bluuebunny/crossref_metadata_2025 huggingface dataset:
Technique Sensitivity: Biological Factors Contributing to Clinical Success with Various Restorative Materials
Authors: Cox Charles F. , Tarim Berna , Kopel Hugh , Gürel Galip , Hafez Abeer
Published: January 2009

Since the 1950s, clinicians have relied on various formulations of Ca(OH)2 to stimulate dentin bridge formation. Various studies (Kozlov and Massler, 1966; Massler, 1967; Brannstrom, 1978; Cox et al., 1987; Snuggs et al., 1993) have demonstrated that pulp healing and dentin bridging can occur against a pH spectrum of materials. Recent studies (Akimoto et al., 1998; Cox et al., 1998, 1999; Tarim et al., 1998; Kitasako et al., 1999; Hafez et al., 2000) have reported successful pulp healing and dentin bridging using adhesives for direct capping of exposed pulps. However, others (Costa et al., 1997; Stanley and Pameijer, 1997; Pameijer, 1998; Hebling et al., 1999; Carvalho et al., 2000) have reported unsatisfactory results when exposures were direct-capped with adhesives. Biological and technical factors, or a combination of both, might be postulated to explain these differences. Recent studies have demonstrated that biological success is dependent upon proper hemorrhage control at the exposure site. This review explores the differences and common factors influencing successful dentin bridging, focusing on data derived from animal studies conducted according to ISO usage guidelines for cavity preparation and material placement. In the past, there has been concern that etching of vital dentin leads to immediate pulp death due to low pH. Recent studies have reported that acidic cements cause breakdown of only the smear layer and fail to seal the restoration interface, leading to inflammation and necrosis. A properly hybridized dentin-adhesive interface provides a "bacteriometic" seal to both dentin and pulp tissues. Recent ISO usage studies have shown a high incidence of dentin bridging with adhesives following proper hemorrhage control and removal of both operative debris and biofilm at the dentin-pulp interface by agents such as NaOCl. These are important technique-sensitivity factors to be considered for pulp healing and dentin bridge formation.
Application of Bioactive Molecules in Pulp-capping Situations
Authors: Goldberg M. , Six N. , Decup F. , Buch D. , Soheili Majd E. , Lasfargues J.-J. , Salih E. , Stanislawski L.
Published: January 2009

To evaluate the effects of bioactive molecules in pulpal wound healing, we carried out experiments using the rat upper molars as an in vivo model. Cavities were prepared on the mesial aspect, and pulp perforation was accomplished by the application of pressure with the tip of a steel probe. After the pulp-capping procedure, the cavities were filled with a glass-ionomer cement. Comparison was made between and among: (1) sham-operated controls with dentin and predentin fragments implanted in the pulp during perforation after 8, 14, and 28 days; (2) carrier without bioactive substance; (3) calcium hydroxide; (4) Bone Sialoprotein (BSP); (5) different concentrations of Bone Morphogenetic Protein-7 (BMP-7), also termed Osteogenic Protein-1 (OP-1); and (6) N-Acetyl Cysteine (NAC), an anti-oxidant agent preventing glutathione depletion. Histologic and morphometric comparison, carried out among the first 4 groups on demineralized tissue sections, indicated that, at 28 days after implantation, BSP was the most efficient bioactive molecule, inducing homogeneous and well-mineralized reparative dentin. BMP-7 gave reparative dentin of the osteodentin type in the coronal part of the pulp, and generated the formation of a homogeneous mineralized structure in the root canal. These findings indicate that the crown and radicular parts of the pulp bear their own specificity. Both BSP and BMP-7 were superior to calcium hydroxide in their mineralization-inducing properties, and displayed larger areas of mineralization containing fewer pulp tissue inclusions. The overall mineralization process to these molecules appeared to proceed by mechanisms that involved the recruitment of cells which differentiate into osteoblast-like cells, producing a mineralizing extracellular matrix. We also provide preliminary evidence that NAC induces reparative dentin formation in the rat molar model. Pulp-capping with bioactive molecules provides new prospects for dental therapy.
Dentin Regeneration in Vital Pulp Therapy: Design Principales
Authors: Tziafas D. , Belibasakis G. , Veis A. , Papadimitriou S.
Published: January 2009

