posterior teeth. One of the most frequent causes for the failure of composite resin restorations is microleakages. The first aim of this work is to introduce a new type of self-etched dental adhesive doped with magnetic nanoparticles (MPs) synthetized in the laboratory. The scope is to produce adhesives with a minimized width/thickness to decrease the risk of microleakages. The second aim is to assess the width/thickness of the adhesive layer in all the characteristic areas of the teeth using both the less precise but most common optical microscopy and the more accurate and volumetric micro-Computed Tomography (CT) investigations. Twenty extracted teeth have been divided into four groups: Group 1 includes ‘blank’ samples with adhesives that are not doped with MPs; Group 2 includes samples with adhesives doped with MPs; Groups 3 and 4 include samples with adhesives doped with MPs that are subjected to an active magnetic field for 5 and 10 min, respectively. Microscopy investigations followed by micro-CT and EDAX are performed on the adhesive. While a rather good agreement is obtained between the microscopy and micro-CT results, the capability of the latter to offer a full volumetric reconstruction of the layer is exploited to analyze the adhesion of the four considered dental materials. Thus, from micro-CT results the graphs of the surface areas as functions of the adhesive layer width are modeled mathematically, as well as the volume of sealants, for each of the four groups. To our knowledge, it is the first time that such a methodology is used. Characteristic parameters are extracted and the ascertainment of the optimal parameter that should be utilized for such assessments is discussed. The study demonstrates the adhesion improvement produced for Groups 3 and 4, where MPs are used. It also concludes that the magnetic field should be applied to the adhesive material for the longest possible exposure time (with a trade-off with the clinical duration of the treatment). Full article
(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)
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