998 resultados para Dental polymers


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Conductive textiles with specific properties can be produced by the chemical polymerisation of a range of 3-alkylpyrroles in the presence of textiles. The morphologies of these coatings are altered from the traditional conductive coatings. Comparison using a SEM reveals substantial differences.

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Soluble conducting poly(3-decanylpyrrole) was directly applied to textiles as a nanoparticle emulsion, using a variety of techniques including hand-brushing, dipping and spray painting. These coatings were compared to those formed by chemical polymerization of 3-decanylpyrrole on the surface of the textile by solution, using vapor and spray polymerization methods. The coating formed using chemical polymerization methods had lower surface resistivity than that formed by direct application of a soluble polymer.

It was observed that applied coatings of poly(3-decanylpyrrole) showed a smoother surface morphology with a more even dispersion compared to those formed by chemical methods.

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Processable conjugated polymers such as those shown in the Figure are highly desirable for applications in, for example, light emitting devices, especially electrochemical light-emitting cells. Here recent progress in Australia on the synthesis and device applications of such polymers is reviewed and the possibility of tuning the emitted color via an intercalation-induced conformational change of the polymer backbone is examined.

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Various types of titanium alloys with high strength and low elastic modulus and, at the same time, vanadium and aluminium free have been developed as surgical biomaterials in recent years. Moreover, porous metals are promising hard tissue implants in orthopaedic and dentistry, where they mimic the porous structure and the low elastic modulus of natural bone. In the present study, new biocompatible Ti-based alloy foams with approximate relative densities of 0.4, in which Sn and Nb were added as alloying metals, were synthesised through powder metallurgy method.
The new alloys were prepared by mechanical alloying and subsequently sintered at high temperature using a vacuum furnace. The characteristics and the processability of the ball milled powders and the new porous titanium-based alloys were characterised by X-ray diffraction, optical
microscopy and scanning electron microscopy .The mechanical properties of the new titanium alloys were examined by Vickers microhardness measurements and compression testing.

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In this paper we present our preliminary studies on the efficacy of eugenol for the recovery of erased characters on polymers. We have found that eugenol rapidly recovers erased characters when applied to the surface of polymer substrates. By applying eugenol to the surface to be treated using a cotton bud or paintbrush, we were able to revisualize erased characters from a range of polymers, inclluding acrylonitrile butadiene styrene, acrylic, high-impact polystrene, and polystyrene. Eugenol is safe, nonhazardour, and easily sourced reagent for this purpose.

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This paper is a result of a fruitful cooperation between the computer science and the dental diagnosis experiences. The study presents a new approach of applying computer algorithms to radiographic images of dental implantation used for bone regeneration. We focus here only on the contribution of the computer assistance to the clinical research as the periodontal therapy is beyond the scope of this paper. The proposed system is based on a pattern recognition approach, directed to recognize density changes in the intra-bony affected areas of patients. It comprises different modules with new algorithms specially designed to treat the patients’ radiographic images more accurately. The system includes digitizing, detecting the complicated region of interest (ROI), defining reference area to correct any projection discrepancy of the follow up images, and finally to extract the distinguishing features of the ROI as a basis for determining the rate of new bone density accumulation. This study is applied to two typical dental cases for a patient who received two different operations. The results are very encouraging and more accurate than traditional techniques reported before.

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Dental services in Australia are available both privately and publicly. However, access to public dental services, like access to public hospital services for non-urgent treatment, is subject to a considerable waiting period. Moreover, access to public dental services is restricted to certain categories of welfare beneficiaries who qualify for a health care card. Because of the waiting time for public treatment, there is a frequent call for more public dental resources. This paper addresses the issue of what the waiting time for public dental services represents. One view largely confirmed by our research is that state governments are using the waiting time as a way of trying to push more and more people into the private sector. We find that more and more health care card holders are using the
private sector for dental services.

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Weak photo-induced chemiluminescence (PICL) emission is observed when polymers are exposed to UVA or visible light. The presence of dyes can either increase PICL intensity via Type I photosensitisation which generates polymer free radicals, or reduce it via photo-protection. PICL studies on the eight Blue Wool Standards (BWSs) that are used commercially as lightfastness standards show higher PICL intensity from the least photostable BWSs that use triphenylmethane dyes and lower intensity from more photostable BWSs using UVA and visible wavelengths. The relative PICL intensities do not correlate in a stepwise manner with lightfastness ratings of the BWSs. However dye/polymer combinations that emit high levels of PICL relative to the undyed material are unlikely to have acceptable lightfastness. The xanthene dyes fluorescein and eosin Y are more strongly photosensitising than triphenylmethane dyes on wool and both produce higher PICL emission than undyed wool when irradiated with visible light.

