Research

25 pages, 9653 KiB

Open AccessArticle

Controlling the Degradation Rate of Biodegradable Mg–Zn-Mn Alloys for Orthopedic Applications by Electrophoretic Deposition of Hydroxyapatite Coating

by Iulian Antoniac, Florin Miculescu, Cosmin Cotrut, Anton Ficai, Julietta V. Rau, Elena Grosu, Aurora Antoniac, Camelia Tecu and Ioan Cristescu

Materials 2020, 13(2), 263; https://doi.org/10.3390/ma13020263 - 07 Jan 2020

Cited by 38 | Viewed by 3723

Abstract

Magnesium alloys as bioresorbable materials with good biocompatibility have raised a growing interest in the past years in temporary implant manufacturing, as they offer a steady resorption rate and optimal healing in the body. Magnesium exhibits tensile strength properties similar to those of [...] Read more.

Magnesium alloys as bioresorbable materials with good biocompatibility have raised a growing interest in the past years in temporary implant manufacturing, as they offer a steady resorption rate and optimal healing in the body. Magnesium exhibits tensile strength properties similar to those of natural bone, which determines its application in load-bearing mechanical medical devices. In this paper, we investigated the biodegradation rate of Mg-Zn-Mn biodegradable alloys (ZMX410 and ZM21) before and after coating them with hydroxyapatite (HAP) via the electrophoretic deposition method. The experimental samples were subjected to corrosion tests to observe the effect of HAP deposition on corrosion resistance and, implicitly, the rate of biodegradation of these in simulated environments. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) provided detailed information on the quality, structure, and morphology of the HAP coating. The obtained results demonstrate that coating of Mg-Zn-Mn alloys by HAP led to the improvement of corrosion resistance in simulated environments, and that the HAP coating could be used in order to control the biodegradation rate. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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13 pages, 8263 KiB

Open AccessArticle

Investigation of the Microstructure, Hardness and Corrosion Resistance of a New 58Ag24Pd11Cu2Au2Zn1.5In1.5Sn Dental Alloy

by Dan Gheorghe, Ion Pencea, Iulian Vasile Antoniac and Ramona-Nicoleta Turcu

Materials 2019, 12(24), 4199; https://doi.org/10.3390/ma12244199 - 13 Dec 2019

Cited by 5 | Viewed by 1970

Abstract

Higher-noble dental alloys (Au, Ag, and Pd) are the most desirable for dentistry applications, but they are expensive. Low-noble (Ag, Pd, Cu) dental alloys are alternatives to higher-noble ones due to their lower price. In this regard, the paper supports the price lowering [...] Read more.

Higher-noble dental alloys (Au, Ag, and Pd) are the most desirable for dentistry applications, but they are expensive. Low-noble (Ag, Pd, Cu) dental alloys are alternatives to higher-noble ones due to their lower price. In this regard, the paper supports the price lowering of dental alloy by increasing the Cu content, i.e., a new 58Ag24Pd11Cu2Au2Zn1.5In1.5Sn dental alloy. The increasing addition of the Cu leads to a complex structure consisting of a solid solution that engulfs compounds of micrometric and nanometric sizes. The 58Ag24Pd11Cu2Au2Zn1.5In1.5Sn has demonstrated a much better electrochemical corrosion behavior in artificial saliva compared to the Paliag and Unique White dental alloys. The improved corrosion behavior of the new alloy is supported by the diminishing of the Cu selective diffusion into the electrolyte due to its retaining into compounds and into Ag-Pd solid solution. Also, the synergic effects of Cu, Zn, In, Sn may improve the corrosion resistance, but they have strengthened the 58Ag24Pd11Cu2Au2Zn1.5In1.5Sn matrix. The main finding addressed in the paper consists in a new 58Ag24Pd11Cu2Au2Zn1.5In1.5Sn dental alloy with improved corrosion resistance in artificial saliva. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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20 pages, 4372 KiB

Open AccessArticle

New Pre-reacted Glass Containing Dental Composites (giomers) with Improved Fluoride Release and Biocompatibility

by Loredana Colceriu Burtea, Cristina Prejmerean, Doina Prodan, Ioana Baldea, Mihaela Vlassa, Miuta Filip, Marioara Moldovan, Madalina-Anca Lazar (Moldovan), Aurora Antoniac, Vasile Prejmerean and Ioana Ambrosie

Materials 2019, 12(23), 4021; https://doi.org/10.3390/ma12234021 - 03 Dec 2019

Cited by 22 | Viewed by 3988

Abstract

The aim of the present work was to prepare a series of novel restorative giomers and investigate the morphology, the physico-chemical properties (residual monomer, fluoride release), and the cytotoxicity of the new materials. The experimental giomers were prepared as light-cured pastes by blending [...] Read more.

