Protection Of Enamel Research Articles

In vitro assessment of NaF/Chit supramolecular complex: Colloidal stability, antibacterial activity and enamel protection against S. mutans biofilm

ObjectivesThis study assessed the effect of NaF/Chit suspensions on enamel and on S. mutans biofilm, simulating application of a mouthrinse. MethodsThe NaF/Chit particle suspensions were prepared at molar ratio [NaF]/Chitmon]≈0.68 at nominal concentrations of 0.2 % and 0.05 % NaF and characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering and zeta potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. The S. mutans biofilm was formed for 7 days on eighty human enamel blocks that were divided into eight groups (n = 10/group): i) 0.05 % NaF solution; ii) 0.31 % Chit solution; iii) NaF/Chit(R=0.68) suspension at 0.05 % NaF; iv) 1.0 % HAc solution (Control); v) 0.2 % NaF solution; vi) 1.25 % Chit solution; vii) NaF/Chit(R=0.68) suspension at 0.2 % NaF; viii) 0.12 % chlorhexidine digluconate. The substances were applied daily for 90 s. S. mutans cell counts (CFU/mL) were performed, and the Knoop microhardness (KHN) of enamel samples were measured before and after biofilm formation. The KHN and CFU/mL data were analyzed by repeated measure ANOVA and Tukey's test (α = 0.05). ResultsInteractions between NaF and Chit were evidenced in solid state by FTIR spectra. The NaF/Chit complexes showed spontaneous microparticle formation and colloidal stability. The MIC and MBC ranged from 0.65 to 1.31 mg/mL. The NaF/Chit(R=0.68) suspension at 0.2 %NaF Group showed lower CFU/mL values than other groups. The NaF/Chit(R=0.68) suspensions Groups had the highest KHN values after biofilm formation. ConclusionsThe NaF/Chit(R=0.68) complexes exhibited an antibacterial effect against S. mutans biofilm and reduced the enamel hardness loss. Clinical significanceThe NaF/Chit(R=0.68) suspensions showed potential to be used as a mouthrinse for caries prevention.

Antithrombotic and anticariogenic activity of peptide fractions from cowpea (Vigna unguiculata) protein hydrolysates.

Protein-derived peptide fractions can play a key role in the physiological and metabolic regulation and modulation of the body, which suggests that they could be used as functional ingredients to improve health and to reduce the risk of disease. This work aimed to evaluate the in vitro antithrombotic and anticariogenic bioactivity of hydrolysates and protein fractions obtained from cowpea (Vigna unguiculata) by biocatalysis. Cowpea protein concentrate was hydrolyzed by sequential action with two enzyme systems, Pepsin-Pancreatin or Alcalase-Flavourzyme. There was extensive enzymatic hydrolysis, with degrees of hydrolysis of 34.94% and 81.43% for Pepsin-Pancreatin and Alcalase-Flavourzyme, respectively. The degree of hydrolysis for the control treatments, without the addition of the enzymes Pepsin-Pancreatin and Alcalase-Flavourzyme was 1.1% and 1.2%, respectively. The hydrolysates were subjected to fractionation by ultrafiltration, with five cut-off points according to molecular weight (<1, 1-3, 3-5, 5-10 and >10 kDa). The Alcalase-Flavourzyme hydrolysate led to 100% inhibition of platelet aggregation, while the Pepsin-Pancreatin hydrolysate showed 77.41% inhibition, but this was approximately 100% in the ultrafiltered fractions. The highest anticariogenic activity was obtained with the Pepsin-Pancreatin system, with 61.55% and 56.07% for calcium and phosphorus demineralization, respectively. Hydrolysates and their peptide fractions from Vigna unguiculata exhibited inhibition of platelet aggregation and protection of tooth enamel and have the potential for use in the development of functional products with beneficial health effects. © 2024 Society of Chemical Industry.

