Esthetic Coatings Research Articles

Investigating the Incipient Dynamics of Nucleation and Growth in Electrodeposition: Uncovering Key Relationships for Strategic Exploitation

The objective of this study is to tailor the structure and properties of electrodeposited coatings through real-time parameter variations. Electrodeposition has been used for centuries to apply both functional and aesthetic coatings to a range of materials. This process is, in general, relatively simple, robust, and cost-effective for depositing films of one material onto another. These favorable characteristics though, have resulted in a deficiency in the fundamental understanding of time-dependent microstructural control and key relationships between process parameters and the resulting coating performance. The development of microelectronics and other devices that require increasingly tighter tolerances on coating deposition and performance, pushing the limits of what is currently achievable, has facilitated a resurgence in the advancement of electrodeposition technologies.While it is generally understood how changing parameters (e.g. potential, electrolyte composition, temperature, pH, etc.) affects the developing coating, much of this work has been done through empirical research and post-mortem correlations. Herein, we develop a methodology for tailoring coating structure (size, shape, and texture) to exploit different physical properties (hardness, ductility, electrical conductivity, etc.) of electrodeposited coatings through parameter variation and direct linkage to observable events and physical characteristics in real-time. Modern instruments such as transmission electron microscopy (TEM) and small-angle electron scattering (SAXS) theoretically have the ability to observe these phenomena, with both time and spatial resolution falling in range of physical requirements. However, few studies have developed or demonstrated these techniques for in-situ measurements.In this presentation, preliminary experiments utilizing nickel (Ni) and silver (Ag) salt electrolytes as model systems for the investigation of incipient nucleation and growth behavior of electrodeposited Ni and Ag coatings will be defined, as well as confirmation of SAXS as a complementary technique for characterizing island growth in the first stages of deposition. Electrochemical techniques including cyclic voltammetry and chronoamperometry were applied to study the nucleation mechanisms for these materials. Additionally, potentiostatic electrodeposition was used to deposit the nanoparticle islands. For this study, we artificially promoted instantaneous growth of the coating using an initial “seed” pulse, followed by a subsequent growth pulse. This serves to improve the monodispersity of the islands that are deposited on the substrate surface, simplifying the analysis of the initial SAXS measurements.Utilization of a laboratory-source SAXS and wide-angle x-ray scattering (WAXS) instrument for physical and chemical characterization of island growth allowed us to quickly characterize the deposited particles. A comparison of these measurements to equivalent SEM/EDS imaging of the samples for size, shape, number density, and elemental composition confirmation of the deposited particles will also be described. Additionally, we will briefly discuss the state of the literature and our current plans for transitioning these post-mortem experiments to in-situ measurements, allowing for time resolved data, directly observing nucleation and growth of electrodeposited coatings to be collected.

Assessment of Mutans Streptococci Adhesion on Different Esthetic Coatings of Nickel-Titanium (Niti) Archwires: An In Vitro Study

Plaque and enamel demineralization can occur when orthodontic archwires are present in the oral cavity because they provide a unique surface for bacterial adhesion. Bacterial biofilm plays a major role in the development of complications such dental caries and periodontal disease. The purpose of the study was to examine the effect that an esthetic surface coating of NiTi archwires would have on the adherence of mutans streptococci. Material and method: three types of coated NiTi archwires (rhodium, gold and flexy blue) and one uncoated NiTi archwire with round cross section 0.016 inch were tested in the current study. Five pieces of each types of archwire were incubated in phosphate-buffered saline for two hours. Then, these wire segments were immersed for 5, 90, and 180 minutes with mutans streptococci suspension to conduct the bacterial adhesion assay. Result: there were statistically significant differences in the degree to which bacteria adhered to the various archwires at each time interval, with the level of adhesion being statistically highest on the uncoated NiTi wire and the level being statistically lowest on the gold-coated NiTi wire (p < 0.05). The result showed that the highest bacterial adhesion in 180 min followed by 90 min and the lowest in 5 min. A positive correlation was detected between bacterial adhesion and incubation time. Conclusion: the esthetic surface coating were influence the biofilm adhesion on the archwires, gold coated significantly decrease mutans streptococci adhesion when compare with uncoated NiTi wire. Higher incubation time increased the number of bacterial adherence for all types of archwires.