The aim of the present work was to prepare a series of novel restorative giomers and investigate the morphology, the physico-chemical properties (residual monomer, fluoride release), and the cytotoxicity of the new materials. The experimental giomers were prepared as light-cured pastes by blending different resin matrices comprising aromatic/aliphatic/urethane (di) methacrylates, with hybrid fillers containing pre-reacted glasses (PRGs), a radiopaque glass, and nano fluorhydroxyapatite. Polyalkenoic acids based on acrylic acid/itaconic acid/N-acryloyl -L-leucine modified or not with methacrylic groups, together with a superficially active glass, were used to prepare the PRGs. The fluoride ion release of the experimental giomers was investigated within a period of 60 days of storage in bidistilled water while using a fluoride ion selective electrode. Beautifil II commercial product was used as a reference. Cell cytotoxicity tests were done in vitro, in accordance with ISO 10993-122012 proceedings. Human dermal fibroblasts and umbilical endothelial vein cultures were used. The values that were obtained for cumulative fluoride release for all experimental giomers were higher than for the Beautifil II product, being more than twice the ones that were obtained for the commercial product after 60 days of storage in bidistilled water. The experimental biomaterials showed similar and/or better results when compared to the commercial one; this effect was maintained in all tested conditions. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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26 pages, 6224 KiB

Open AccessArticle

New Dental Implant with 3D Shock Absorbers and Tooth-Like Mobility—Prototype Development, Finite Element Analysis (FEA), and Mechanical Testing

by Avram Manea, Grigore Baciut, Mihaela Baciut, Dumitru Pop, Dan Sorin Comsa, Ovidiu Buiga, Veronica Trombitas, Horatiu Colosi, Ileana Mitre, Roxana Bordea, Marius Manole, Manuela Lenghel, Simion Bran and Florin Onisor

Materials 2019, 12(20), 3444; https://doi.org/10.3390/ma12203444 - 21 Oct 2019

Cited by 6 | Viewed by 4033

Abstract

Background: Once inserted and osseointegrated, dental implants become ankylosed, which makes them immobile with respect to the alveolar bone. The present paper describes the development of a new and original implant design which replicates the 3D physiological mobility of natural teeth. The first [...] Read more.

Background: Once inserted and osseointegrated, dental implants become ankylosed, which makes them immobile with respect to the alveolar bone. The present paper describes the development of a new and original implant design which replicates the 3D physiological mobility of natural teeth. The first phase of the test followed the resistance of the implant to mechanical stress as well as the behavior of the surrounding bone. Modifications to the design were made after the first set of results. In the second stage, mechanical tests in conjunction with finite element analysis were performed to test the improved implant design. Methods: In order to test the new concept, 6 titanium alloy (Ti6Al4V) implants were produced (milling). The implants were fitted into the dynamic testing device. The initial mobility was measured for each implant as well as their mobility after several test cycles. In the second stage, 10 implants with the modified design were produced. The testing protocol included mechanical testing and finite element analysis. Results: The initial testing protocol was applied almost entirely successfully. Premature fracturing of some implants and fitting blocks occurred and the testing protocol was readjusted. The issues in the initial test helped design the final testing protocol and the new implants with improved mechanical performance. Conclusion: The new prototype proved the efficiency of the concept. The initial tests pointed out the need for design improvement and the following tests validated the concept. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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8 pages, 3779 KiB

Open AccessArticle

Histological Change in Soft Tissue Surrounding Titanium Plates after Jaw Surgery

by Gabriel Armencea, Dan Gheban, Florin Onisor, Ileana Mitre, Avram Manea, Veronica Trombitas, Madalina Lazar, Grigore Baciut, Mihaela Baciut and Simion Bran

Materials 2019, 12(19), 3205; https://doi.org/10.3390/ma12193205 - 30 Sep 2019

Cited by 12 | Viewed by 2956

Abstract

The aim of this study was to evaluate the microscopic structure of soft tissue covering titanium plates and screws used in jaw surgery (mandible fracture and orthognathic surgery), after a minimum period of 12 months from insertion, and to quantify the presence of [...] Read more.

The aim of this study was to evaluate the microscopic structure of soft tissue covering titanium plates and screws used in jaw surgery (mandible fracture and orthognathic surgery), after a minimum period of 12 months from insertion, and to quantify the presence of any metallic particles. Periosteum covering the osteosynthesis plates was removed from 20 patients and examined by light microscopy in order to assess the cell morphological changes and the possibility of metal particles presence in the soft tissue. Local signs of tissue toxicity or inflammation were taken into consideration when evaluating the routine removal of titanium maxillofacial miniplates. No signs of screw loosening or acute inflammation were detected on the osteosynthesis site, but de-coloration of the periosteum was seen, and metallic particles were observed to have migrated into the soft tissues. Even if the titanium is well-tolerated by the human body in time, without severe local or general complications, our findings suggest that plate removal should be considered after bone healing has occurred. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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14 pages, 6665 KiB

