Rigid-to-Flexible Transition in a Molecular Brush in a Good Solvent at a Semidilute Concentration.

The structures of a molecular brush in a good solvent are investigated using synchrotron small-angle X-ray scattering in a wide range of concentrations. The brush under study, PiPOx239-g-PnPrOx14, features a relatively long poly(2-isopropenyl-2-oxazoline) (PiPOx) backbone and short poly(2-n-propyl-2-oxazoline) (PnPrOx) side chains. As a solvent, ethanol is used. By model fitting, the overall size and the persistence length as well as the interaction length and interaction strength are determined. At this, the interplay between form and structure factor is taken into account. The conformation of the molecular brush is traced upon increasing the solution concentration, and a rigid-to-flexible transition is found near the overlap concentration. Finally, the results of computer simulations of the molecular brush solutions confirm the experimental results.

Factors influencing tooth loss in European populations.

AIM: This study aimed to identify the factors influencing the changes in the number of teeth present and the number of healthy or filled surfaces between two time points. MATERIALS AND METHODS: Repeated cross-sectional data from population-based studies, namely the German Oral Health Studies (DMS-III vs. DMS-V), the Studies of Health in Pomerania (SHIP-START-0 vs. SHIP-TREND-0), and the Jönköping study (2003 vs. 2013), were analysed. Oaxaca decomposition models were constructed for the outcomes (number of teeth, number of healthy surfaces, and number of filled surfaces). RESULTS: The number of teeth increased between examinations (DMS: +2.26 [adults], +4.92 [seniors], SHIP: +1.67, Jönköping: +0.96). Improvements in education and dental awareness brought a positive change in all outcomes. An increase in powered toothbrushing and inter-dental cleaning had a great impact in DMS (adults: +0.25 tooth, +0.78 healthy surface, +0.38 filled surface; seniors: +1.19 teeth, 5.79 healthy surfaces, +0.48 filled surface). Inter-dental cleaning decreased by 4% between SHIP-START-0 and SHIP-TREND-0, which negatively affected the outcomes. CONCLUSIONS: From this study, it can be concluded that education may be the most important factor having a direct and indirect effect on the outcomes. However, for better oral health, powered toothbrushing and inter-dental cleaning should not be neglected.

[Trends in dental and oral health status in Germany between 1997 and 2014]. / Entwicklung der Zahn- und Mundgesundheit in Deutschland von 1997 bis 2014.

BACKGROUND: Currently, there is no comprehensive presentation of trends in oral diseases in the German general population over the last 20 years. OBJECTIVES: How did prevalences of caries, periodontitis, and tooth loss and their determinants change in Germany between 1997 and 2014? MATERIALS AND METHODS: We analysed data from 35- to 44-year-olds and 65- to 74-year-olds from the German Oral Health Studies ("Deutsche Mundgesundheitsstudien" [DMS]) III to V and of 25- to 74-year-olds from the Studies of Health in Pomerania (SHIP­0 and SHIP-Trend-0). The decayed, missing, filled teeth index (DMFT), the number of sound teeth, the community periodontal index (CPI), and data on tooth count and edentulism were analysed. RESULTS: Regarding determinants, an increase in subjects with high school education, a slight decrease in smokers, and an increase in better oral hygiene patterns was observed in both studies. In 35- to 44-year-olds, the number of sound teeth increased from 11.9 in DMS III to 16.8 in DMS V, while in 65- to 74-year-olds the number of sound teeth increased by 5.9. A similar trend was observed in SHIP. In DMS, the prevalence of the highest CPI score of 4 decreased from 9.3% to 3.5% in 35- to 44-year-olds; in 65- to 74-year-olds, the 2014 prevalence was at the same level as in 1997 (10.5% and 9.8%). In parallel, the percentage of edentulous 65- to 74-year-olds halved in both studies. The number of teeth increased across all age strata. CONCLUSIONS: DMS and SHIP consistently showed an increase in the number of healthy teeth free of fillings, a slight reduction of subjects with a CPI score of 4, more tooth retention, and less edentulism. Because of more tooth retention and current demographic changes, higher periodontal treatment needs might be expected for the future.