Hydrated Calcium Silicate in Resin Composites for Prevention of Secondary Caries

Introduction and aimsThe gaps at the margins of restorative composite resin can increase as the carious process occurs underneath the materials, causing further demineralization along the tooth cavity wall. The aim of this study was to evaluate the effects of restorative resin composite containing hydrated calcium silicate (hCS) filler on enamel protection against demineralization by simulating microleakage between the test material and teeth in a cariogenic environment. MethodsThe experimental resin composites were composed of 70 wt.% filler, which was mixed with a glass filler and hCS in a weight ratio of 70.0% glass (hCS 0), 17.5% hCS + 52.5% glass (hCS 17.5), 35.0% hCS + 35.0% glass (hCS 35.0), and 52.5% hCS + 17.5% glass (hCS 52.5). A light-cured experimental resin composite disk was positioned over a polished bovine enamel disk, separated by a 30-µm gap, and immersed in artificial saliva with pH 4.0 for 15, 30, and 60 days. After the immersion period, the enamel disk was separated from the resin composite disk and evaluated using a microhardness tester, atomic force microscopy, and polarized light microscopy. The opposing sides of the enamel and resin composite disks were observed using scanning electron microscopy/energy dispersive X-ray spectrometry. ResultsThe enamel surface showed a significant increase in microhardness, decreased roughness, and remineralization layer as the proportion of hCS increased (P < .05). In the scanning electron microscopy image, the enamel surface with hCS 35.0 and 52.5 after all experimental immersion periods, showed a pattern similar to that of a sound tooth. ConclusionsThe results demonstrated that increasing the hCS filler level of restorative resin composites significantly decreased enamel demineralization. Clinical relevanceHydrated calcium silicate laced restorative resin composites may be a promising dental biomaterial for protecting teeth against demineralization and preventing secondary caries around restorations.

Stain removal, abrasion and anticaries properties of a novel low abrasion dentifrice containing micro-fibrillated cellulose: in vitro assessments

ObjectivesThis laboratory study assessed the performance of a novel fluoride dentifrice containing micro-fibrillated cellulose (MFC) and entrapped silica. MethodsRemoval of extrinsic stains was assessed using the pellicle cleaning ratio (PCR) method, and radioactive dentin abrasivity (RDA) was measured, to calculate a cleaning efficiency index (CEI). Fluoride efficacy was evaluated using widely used remineralization and fluoride uptake methods. The test product (Protegera™) was compared to common dentifrices (Crest - Cavity Protection™ and ProHealth™, Sensodyne Pronamel™, Arm & Hammer™ Advanced Whitening, Crest ProHealth™, and Colgate Optic White™). ResultsThe PCR for the MFC dentifrice (141) was comparable to three known marketed stain-removing dentifrices (Arm & Hammer™ Advanced Whitening, Crest ProHealth™, and Colgate Optic White™) but it had a significantly lower RDA (88 ± 6) than 5 other products. This gave it the highest CEI of the tested products (2.0). In a 10-day pH cycling study, the fluoride efficacy of the MFC product was comparable to Sensodyne Pronamel and Crest Cavity Protection. The MFC dentifrice was superior for promoting fluoride uptake into incipient enamel lesions compared to the USP reference dentifrice. ConclusionThe MFC dentifrice has low abrasion, but despite this, it is highly effective in removing stained pellicle. It also is an efficacious fluoride source when compared to relevant commercially available fluoride dentifrices with high dentin abrasivity. Clinical significanceThe addition of micro-fibrillated cellulose to a fluoride dentifrice gives a low abrasive product that can effectively remove external stains, and serve as an effective fluoride source. This combination of benefits seems well suited to enamel protection and caries prevention.