The nature and specificity of the mechanisms by which the amputated dentin-pulp interface is therapeutically healed determine the properties of the barrier at this site and play a critical role in the outcome of vital pulp therapy. Healing of the dentin-pulp complex proceeds either by natural repair-which results in defensive hard-tissue formation, or therapeutically regulated dentin regeneration, which aims to reconstitute the normal tissue architecture at the pulp periphery. Progress in biomedical research opens new directions for the design of biologically effective pulp therapies. Application of biocompatible and biodegradable carrier vehicles for local delivery of signaling molecules in pulp-capping situations showed induction of fibrodentin/reparative dentin formation, but often at the expense of underlying pulp tissue. An alternative pre-clinical model aiming to reconstitute normal tissue architecture directly at the dentin-pulp interface should be designed on the basis of the direct induction of odontoblast-like cell differentiation and reparative dentin formation at the pulp-capping material interface. Experimental data clearly showed that pulpal cells can differentiate directly into odontoblast-like cells in association with specific extracellular matrices (dentinal or fibrodentinal matrix) or TGFβ1-containing artificial substrates. Dentin-induced dentinogenesis can be used as a master plan for the achievement of new therapeutic opportunities. In the present study, several short-term experimental studies on dog teeth for potential direct induction of odontoblast-like cell differentiation at the surface of rhTGFβ1-containing artificial substrates (Millipore filters, hydroxyapatite granules, calcium hydroxide, pure titanium) failed to induce any specific reparative dentinogenic effects.
Effects of Fluoride-Supplemented Sucrose on Experimental Dental Caries and Dental Plaque PH
Authors: Cutress T.W. , Sissons C.H. , Pearce E.I.F. , Wong L. , Anderssén K. , Angmar-Månsson B.
Published: January 2009

Sucrose, 5% and 10% (w/v), supplemented with between 0 and 5 ppm fluoride (F), was tested for its influence in vitro on plaque-induced experimental in vitro enamel caries and plaque pH. Plaque growth on bovine enamel was initiated from saliva inocula and sustained in a multiple plaque growth system for up to 31 days by means of a basal medium with periodic applications of sucrose or sucrose supplemented with F. Change in enamel mineralization was assessed, before and after plaque growth, by microhardness testing and microradiography; pH was monitored with microelectrodes. It was found that enamel demineralization was inversely related to the F concentration in the range 2 to 5 ppm, for both 5% and 10% sucrose. Plaque pH responses were unaffected by the F supplements.
Fluoride and Sugar Intake Among Adults and Youth in Mauritius: Preliminary Results
Authors: Lahti S.M. , Uusitalo U. , Feskens E. , Haw U. , Tuomilehto J. , Luoma H.
Published: January 2009

The potential use of different vehicles for delivering fluoride to prevent dental caries has been discussed recently in Mauritius. Water fluoridation was found not to be feasible, and extending the fluoride tablet program would not be easy. Thus, sugar fluoridation as one possibility was considered. For these purposes, the average fluoride and sugar intake was estimated in Mauritius. The results are based on two studies-a Survey on Diet, Health and Lifestyle of Youth in Mauritius (1990) and the Mauritius Diet and Health Survey. Information was collected by trained interviewers using food-frequency and 24-hour-recall questionnaires. The daily total sugar intake, manufactured and natural, was found to be 62 g per day in young people and 50 g per day in adults. In the younger groups, daily frequencies of raw sugar, sweets, and biscuit (cookie) consumption were 1.5, 0.2, and 0.2 times a day, respectively. For adults, the mean daily frequency of consuming sugar-containing foods was 2.6 (SD = 1.3). The daily sucrose intake was rather high, representing about 10% of the daily energy intake. The fluoride levels of foods were calculated by use of Finnish and other available fluoride tables. The mean fluoride intakes per day were 0.64, 0.72, and 0.62 mg per day for 8-17-year-, 18-24-year-, and 30-64-year-old groups, respectively. The median fluoride intake for the oldest group was 0.62 mg/day. The estimated fluoride intake from food did not correspond with the proposed level for the prevention of caries (Murray, 1986) except for the 18-24-year-olds, where it might have been just above the lower recommended limit. However, further data based on analysis of the fluoride contents of Mauritian food samples, especially of whole daily diet, are needed.
Teamwork in Prevention: Possibilities and Barriers to Integrating Oral Health Into General Health
Authors: Nowjack-Raymer R.E.
Published: January 2009

