bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monitoring of Subgingival Bacteroides Gingivalis and Actinobacillus Actinomycetemcomitans in the Management of Advanced Periodontitis
Authors: Christersson L.A. , Rosling B.G. , Dunford R.G. , Wikesjö U.M.E. , Zambon J.J. , Genco R.J. 
Published: January 2017

In a series of clinical trials involving 79 adult periodontitis patients, we evaluated the clinical and microbiological effects of H2O2, NaHCO3, and a commercially available povidine solution, as adjuncts to mechanical periodontal debridement. Each trial included a placebo as a control. The healing response was monitored clinically by measurement of changes in probing attachment levels after treatment. The current report includes data from single-rooted teeth only. In general, healing in severely advanced periodontal lesions (initial pocket depth ≥ 7 mm) was enhanced by the use of the listed topical antimicrobial agents administered subgingivally during mechanical debridement. Correlations were sought between changes in probing attachment levels 12 months after treatment, and the presence of subgingival B. gingivalis and A. actinomycetemcomitans in the periodontal lesions. For a total of 428 lesions included in this report, B. gingivalis was detected in 53.1% of lesions showing probing attachment loss (≥1.5 mm), but in only 4.7% of lesions showing gain (≥ 1.5 mm). Either B. gingivalis or A. actinomycetemcomitans was detected in 70.1% of the lesions showing loss and in only 4.8% of those showing gain. These studies indicate the benefits of the adjunctive antimicrobial therapy described, and the usefulness of specific microbiological monitoring as an aid to clinical measurements in the evaluation of success or failure of treatment of chronic adult periodontitis.
Effect of Prenatal and Postnatal Fluoride on the Human Deciduous Dentition. A Literature Review
Authors: Gedalia I. , Shapira L. 
Published: January 2017

Fluoride passes from the mother to fetal teeth. Much of the fluoride is taken up in secretory enamel, probably by the forming mineral apatite crystals. Some is retained with residual proteins. The low concentration of fluoride in the inner enamel is incorporated mainly during the secretory stage, while the enhanced concentration in the surface enamel is produced during the much longer maturation stage. Mature, hard enamel is generally absent during fetal life. The clinical question is whether prenatal fluoride imparts an additional benefit to the universally accepted effect of postnatal fluoride. In general, surface enamel fluoride levels of deciduous teeth increase with increasing pre- and postnatal fluoride administration. A consistent level of caries protection has been reported with pre- and postnatal administration of fluoride unrelated to the acquisition of fluoride in the surface enamel. Many children develop enamel opacities in their deciduous dentition related by various factors to enamel mineralization disturbances in drinking water areas even low in fluoride. Accumulation of fluoride due to an increased fluoride intake is a feature of fluorosed enamel in the deciduous as well as permanent dentition. The resulting mature fluorosed enamel retains a relatively high proportion of immature matrix proteins onto the crystal surface. The degree of fluorosis of the deciduous dentition is less compared with that of the permanent dentition, due probably to a partial protection afforded by the maternal loss of fluoride, formerly known as the "placental barrier".
Geriatric Dentistry and Prevention: Research and Public Policy
Authors: Gershen J.A. 
Published: January 2017

Changing demographics, including the increase in life expectancy and the growing numbers of elderly, has focused attention on the need for dental research activities to be expanded for geriatric dentistry. The elderly are at greater risk for oral disease, since gains in longevity result in more medically compromising conditions or systemic disease with oral manifestations. Also, as edentulism decreases and as more teeth are retained by the elderly, the pattern of oral diseases and the treatment of dental conditions will be altered. Barriers to self-care and professional care must be removed, and prevention and early intervention strategies must be formulated to reduce the risk of oral diseases. Risk factors for oral diseases in the elderly can be reduced by personal home-care regimens, professionally provided preventive, diagnostic, and therapeutic care, changes in high-risk behavior, and a supportive environment. Generating new information about the prevention of oral diseases and conditions that have an impact on the elderly requires a substantial research effort. A research agenda for the elderly should include: epidemiologic studies of relevant oral diseases and related risk factors; investigations of patient and provider attitudes and behavior related to oral health; studies of the relationship between general health and oral health; development and testing of preventive and treatment strategies for conditions such as xerostomia, root caries, secondary caries, and gingival recession; and studies for the evaluation of the impact of the aging population on the dental delivery system. Public policy options to support geriatric oral health care and research are limited by the Government's pre-occupation with cost containment and the lack of visibility for dental programs. Many of the national health proposals for universal coverage and for elimination of financial barriers to health care do not include disease prevention or health promotion programs; dentistry is not mentioned even in those proposals that do include prevention. NIDR is gathering support for geriatric oral health research with its new initiative, entitled the "Research and Action Program to Improve the Oral Health of Older Americans and Other Adults at High Risk". Funding for this program may depend in part on changing national priorities and the dental profession's ability to become more intimately involved in the public debate regarding the future of the nation's health care system.
Interactions Between Dental Amalgams and the Oral Environment
Authors: Marek M. 
Published: January 2017