Surface Grafting "Band-Aid" for "Everyone": Filter Paper-Assisted Surface-Initiated Polymerization in the Presence of Air.

We report herein a facile and generalized approach to the modification of solid surfaces with polymer brushes under ambient conditions: filter paper-assisted surface-initiated Cu0 -mediated controlled radical polymerization (PSI-CuCRP). The polymerization solution wetted filter paper is sandwiched between a copper plate and an initiator-modified substrate, which allows the creation of a surface-initiated polymerization (SIP) "band-aid" so that everyone can perform the surface grafting selectively with good control over the quality of the polymer brushes employing low concentration and microliter amounts of the monomer solution. The versatility of this method is demonstrated by grafting different homo-, block-, and multicomponent polymer brushes by using the same activation system and reaction conditions, the polymerization process can be precisely controlled to yield uniform polymers and show high chain-end functionality which is exemplified by in situ tetra-copolymerization. The combination of photolithography and paper cutting enables to prepare arbitrary three-dimensional patterned polymer brushes on the surface.

Facile Fabrication of Bio- and Dual-Functional Poly(2-oxazoline) Bottle-Brush Brush Surfaces.

Poly(2-oxazoline)s (POx) bottle-brush brushes have excellent biocompatible and lubricious properties, which are promising for the functionalization of surfaces for biomedical devices. Herein, a facile synthesis of POx is reported which is based bottle-brush brushes (BBBs) on solid substrates. Initially, backbone brushes of poly(2-isopropenyl-2-oxazoline) (PIPOx) were fabricated via surface initiated Cu0 plate-mediated controlled radical polymerization (SI-Cu0 CRP). Poly(2-methyl-2-oxazoline) (PMeOx) side chains were subsequently grafted from the PIPOx backbone via living cationic ring opening polymerization (LCROP), which result in ≈100 % increase in brush thickness (from 58 to 110 nm). The resultant BBBs shows tunable thickness up to 300 nm and high grafting density (σ) with 0.42 chains nm-2 . The synthetic procedure of POx BBBs can be further simplified by using SI-Cu0 CRP with POx molecular brush as macromonomer (Mn =536 g mol-1 , PDI=1.10), which results in BBBs surface up to 60 nm with well-defined molecular structure. Both procedures are significantly superior to the state-of-art approaches for the synthesis of POx BBBs, which are promising to design bio-functional surfaces.

Epidemiological trends, predictive factors, and projection of tooth loss in Germany 1997-2030: part II. Edentulism in seniors.

OBJECTIVE: This is the second part of a report on tooth loss in Germany 1997-2030. Here, we describe trends in the prevalence of edentulism in seniors 1997-2014, assess predictive factors for edentulism, and projected it into 2030. MATERIAL AND METHODS: We used data from three waves of the cross-sectional, multi-center, nationwide representative German Oral Health Studies. Overall, 3449 seniors (65-74 years) were included (1997: 1367; 2005: 1040; 2016: 1042). Age, sex, educational level, smoking status, and the cohort were entered into age-cohort binary-logistic regression models to assess the association of predictors with edentulism and to project edentulism in 2030 via Monte Carlo simulations. RESULTS: Between 1997 and 2014, the prevalence of edentulism decreased from 24.8 to 12.4%. With each year of age, the risk of being edentate increased (by 11%, p < 0.001); it was also significantly increased in female versus male (by 40%, p = 0.001), low versus medium and high educational level (up to 257%, p < 0.001), and in former and current smokers (up to 258%, p < 0.001). We predict the prevalence of edentulism to be reduced to 4.2% in 2030. The reduction will be higher in males, never and former smokers, and those with low socio-educational level. On an absolute level and despite a growing elderly population (aged 60-80 years), the number of edentate individuals will have decreased by 3.6 million in 2030 compared with 1997. CONCLUSIONS: Edentulism in seniors has declined equitably in Germany. The decline is expected to continue until 2030. Further efforts are needed to tackle the underlying risk factors. CLINICAL RELEVANCE: This study presents trends of edentulism in Germany for a period of three decades. It provides clinically relevant data for health care planning by 2030.

