Brushing Behavior Research Articles

Determinants of Oral Health: Does Oral Health Literacy Matter?

Objective. To evaluate oral health literacy, independent of other oral health determinants, as a risk indicator for self-reported oral health. Methods. A cross-sectional population-based survey conducted in Tehran, Iran. Multiple logistic regression analysis served to estimate the predictive effect of oral health literacy on self-reported oral health status (good versus poor) controlling for socioeconomic and demographic factors and tooth-brushing behavior. Results. In all, among 1031 participants (mean age 36.3 (SD 12.9); 51% female), women reported brushing their teeth more frequently (P < 0.001) and scored higher for oral health literacy (mean 10.9 versus 10.2, P < 0.001). In the adjusted model, high age (OR = 1.01, 95% CI 1.003–1.034), low education (OR = 1.88, 95% CI 1.23–2.87), small living area in square meters per person (OR = 1.85, 95% CI 1.003–3.423), poor tooth brushing behavior (OR = 3.35, 95% CI 2.02–5.57), and low oral health literacy scores (OR = 1.58, 95% CI 1.02–2.45) were significant risk indicators for poor self-reported oral health. Conclusions. Low oral health literacy level, independent of education and other socioeconomic determinants, was a predictor for poor self-reported oral health and should be considered a vital determinant of oral health in countries with developing health care systems.

Surface and Interface Analyses of Polymer Brushes by Synchrotron Radiation

In the present review, we focus on the characterization of polymer brushes by quantum beam, which is regarded as a promising probe of surface and interface analysis. The polymer brushes were prepared on various shapes of surface, and proved to be benefit to various applications. Among them, the polymer brushes grafted on sphere nanoparticles and flat substrates are investigated as representative cases. The static structure of polymer brushes, especially the chain dimension of polymer brushes grafted on nanoparticles and a flat substrate, have been studied by small angle X-ray scattering (SAXS) and neutron reflectivity (NR), respectively. The microscopic dynamical properties of polymer brushes are also expected to be revealed by quantum beam. X-ray photon correlation spectroscopy (XPCS), a technique using a coherent X-ray, is one of the promising methods for microscopically understanding of dynamical properties of polymer brushes. Some of our recent studies about dynamical behavior of polymer brush immobilized nanoparticle by XPCS are also presented.

Synthesis and self-assembly of thermo/pH-responsive double hydrophilic brush–coil copolymer with poly(l-glutamic acid) side chains

We report on the synthesis and self-assembly behavior of a well-defined double hydrophilic brush–coil copolymer with poly(N-isopropylacrylamide)-b-poly(glycidly methacrylate) (PNIPAM-b-PGMA) as backbone and poly(l-glutamic acid) (PLGA) as brush. The PNIPAM-b-PGMA was firstly prepared by the sequential reversible addition–fragmentation chain transfer polymerization of N-isopropylacrylamide and glycidly methacrylate. The obtained diblock copolymer was reacted with ethylenediamine (EDA) yielding the aminated macroinitiator (PNIPAM-b-PGMA-EDA), which was then used to initiate ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydride (BLG-NCA) to give PNIPAM-b-(PGMA-g-PBLG) copolymer. After the deprotection of benzyl groups on PBLG, double hydrophilic brush–coil copolymer, PNIPAM-b-(PGMA-g-PLGA), was obtained. The thermo- and pH-responsive micellization behaviors of PNIPAM-b-(PGMA-g-PLGA) in aqueous solution were investigated by fluorescence spectroscopy, 1H NMR, dynamic light scattering, scanning electron microscopy, and circular dichroism. It can self-assemble into PNIPAM-core micelles at pH 10 and elevated temperature and PLGA-core micelles at pH 4 and room temperature. Such brush–coil copolymers have the potential applications as biomedical and intelligent materials.