While the term "teamwork" has been used in preventive dentistry for decades, little work has been done in the area of integrating oral health into general health via participation in primary health care or interdisciplinary teams. Oral health professionals must be prepared at the pre-professional and professional levels with the knowledge and skills required to become effective members and leaders of collaborative teams. This paper describes guiding principles for successful team development that are derived from the experience of other disciplines. As oral health professionals take a more active part in interdisciplinary collaborative teams, they must be prepared for roles beyond that of clinician. Five additional roles and examples of their importance to the prevention of oral disease and conditions are discussed.
Can Prevention Eliminate Caries?
Authors: O'Mullane D.
Published: January 2009

There are four main factors involved in the carious process: at-risk tooth structure, plaque flora, fermentable carbohydrates, and time. Based on our knowledge of the carious process, four main preventive strategies have been developed over the years, namely, fluorides, fissure sealing, dietary choice, and plaque control. Fluorides are having a major impact on smooth-surface caries; hence, strategies combining fluorides and fissure sealing are very effective. However, use of fissure sealing is still problematic. Changing dietary practices with a view to reducing dental caries seems to be having little impact on a global scale. Plaque control, as practiced routinely by the majority of people, is not sufficient to result in caries reductions. Deprivation and poverty are strongly associated with high caries levels. Although the preventive strategies currently available are likely to result in lower caries levels for many, for logistical reasons and because of factors associated with deprivation and poverty, caries is likely to remain a major public health problem in most communities for the foreseeable future.
Objectives and Review of the International Milk Fluoridation Program
Authors: Pakhomo G.N.
Published: January 2009

The WHO Global Oral Data Bank (GODB) demonstrates wide varieties of dental caries levels. During the last 10 years, dental caries prevalence in many countries has decreased from very high and high to moderate and low levels. However, there also are countries where dental caries has increased from very low and low to a moderate level. In total in 1993, of the 158 countries for which the WHO GODB has data available, 16 countries indicate a very low level (69 - low, 53 - moderate, 17 - high), and only three a very high level of dental caries. Very high levels of dental caries have been recorded in Costa Rica, Jamaica, and Uruguay. All these data, based on the weighted mean of DMF in 12-year-old children, have been obtained from national surveys or collected from published papers on oral health surveys conducted in selected areas of the countries. Very often, these papers indicated an increase (or decrease) in dental caries in people living in different areas of a particular country; however, the DMF weighted mean at the national level is still without change. One of the most populated countries in the world, China, shows clear evidence from several recent epidemiological studies that the level of dental caries in the urban population is persistently increasing. Dental caries still remains one of the most common diseases affecting a substantial number of children and adults around the world. There is evidence that water or
Feasibility of Milk Fluoridation and Trends in Dental Caries of Children in China
Authors: Bian J.Y. , Li R.Y. , Wang W.J.
Published: January 2009