A new role for resveratrol: Protection of enamel against erosion

ObjectiveThe aim of this study was to determine the effect of different concentrations of resveratrol in protecting enamel against initial dental erosion in vitro. MethodsNinety bovine enamel samples (4 × 4 mm) were divided into six groups: Phosphate buffered saline (negative control; PBS), Commercial solution (Elmex Erosion Protection™; positive control) and resveratrol at 4 different concentrations (1, 10, 100 or 400 µg/mL). Initially, the samples were incubated in saliva for the formation of the acquired pellicle (250 µL, 1 h, 37 °C, 250 rpm). Afterward, the samples were incubated in the respective treatments (250 µL, 1 min, 37 °C, 250 rpm) and then reincubated in saliva (250 µL, 1 h, 37 °C, 250 rpm). Finally, the samples were subjected to an erosive challenge by incubating in 1 % citric acid (1 mL, pH 3.5, 1 min, 25 °C, 250 rpm). The percentage surface microhardness change (% SMC) was assessed using a microhardness tester. Data were analyzed by Kruskal-Wallis and Dunn's tests (p < 0.05). ResultsThe treatments with Elmex™ and resveratrol (1, 10 and 100 µg/mL) significantly protected enamel compared to the negative control, without significant differences among them. However, the group treated with the highest resveratrol concentration (400 µg/mL) did not show a significant difference from the negative control. ConclusionsResveratrol at concentrations ranging from 1 to 100 µg/ml was effective in preventing loss of enamel surface microhardness. Clinical significanceThis result suggests a potential new direction for the development of dental products based on resveratrol for the prevention of dental erosion.

THE USE OF XYLITOL IN PERIODONTAL TREATMENT. CASE REPORT

Periodontal treatment is an important branch of dentistry that deals with the diagnosis and treatment of periodontal diseases, which affect the supporting tissues of the teeth. These diseases include gingivitis and periodontal disease, both having an impact on the patient's oral and general health. Over time, researchers and dentists have made significant progress in understanding and treating these conditions, and this article explores the evolution of this fascinating field. The use of xylitol in periodontal diseases has been the subject of a significant number of studies and research. Xylitol is a natural sweetener that has beneficial effects on oral health. Below are some important conclusions from studies to date: Reduced bacterial plaque formation: Xylitol has demonstrated the ability to inhibit the formation of bacterial plaque, especially cariogenic bacteria, such as Streptococcus mutants. By reducing plaque formation, xylitol can help prevent the onset and progression of periodontal disease. Antibacterial and anti-inflammatory effects: Xylitol has antibacterial properties, helping to combat the growth of pathogenic bacteria in the oral cavity. Xylitol has also been observed to have anti-inflammatory effects, reducing gingival inflammation associated with periodontal disease. Remineralization and protection of dental enamel: Regular consumption of xylitol can contribute to the remineralization of dental enamel and increase its resistance to the action of acid. By protecting the enamel, xylitol can help prevent cavities and dental injuries that can aggravate periodontal disorders.

Improved Enamel Protection by Laser/Silver Nanoparticles Combination

Modern Research in Dentistry Improved Enamel Protection by Laser/Silver Nanoparticles Combination Walid K Hamoudi* Department of Optic Techniques, Iraq *Corresponding author: Walid K Hamoudi, Department of Optic Techniques, Baghdad,Iraq Submission: December 10, 2021;Published: August 19, 2022 DOI: 10.31031/MRD.2022.07.000665 ISSN:2637-7764Volume7 Issue3

Microbial Poly-γ-Glutamic Acid (γ-PGA) as an Effective Tooth Enamel Protectant.

Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, non-immunogenic nylon-like polymer with the biochemical characteristics of a polypeptide. This Bacillus-derived material has great potential for a wide range of applications, from bioremediation to tunable drug delivery systems. In the context of oral care, γ-PGA holds great promise in enamel demineralisation prevention. The salivary protein statherin has previously been shown to protect tooth enamel from acid dissolution and act as a reservoir for free calcium ions within oral cavities. Its superb enamel-binding capacity is attributed to the L-glutamic acid residues of this 5380 Da protein. In this study, γ-PGA was successfully synthesised from Bacillus subtilis natto cultivated on supplemented algae media and standard commercial media. The polymers obtained were tested for their potential to inhibit demineralisation of hydroxyapatite (HAp) when exposed to caries simulating acidic conditions. Formulations presenting 0.1, 0.25, 0.5, 0.75, 1, 2, 3 and 4% (w/v) γ-PGA concentration were assessed to determine the optimal conditions. Our data suggests that both the concentration and the molar mass of the γ-PGA were significant in enamel protection (p = 0.028 and p < 0.01 respectively). Ion Selective Electrode, combined with Fourier Transform Infra-Red studies, were employed to quantify enamel protection capacity of γ-PGA. All concentrations tested showed an inhibitory effect on the dissolution rate of calcium ions from hydroxyapatite, with 1% (wt) and 2% (wt) concentrations being the most effective. The impact of the average molar mass (M) on enamel dissolution was also investigated by employing commercial 66 kDa, 166 kDa, 440 kDa and 520 kDa γ-PGA fractions. All γ-PGA solutions adhered to the surface of HAp with evidence that this remained after 60 min of continuous acidic challenge. Inductively Coupled Plasma analysis showed a significant abundance of calcium ions associated with γ-PGA, which suggests that this material could also act as a responsive calcium delivery system. We have concluded that all γ-PGA samples tested (commercial and algae derived) display enamel protection capacity regardless of their concentration or average molar mass. However, we believe that γ-PGA D/L ratios might affect the binding more than its molar mass.