Polymers as Templates for Au and Au@Ag Bimetallic Nanorods: UV–Vis and Surface Enhanced Raman Spectroscopy

In this study, we report on the fabrication of nanoassemblies composed by Au and bimetallic core–shell Au@Ag nanorods immobilized onto pH-responsive poly(2-vinylpyridine) (P2VP) brushes. The general process includes the synthesis of gold nanorods (through the seed mediated method) and a subsequent reduction of AgNO3 on the gold surface. These colloidal particles were immobilized onto carboxy-terminated P2VP brushes (COOH-P2VP), previously grafted on underlying substrates (silicon wafers and glass slides). UV–vis spectroscopy and transmission electron microscopy (TEM) images confirmed the morphology of the gold nanorods and the core–shell structure of the bimetallic Au@Ag nanorods. The presence of metal nanoparticles on the P2VP-functionalized substrates was demonstrated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) images. The swelling–deswelling behavior of the pH responsive polymer brushes was confirmed using UV–vis spectroscopy over P2V...

Molecular simulation of 2-dimensional microphase separation of single-component homopolymers grafted onto a planar substrate

The structural phase behavior of polymer brushes, single-component linear homopolymers grafted onto a planar substrate, is studied using the molecular Monte Carlo method in 3 dimensions. When simulation parameters of the system are set in regions of macrophase separation of solution for the corresponding non-grafted homopolymers, the grafted polymers also prefer segregation. However, macrophase separation is disallowed due to the spatially fixed grafting points of the polymers. Such constraints on the grafting are similar to connecting points between blocks of non-grafted diblock copolymers at the microphase separation in the melt state. This results in “microphase separation” of the homopolymer brush in the lateral direction of the substrate. Here we extensively search the parameter space and reveal various lateral domain patterns that are similar to those found in diblock copolymer melts at microphase separation.

Response behavior of diblock copolymer brushes in explicit solvent

The understanding of phase behavior of copolymer brushes is of fundamental importance for the design of smart materials. In this paper, we have performed classical density functional theory calculations to study diblock copolymer brushes (A-B) in an explicit solvent which prefers the A block to B block. With increasing B-block length (N(B)), we find a structural transition of the copolymer brush from mixed to collapsed, partial-exposed, and exposed structure, which is qualitatively consistent with experiments. The phase transitions are attributed to the interplay between entropic cost of folding copolymer brushes and enthalpic effect of contact between unlike components. In addition, we examine the effect of different parameters, such as grafting density (ρ(g)), the bottom block length (N(A)), and the chain length of solvent (N(S)) on the solvent response of copolymer brushes. The transition chain length (N(B)) increases with decreasing ρ(g) and N(A), and a smaller solvent molecule makes the collapsed structure less stable due to its lower penetration cost. Our results provide the insight to phase behavior of copolymer brushes in selective solvents from a molecular view.

Variable density self consistent field study on bounded polymer layer around spherical nanoparticles

A computational study focused on the interfacial region between polymer bulk and solid surface of spherical nanoparticles is presented. Our tool is a recently developed, properly modified for curved surfaces, variable density self-consistent field method. Grafted poly(styrene) on flat or curved surfaces and physically adsorbed poly(dimethylsiloxane) macromolecular chains on silica are examined. In the poly(styrene) study the existence of a depletion layer and an associating strong elongation of the polymeric chains is observed. On the detailed investigation of poly(dimethylsiloxane)/silica interface good agreement of the numerical results with the experimental data for the dependence of the width and the structure of the rigid amorphous inter-phase on the radius of the nanoparticle is reported. Moreover, a well understood dependence of the bounded polymer layer structure on the polydispersity (mainly bipolar structures) of the polymeric sample was found. Overall, we have shown evidence for the chain immobilization in the interfacial region and found that the thickness of the interphase is sensitive to the strength of the polymer-nanoparticle interaction and strongly depends on the curvature of the surface. Based on the unique behavior of bimodal brushes in equilibrium, confirmed by our findings, we have tried to enlighten silent and unclarified polymeric characteristics, which are not experimentally observable, and point the significance of the thermodynamic factor.