Open AccessArticle

Toothpaste Composition Effect on Enamel Chromatic and Morphological Characteristics: In Vitro Analysis

by Alexandrina Muntean, Sorina Sava, Ada Gabriela Delean, Ana Maria Mihailescu, Laura Silaghi Dumitrescu, Marioara Moldovan and Dana Gabriela Festila

Materials 2019, 12(16), 2610; https://doi.org/10.3390/ma12162610 - 16 Aug 2019

Cited by 8 | Viewed by 4902

Abstract

The aim of this in vitro study was to assess the effect of toothpastes, with different compositions, on optical and morphological features of sound and demineralized enamel. We selected twenty-five teeth, recently extracted for orthodontic purposes, for this in vitro study. The teeth [...] Read more.

The aim of this in vitro study was to assess the effect of toothpastes, with different compositions, on optical and morphological features of sound and demineralized enamel. We selected twenty-five teeth, recently extracted for orthodontic purposes, for this in vitro study. The teeth were caries free, without stains, fissures, filling or hypoplasia observed at inspection under standard conditions. Teeth were brushed (for 2–3 min, twice a day, for 21 days), with five different toothpastes (four commercially available and an experimental one) containing fluoride and hydroxyapatite. After that, teeth were demineralized with 37% orthophosforic acid (Ultra Etch^®, Ultradent Products Inc., South Jordan, UT, USA) for 60 s. We repeated the brushing protocol for another 21 days on demineralized enamel. Enamel vestibular surfaces were examined using a spectrophotometer (Vita EasyShade -Vita Zahnfabrik, Bad Sackingen, Germany) and a Scanning Electron Microscope (Inspect S^®, FEI Company, Hillsboro, OR, USA). Differences were statistically significant for colour parameters L* and ΔE*. SEM evaluation reveals demineralized enamel mineral gain after brushing with selected toothpastes. Toothpastes with specific ingredients can represent a balance between aesthetic and mineralization, and an oral hygiene correct algorithm is able to preserve enamel characteristics during ortodontic treatement with fixed appliances. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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13 pages, 3291 KiB

Open AccessArticle

The Influence of Graphene in Improvement of Physico-Mechanical Properties in PMMA Denture Base Resins

by Cecilia Bacali, Mindra Badea, Marioara Moldovan, Codruta Sarosi, Vivi Nastase, Ioana Baldea, Radu Stefan Chiorean and Mariana Constantiniuc

Materials 2019, 12(14), 2335; https://doi.org/10.3390/ma12142335 - 23 Jul 2019

Cited by 47 | Viewed by 5115

Abstract

The clinical performances of dental materials depend on their mechanical profiles, determining their long-term deformation and wear resistance. This paper describes a study on the mechanical properties, water absorption and morphological properties of a polymethyl methacrylate (PMMA) resin enriched with graphene-silver nanoparticles (Gr-Ag). [...] Read more.

The clinical performances of dental materials depend on their mechanical profiles, determining their long-term deformation and wear resistance. This paper describes a study on the mechanical properties, water absorption and morphological properties of a polymethyl methacrylate (PMMA) resin enriched with graphene-silver nanoparticles (Gr-Ag). Two different concentrations—1 and 2 wt.%—of Gr-Ag were loaded into the PMMA material. For the mechanical characterization, the compression behavior, flexural strength and tensile strength were evaluated. Optical microscopy in polarized light and scanning electron microscopy were used for filler analysis. The filler addition led to an improvement in all mechanical properties, with slight changes being derived from the filler content variation. Gr-Ag use led to an increase in the applied maximum loads. Moreover, 1 wt.% Gr-Ag determined an increase of 174% in the modulus of rupture, which indicates high flexibility. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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14 pages, 1810 KiB

Open AccessArticle

Evaluation of the Degree of Conversion, Residual Monomers and Mechanical Properties of Some Light-Cured Dental Resin Composites

by Marioara Moldovan, Robert Balazsi, Andrada Soanca, Alexandra Roman, Codruta Sarosi, Doina Prodan, Mihaela Vlassa, Ileana Cojocaru, Vicentiu Saceleanu and Ioan Cristescu

Materials 2019, 12(13), 2109; https://doi.org/10.3390/ma12132109 - 30 Jun 2019

Cited by 91 | Viewed by 5282

Abstract

The novelty of this study consists in the formulation and characterization of three experimental dental composites (PM, P14M, P2S) for cervical dental lesion restoration compared to the commercial composites Enamel plus HRi® - En (Micerium S.p.A, Avengo, Ge, Italy), G-ænial Anterior® - Ge, [...] Read more.