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Oral diseases including dental caries and periodontal disease are among the most prevalent and costly diseases in Australia today. Around 5.4% of Australia’s health dollar is spent on dental services totalling around $2.6 billion, 84% of which are delivered through the private sector (AIHW 2001). The other 16% is spent providing public sector services in varied and inadequate ways. While disease rates among school children have declined significantly in the past 20 years the gains made among children are not flowing on to adult dentitions and our aging population will place increasing demands on an inadequate system into the future (AHMAC 2001). Around 50% of adults do not received regular care and this has implications for widening health inequalities as the greatest burden falls on lower income groups (AIHW DSRU 2001). The National Competition Policy agenda has initiated, Australia-wide, reviews of dental legislation applying to delivery of services by dentists, dental specialists, dental therapists and hygienists and dental technicians and prosthetists. The review of the Victorian Dentists Act 1972, was completed first in 1999, followed by the other Australian states with Queensland, the ACT and the Northern Territory still developing legislation. One of the objectives of the new Victorian Act is to ‘…promote access to dental care’. This study has grown out of the need to know more about how dental therapists and hygienists might be utilised to achieve this and the legislative frameworks that could enable such roles. This study used qualitative methods to explore dental health policy making associated with strategies that may increase access to dental care using dental therapists and hygienists. The study used a multiple case study design to critically examine the dental policy development process around the Review of the Dentists Act 1972 in Victoria; to assess legislative and regulatory dental policy reforms in other states in Australia and to conduct a comparative analysis of dental health policy as it relates to dental auxiliary practice internationally. Data collection has involved (I) semi-structured interviews with key participants and stakeholders in the policy development processes in Victoria, interstate and overseas, and (ii) analysis of documentary data sources. The study has taken a grounded theory approach whereby theoretical issues that emerged from the Victorian case study were further developed and challenged in the subsequent interstate and international case studies. A component of this study has required the development of indicators in regulatory models for dental hygienists and therapists that will increase access to dental care for the community. These indicators have been used to analyse regulation reform and the likely impacts in each setting. Despite evidence of need, evidence of the effectiveness and efficiency of dental therapists and hygienists, and the National Competition Policy agenda of increasing efficiency, the legislation reviews have mostly produces only minor changes. Results show that almost all Australian states have regulated dental therapists and hygienists in more prescriptive ways than they do dentists. The study has found that dental policy making is still dominated by the views of private practice dentists under elitist models that largely protect dentist authority, autonomy and sovereignty. The influence of dentist professional dominance has meant that governments have been reluctant to make sweeping changes. The study has demonstrated alternative models of regulation for dental therapists and hygienists, which would allow wider utilisation of their skills, more effective use of public sector funding, increased access to services and a grater focus on preventive care. In the light of theses outcomes, there is a need to continue to advocate for changes that will increase the public health focus of oral health care.

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The thesis used a model of health behaviour to examine the predictors of dental attendance. Older respondents who had strong intentions, low perceived vulnerability, stable plans to attend, and were influenced by significant others were more likely to have attended the dentist for preventive care in the last 12 months. The portfolio concludes that attachment theory is a useful conceptual framework for enhancing our understanding of the antecedents and consequences of childhood sexual abuse.

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Most industrially applied polymer resins and composites have low surface free energy and lack polar functional groups on their surface, resulting in inherently poor adhesion properties. A strong research momentum to understand polymer adhesion in the last decade has been motivated by the growing needs of the automotive and aerospace industries for better adhesion of components and surface coatings. This paper reviews the recent research efforts on polymer adhesion with a special focus on adhesion mechanisms. It starts with an introduction to adhesion with explanatory notes on adhesion phenomena. Recent research on the adhesion mechanisms of mechanical coupling, chemical bonding and thermodynamic adhesion is then discussed. The area of adhesion promoters is reviewed with the focus on plasma and chemical treatments, along with direct methods for adhesion measurement. The topics of polymer blends and reactive polymerization are considered and the interactions with adhesion mechanisms are reported. The concluding section provides recommendations regarding future research on the contentious aspects of currently accepted adhesion mechanisms and on strategies for enhancing polymer adhesion strength.