Effect of inorganic fillers on the light transmission through traditional or flowable resin-matrix composites for restorative dentistry

Objectives: The aim of this in vitro study was to evaluate the light transmission through five different resin-matrix composites regarding the inorganic filler content. Methods: Resin-matrix composite disc-shaped specimens were prepared on glass molds. Three traditional resin-matrix composites contained inorganic fillers at 74, 80, and 89 wt. % while two flowable composites revealed 60 and 62.5 wt. % inorganic fillers. Light transmission through the resin-matrix composites was assessed using a spectrophotometer with an integrated monochromator before and after light curing for 10, 20, or 40s. Elastic modulus and nanohardness were evaluated through nanoindentation’s tests, while Vicker’s hardness was measured by micro-hardness assessment. Chemical analyses were performed by FTIR and EDS, while microstructural analysis was conducted by optical microscopy and scanning electron microscopy. Data were evaluated using two-way ANOVA and Tukey’s test (p < 0.05). Results: After polymerization, optical transmittance increased for all specimens above 650-nm wavelength irradiation since higher light exposure time leads to increased light transmittance. At 20- or 40-s irradiation, similar light transmittance was recorded for resin composites with 60, 62, 74, or 78–80 wt. % inorganic fillers. The lowest light transmittance was recorded for a resin-matrix composite reinforced with 89 wt. % inorganic fillers. Thus, the size of inorganic fillers ranged from nano- up to micro-scale dimensions and the high content of micro-scale inorganic particles can change the light pathway and decrease the light transmittance through the materials. At 850-nm wavelength, the average ratio between polymerized and non-polymerized specimens increased by 1.6 times for the resin composite with 89 wt. % fillers, while the composites with 60 wt. % fillers revealed an increased ratio by 3.5 times higher than that recorded at 600-nm wavelength. High mean values of elastic modulus, nano-hardness, and micro-hardness were recorded for the resin-matrix composites with the highest inorganic content. Conclusions: A high content of inorganic fillers at 89 wt.% decreased the light transmission through resin-matrix composites. However, certain types of fillers do not interfere on the light transmission, maintaining an optimal polymerization and the physical properties of the resin-matrix composites. Clinical significance: The type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization mode. As a consequence, the clinical performance of resin-matrix composites can be compromised, leading to variable physical properties and degradation. Graphical Abstract: [Figure not available: see fulltext.].info:eu-repo/semantics/publishedVersio

Effect of inorganic fillers on the light transmission through traditional or flowable resin-matrix composites for restorative dentistry

Objectives The aim of this in vitro study was to evaluate the light transmission through five different resin-matrix composites regarding the inorganic filler content. Methods Resin-matrix composite disc-shaped specimens were prepared on glass molds. Three traditional resin-matrix composites contained inorganic fillers at 74, 80, and 89 wt. % while two flowable composites revealed 60 and 62.5 wt. % inorganic fillers. Light transmission through the resin-matrix composites was assessed using a spectrophotometer with an integrated monochromator before and after light curing for 10, 20, or 40s. Elastic modulus and nanohardness were evaluated through nanoindentation’s tests, while Vicker’s hardness was measured by micro-hardness assessment. Chemical analyses were performed by FTIR and EDS, while microstructural analysis was conducted by optical microscopy and scanning electron microscopy. Data were evaluated using two-way ANOVA and Tukey’s test (p < 0.05). Results After polymerization, optical transmittance increased for all specimens above 650-nm wavelength irradiation since higher light exposure time leads to increased light transmittance. At 20- or 40-s irradiation, similar light transmittance was recorded for resin composites with 60, 62, 74, or 78–80 wt. % inorganic fillers. The lowest light transmittance was recorded for a resin-matrix composite reinforced with 89 wt. % inorganic fillers. Thus, the size of inorganic fillers ranged from nano- up to micro-scale dimensions and the high content of micro-scale inorganic particles can change the light pathway and decrease the light transmittance through the materials. At 850-nm wavelength, the average ratio between polymerized and non-polymerized specimens increased by 1.6 times for the resin composite with 89 wt. % fillers, while the composites with 60 wt. % fillers revealed an increased ratio by 3.5 times higher than that recorded at 600-nm wavelength. High mean values of elastic modulus, nano-hardness, and micro-hardness were recorded for the resin-matrix composites with the highest inorganic content. Conclusions A high content of inorganic fillers at 89 wt.% decreased the light transmission through resin-matrix composites. However, certain types of fillers do not interfere on the light transmission, maintaining an optimal polymerization and the physical properties of the resin-matrix composites. Clinical significance The type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization mode. As a consequence, the clinical performance of resin-matrix composites can be compromised, leading to variable physical properties and degradation.Open access funding provided by FCT|FCCN (b-on). This work was supported by FCT (Portugal) in the subject of the following project: PTDC/EMEEME/4197/2021; by CAPES regarding the following projects: CAPES-PRINT/88881.310728/2018–01; and CAPESHUMBOLDT Program (grant number 88881.197684/2018–01). S.C. thanks FCT for her contract funding provided through 2020.00215. CEECIND