Simulation and modelling of slip flow over surfaces grafted with polymer brushes and glycocalyx fibres

Fabrication of functionalized surfaces using polymer brushes is a relatively simple process and parallels the presence of glycocalyx filaments coating the luminal surface of our vasculature. In this paper, we perform atomistic-like simulations based on dissipative particle dynamics (DPD) to study both polymer brushes and glycocalyx filaments subject to shear flow, and we apply mean-field theory to extract useful scaling arguments on their response. For polymer brushes, a weak shear flow has no effect on the brush density profile or its height, while the slip length is independent of the shear rate and is of the order of the brush mesh size as a result of screening by hydrodynamic interactions. However, for strong shear flow, the polymer brush is penetrated deeper and is deformed, with a corresponding decrease of the brush height and an increase of the slip length. The transition from the weak to the strong shear regime can be described by a simple 'blob' argument, leading to the scaling γ̇0 ∝ σ3/2, where γ̇0 is the critical transition shear rate and σ is the grafting density. Furthermore, in the strong shear regime, we observe a cyclic dynamic motion of individual polymers, causing a reversal in the direction of surface flow. To study the glycocalyx layer, we first assume a homogeneous flow that ignores the discrete effects of blood cells, and we simulate microchannel flows at different flow rates. Surprisingly, we find that, at low Reynolds number, the slip length decreases with the mean flow velocity, unlike the behaviour of polymer brushes, for which the slip length remains constant under similar conditions. (The slip length and brush height are measured with respect to polymer mesh size and polymer contour length, respectively.) We also performed additional DPD simulations of blood flow in a tube with walls having a glycocalyx layer and with the deformable red blood cells modelled accurately at the spectrin level. In this case, a plasma cell-free layer is formed, with thickness more than three times the glycocalyx layer. We then find our scaling arguments based on the homogeneous flow assumption to be valid for this physiologically correct case as well. Taken together, our findings point to the opposing roles of conformational entropy and bending rigidity - dominant effects for the brush and glycocalyx, respectively - which, in turn, lead to different flow characteristics, despite the apparent similarity of the two systems.

Investigation of eccentric PVA brush behaviors in post-Cu CMP cleaning

Behavior of an eccentric PVA brush is investigated during post-Cu chemical mechanical planarization (CMP) brush cleaning. It is observed that the measured contact pressure and contact area of the eccentric brush vary significantly under different brush orientations. Moreover, the eccentric brush behaves differently from the good (i.e. concentric) brush in both the variance of shear force as well as the force spectra during cleaning. This study provides a rapid detection method to screen out eccentric brushes before they are used in semiconductor manufacturing, thereby potentially reducing wafer defects as well as chemical, water, and energy consumption associated with using eccentric PVA brushes.

Correlation analysis of brush temperature in brush-type DC motor for predicting motor life

Some critical components of motors and generators have sliding electrical contacts. Electrical brushes are usually used in these contact points to conduct current between the stationary part and the moving part of the motor. In this paper, studies on brush wear against copper commutators are briefly reviewed. The main influential factors in brush wear are associated with both mechanical wear and electrical wear. Brush wear is affected by various factors, including temperature, material properties, sliding speed, contact force, and interfacial as well as environmental conditions. The mechanical wear of brushes is proportional to brush spring pressure and sliding speed, and the electrical wear of brushes is associated with current and contact voltage drop. For characterization, a brush wear test machine is designed, and influential factors, such as electrical contact resistance, temperature, wear mass loss, and so on, are measured. The wear tests are processed using a small brush-type automotive DC motor. The study primarily aims to investigate the effects of the wear behavior of copper-graphite brushes on small brush-typed DC motors. The variable conditions of electrical current are obtained by changing the brush spring pressure and the sliding speed. The results are electrical contact resistance, voltage drop, brush surface temperature rise, and so on. Brush wear is greatly changed by electrical current, which indicates that high current itself not only produces more Joule heating but also causes an increase in voltage drop that will result in additional Joule heating.