The aim of the study is to investigate the feasibility of milk fluoridation as a vehicle for caries prevention, based on the current epidemiological status and its trends of dental caries in preschool children in the area of the Haidian District of Beijing, where the indications exist: Fluoride level in drinking water is low (0.2-0.3 ppm), and water fluoridation and other systemic uses of fluorides are unilkely. From 75.9 to 79.7% of 3-6-year-old children were identified as having high caries experience (dmft 4.29-4.35). It was found that 60% of the preschool children who attended kindergarten were 3-6 years old, and 40% of the 1-2-yearolds were living with their families. There is a local dairy to produce milk for the population living in this district. The amount of fresh milk produced daily is about 50,000-60,000 kg. A special kind of milk with vitamins A and D is also available for the preschool children. Data available from the Community MCH Centre indicated that the percentage of breast-feeding is 12% only. The first choice by parents for artificial feeding to the babies is fresh or powdered milk. Therefore, the breast-feeding project started in 1992. It is recommended that mothers' milk should be provided to the babies for at least four months after birth, when a specially prescribed milk for the babies, produced by the dairy, will be provided on a daily basis. The cost of milk is cheaper than others. In this connection, a five-year project on milk fluoridation as a pilot study at the community level for caries prevention of preschool children is now planned. The project is supported by BDMF, WHO, and Chinese MOPH.
Saliva Stimulants and the Oral Health of Geriatric Patients
Authors: Mäkinen K.K. , Pemberton D. , Cole J. , Mäkinen P.-L. , Chen C.-Y. , Lambert P.
Published: January 2009

Root-surface caries (RSC) has been recognized as a specific and important dental disease. Significant advances have been made in the pathology and microbiology of RSC, and the need to standardize the guidelines for recording RSC data has been recognized. Researchers have emphasized the increasing impact RSC will have on the geriatric population, especially since the methods to treat and prevent this disease are limited. The purpose of this study was to investigate the possibility of limiting RSC in a Veterans Administration (VA) patient population, using polyol-containing saliva stimulants that were voluntarily consumed by residents of a VA Medical Center (VAMC) over a period of from six to 30 months. Another aim was to study the effect of this program on the gingival health of periodontal patients.
The Value of Anti-Caries and Anti-Plaque Dentifrices at a Community Level
Authors: Stephen K.W.
Published: January 2009

Although dentifrices (in a modem sense) were first introduced at the turn of the century, it was not until the advent of fluoride-containing compounds that any of therapeutic value was produced. In the early post-war years, formulation compatibility difficulties occurred, with the result that none was demonstrated to have clinically proven efficacy until stannous fluoride was successfully incorporated in the "Crest" formulation of 1955. Thereafter, sodium monofluorophosphate (SMFP) appeared, to be followed by organic and acid-phosphate fluoride preparations, most of which were shown to produce clinical benefit over placebo controls. Since the late 1970's, however, such studies have been deemed unethical in many countries in view of the almost universal availability of efficacious fluoride dentifrices. While an NaF formulation was the first to be tested (albeit unsuccessfully) by Bibby (1945), there was a considerable time period before the arrival of both stable and effective silica-based systems in the early 1980's. Results of studies have varied, but the largest ever double-blind NaF/SMFP head-to-head dentifrice trial yet published (Stephen et al., 1994) has indicated a 6.4% significant benefit in favor of NaF (in silica) over SMFP. With respect to the effect of dentifrice fluoride levels, above 1000 ppm dose-response caries reductions have been obtained, but the efficacy of preparations containing 500 ppm F or less has yet to be demonstrated. In relation to root caries, Jensen and Kohout (1988) reported a 41.4% DFS significant reduction in subjects who used a NaF/silica dentifrice at 1100 ppm F, over a one-year period.
Evaluating the Social Impact and Effectiveness of Four-Year "Love Teeth Day" Campaign in China
Authors: Bian J.Y. , Zhang B.X. , Rong W.S.
Published: January 2009

A massive campaign on "Love Teeth Day" (LTD) has been celebrated nationwide each year in China since 1989. As announced in an official document, nine government and non-government organizations have jointly issued a circular designating that the 20th of September of each year be kept for the Love Teeth Festival in this country. The main activities were planned and conducted by the National Committee for Oral Health, which was set up in 1988. It aims to motivate the people's awareness of dental self-care, participation, and to promote community involvement in oral health education programs. For feedback, two types of questionnaires were designed and sent to the public and the organizers, respectively, after each campaign, and then returned to the office for data processing. The findings from a four-year study indicated that: (1) The activities started from three municipalities, 29 capitals of provinces, and some large cities (1989), and spread to most cities in the urban area, and about 300 counties in the rural area (1992); (2) 14,000 dental professionals and health workers participated in 1989 as information providers, and increased to 40,000 in 1992; (3) oral health knowledge has increased to 76.2% (1992) from 37% (1989); and (4) the people's will in dental prevention was strengthened.
Salt Fluoridation and General Health
Authors: Bergmann K.E. , Bergmann R.L.
Published: January 2009