Biofilm formation and Streptococcus mutans adhesion on different coated and noncoated nickel-titanium archwires: An in vitro study

Abstract Aim: The orthodontic archwires used in routine practice are coated with esthetic coatings to keep up with the aesthetic demand among patients seeking orthodontic treatment, which have been reported to increase the surface roughness (SR) of archwires and lead to an increase in bacterial and plaque accumulation. This in vitro study aims to compare the biofilm formation and bacterial adherence between esthetic coated and noncoated archwires. Material and Methods: This experimental in vitro study was conducted using three aesthetic coated and two noncoated nickel-titanium (NiTi) archwires (n = 5/group). The archwires were subjected to artificially cultured Streptococcus mutans broth followed by colony count assessment (CFU) and crystal violet staining assay to determine S. mutans adhesion and biofilm formation. Statistical analysis was performed using the SPSS software for inter-group and intra-group comparisons of CFU and biofilm formation (optical density) with one-way ANOVA with post hoc Tukey’s test and Mann–Whitney’s U test. Results: A significant difference in CFU/biofilm was observed at 3% sucrose concentration between the tested archwires (P = 0.029) and epoxy coated (Libral) archwire had higher S. mutans adhesion when compared to its noncoated counterpart (P = 0.035). The biofilm formation however showed no statistical difference between the tested archwires. Conclusion: A significant difference was noted in S. mutans adherence (CFU/biofilm) under 3% sucrose condition, with greater S. mutans adherence in epoxy coated archwire. In vivo use of aesthetic coated archwires is at a similar risk of biofilm accumulation as their noncoated counterparts.

Influence of Aesthetic Archwire Coatings on Bacterial Adhesion

Bacterial biofilm plays a key role in the development of complications in orthodontic treatment in the form of caries or periodontal disease. The coating of orthodontic archwires can affect their mechanical properties and their bactericidal properties. In connection with the growing interest in aesthetic archwires, it was examined whether aesthetic archwire coatings contribute to the reduction of bacterial adhesion. Based on the available literature, a review was conducted on the basis of the risk of bias (RoB) assessment and GRADE (Grading of Recommendations, Assessment, Development and Evaluations) analysis. The study took into account the results of research on different aesthetic archwire coatings. The analysis shows that there is a lack of homogeneity in the research results. The data on the different aesthetic coatings are inconclusive. On the basis of the data collected, it is impossible to determine whether aesthetic coatings reduce bacterial adhesion. Further studies, standardised in terms of research methods and statistical analysis, are needed to definitively establish whether aesthetic coatings influence bacterial adhesion.

Optical properties investigation of reactively sputtered tantalum oxynitride films

The coalescent behavior of metal oxide and metal nitride in metal oxynitride (MON) is making the material more conspicuous. Along with tunable optical properties, enhances mechanical properties, better chemical stability can be derived for MONs, which are of prime importance in the fields, such as photovoltaic, photo-chromatics, photocatalytic, protective and aesthetic coatings. In this paper, the optical properties of tantalum oxynitride thin film deposited through a reactive magnetron sputtering method were explored. Pure tantalum target was sputtered with argon gas in the presence of an optimized O2/N2 gas ratio. The chemical and physical properties of the film were investigated by X-ray diffraction technique, Scanning Electron Microscopy and AFM. Optical properties were explored with UV–visible spectroscopy and Spectroscopic Ellipsometry (SE). Transmittance and reflectance of the films show that the optical properties of the films have transparency (70–90%) and an absorption edge near 350 nm. For the analysis of SE data, the Tauc-Lorentz optical model with an additional Lorentz oscillator for semiconductor or insulator material were used. Here, the Ellipsometry technique has provided detailed optical nature of the film in terms of refractive index (n) ranging from 1.82 to 2.62, Energy Bandgap (Eg) 3.6 eV along with film thickness (∼200 nm) and surface roughness (∼6 nm).All these optical properties make the material a suitable candidate for antireflective coating, preparation of optical filters, photocatalytic agent, transparent coating for optical devices.

Color stability of esthetic coatings applied to nickel-titanium archwires

Abstract Introduction Color stability is an important feature to be considered when using esthetic coated archwires. Objective To evaluate color changes on the surface of esthetic nickel-titanium archwires coated with Teflon (Ortho Organizers, USA) or epoxy resin (Tecnident, Brazil) after immersion in staining solution. Material and method Twelve 20-mm-long wire segments were used for each type of coating, which were mounted as two test specimens with a width of 7 mm each. The buccal surface of the archwires was evaluated for fluorescence and color measurements both at baseline and after immersion in a staining solution for 21 days using the VITA Easyshade® Compact spectrophotometer (Model DEASYC220). Differences in total color change according to coating type were compared using an independent samples t-test (p<0.05). The surface characteristics of as-received coated archwires were assessed using scanning electron microscopy. Result Color changes were observed on the esthetic coatings, with a significant difference between the two brands analyzed. Surface analysis revealed flaws such as wear, pitting, elevations, lack of material, granulation, grooves, cracks, and lack of standardization in the coating process in all as-received archwires, but flaws were less evident in epoxy-resin coatings. Conclusion The two esthetic coatings did not show color stability, but Teflon coatings showed a more intense color change than epoxy-resin coatings.