The novelty of this study consists in the formulation and characterization of three experimental dental composites (PM, P14M, P2S) for cervical dental lesion restoration compared to the commercial composites Enamel plus HRi® - En (Micerium S.p.A, Avengo, Ge, Italy), G-ænial Anterior® - Ge, (GC Europe N.V., Leuven, Belgium), Charisma® - Ch (Heraeus Kulzer, Berkshire, UK). The physio-chemical properties were studied, like the degree of conversion and the residual monomers in cured samples using FTIR-ATR (attenuated total reflectance) and HPLC-UV (ultraviolet detection), as well as the evaluation of the mechanical properties of the materials. The null hypothesis was that there would be no differences between experimental and commercial resin composites regarding the evaluated parameters. Statistical analysis revealed that water and saliva storage induced significant modifications of all mechanical parameters after three months for all tested materials, except for a few comparisons for each type of material. Storage medium seemed not to alter the values of mechanical parameters in comparison with the initial ones for: diametral tensile strength (DTS-saliva for Ge and PM, compressive strength (CS)-water for Ch, DTS-water and Young’s modulus YM-saliva for P14M and YM-water/ saliva for P2S (p > 0.05). Two of the experimental materials showed less than 1% residual monomers, which sustains good polymerization efficiency. Experimental resin composites have good mechanical properties, which makes them recommendable for the successful use in load-bearing surfaces of posterior teeth. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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18 pages, 7939 KiB

Open AccessFeature PaperArticle

Failure Analysis of a Humeral Shaft Locking Compression Plate—Surface Investigation and Simulation by Finite Element Method

by Iulian Vasile Antoniac, Dan Ioan Stoia, Brandusa Ghiban, Camelia Tecu, Florin Miculescu, Cosmina Vigaru and Vicentiu Saceleanu

Materials 2019, 12(7), 1128; https://doi.org/10.3390/ma12071128 - 06 Apr 2019

Cited by 38 | Viewed by 7717

Abstract

A case study of a failed humeral shaft locking compression plate is presented, starting with a clinical case where failure occurred and an implant replacement was required. This study uses finite element method (FEM) in order to determine the failure modes for the [...] Read more.

A case study of a failed humeral shaft locking compression plate is presented, starting with a clinical case where failure occurred and an implant replacement was required. This study uses finite element method (FEM) in order to determine the failure modes for the clinical case. Four loading scenarios that simulate daily life activities were considered for determining the stress distribution in a humeral shaft locking compression plate (LCP). Referring to the simulation results, the failure analysis was performed on the explant. Using fracture surface investigation methods, stereomicroscopy and scanning electron microscopy (SEM), a mixed mode failure was determined. An initial fatigue failure occurred followed by a sudden failure of the plate implant as a consequence of patient’s fall. The fracture morphology was mostly masked by galling; the fractured components were in a sliding contact. Using information from simulations, the loading was inferred and correlated with fracture site and surface features. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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10 pages, 2885 KiB

Open AccessArticle

Investigations into Ti-15Mo-W Alloys Developed for Medical Applications

by Mihai Buzatu, Victor Geantă, Radu Ştefănoiu, Mihai Buţu, Mircea-Ionuţ Petrescu, Mihai Buzatu, Iulian Antoniac, Gheorghe Iacob, Florentina Niculescu, Ştefan-Ioan Ghica and Horaţiu Moldovan

Materials 2019, 12(1), 147; https://doi.org/10.3390/ma12010147 - 04 Jan 2019

Cited by 17 | Viewed by 3228

Abstract

The β-Ti alloys have attracted the attention of researchers due to their excellent properties and their remarkable biocompatibility. The present study evaluated the mechanical behavior analysis (hardness, compressive strength, and modulus of elasticity) of the Ti-15Mo-W system. For experimental research, we chose the [...] Read more.

The β-Ti alloys have attracted the attention of researchers due to their excellent properties and their remarkable biocompatibility. The present study evaluated the mechanical behavior analysis (hardness, compressive strength, and modulus of elasticity) of the Ti-15Mo-W system. For experimental research, we chose the TiMo15 biocompatible alloy as a starting material. In order to improve the mechanical properties, we added tungsten amounts of 3.88 to 12.20 wt.% and analyzed the results obtained. The successive melting of the samples was done using a vacuum arc furnace in a copper crucible cooled with water. Following micro-structural investigations, we found this alloy possessed a homogeneous structure and showed β-phase predominance. The investigated alloys have good mechanical properties—the mean Vickers micro-hardness values are between 251 to 321 HV, the compressive strength values range from 717 to 921 MPa, and the modulus of elasticity is between 17.86 and 45.35 GPa. These results are compatible to the requirements of a metallic material for medical applications as artificial implant devices. Full article

(This article belongs to the Special Issue Selected Papers from BIOMMEDD 2018 Conference—Biomaterials)

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