Salt fluoridation is a systemic form of fluoride supplementation, leaving it to the consumer whether he wants fluoride supplements or not, but thereafter not requiring special dependability for daily compliance. Most German drinking water has low fluoride concentrations. The estimated fluoride intake in German children is between 100 and 300 μg/day, and in adults, between 400 and 600 μg/day. Male subjects have higher mean intakes than females.

From 70 to 90% of the salt intake of 10 to 13.5 g/day in German adults comes from commercially prepared foods. This leaves about 1 to 4 g of salt to be added as table salt at the individual level and to become the source of supplementary fluoride. To increase fluoride intake by at least 500 μg/d, and to prevent an additional intake of more than 3000 μg/day, it may be necessary to have salt at a fluoride level of around 500 μg/g or to include one commercial food to be prepared with fluoridated salt, e.g., bread. A salt fluoride concentration of 250 μg/g does not present a risk of dental fluorosis. However, clear recommendations about systemic fluoride supplementation must be given as long as there are fluoride tablets, fluoride-rich mineral waters, and fluoridated table salt available simultaneously. Persons at risk for hypertension from salt consumption require different means of fluoride supplementation. By and large, in areas of low drinking water fluoride, fluoridated table salt has the potential to become a means of systemic supplementation comparable with drinking water fluoridation.
Global Aspects of HIV Pandemic
Authors: Pindborg J.J.
Published: January 2009

Twice a year, the World Health Organization publishes reports on AIDS from member countries. At the most recent publication, 190 countries reported that they had no AIDS cases. The other countries reported 611,589 AIDS cases. The introduction will give a brief account of the HIV epidemiology, pointing out the areas where a rapid worsening is taking place.
Periodontal Problems Related to HIV-1 Infection
Authors: Barr C.E.
Published: January 2009

The prevalence of periodontal diseases in HIV-infected persons is unresolved. While numerous reports have been published, the data are conflicting in part due to different populations studied, lack of consensus criteria for disease, study location, and biased samples. This presentation will be a collation of information available for the diagnosis and treatment of HIV/AIDS-associated periodontal diseases. The use of "HIV" is no longer accepted as a diagnostic designation. Instead, the diagnostic categories of atypical gingivitis (erythematous gingival banding), necrotizing gingivitis, necrotizing periodontitis, and necrotizing stomatitis and distinguishing characteristics will be presented. It is essential that a distinction be made between those periodontal lesions that may occur in seropositive and seronegative individuals and those which appear to have more specific signs and symptoms associated with HIV infection and with immunosuppression in general. A simplified algorithm has been developed to help differentiate between periodontal diseases specific to the HIV-positive individual and those in the general population. Additionally, the grid may also be used to distinguish the different periodontal diseases known to be associated with HIV infection. Supported by NIH grant DE 08560.
Animal Caries Models: Reaction Paper
Authors: Mundorff-Shrestha S.A.
Published: January 2009

All caries models, including animal models, must demonstrate validity, which is the ability to assess the caries process as it relates to humans. One aspect in assessing validity is the establishment of fluoride dose response. A review of the literature regarding dose response from topical fluorides in rat caries models has indicated that validity has already been shown for fluoride in dentifrices and for fluoride in food and water.