Pellicle modification with natural bioproducts: Influence on tooth color under erosive conditions.

Salivary pellicle was modified with bioproducts and we assessed the change in tooth color and the protection of enamel to erosion. Human enamel specimens were assigned to one of three solutions: grape seed extract or black tea (bioproducts), or deionized water (negative control); after which one half the specimens underwent erosive challenges. The specimens underwent 15 cycles involving salivary pellicle formation (10min, 37°C), incubation in solution (2min, 25°C), subsequent pellicle formation (90min, 37°C). Half of the specimens was kept in a humid chamber and the other half was submitted to erosion (2min, 1% citric acid). After 15 such cycles, the pellicle was removed. Tooth color and the surface reflection intensity were assessed after every five cycles and after pellicle removal. For non-eroded specimens, the exposure to bioproducts promoted significantly greater color change than the deionized water, with increases in yellow appearance. After pellicle removal, the color was similar in all non-eroded specimens. The bioproducts increased the surface reflection intensity over cycles. For the erosion-exposed specimens, erosion itself resulted in color change. Black tea and deionized water resulted in increased yellow appearance. Exposure to the bioproducts resulted in higher relative surface reflection intensity values over time, but only grape seed extract resulted in higher relative surface reflection intensity value at the time of pellicle removal. The bioproducts caused transient staining effect, which was reduced after pellicle removal. For enamel submitted to erosion, grape seed extract resulted in less color change and better protection of enamel against erosion than black tea or water.

Barniz polimerizable de vidrio ionómero modificado con resina “Clinpro XT”: una alternativa de tratamiento para la sensibilidad dentaria. Revisión sistemática de la literatura

Introduction: In response to dentin sensitivity, multiple products have been developed, including Clinpro XT, a lightcuring resin-modified ionomer glass varnish with fluoride, calcium andphosphate.Methodology: A systematic review of the literature was carried out. The selection was based on title, abstract and full text according to the inclusion and exclusioncriteria.Results: Of 299 articles, systematic reviews, meta-analysis, in vivo and in vitro studies and 2 surveys were selected.Discussion: Clinpro XT reduces dentin permeability, occludes dentin tubules andinhibits their reopening, increases the bioavailability of minerals in saliva andpromotes enamel remineralization.Meaning greater protection of enamel and dentin immediately and in the long term.Conclusions: Clinpro XT was shown todecrease dentin hypersensitivity even 6 months after application.

Nanosized calcium deficient hydroxyapatites for tooth enamel protection.

Calcium phosphates (CaP) are extensively studied as additives to dental care products for tooth enamel protection against caries. However, it is not clear yet whether substituted CaP could provide better enamel protection. In this study we produced, characterized and tested in vitro substituted and co‐substituted calcium deficient hydroxyapatite (CDHAp) with Sr2+ and F− ions. X‐ray powder diffractometry, Fourier transformation infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray analysis, Brunauer–Emmett–Teller were used to characterize synthesized powders and also cytotoxicity was evaluated. pH = f(t) test was performed to estimate, weather synthesized CDHAp suspensions are able to increase pH of experimental media after acid addition. Synthesis products were incorporated into paste to perform in vitro remineralization on the bovine enamel. In addition to mentioned instrumental methods, profilometry was used for evaluation of remineralised enamel samples. The obtained results confirmed formation of CDHAp substituted with 1.5–1.6 wt% of fluoride and 7.4–7.8 wt% of strontium. pH = f(t) experiment pointed out that pH increased by approximately 0.3 within 10 min after acid addition for all CDHAp suspensions. A new layer of the corresponding CDHAp was formed on the enamel. Its thickness increased by 0.8 ± 0.1 μm per day and reached up to 5.8 μm after 7 days. Additionally, octa calcium phosphates were detected on the surface of control samples. In conclusion, we can assume that CDHAp substituted with Sr2+ and/or F− could be used as an effective additive to dental care products promoting formation of protecting layer on the enamel, but there was no significant difference among sample groups.