Clustering effects of oral conditions based on clinical and radiographic examinations.

OBJECTIVES: The intra-class correlation coefficient (ICC) is a measure of intra-subject clustering effects. A priori estimates of the ICC and the associated design effect (DE) are required for sample size estimation in clustered studies, and should be considered during their analysis, too. We aimed to determine the clustering effects of carious lesions, apical lesions, periodontal bone loss, and periodontal pocketing, assessed in clinical or radiographic examinations. METHODS: A subsample of patients (n = 175) enrolled in the fifth German Oral Health Study provided data on clinically determined carious teeth (i.e., with untreated carious lesions, WHO method) as well as teeth with periodontal pocketing (i.e., with maximum probing-pocket-depths ≥ 4 mm). A sample of panoramic radiographs (n = 85) from randomly chosen patients, examined from 2010 to 2017 at the Charité dental hospital, provided data on radiographically determined carious teeth (i.e., with lesions extending into dentine or enamel), teeth with apical lesions (determined by dentists via majority vote), and teeth with periodontal bone loss (≥ 20% of root-length). The ICC and its 95% confidence interval (95% CI) were determined. RESULTS: There were 3839 and 1961 teeth assessed in clinical and radiographic evaluations, respectively. For clinically or radiographically determined carious lesions, the ICC (95% CI) was 0.20 (0.16-0.24) or 0.19 (0.14-0.25), respectively. For clinical pocketing or radiographic bone loss, the ICC was 0.40 (0.35-0.46) or 0.30 (0.24-0.38), respectively. The lowest ICC was found for apical lesions at 0.08 (0.06-0.13). CONCLUSIONS: The ICC varied between assessment methods and conditions. Clustered trials should account for this during study planning and data analysis. CLINICAL RELEVANCE: Within the limitations of this study, and considering the risk of selection bias and the limited sample sizes of both datasets, clustering effects were substantial but varied between dental conditions. Studies not accounting for this during planning and analysis may yield misleading estimates if clustering is present.

Polymer Brushes on Hexagonal Boron Nitride.

Direct covalent functionalization of large-area single-layer hexagonal boron nitride (hBN) with various polymer brushes under mild conditions is presented. The photopolymerization of vinyl monomers results in the formation of thick and homogeneous (micropatterned, gradient) polymer brushes covalently bound to hBN. The brush layer mechanically and chemically stabilizes the material and allows facile handling as well as long-term use in water splitting hydrogen evolution reactions.

Influence of the average molar mass of poly(N-vinylpyrrolidone) on the dimensions and conductivity of silver nanowires.

We investigate the influence of the average molar mass (Mw) of the capping agent poly(N-vinylpyrrolidone) (PVP) on the conductivity of a silver nanowire (AgNW) network. During the polyol process, the chain length of PVP is known to influence the AgNW diameters and lengths. By altering the reaction temperature and time and using PVP of different chain lengths, we synthesized AgNWs with varying diameters, lengths and PVP coverage. The obtained plethora of AgNWs is the basis for conductivity investigations of networks made of AgNWs with a diameter of either 60 nm or 80 nm. The results show a negative influence of long-chain PVP on the conductivity of the subsequent network if 60 nm thick AgNWs are employed. Overall, we obtain well performing AgNW transparent electrodes on glass with RS = 24.4 Ω sq-1 at 85.5%T550nm.

When to intervene in the caries process? An expert Delphi consensus statement.