Influence of aesthetic coating on the load-deflection ratio of nickel–titanium archwires

Aim: To assess the influence of aesthetic surface coating on load-deflection ratios in nickel-titanium (NiTi) orthodontic wires compared with uncoated wires. Methods: NiTi wires (0.016") from four different manufacturers (Morelli, Sorocaba, SP, Brazil; TP, La Porte, IN, USA; Eurodonto, Curitiba, PR, Brazil; Ortho Organizers, San Marcos, CA, USA) were divided into eight groups, according to presence or absence of coating: group 1, Morelli coated wire; group 2, Morelli uncoated; group 3, TP coated; group 4, TP uncoated; group 5, Eurodonto coated; group 6, Eurodonto uncoated; group 7, Ortho Organizers coated; group 8, Ortho Organizers uncoated. To determine the load-deflection ratio, a three-point bending test was performed in a AGS-X 250 KN (Shimadzu) universal testing machine. Results: The results showed that aesthetic coatings did not influence load-deflection ratio in NiTi orthodontic wires at 1-mm and 2-mm activation. However, comparison across the four tested brands revealed that Eurodonto coated wires exhibited the greatest force levels at 1-mm, 2-mm, and 3-mm deflection. At 3-mm deflection, Ortho Organizers coated wires exhibited lower force levels than all other tested brands, except for TP wires. Conclusions: We conclude that the load-deflection ratio of NiTi wires was not influenced significantly by aesthetic coatings, especially at lower activations.

Contemporary Esthetic Orthodontic Archwires - A Review

Growing demand of invisible braces byesthetically conscious patients has led to remarkable inventions in materials for esthetic labial archwires. Archwires with excellent optical clarity and mechanical properties comparable to conventional archwires have been manufactured by almost all the leading companies of orthodontic products in the past two decades, but their clinical use is still limited. Esthetic archwires can be divided into two main types, which are transparent non-metallic archwires (composite wires) and metallic wires with esthetic coatings. This article intends to provide an overview of various types of esthetic archwires available, and to gather evidence from the literature regarding their clinical applicability.

Color evaluation of a dielectric mirror coating using porcine tissue and prosthetic gingival material: a comparison of two models.

The aim of this study was to firstly evaluate the esthetics of a dielectric multilayer coating on titanium below porcine tissue (in vitro porcine model). Secondly, a polymer model was used to investigate the same samples to compare the models to each other and discuss their validity for optical assessment of esthetic coatings for implant applications. A dielectric mirror coating was deposited on titanium substrates (Ti- Bragg) and tested below porcine tissue and polymer platelets of three test thicknesses (1mm, 2mm and 3mm). Titanium without coating (Ti) was used as a negative control. Furthermore, the substrates were subjected to three different surface treatments (polished, machined and sand-blasted). The color difference values ΔL, Δa, Δb and ΔE were calculated for each sample. In total, six samples were tested in both models. Statistical analysis of the data (one sample Wilcoxon test, Kruskal-Wallis with Bonferroni-Holm corrected Mann-Whitney post hoc tests for multiple testing) was conducted for each sample in both evaluation methods. In the in vitro porcine model, sand-blasted Ti-Bragg and Ti samples showed ΔE values significantly above the threshold value of 3.70, indicating a dark appearance of the 1 mm thick covering tissue. As the test thickness increased, polished and machined Ti-Bragg samples were significantly invisible (ΔE<3.70 with P<0.05). Excessive brightening effects from Ti-Bragg samples were not observed from the in vitro porcine model, but below polymer platelets the samples exhibited significantly high ΔL values, which also resulted in a significant and visible color change (ΔE>>3.70 with P<0.05). Ti-Bragg was suggested to be an appropriate coating system for dental implants to improve the soft tissue esthetics. The design of this coating system can be adjusted by varying different parameters to satisfy the requirements of an esthetic coating. The polymer model is valid for test thicknesses of 2 and 3mm, however, one might have to increase the thickness to 1.5mm or alter the composition of the resin for 1mm thick platelets to increase the opacity and therefore adapt to the soft tissue situation.

In vitro color evaluation of esthetic coatings for metallic dental implants and implant prosthetic appliances.