Water Is a Poor Solvent for Densely Grafted Poly(ethylene oxide) Chains: A Conclusion Drawn from a Self-Consistent Field Theory-Based Analysis of Neutron Reflectivity and Surface Pressure–Area Isotherm Data

By use of a combined experimental and theoretical approach, a model poly(ethylene oxide) (PEO) brush system, prepared by spreading a poly(ethylene oxide)-poly(n-butyl acrylate) (PEO-PnBA) amphiphilic diblock copolymer onto an air-water interface, was investigated. The polymer segment density profiles of the PEO brush in the direction normal to the air-water interface under various grafting density conditions were determined by using the neutron reflectivity (NR) measurement technique. To achieve a theoretically sound analysis of the reflectivity data, we used a data analysis method that utilizes the self-consistent field (SCF) theoretical modeling as a tool for predicting expected reflectivity results for comparison with the experimental data. Using this data analysis technique, we discovered that the effective Flory-Huggins interaction parameter of the PEO brush chains is significantly greater than that corresponding to the θ condition in Flory-Huggins solutions (i.e., χ(PEO-water)(brush chains)/χ(PEO-water)(θ condition) ≈ 1.2), suggesting that contrary to what is more commonly observed for PEO in normal situations (χ(PEO-water)(free chains)/χ(PEO-water)(θ condition) ≈ 0.92), the PEO chains are actually not "hydrophilic" when they exist as polymer brush chains, because of the many body interactions that are forced to be effective in the brush situation. This result is further supported by the fact that the surface pressures of the PEO brush calculated on the basis of the measured χ(PEO-water) value are in close agreement with the experimental surface pressure-area isotherm data. The SCF theoretical analysis of the surface pressure behavior of the PEO brush also suggests that even though the grafted PEO chains experience a poor solvent environment, the PEO brush layer exhibits positive surface pressures, because the hydrophobicity of the PEO brush chains (which favors compression) is insufficient to overcome the opposing effect of the chain conformational entropy (which resists compression).

Influence of Solutes on Hydration and Lubricity of Dextran Brushes

The characteristic lubricity and non-fouling behavior of polymer brushes is critically dependent on the solvation of the polymer chains, as well as the chain-chain interactions. Dextran brushes have shown promise as non-toxic aqueous lubricant films, and are similar in composition to natural lubricating systems, while their comparative simplicity allows for controlled preparation and fine characterization. This project entails measuring the solvation and lubricity of dextran brushes in the presence of additives which modify the inter-chain hydrogen bonding. The thickness and refractive index of the film were measured during adsorption of the brush layer onto a silica substrate and the subsequent immersion in solutions of potassium sulfate and α, α-trehalose. We also studied the lubricity of the system as a function of normal loading using colloidal-probe AFM. Both solutes are shown to have a minimal effect on the hydration of the brush while significantly reducing the brush lubricity, indicating that inter-chain hydrogen bonding supports the load-bearing capacity of polysaccharide brushes.

Solid Phase Synthesis of Polymacromer and Copolymacromer Brushes

We report a novel solid phase method for the sequential coupling of heterobifunctional macromonomers to form a new class of polymeric materials that we refer to as polymacromers. Starting from an azide functional substrate, α-azido, ω-protected-alkyne macromonomers are added sequentially by thermally initiated click reactions to form polymacromer brushes wherein macromonomers are linked via triazole groups. After each addition step, the terminal alkyne group can be deprotected to allow addition of the next macromonomer. The use of highly chemoselective click chemistry for the coupling reactions allows virtually any macromonomer to be employed, regardless of its chemical nature. The method is illustrated by formation of two different homopolymacromer brushes: one made by sequentially coupling four polystyrene macromonomers and another by sequentially coupling eight poly(tert-butyl acrylate) macromonomers. Two different types of copolymacromer brushes are also prepared: one by alternating sequential coupling of polystyrene macromonomers with poly(methyl methacrylate) macromonomers and another by alternating sequential coupling of polystyrene macromonomers with poly(tert-butyl acrylate) macromonomers. The polymacromer brushes are characterized by ellipsometry, contact angle analysis, X-ray photoelectron spectroscopy, and X-ray reflectivity measurements. In all cases the coupling reactions are found to be highly efficient. Analysis of thickness data for the poly(tert-butyl acrylate) homopolymacromer brushes indicates that a conversion within the range of 97.5–100% is achieved for each cycle. This solid phase synthesis method is extremely versatile because it can be used to prepare complex sequenced block copolymers from almost any polymers and because the brushes formed can be made to span the entire region of brush behavior between the “grafting from” and grafting to” limits by varying the macromonomer molecular weight.