Embry-Riddle Fly Paper 1943-01-15

https://commons.erau.edu/fly-paper/1159/thumbnail.jp

Bone Tissue Response to Porous and Functionalized Titanium and Silica Based Coatings

Background: Topography and presence of bio-mimetic coatings are known to improve osseointegration. The objective of this study was to evaluate the bone regeneration potential of porous and osteogenic coatings. Methodology: Six-implants [Control (CTR); porous titanium coatings (T1, T2); thickened titanium (Ti) dioxide layer (TiO2); Amorphous Microporous Silica (AMS) and Bio-active Glass (BAG)] were implanted randomly in tibiae of 20-New Zealand white rabbits. The animals were sacrificed after 2 or 4 weeks. The samples were analyzed histologically and histomorphometrically. In the initial bone-free areas (bone regeneration areas (BRAs)), the bone area fraction (BAF) was evaluated in the whole cavity (500 mm, BAF-500), in the implant vicinity (100 mm, BAF-100) and further away (100–500 mm, BAF-400) from the implant. Bone-to-implant contact (BIC-BAA) was measured in the areas where the implants were installed in contact to the host bone (bone adaptation areas (BAAs)) to understand and compare the bone adaptation. Mixed models were used for statistical analysis. Principal Findings: After 2 weeks, the differences in BAF-500 for different surfaces were not significant (p.0.05). After 4 weeks, a higher BAF-500 was observed for BAG than CTR. BAF-100 for AMS was higher than BAG and BAF-400 for BAG was higher than CTR and AMS. For T1 and AMS, the bone regeneration was faster in the 100-mm compared to the 400-mm zone. BIC-BAA for AMS and BAG was lower after 4 than 2 weeks. After 4 weeks, BIC-BAA for BAG was lower than AMS and CTR. Conclusions: BAG is highly osteogenic at a distance from the implant. The porous titanium coatings didn’t stimulate bone regeneration but allowed bone growth into the pores. Although AMS didn’t stimulate higher bone response, it has a potential of faster bone growth in the vicinity compared to further away from the surface. BIC-BAA data were inconclusive to understand the bone adaptation.status: publishe

Development of Biofunctional Porous Coatings for Bone Implants (Ontwikkeling van biofunctionele poreuze deklagen voor botimplantaten)