The aim of this study was to characterize the optical properties of newly developed esthetic coatings for metallic implants and components for an improved peri-implant soft tissue appearance. Pig maxillae (n = 6) were used for the in vitro color evaluation of coated and uncoated samples. Three different coating systems (Ti-ZrO(2), Ti-Al-ZrO(2), and Ti-Ag-ZrO(2)) were deposited on titanium substrates, which exhibited different roughness (polished, machined, and sand-blasted) and interference colors (pink, yellow, and white). Spectrophotometric measurements were made of samples below three different mucosa thicknesses (1 mm, 2 mm, and 3 mm) and titanium served as negative control. Color difference ΔE was calculated using ΔL, Δa, and Δb values for each sample (in total 30 samples). ΔE values were significantly above the threshold value of 3.70 for sand-blasted Ti and Ti-ZrO(2) samples when tested below 1 mm thick soft tissue, hence resulted in a dark appearance of the soft tissues. In contrast, Ti-Al-ZrO(2) and Ti-Ag-ZrO(2) samples showed significant ΔL values below 1 mm, which indicates a brightening of the covering tissue. In general, ΔE values decreased with increasing thickness of the tissue. At 3 mm thick tissue, ΔE values were significantly below 3.70 for Ti-Al-ZrO(2) and Ti-Ag-ZrO(2) samples. The preferable substrate surface should be machined due increased color brightness, good soft tissue integration and improved adhesion between coating and substrates. Improvement of the optical appearance of the metal was achieved with the coating systems Ti-Al-ZrO(2) and Ti-Ag-ZrO(2). Darkening effects could not be observed for these systems, and partially light brightening of the tissue was observed. Advantageous colors were suggested to be pink and yellow.

Comparative short-term in vitro analysis of mutans streptococci adhesion on esthetic, nickel-titanium, and stainless-steel arch wires

To test the hypothesis that there are no differences in mutans streptococci (MS) adhesion between esthetic and metallic orthodontic arch wires based on their surface characteristics. Surface roughness (Ra) and apparent surface free energy (SFE) were measured for six wires-four esthetic, one nickel-titanium (NiTi), and one stainless-steel (SS)-using profilometry and dynamic contact angle analysis, respectively. The amount of MS (Streptococcus mutans and Streptococcus sobrinus) adhering to the wires was quantified using the colony-counting method. The surfaces, coating layers, and MS adhesion were also observed by scanning electron microscopy. Statistical significance was set at P < .05. The Ra values of the esthetic wires were significantly different from one another depending on the coating method (P < .05). The NiTi wire showed the highest SFE, followed by the SS wire and then the four esthetic wires. The NiTi wires produced a significantly higher MS adhesion than did the SS wires (P < .05). The esthetic wires showed significantly lower MS adhesions than did the NiTi wire (P < .05). Pearson correlation analyses found moderate significant positive correlations between the SFE and the S mutans and S sobrinus adhesions (r = .636/.427, P < .001/P = .001, respectively). The hypothesis is rejected. This study indicates that some esthetic coatings on NiTi alloy might reduce MS adhesion in vitro in the short term.

Aesthetic coatings for silver based alloys with improved protection efficiency

Ag-based alloy samples are submitted to innovative chemical and low pressure plasma treatments that lead to the deposition of aesthetic coatings with improved corrosion protection properties. The chemical treatments are carried out in alkaline dithionate solution in order to clean the surface and eventually remove the patina on aged samples, then the surface is protected by a Paraloid B72 coating containing different percentages of Al 2O 3 nanopigments. The plasma treatments are carried out by deposition of SiO x thin films in plasma fed with TEOS, Ar and O 2. Before the PECVD deposition, a glow discharge in a low pressure hydrogen plasma eventually removes tarnishing, reducing the corrosion products layer back to silver. The coating protective effectiveness is assessed by means of electrochemical impedance spectroscopy and accelerated ageing tests. The corrosion mechanism of the coated samples is investigated by XRD analyses. Both the chemical and the plasma treatments show satisfactory results from an aesthetic point of view and good barrier effect against aggressive environmental agents.

Mica pigments in solvent free coatings systems

Mica pigments are nowadays extensively used in different solvent containing paint systems, e.g. in automotive paints. Although water-borne coatings are gaining more and more importance, the need for even more environmentally safe to use coatings calls for coatings with less or even no solvents. To achieve this goal—no solvents—basically two technologies are used: one is powder coating, the other is radiation curing like UV- and electron beam-curable systems. Together with the need for more environmentally safe paint systems the consumer also requests highly esthetic coatings, especially concerning colour and effect. This paper describes how mica pigments, which are themselves environmentally safe and are used for high esthetic requirements, work in solvent free paint systems like powder coating and radiation-curable systems. Special attention is given to how mica pigments can be incorporated into powder coatings and what measures have to be taken to achieve an optimised effect. Concerning radiation, especially UV-curable systems, the advantages of mica pigments compared to other effect pigments are discussed.