Structure and Collapse of a Surface-Grown Strong Polyelectrolyte Brush on Sapphire

We have used neutron reflectometry to investigate the behavior of a strong polyelectrolyte brush on a sapphire substrate, grown by atom-transfer radical polymerization (ATRP) from a silane-anchored initiator layer. The initiator layer was deposited from vapor, following treatment of the substrate with an Ar/H(2)O plasma to improve surface reactivity. The deposition process was characterized using X-ray reflectometry, indicating the formation of a complete, cross-linked layer. The brush was grown from the monomer [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), which carries a strong positive charge. The neutron reflectivity profile of the swollen brush in pure water (D(2)O) showed that it adopted a two-region structure, consisting of a dense surface region ∼100 Å thick, in combination with a diffuse brush region extending to around 1000 Å from the surface. The existence of the diffuse brush region may be attributed to electrostatic repulsion from the positively charged surface region, while the surface region itself most probably forms due to polyelectrolyte adsorption to the hydrophobic initiator layer. The importance of electrostatic interactions in maintaining the brush region is confirmed by measurements at high (1 M) added 1:1 electrolyte, which show a substantial transfer of polymer from the brush to the surface region, together with a strong reduction in brush height. On addition of 10(-4) M oppositely charged surfactant (sodium dodecyl sulfate), the brush undergoes a dramatic collapse, forming a single dense layer about 200 Å in thickness, which may be attributed to the neutralization of the monomers by adsorbed dodecyl sulfate ions in combination with hydrophobic interactions between these dodecyl chains. Subsequent increases in surfactant concentration result in slow increases in brush height, which may be caused by stiffening of the polyelectrolyte chains due to further dodecyl sulfate adsorption.

Perceived behavioural control and coping planning predict dental brushing behaviour among Iranian adolescents

The aim of this prospective study was to test the role of the direct predictors in the theory of planned behaviour (TPB), perceived behavioural control (PBC) and intention as well as action planning and coping planning as predictors of changes in dental brushing behaviour among Iranian adolescents. One thousand students were selected from 57 high schools in Qazvin, IR Iran. N = 983 participants completed an initial questionnaire at Time 1 and they were asked to complete a follow-up questionnaire 1 month later (Time 2). At Time 1, PBC, behavioural intention, action planning and coping planning were assessed. Dental brushing behaviour was assessed both at Time 1 and 4 weeks later at Time 2. A hierarchical regression analysis was conducted to examine the predictive validity of PBC, intention, action planning and coping planning both, as main effects and as interactions on dental brushing behaviour. Past behaviour, gender and age explained 46.5% of the variance in dental brushing at Time 2 in step 1. Adding intention to brush, PBC, action planning and coping planning in the second and third step explained an additional 24.9% of the variance in dental brushing at Time 2. Adding the interactions terms for action planning × coping planning, action planning × PBC and coping planning × PBC further increased the predictive validity of the model by 6.00% over and above the main effects. Intentions, PBC, action planning and coping planning are predictive variables for oral self-care behaviour. This finding suggests that an intervention simultaneously targeting PBC, action planning and coping planning might be particularly promising to promote oral self-care in adolescence.