The Combination of Laser and Nanoparticles for Enamel Protection: An In Vitro Study.

Introduction: Dental decay is caused by the fermentation of carbohydrates and the production of acids which demineralize teeth. The fermented food debris lowers the pH under 5.5, resulting in the mineral loss of teeth. Anti-decay factors are used to reduce decay rates and increase dental protection. Methods: Fifteen sectioned teeth samples were immersed in Ag NPs solution and then irradiated with laser pulses. Structures, morphologies, chemical compositions and microhardness were studied using the Vickers micro-hardness tester, energy dispersive x-ray machine, atomic force microscope and scanning electron microscopes. Results: Nine mature extracted human third molars, cleaned and placed in plastic molds then filled with a warm epoxy resin, were sectioned longitudinally and polished. The samples were then cleaned ultrasonically and stored in distilled water and taken immediately one by one for laser treatment. Sharper, overlapping, interconnected rods and higher resistance against enamel decay were demonstrated with little alterations of the mineral percentages of the teeth samples. Conclusion: The combination of laser light and silver annoparticles improved the decay resistance; where regular inter-connected chain-like merged grains were formed. These laser-induced modifications in enamel components have reduced the lattice stress and enamel solubility and improved resistance against decay. The computer model indicated a possible prediction of the laser-treated profile prior to laser treatment.

Anti-demineralizing protective effects on enamel identified in experimental and commercial restorative materials with functional fillers

The aim of this study was to investigate whether experimental and commercial dental restorative materials with functional fillers can exert a protective anti-demineralizing effect on enamel that is not immediately adjacent to the restoration. Four experimental resin composites with bioactive glass and three commercial restorative materials were investigated. Enamel blocks were incubated in a lactic acid solution (pH = 4.0) at a standardized distance (5 mm) from cured specimens of restorative materials. The lactic acid solution was replenished every 4 days up to a total of 32 days. Surfaces of enamel blocks were periodically evaluated by Knoop microhardness measurements and scanning electron microscopy. The protective effect of restorative materials against acid was identified as enamel microhardness remaining unchanged for a certain number of 4-day acid addition cycles. Additionally, the pH of the immersion medium was measured. While enamel microhardness in the control group was maintained for 1 acid addition cycle (4 days), restorative materials postponed enamel softening for 2–5 cycles (8–20 days). The materials capable of exerting a stronger alkalizing effect provided longer-lasting enamel protection. The protective and alkalizing effects of experimental composites improved with higher amounts of bioactive glass and were better for conventional bioactive glass 45S5 compared to a fluoride-containing bioactive glass. Scanning electron micrographs evidenced the protective effect of restorative materials by showing a delayed appearance of an etching pattern on the enamel surface. A remotely-acting anti-demineralizing protective effect on enamel was identified in experimental composites functionalized with two types of bioactive glass, as well as in three commercial ion-releasing restorative materials.

Protective effect of calcium silicate toothpaste on enamel erosion and abrasion in vitro