Dental amalgam fillings interact in a complex way with the environment in the oral cavity as they are subjected to chemical, biological, mechanical, and thermal forces. These forces change the restoration's appearance and properties, while metal ions, amalgam debris, non-metallic corrosion products, and mercury vapor are released into the oral cavity. The phenomena and conditions that affect the amalgam/ environment interaction include the chemistry and biochemistry of the environment, formation of biofilms on the amalgam surfaces, existence of localized corrosion cells, galvanic contacts with other metallic restorations, abrasion during mastication, and synergistic effects of the different forces. Corrosion processes result in a degradation of the functional amalgam properties, while tarnishing reactions cause discoloration. Corrosion degradation of amalgam fillings is due mainly to localized corrosion cells in pores and crevices. Corrosion on occlusal surfaces is accelerated by abrasion during mastication, which removes the protective surface films. The average total amounts of metal species, including mercury, released per day in vivo from a restoration have not been determined. Much of the reported indirect evidence for high mercury release rates is either unreliable or controversial. A more detailed investigation is needed and will require the development of more sophisticated techniques of sampling in vivo, as well as both experimental and theoretical modeling in vitro.
Teratological Aspects of Dental Amalgam
Authors: Larsson K.S. 
Published: January 2017

The teratogenic effect is determined by four factors: (1) the agent, (2) the dose, (3) the stage of embryonic development, and (4) the genetic constitution of the embryo. The first two factors are of particular interest and warrant further comment. It should be emphasized that the mercury released from dental amalgam is mainly metallic mercury vapor. The dose of mercury vapor from dental amalgam fillings in the order of 5 ug/day is very low compared with the doses in a teratological study and is not likely to exceed the threshold necessary for a teratogenic effect to occur. The concentration of the teratogen at the target tissue is determined not only by the degree of placental transfer but also by other factors, such as the distribution within the maternal organism, the affinity to the fetal liver and blood, the hematocrit value, and the passage through the ductus venosus. These factors might help to explain toxicological mechanisms and species differences and have to be considered if the results of animal experiments are to be extrapolated to human conditions. Neither epidemiological data nor animal experimental data indicate that the release of metallic mercury vapor from dental amalgam therapy should cause teratogenic effects. A comparison with the incorporation of the fetotoxic methyl mercury might be justified.
Oral Mucosa and Skin Reactions Related to Amalgam
Authors: Holmstrup P. 
Published: January 2017

Documented cases of oral mucosa and skin affections related to amalgam restorations are rare, although the exact incidence is unknown. Lesions of the oral mucosa may be due to specific immunologic or non-specific toxic reactions toward products generated from restorations. The immunologic reaction most probably involved in mucosal affections related to amalgam is the delayed or cell-mediated (type IV) reaction. Such reactions are seen in contact allergy, and the term "contact lesions of the oral mucosa" has been used. There is a much lower tendency of sensitization through mucous membranes than through skin, and it is questionable whether mercury released from amalgam restorations is able to sensitize a patient. A chronic toxic reaction may be established due to repeated or constant influence to toxic agents in low concentrations over long periods. Such reactions are most frequently localized to the contact zone with the toxic agent. Chronic toxic reactions may possibly be seen in areas of the oral mucosa in direct contact with amalgam fillings. Since the clinical features of these lesions do not differ from those of lesions due to contact hypersensitivity, the diagnosis is obtained by exclusion based on a negative patch test.
Dental Amalgam— Environmental Aspects
Authors: Arenholt-Bindslev D. 
Published: January 2017

Increasing knowledge about the risk of toxic effects caused by anthropogenic mercury accumulation in ecosystems has resulted in a growing pressure for reduction of the discharge of mercury waste. Consequently, the mercury waste problems of dental clinics have been given increased attention, and restrictions on handling and discharge of contaminated waste have been established in several countries. Major amalgam particles from trituration surplus of those produced during the carving and burnishing of new amalgam restorations are generally collected in coarse filters and sold for refinement. Minor amalgam particles released by production of new fillings or by removal of old restorations partly sediment in tubes and drains. The remaining particles are carried with the waste water stream to the local purifying plant. In Scandinavia, the industrial discharge of mercury-contaminated waste water has been reduced to a minimum. According to recent investigations, dental clinics appear to be responsible for the major amount of mercury collected in the sludge generated in purifying plants. If threshold values for heavy metal content, including mercury, are exceeded, the sludge is not allowed to be recycled as fertilizer. Installation of an approved amalgam-separating apparatus in dental clinics is now mandatory in several countries-for example, Switzerland, Germany, Sweden, and Denmark. Approval of amalgam separators is based on national testing programs, including clinical or laboratory tests demanding 95-99% separating efficiency.
Dental Composites/Glass Ionomers: the Materials
Authors: Bowen Rafael L. , Marjenhoff William A. 
Published: January 2017