Synthesis of pH-Sensitive Amphiphilic Copolymer Brush by the Combination of ARGET ATRP with ROP and Its Self-Assembly Behavior

A random hydrophobic/pH-sensitive copolymer brush poly(polylactide methacrylate-co- methacrylic acid)-b-poly(poly(ethylene glycol) methyl ether methacrylate) (P(PLAMA-co-MAA)-b- PPEGMA) was synthesized by the combination of activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) with ring opening polymerization (ROP). The chemical structure, molecular weight and polydispersity index were characterized by nuclear magnetic resonance hydrogen spectrum ( 1 H NMR) and gel permeation chromatography (GPC). The reaction conditions of polymerization were optimized and polymer products with controllable molecular weight and narrow distribution were ob- tained. The self-assembly behavior (micelle size, morphology and pH-sensitive properties) of the polymer brush was investigated by dynamic light scattering (DLS) and scanning electron microscopy (SEM). The P(PLAMA-co-MAA)-b-PPEGMA self-assembled micelles were sphere in morphology and with an uniform

Hybrid Particle–Continuum Simulations of Polymer Brushes in Shear Flow

A hybrid particle–continuum method is used to study the shear flow confined between two opposing walls, one of which is coated with polymer chains. Molecular dynamics (MD) is used in the particle region near the brush and Navier–Stokes (NS) equations are applied in the remaining region where the continuum assumption holds. The information exchange from the continuum region to the particle region is implemented using the constrained particle dynamics. Both Couette shear flow and oscillatory flow are considered in the present work. The effect of the shear flow on the conformational characteristics of polymer brushes is analyzed. In the overlap region, the velocities obtained from MD simulations are smoothly connected with those from NS equations. Our investigations demonstrate that the hybrid particle–continuum model is valid in exploring the shear behavior of polymer brushes.

Novel Glycopolymer Brushes via ATRP: 2. Thermal and Mechanical Properties

AbstractThe thermal and mechanical properties of a series of novel glycopolymer brushes with various degrees of polymerization of the backbone and various grafting densities are established. Modulated differential scanning calorimetry (MDSC) is found to be an effective tool for the characterization of the thermal behavior of these glycopolymer brushes. There is little difference among the glass transition temperatures of the different glycopolymer brushes. The elastic features of each glycopolymer predominate (G′ &gt; G″) at low frequency, while at higher frequencies the G″ curve overtakes the G′ curve, indicating the predominance of the viscous response.

Dental caries risk indicators by using International Caries Detection and Assessment System in Mosul City.

Aims: To determine the effect of risk factors such as income level, socioeconomic status, parents education, brushing behavior , dental attendance, type of treatment performed and others on dental ca- ries severity of permanent teeth. Materials and Methods: Sample size was (531) students (260 males and 271 females) who were selected randomly from (10) primary and intermediate schools in Mosul City, their ages were ranged between (6-16) years. Risk factors considered on caries severity included parent's income level, parent's education, visiting the dentist, types of dental treatment performed and brushing behavior. Distribution of dental caries on each side of the mouth, DMFT and the percentage of caries free students were also considered. Caries severity was measured using International Caries Detection and Assessment System. Results: These factors have an effect to increase or decrease caries severity either significantly or not significantly. Conclusion: These risk factors should be kept in mind when we decide to reduce caries severity.

Action and coping planning with regard to dental brushing among Iranian adolescents

The aims of this study were two-fold: (i) to examine the validity of the proposed three-factor structure (intention, action-, and coping planning) in an Iranian sample of adolescents, and (ii) to assess the predictive ability of the Theory of Planned Behavior (TPB) measures of action planning and coping planning for dental brushing. Eight hundred adolescents were randomly selected to participate in the study. 90% (721) of adolescents agreed to participate. Perceived behavioral control, action and coping planning scales and a self-report questionnaire related to dental brushing behavior were completed by the adolescents at baseline. One month later (time-point 2), the adolescents were asked to reassess their frequency of dental brushing over the four week period. Data were analyzed by a confirmatory factor analysis (CFA) on an original three-factor structure (intention, action plan, and coping plan). A hierarchical linear regression analysis was also performed. The CFA for the original three-factor structure showed a good fit index (χ2 = 637.60, degrees of freedom df = 116), goodness-of-fit index (GFI) = 91, and root mean square error of approximation (RMSEA) = 0.079. Adjusting for demographic variables, action- and coping planning together accounted for 7.9% of the variance associated with dental brushing behavior at one month. In conclusion, results suggest that action planning and coping planning are associated with higher frequency in dental brushing among Iranian adolescents.