OBJECTIVES: To define an expert Delphi consensus on when to intervene in the caries process and on existing carious lesions using non- or micro-invasive, invasive/restorative or mixed interventions. METHODS: Non-systematic literature synthesis, expert Delphi consensus process and expert panel conference. RESULTS: Carious lesion activity, cavitation and cleansability determine intervention thresholds. Inactive lesions do not require treatment (in some cases, restorations will be placed for reasons of form, function and aesthetics); active lesions do. Non-cavitated carious lesions should be managed non- or micro-invasively, as should most cavitated carious lesions which are cleansable. Cavitated lesions which are not cleansable usually require invasive/restorative management, to restore form, function and aesthetics. In specific circumstances, mixed interventions may be applicable. On occlusal surfaces, cavitated lesions confined to enamel and non-cavitated lesions radiographically extending deep into dentine (middle or inner dentine third, D2/3) may be exceptions to that rule. On proximal surfaces, cavitation is hard to assess visually or by using tactile methods. Hence, radiographic lesion depth is used to determine the likelihood of cavitation. Most lesions radiographically extending into the middle or inner third of the dentine (D2/3) can be assumed to be cavitated, while those restricted to the enamel (E1/2) are not cavitated. For lesions radiographically extending into the outer third of the dentine (D1), cavitation is unlikely, and these lesions should be managed as if they were non-cavitated unless otherwise indicated. Individual decisions should consider factors modifying these thresholds. CONCLUSIONS: Comprehensive diagnostics are the basis for systematic decision-making on when to intervene in the caries process and on existing carious lesions. CLINICAL RELEVANCE: Carious lesion activity, cavitation and cleansability determine intervention thresholds. Invasive treatments should be applied restrictively and with these factors in mind.

[Future of Regional Health Care in Germany: Where Do Young Dentists Want to Work?] / Zukunft der regionalen Versorgung in Deutschland ­ Wohin wollen junge Zahnärztinnen und Zahnärzte?

STUDY AIM: In the context of a shortfall in medical care, the question arises whether a similar trend in dental care may be anticipated. This study analyses preferred working regions and future town-country distribution of young dentists in Germany. METHODS: This online-survey was conducted in spring 2017. It is the second wave of the longitudinal nationwide study "Y-dent: Professional identity of future and young dentists". Study end points were (1) favoured permanent working region of young dentists, (2) favoured future working city size, and (3) correlation between the region of origin and the favoured working region. RESULTS: 625 (51.2% of contacted) young dentists participated in this study. Dental chambers and associations of health insurance dentists in southern and western Germany were the most favoured future working regions. Regions in eastern Germany as well as smaller regions were chosen less often (<10%). For approximately half of the participants, medium-sized cities were an option, and some young dentists were ready to work in smaller cities. Depending on the federal state, 57-95% of young dentists entertained the idea of working in their region of origin. CONCLUSION: Based on young dentists' statements on their favoured future working region, it can be concluded that there is no risk of a shortfall in dental care comparable to the shortfall in medical care. A proportion of young dentists is willing to work in thinly populated or rural areas.

Mussel-Inspired Two-Dimensional Freestanding Alkyl-Polydopamine Janus Nanosheets.

Mussel-inspired two-dimensional freestanding, alkyl-polydopamine (alkyl-PDA) Janus nanosheets, with a well-controlled nanometer thickness and a lateral size of up to micrometers, have been developed. A self-assembled octadecylamine (ODA) bilayer is used as the reactive template for the dopamine polymerization, resulting in the formation of well-defined nanosheets. The alkyl-PDA nanosheets show an amphiphilic nature with hydrophilic PDA and hydrophobic alkyl chains on opposing sides. The nanosheets can be used to functionalize many substrates and is dependent on the configuration of surface of the nanosheets. The nanosheets are quite stable, as the morphology is preserved after carbonization at 900 °C. Post-modification of the nanosheets can be easily achieved because of the reactive nature of PDA. This work will provide a new strategic approach for fabricating polymeric Janus nanosheets, which can find applications for surface modifications, catalyst supports, and guided self-assembly.

Changes in Cholesterol Level Alter Integrin Sequestration in Raft-Mimicking Lipid Mixtures.