Most commercial dental composites contain liquid dimethacrylate monomers (including BIS-GMA or variations of it) and silica-containing compositions as inorganic reinforcing filler particles coated with methacrylate-functional silane coupling agents to bond the resin to the filler. They also contain initiators, accelerators, photo-initiators, photosensitizers, polymerization inhibitors, and UV absorbers. Durability is a major problem with posterior composites. The typical life-span of posterior composites is from three to 10 years, with large fillings usually fewer than five years. Polymerization shrinkage and inadequate adhesion to cavity walls are remaining problems. Some pulp irritation can occur if deep restorations are not placed over a protective film. Some have advocated the use of glass-ionomer cement as a lining under resin composite restorations in dentin. The concept of glass-ionomer cements (GICs) was introduced to the dental profession in the early 1970's. Current GICs may contain poly(acrylic acid) or a copolymer. Higher-molecular-weight copolymers may also be used to improve the physical properties of some GICs. Stronger and less-brittle hybrid materials have been produced by the addition of watersoluble compatible polymers to form light-curing GIC formulations. The ion-leachable aluminosilicate glass powder, in an aqueous solution of a polymer or copolymer of acrylic acid, is attacked by the hydrated protons of the acid, causing the release of aluminum and calcium ions. Salt bridges are formed, and a gel matrix surrounds the unreacted glass particles. The matrix is adhesive to mineralized tissues. Provisions must be made for maintenance of the water balance of restorations for the first 24 hours. A varnish to seal newly-placed restorations is provided by most manufacturers. The introduction of metal powder to GICs significantly improved abrasion resistance.
Biodegradation of Dental Composites/ Glass-Ionomer Cements
Authors: Øilo G. 
Published: January 2017

Studies of the degradation processes, types of tests, and measurements and analyses of substances leaching out from resin-based composite materials and glass-ionomer cements are reviewed. For both types of materials, the initial release rate rapidly decreases to a low, but nearly constant, level. For composites, various types of degradation processes have been demonstrated. Elements from filler particles and degradation products from the resin ( e.g., formaldehyde) leak out. Many substances are not properly identified. It is, however, difficult for in vitro and in vivo degradation to be compared. For glass ionomers, a total disintegration of a surface layer is observed, together with a slow release of elements from the bulk. Of the elements released, fluoride is the most interesting. Marked differences have been shown between in vitro and in vivo solubility tests.
Local and Systemic Responses To Dental Composites and Glass Ionomers
Authors: Stanley Harold R. 
Published: January 2017

For many years, the dental profession worked mainly with rather inert restorative materials that had a limited contact with vital tissue, and the opportunity for local and systemic complications was minimal. However, conditions have changed in recent years where the two leading non-mercury-containing materials, resin composites and glass-ionomer cements, are chemically active compounds and can have detrimental effects on pulp tissue. With the advent of light-curing techniques with incremental layering, resin component formulae that were formerly found to be quite irritating to the pulp have become less so with the elimination of the need for matrices and pressure for good adaptation to be gained. As experience revealed the deficiencies and dangers of ultraviolet-light-curing techniques, visible-light-curing systems were developed that provided greater depth of cure, a higher degree of polymerization with less shrinkage with incremental layers, and less porosity. When glass-ionomer cements (GICs) were first introduced, with just one acid (polyacrylic), pulpal responses were classified as bland. With the addition of many more acids to enhance certain characteristics and reduce the setting time, GICs have become more irritating, especially when used as luting agents in areas where the remaining dentin thickness is 0.5 mm or less. Gold foil and amalgam are inert and innocuous restorative materials but require pressure for condensation which creates an exaggerated inflammatory response. This presentation emphasizes the pulpal responses and side-effects of these non-mercury-containing restorative materials and how to keep them within an acceptable range of biocompatibility. Despite the lack of any substantial appearance of soft tissue and systemic responses to resin composites and GICs, the results of a survey of recent literature are included.
Dental Amalgam: the Materials
Authors: Marshall S.J. , Marshall G.W. 
Published: January 2017