ObjectivesTo compare in vitro the effect of a toothpaste containing fluoride (F), calcium silicate (CaSi) and sodium phosphate salts to conventional toothpaste (NaF) on human enamel specimens submitted to erosive and abrasive challenges. Methods48 sound and 48 enamel samples pre-treated with 1% citric acid were divided into 4 groups (n = 12): Group 1- Non-fluoride toothpaste; Group 2- NaF toothpaste (1450 ppmF); Group 3- CaSi toothpaste (1450 ppmF; MFP); Group 4- Erosion only. The samples were subjected to pH cycling (3 cycles/day; 90s; 1% citric acid, pH 3.6) and to abrasion for 7 days. After the 1st and the last cycle, they were submitted to abrasion (15s, 1.5N load), using a brushing machine, soft toothbrush and toothpaste slurry (1:3; 15ml/sample) and then immersed in the slurry for 45s. Samples were immersed in artificial saliva between the challenges. Enamel loss was evaluated using profilometry on days 3 and 7. Data were analysed by ANOVA and Tukey's test (p < 0.05). ResultsFor sound enamel at baseline, mean (±SD) enamel loss (μm) for groups 1–4 on day 3 was 2.15 ± 0.35a, 1.20 ± 0.22b, 0.95 ± 0.19b and 1.98 ± 0.32a; on day 7 was 3.05 ± 0.40a, 2.07 ± 0.32b, 1.36 ± 0.33c and 3.69 ± 0.27d respectively. For acid-softened enamel at baseline, enamel loss on day 3 was 3.16 ± 0.19a, 2.17 ± 0.14b, 1.70 ± 0.11c and 3.04 ± 0.19a; on day 7 was 3.92 ± 0.25a, 3.07 ± 0.13b, 2.09 ± 0.15c and 3.87 ± 0.25a respectively. ConclusionsBoth F toothpastes led to significantly higher enamel protection from short-term erosion and abrasion in comparison to the non-F toothpaste and erosion only. In the longer term, CaSi toothpaste conferred significantly higher protection than NaF toothpaste. Clinical significanceThe results showed that for the longer term the CaSi toothpaste provided significantly higher protection than the NaF toothpaste, which indicates a good potential of the former to help prevent erosive tooth wear.

A Content Analysis of “Ultra morphology, Surface Roughness of Enamel, and Clinical Manifestations on Dental Health after Various Enamel Stripping, Polishing, and Poststripping Enamel Protection Methods”

Background: The purpose of the study is to qualitatively evaluate the ultramorphology, surface roughness, and clinical manifestations on dental health after various stripping, polishing, and postpolishing enamel protection methods which were followed by various researchers to sum up the more pragmatic and less pragmatic results through the research methodology of content analysis. Objectives: To qualitatively and inductively evaluate various stripping, polishing, and postpolishing enamel protection methods on ultramorphology and enamel surface roughness along with its clinical effects on dental health after thorough content analysis to provide a sound knowledge to the clinician to justify their decisions related to interproximal reduction (IPR), to make it an extremely useful space gaining tool if used with due caution. Materials and Methods: A comprehensive search of articles related to this study was collected from the past 25 years and a conceptual type of content analysis of all the selected articles was done. Inferences obtained through the analysis of the documented research data were then summed up in tabular form. Results: The results summated to the very important fact that all stripping methods microscopically leave a roughened enamel surface but clinically have no deleterious effects on dental health if performed judiciously followed by appropriate polishing and postpolishing protection methods. Conclusion: It can be determined that IPR should be carried out with greatest caution when using coarser stripping devices followed by prolonged polishing, but cautious use of finer stripping devices could be a better choice along with suitable polishing and protection methods.

Low-level gallium-aluminum-arsenide (GaAlAs) diode laser irradiation (λ 830 nm) associated with and without fluoridated gel in the prevention of enamel erosion

This in vitro study evaluated the effect of a low-level gallium-aluminum-arsenide (GaAlAs) diode laser irradiation against erosion in bovine enamel without and combined with fluoride (F), as well as compared the effect of the F treatment alone. Eight-four enamel samples were used for 8 groups: negative control (artificial saliva, S); positive control (neutral fluoride gel, F); diode laser (222 J/cm2, L1); diode laser (444 J/cm2, L2); F_L1; F_L2; L1_F; L2_F. Fluoride gel was applied only once before or after irradiation. Laser treatment occurred with an 830-nm diode laser (continuous, beam diameter 0.028 cm2, power 100 mW, power density 3.57 W/cm2). The irradiation was conducted one time (L1, energy 6.2 J, 62 s, energy density 222 J/cm2) or two times (L2, energy 12.4 J, 124 s, energy density 444 J/cm2). The specimens were submitted to erosive challenge using orange juice. Surface compositional changes by micro energy-dispersive X-ray fluorescence spectrometry (μ-EDXRF), surface roughness, and surface morphology by scanning electron microscopy (SEM) were evaluated after cycling. The laser energy density and the fluoride application (before or after laser) affected the mineral content. Treatments with the association laser/fluoride resulted in lower roughness values (Ra, μm) than in the negative control (p < 0.05). L1 treatment produced higher Ra values in the enamel than in the positive control (p < 0.05). The SEM images showed clear enamel loss after S and F and erosion compared with those of the laser-irradiated groups. The association of F gel with laser in this order resulted in relevant enamel protection.