The influence of cholesterol (CHOL) level on integrin sequestration in raft-mimicking lipid mixtures forming coexisting liquid-ordered (lo) and liquid-disordered (ld) lipid domains is investigated using complementary, single-molecule-sensitive, confocal detection methods. Systematic analysis of membrane protein distribution in such a model membrane environment demonstrates that variation of CHOL level has a profound influence on lo-ld sequestration of integrins, thereby exhibiting overall ld preference in the absence of ligands and lo affinity upon vitronectin addition. Accompanying photon-counting histogram analysis of integrins in the different model membrane mixtures shows that the observed changes of integrin sequestration in response to variations of membrane CHOL level are not associated with altering integrin oligomerization states. Instead, our experiments suggest that the strong CHOL dependence of integrin sequestration can be attributed to CHOL-mediated changes of lipid packing and bilayer thickness in coexisting lo and ld domains, highlighting the significance of a biophysical mechanism of CHOL-mediated regulation of integrin sequestration. We envision that this model membrane study may help clarify the influence of CHOL in integrin functionality in plasma membranes, thus providing further insight into the role of lipid heterogeneities in membrane protein distribution and function in a cellular membrane environment.

Polymer-based doping control for performance enhancement of wet-processed short-channel CNTFETs.

The electrical transport properties of short-channel transistors based on single-walled carbon nanotubes (CNT) are significantly affected by bundling along with solution processing. We report that especially high off currents of CNT transistors are not only related to the incorporation of metallic CNTs but also to the incorporation of CNT bundles. By applying device passivation with poly(4-vinylpyridine), the impact of CNT bundling on the device performance can be strongly reduced due to increased gate efficiency as well as reduced oxygen and water-induced p-type doping, boosting essential field-effect transistor performance parameters by several orders of magnitude. Moreover, this passivation approach allows the hysteresis and threshold voltage of CNT transistors to be tuned.

More teeth in more elderly: Periodontal treatment needs in Germany 1997-2030.

OBJECTIVE: With more teeth retained for longer in an ageing population, population-wide periodontal treatment needs may increase. We assessed and projected periodontal treatment needs from 1997 to 2030 in Germany. METHODS: Partial-mouth probing-pocket depths (PPDs) from repeated waves (1997, 2005, 2014) of the nationally representative German Oral Health Studies were transformed into full-mouth PPDs via decision-tree-based ensemble-modelling. In line with German healthcare-regulations, teeth with PPD ≥ 4 mm were regarded as needing periodontal treatment. Weighted means were interpolated cross-sectionally by fitting spline-curves and then regressed longitudinally 1997-2030. RESULTS: In 1997, younger adults (35-44 years old) had a mean of 7.4 teeth needing treatment (overall 93.8 million teeth); this decreased to 4.8 teeth (47.3 million teeth) in 2014. For 2030, we project 3.2 teeth (33.7 million teeth). In seniors, an increase was recorded (1997: 4.5 teeth, 33.5 million teeth; 2014: 7.5 teeth, 63.4 million teeth); this is expected to continue until 2030 (to 12.2 teeth, 140.8 million teeth). The cumulative number of teeth needing treatment increased from 2000 (355 million) to 2015 (365 million), and will increase further to 2030 (464 million). CONCLUSIONS: Population-wide periodontal treatment needs may increase until 2030, mainly in the elderly. Concepts for addressing, these growing needs are required.

"On Water" Surface-initiated Polymerization of Hydrophobic Monomers.

We present the "on water" surface-initiated Cu-mediated controlled radical polymerization ("on water" SI-CuCRP) that converts hydrophobic monomers in aqueous reaction medium to polymer brushes at unparalleled speed and efficiency. The method allows the facile conversion of a variety of common monomers under most simple reaction conditions and with minimal monomer amounts to thick and homogeneous polymer brushes. The highly living character of the "on water" SI-CuCRP allowed the preparation of decablock (homo)polymer brushes and opens the pathway to sequentially controlled polymer brushes on solids.

Dual-Graphene Rechargeable Sodium Battery.