The goal of this presentation is to describe the material as it is used clinically, explain why small quantities of Hg can be released, and suggest ideas for amalgams that do not release mercury. A set amalgam is a dynamic material that undergoes many microstructural changes during clinical use, related to both the elevated temperature and corrosion-prone environment in the mouth and mechanical forces applied to the restoration. Amalgams can be divided roughly into two groups by their copper content: low Cu (traditional) and high Cu. High-Cu amalgams generally perform better clinically, but all amalgams corrode to some extent in the mouth. Some corrosion is deemed to be a positive factor, because corrosion product deposition reduces leakage at the margins of restorations; that is, the restorations are partly self-sealing. One of the reasons cited for the improved clinical performance of high-Cu amalgams over low-Cu amalgams is that the corrosion-prone phase, γ 2, is nearly eliminated in high-Cu amalgams. Future research should involve improvements in the clinical performance of dental amalgams, studies of the mercury release from various types of amalgams and the toxic potential of this exposure, and the development of new amalgam systems that reduce the mercury exposure. Although the longevity of modern amalgams is impressive, it is important for their stability to be increased both clinically and microstructurally. An amalgam should be developed with a stable microstructure that, once set, would not change during clinical use. Microstructural changes lead to clinical deterioration. A stable system would not corrode, and the matrix transformation γ 1 to β1 would be prohibited. The latter effect could be achieved by stabilization of the γ1 phase or development of a system that would form the stable β1 phase during amalgamation. Such a system would simultaneously improve clinical performance and reduce the potential for biological side-effects from its deterioration. Studies of the potential for Hg release should be conducted with proper consideration of the microstructures of amalgam systems and alterations in the structures induced by clinical use. Careful studies are needed of the toxic potential from exposure to these materials as they are used clinically.
Chemical Sensors and Biosensors for Fluoride: Current Status and Developing Technologies
Authors: Schultz J.S. 
Published: January 2017

Portable sensors for bioanalytes are becoming of increasing interest, because their development will permit analyses of biological samples at the point of sampling, i.e., at the time when an individual is being examined by a health professional. In this paper, the design requirements for a fluoride sensor are outlined. Currently, commercially available fluoride sensors, ion-selective electrodes, do provide the capability to measure fluoride content in samples directly. However, the sensitivity of these devices is lower than the normal content of fluoride in plasma, and thus, samples must be concentrated before measurement. Recent progress in improving the sensitivity of chemical sensors for fluoride shows sensitivities up to 0.1 μmol/L, which is within the range of interest. In addition, the use of biological systems for developing sensors (biosensors) is expanding rapidly, because of the potential of achieving high selectivity and sensitivity through the use of the amplification power of enzymes. However, relatively few enzyme systems have been discovered that are affected by fluoride-thus the need for expanded research to find appropriate enzymes for this purpose. The characteristics of some enzymes, such as adenylate cyclase, that could be used in the development of a fluoride biosensor are discussed.
The Science Center Movement: contexts, practice, next challenges
Authors: Beetlestone John G. , Johnson Colin H. , Quin Melanie , White Harry 
Published: January 2017

As the science center movement expands worldwide, the time seems ripe to stimulate an informed debate centered on the purpose, practices, and achievements of science centers, together with the challenges they face in the next decade. The first section of this paper focuses on current practice, drawing dimensions from artifact to education, from didactic to empowering, from tutti-frutti to story line, from museum to Disney. Programs beyond the exhibition, and links with the formal education system and the local community, are also considered. The second section deals with the diversity of contexts within which science centers operate—cultural, political, financial, educational—and coins the acronym ASSET: Alternative Settings for Science, Engineering, and Technology. The final section looks to the future, identifying funding gaps, the need for longitudinal evaluation studies, and the challenge of new information technologies. Finally, in the spirit of international challenge, the authors pose three leading questions: What lies beyond the existing-exhibit clone? Can an Art/Science divide be defined? How can we communicate contemporary science and scientific issues?
Does Bank Failure Affect Client Firms? Micro Evidence from Estonia
Authors: Jõeveer Karin 
Published: January 2017

This article explores the effect of a bank’s failure on its client firms using the 1998 bankruptcy of a middle-sized Estonian bank. The firms studied in this article are privately held and do not rely on public equity. The performance of the firms receiving credit from the failed bank is compared to that of a matched set of other firms. The client firms are found to be more likely to fail after their bank’s failure even after controlling for firm characteristics before the event. A decrease in the liquidity of the client firms is also detected just after a bank failure, suggesting that the loss of liquidity may be the linkage between a bank failure and the failure of the clients. JEL Classification: G14, G21, G3
Modelling the Paradox in Stock Markets by Variance Ratio Volatility Estimator that Utilises Extreme Values of Asset Prices
Authors: Shaik Muneer , Maheswaran S. 
Published: January 2017

We document the presence of the random walk effect in stock indices and, at the same time, find that the constituent stocks of the indices are excessively volatile. This gives rise to a paradox in stock markets between the behaviour of the stock index and its constituent stocks. We address this phenomenon in this article and reconcile the seemingly contradictory inferences by extending the Binomial Markov Random Walk (BMRW) model. JEL Classification: C15, C58, G15