The application of orthopaedic and dental implants has revolutionised th e medical treatment of degenerative bone diseases, restoring compromised body functions and quality of life of many. However, despite the vast i mprovements realised during the past decades, implant failure still occu rs, leading to painful and costly revision surgery. The most prominent c auses of failure are implant loosening and infection. Therefore, current implantology research is focusing on strategies to improve implant fixa tion and/or reduce the incidence of infections. A key requirement for a long-term implant fixation is osseointegration, i.e. a direct implant/bo ne contact (without an intervening fibrous tissue layer) maintaining a r igid fixation of the implant during functional loading. Regarding implan t-related infections, which are usually of bacterial etiology, the impla nt should ideally be resistant to bacterial colonisation. From a mat erial s perspective, the events at the implant/bone interface are mainly being mediated by the implant surface topography and chemistry and it i s generally hypothesised that by tuning the surface properties, it is fe asible to control the biological response. Titanium and its alloys, whic h are widely applied as implant materials for load-bearing applications, because of an excellent biocompatibility in combination with a high str ength, are capable of osseointegration under optimised conditions. To fu rther improve the integration in the host bone, porous Ti coatings are o f special interest, because these allow establishing a firm interlocking with the surrounding tissue by ingrowth of bone into the porous structu re. Alternatively, chemical modification or functionalisation of the oth erwise inert Ti surface in order to improve its osteoconductive an d osteoinductive behaviour is also widely investigated. Bioactive glasse s or glass-ceramics are often proposed as coating materials, because of their ability to chemically bond to bone, strengthening the interface be tween implant and host bone, and an osteostimulatory effect enabling fas ter regeneration of bone tissue surrounding the implant. This doctor al research focuses on the development of porous Ti coatings on Ti or Ti -6Al-4V substrates whether or not in combination with a bioactive glass- ceramic surface layer on the internal pore walls. The main objective of this thesis is a qualitative investigation of the relationship between m icrostructure and biological outcome regarding osseointegration and bact erial colonisation. Therefore, after establishing the various coating pr ocesses, a biological screening in comparison to several clinically rele vant reference surfaces is performed, addressing in vitro bacteria l attachment, in vitro cytocompatibility and in vivo bone re sponse. A new powder metallurgical processing route for the production of porous pure Ti coatings on Ti or Ti-6Al-4V is established. By the electrophore tic deposition of various grades of TiH2 powders followed by dehydrogena tion and sintering in high vacuum, porous Ti coatings with varying thick ness, pore morphology, and surface roughness can be obtained. Adhesion s trengths over 100% higher than for a state-of-the-art vacuum plasma spra yed porous Ti reference coating can be obtained. Moreover, in comparison to more conventional processing routes applying pure Ti powders, the us e of hydrides allows lowering the sintering temperature below that of th e alfa-ß transition of the Ti-6Al-4V substr ate, preserving the original microstructure and concomitant mechanical p roperties.Electrophoretic deposition in water-free electrolytes is a lso shown to be a valuable tool in the application of melt derived bioac tive glass-ceramic coatings on dense Ti or Ti-6Al-4V substrates. By coup ling the Ti alloys as cathode and in combination with a high vacuum sint ering atmosphere, uncontrolled oxidation of the Ti at the substrate/glas s interface can be avoided, resulting in a good mechanical strength and strong adhesion of the coatings to the substrate. Both sodium free a nd sodium containing bioactive glass-ceramic coatings inside porous Ti c oatings are synthesised following an all-alkoxide sol-gel approach. Thro ugh vacuum assisted impregnation of the porous coatings with the sol fol lowed by spinning and heat treatment in vacuum, the internal pore surfac e is coated with a fragmented micrometre thin layer of bioactive glass-c eramic, while the original open pore structure is preserved. An in vitro investigation of the bacterial surface colonisation, w hich can be related with an implant s susceptibility to infections, is p erformed for Staphylococcus aureus and Staphylococcus epidermid is, the two bacteria strains most commonly associated with prosthetic joint infections. Bacterial colonisation is found to linearly correlate with the average surface roughness (Sa) for pure Ti or Ti alloy s urfaces. Hence, experimental porous Ti coatings exhibit a strongly reduc ed bacterial colonisation in comparison to a state-of-the-art porous vac uum plasma sprayed Ti coating. Increasing the porosity while maintaining the average roughness level favours again the strong tendency of bacter ia to accumulate in the open surface pores. On the other hand, for chemi cally modified Ti surfaces with increased hydrophilicity, a trend toward s a decreased bacterial colonisation is seen. So, as an enhanced osseoin tegration capacity (increased porosity, pore size,. . . ) inherently inc reases the bacterial colonisation, surface modification of the porous Ti to reduce bacterial adhesion is essential. In vitro cytocompatibility testing reveals an advanced osteoblast differentiation for the experimental porous Ti coatings when compared to various state-of-the-art dense and porous Ti surfaces, highlighting a p otential advantage when envisaging faster osseointegration.In viv o experimentation focusing on the early peri-implant bone formation i n a rabbit model demonstrates bone ingrowth into the porous Ti coatings, shifting the generally accepted lower threshold value for bone ingrowth from 50 &#956;m to the microporosity range below 10 &#956;m . Moreover, ingrown bone displays well-established interconnections to t he surrounding cortical bone, emphasising the potential of these porous coatings for the micro-interlocking of an implant into the host bone. In addition, the in vivo results confirm the osteostimulatory effect of bioactive glass-ceramic coatings. Both a melt derived bioactive glas s-ceramic coating on a dense cp Ti substrate and a sol-gel derived bioac tive glass-ceramic coating in a porous Ti coating significantly enhance bone regeneration with 30% and 70% respectively when compared to the ori ginal Ti substrates.nrpages: 275status: publishe