Abrasion protection of silicate enamel coating of engineering network nodes in field conditions

The paper proposes methods for protecting the internal silicate-enamel coating of pipes in field conditions. It is shown that the proposed methods are highly efficient for manual mechanical cutting, chamfering, cutting edges with abrasive tools with vulcanite cutting discs for welding, in manufacturing and assembling the engineering systems, transportation of aggressive products, and fire fighting systems.It is shown that the most appropriate method for preservation of the internal silicate-enamel coating is its preliminary annular incision and sizing of the cut place with a thin cloth (calico) impregnated with quick-drying glue, and clay coating protection from hot metal particles. This method is recommended to be used when cutting pipes, fittings, segments, processing their chamfers and cutting edges, in manufacturing of network nodes (fire-fighting systems) in field conditions.The proposed methods will significantly increase the operating life and reliability of engineering networks with silicate-enamel coating for the transportation of aggressive products and, as a result, technical safety of trouble-free facilities.

Oxidation protection of enamel coated Ni based superalloys: Microstructure and interfacial reaction

We study the oxidation of SiO2-Al2O3-CaO-BaO-MgO based enamel coated Ni based superalloy at 900°C and find that the enamel coatings are highly capable of protecting the Ni based superalloy from oxidation. During the oxidation, the complicated composition crystals precipitated in enamel lead to two linear variation stages of oxidation weight gain. Moreover, the increased roughness of the superalloy interface due to oxidative attack and the immersion of the enamel coating in superalloy should increase the interface bonding strength. Finally, oxidations of Al, Ti and Cr from superalloy dominates the interfacial reactions.

Differences in the Natural Enamel Surface and Acquired Enamel Pellicle following Exposure to Citric or Hydrochloric Acid

Objectives: The aim of this study was to investigate variations in the interaction between enamel, that is, the acquired enamel pellicle (AEP) and citric or hydrochloric acid. Materials and Methods: A 24-h AEP was formed on natural enamel specimens (n = 40) from pooled whole mouth human saliva. Samples were randomly allocated to citric (0.3%, pH 3.2) or hydrochloric (HCl) acid (0.01 M, pH 2.38) exposure for 30 or 300 s. The total protein concentration (TPC), and phosphorous and calcium concentrations of the pellicle were determined before and after acid exposure, and again after re-immersion in saliva. Surface roughness and tandem scanning confocal microscopy imaging were used to assess enamel changes. Results: After 300 s of citric acid exposure, the mean ± SD TPC reduced from 5.1 ± 1.1 to 3.5 ± 1.1 mg/mL (p < 0.05). In contrast, after 300 s of HCl exposure, the mean TPC did not reduce significantly from baseline (6.6 ± 1.1 to 5.7 ± 0.7 mg/mL) but was significantly reduced in the reformed pellicle to 4.9 ± 1.2 mg/mL (p < 0.001). This reduction occurred after significant release of calcium and phosphorous from the enamel surface (p < 0.001). Thirty seconds of exposure to either acid had no obvious effect on the AEP. The surface roughness of the enamel decreased after acid exposure but no differences between groups was observed. Conclusions: These findings indicate that citric acid interacted with proteins in the AEP upon contact, offering enamel protection. In contrast, HCl appeared to bypass the pellicle, and reduced protein was observed only after changes in the enamel chemical composition.

Adsorption and Substitution of Metal Ions on Hydroxyapatite as a Function of Crystal Facet and Electrolyte pH

Zinc and stannous ions are commonly used in oral care to reduce tooth enamel degradation. However, mechanistic understanding of the role of the ions in the protection of enamel against acid insults...