Sodium (Na) ion batteries are attracting increasing attention for use in various electrical applications. However, the electrochemical behaviors, particularly the working voltages, of Na ion batteries are substantially lower than those of lithium (Li) ion batteries. Worse, the state-of-the-art Na ion battery cannot meet the demand of miniaturized in modern electronics. Here, we demonstrate that electrochemically exfoliated graphene (EG) nanosheets can reversibly store (PF6- ) anions, yielding high charging and discharging voltages of 4.7 and 4.3 V vs. Na+ /Na, respectively. The dual-graphene rechargeable Na battery fabricated using EG as both the positive and negative electrodes provided the highest operating voltage among all Na ion full cells reported to date, together with a maximum energy density of 250 Wh kg-1 . Notably, the dual-graphene rechargeable Na microbattery exhibited an areal capacity of 35 µAh cm-2 with stable cycling behavior. This study offers an efficient option for the development of novel rechargeable microbatteries with ultra-high operating voltage and high energy density.

Caries-Preventive Effect of Salt Fluoridation in Preschool Children in The Gambia: A Prospective, Controlled, Interventional Study.

The aim of this study was to investigate the anticaries effect of fluoridated salt in a communal feeding program for preschool children. In the Gambian city of Brikama, drinking water had a low fluoride content (0.1 mg F-/L) and young children did not use toothpaste for oral hygiene. Its 2 preschools served as clusters for the trial. Random allocation of the kindergartens was performed by one person not involved in the study, and the clinical examinations were carried out using the envelope method. Meals were prepared with fluoridated salt (250 mg F-/kg salt) in the intervention group but not in the control group. According to the inclusion criteria (complete primary dentition and informed consent from legal guardian), 441 children aged 3-5 years were enrolled. The children were examined by calibrated persons according to WHO criteria, allowing the calculation of d3mft scores. The primary end point was the mean difference in the incidence of caries cavities (Δd3/4mft) after 12 months. After 12 months, the mean caries incidence per person was 1.29 d3/4mf teeth (95% CI: 0.96; 1.62) in the test group (n = 304 children) and 3.83 d3/4mf teeth (95% CI: 2.94; 4.72) in the control group (n = 137 children). Thus, the caries-prevented fraction was 66.3%. No signs of harm due to the intervention were observed. The use of fluoridated salt in a communal feeding program and in an environment with negligible availability of fluoride from other sources yields a considerable caries-preventive effect.

POxylation as an alternative stealth coating for biomedical applications.

Polyethylene glycol (PEG) polymers are currently used in a variety of medical formulations to reduce toxicity, minimize immune interactions and improve pharmacokinetics. Despite its widespread use however, the presence of anti-PEG antibodies indicates that this polymer has the potential to be immunogenic and antigenic. Here we present an alternative polymer, poly(2-oxazoline) (POx) for stealth applications, specifically shielding of a proteinaceous nanoparticle from recognition by the immune system. Tobacco mosaic virus (TMV) was used as our testbed due to its potential for use as a nanocarrier for drug delivery and molecular imaging applications.

Poly(2-oxazoline)-Based Microgel Particles for Neuronal Cell Culture.

An increasing number of in vivo and in vitro neuro-engineering applications are making use of colloidal particles as neuronal cell carriers. Recent studies highlight the shortcomings of commercial glass particles and stress the benefit of using soft microgel particles (MGPs) instead. This study describes first the fabrication of MGPs from telechelic poly(2-methyl-2-oxazoline)s (PMeOx) cross-linkers and hydrophilic neutral (hydroxyethyl)methacrylate (HEMA) or charged 2-methacryloxyethyltrimethylammonium (METAC) monomers by emulsion polymerization, and it discusses their ability to support cell growth. It establishes that uncharged copolymers lead to MGPs with nonfouling properties inappropriate for cell culture, and it provides a protocol to amend their surface properties to enable cell adhesion. Finally, it demonstrates that the introduction of positive charges by METAC is necessary to obtain surface properties suitable for neuronal cell development. Through the optimization of the PMeOx30 MGP properties, this work provides general guidelines to evaluate and tune MGP chemistry to obtain microcarriers for neuro-engineering applications.