Electrophoretic deposition of porous Ti coatings for bone implants: in vitro and in vivo evaluation

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Alternating current electrophoretic deposition (AC-EPD) of biomolecule coatings

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Albumin coatings by alternating current electrophoretic deposition for improving corrosion resistance and bioactivity of titanium implants

Although Ti alloys are generally regarded to be highly corrosion resistant, inflammatory conditions following surgery can instigate breakdown of the TiO2 passivation layer leading to an increased metal ion release. Furthermore proteins present in the surrounding tissue will readily adsorb on a titanium surface after implantation. In this paper alternating current electrophoretic deposition (AC-EPD) of bovine serum albumin (BSA) on Ti6Al4V was investigated in order to increase the corrosion resistance and control the protein adsorption capability of the implant surface. The Ti6Al4V surface was characterized with SEM, XPS and ToF-SIMS after long-term immersion tests under physiological conditions and simulated inflammatory conditions either in Dulbecco´s Modified Eagle Medium (DMEM) or DMEM supplemented with fetal calf serum (FCS). The analysis showed an increased adsorption of amino acids and proteins from the different immersion solutions. The BSA coating was shown to prevent selective dissolution of the vanadium (V) rich β-phase, thus effectively limiting metal ion release to the environment. Electrochemical impedance spectroscopy measurements confirmed an increase of the corrosion resistance for BSA coated surfaces as a function of immersion time due to the time-dependent adsorption of the different amino acids (from DMEM) and proteins (from FCS) as observed by ToF-SIMS analysis.publisher: Elsevier articletitle: Albumin coatings by alternating current electrophoretic deposition for improving corrosion resistance and bioactivity of titanium implants journaltitle: Materials Science and Engineering: C articlelink: http://dx.doi.org/10.1016/j.msec.2016.12.129 content_type: article copyright: © 2017 Elsevier B.V. All rights reserved.status: publishe

Biomaterials in temporomandibular joint replacement: current status and future perspectives – a narrative review

The alloplastic total temporomandibular joint (TMJ) prosthesis has a long history, with many different materials and designs used. While several of these materials have proven valuable over time, many others have not been suitable for implantation, resulting in failure and the need for explantation of the implant. Because of the failure of several of these systems, the use of alloplastic prostheses has reduced dramatically, despite their advantages over autogenous restoration. The aim of this narrative review is to discuss the criteria that must be met by a biomaterial in order for it to be considered suitable for implantation, as well as the common complications that can occur. Currently used materials are highlighted, as well as potential future materials that might prove better suitable for implantation. Several surface modification techniques are proposed as an alternative to the materials used in current TMJ prosthesis systems.status: publishe

Alternating current electrophoretic deposition of bovine serum albumin onto magnesium

© (2015) Trans Tech Publications, Switzerland. Magnesium and magnesium alloys are gaining considerable attention for use in biomedical applications due to their capability to completely resorb in the human body without noticeable side effects. For structural biomedical applications however, the resorption rate is too large. In order to decrease this rate researchers are investigating magnesium alloys with an increased corrosion resistance and/or biodegradable coatings, such as dense protein layers, which retard the resorption. In this work, we demonstrate the electrophoretic deposition of Bovine Serum Albumin (BSA) directly onto pure magnesium substrates using unbalanced alternating fields (AC-EPD). The effect of the obtained coatings on the corrosion behavior of the substrates was evaluated by potentiodynamic polarization. The results show that an albumin layer deposited by AC-EPD from a 50/50 ethanol/H2O medium significantly reduces the corrosion rate.status: publishe