Therefore, investing future time and effort in the rat caries model is justified and warranted. Specific areas to be addressed include: performance of thorough literature searches and data analysis, standardization of the model, synchronization of caries measurements, development of a summary "caries value", determination of a human caries "equivalence factor", and determination of best treatment conditions.
In Situ Caries Models
Authors: Zero D.T.
Published: January 2009

By using in situ models, we have the potential to study both fundamental aspects of the caries process as well as more applied research problems such as the effect of food on dental caries and the role of fluoride in caries prevention in human subjects without actually causing caries in the natural dentition. The key experimental parameters that need to be considered in the development of an in situ model are the characteristics of the subject panel, the physical design of the model, the type of hard tissue substrate and the method of assessing mineral status, and the study design and clinical protocol. Each parameter must be carefully considered in relation to the objectives of the research, study design requirements, ethical considerations, impact on clinical relevance, and impact on the control of variation. The major source of variation associated with in situ models should be of biological and not experimental origin. The design and conduct of proper in situ model studies require a clear understanding of the caries process, sound analytical support, and a knowledge of how to work with research subjects to achieve a high level of compliance. Given the complex nature of caries, a combination of hard tissue substrates-including sound, surface-softened lesions and subsurface lesions-may be necessary to model all aspects of caries progression and prevention successfully. Internal validation of in situ models using fluoride dose-response controls is considered to be necessary for studies evaluating the efficacy of new fluoride dentifrice formulations.
In Situ Caries Models: Reaction Paper
Authors: Wefel J.S.
Published: January 2009

In situ caries models can be found in all shapes and sizes and designed for many purposes. Building on previous conferences, Dr. Zero has done a remarkable job in summarizing the many aspects of in situ models, and as such this reactor's paper will be restricted to only several aspects of the model. One of the most important steps in using in situ models involves the reporting of enough details and reasons for choices in model parameters so that the reviewer or reader can judge clinical relevance and applicability. This approach tends to broaden the field as much as restrict it to only one substrate, evaluative technique, or appliance type. Continued work needs to be done on both surface and subsurface lesions; there is a need to establish "gold standards" for model validation in areas such as salivary flow, antimicrobials, food sequencing, etc., and the clinical relevance of each model needs to be explored.
Role of Saliva in Caries Models
Authors: Edgar W.M. , Higham S.M.
Published: January 2009

The crucial role played by the actions of saliva in controlling the equilibrium between de- and remineralization in a cariogenic environment is demonstrated by the effects on caries incidence of salivary dysfunction and by the distribution of sites of caries predilection to those where salivary effects are restricted. However, of the several properties of saliva which may confer protective effects, it is not certain which are most important. A distinction can be made between static protective effects, which act continuously, and dynamic effects, which act during the time-course of the Stephan curve.

Evidence implicates salivary buffering and sugar clearance as important dynamic effects of saliva to prevent demineralization; of these, the buffering of plaque acids may predominate. Enhanced remineralization of white spot lesions may also be regarded as dynamic protective effects of saliva. Fluoride in saliva (from dentifrices, ingesta, etc.) may promote remineralization and (especially fluoride in plaque) inhibit demineralization.

The design of experiments using caries models must take into account the static and dynamic effects of saliva. Some models admit a full expression of these effects, while others may exclude them, restricting the range of investigations possible. The possibility is raised that protective effects of saliva and therapeutic agents may act cooperatively.
Statistical Considerations Related to the Use of Caries Model Systems for the Determination of Clinical Effectiveness of Therapeutic Agents
Authors: Proskin H.M.
Published: January 2009

Caries model systems bear great promise for the eventual determination of clinical benefits of therapeutic agents without the time and expense involved in the conduct of a full-fledged clinical trial. However, before such models can routinely be applied for such purposes, there are several issues which must first be resolved, including the consideration of a number of statistical matters. These include the assessment of the validity and reliability of the models to be so used. A procedure presented by Proskin, Chilton, and Kingman provides a quantitative means by which a conclusion concerning clinical effectiveness can be derived on the basis of data obtained through the use of a model system, given that certain fairly general underlying conditions prevail. The present paper provides some discussion and recommendations of the author related to statistical matters concerning the use of models, and discusses the derivation and logic of the Proskin, Chilton, and Kingman procedure.
Role of Models in Assessing New Agents for Caries Prevention-Non-Fluoride Systems: Reaction Paper
Authors: Quivey R.G. , Smith A.J.
Published: January 2009

Several important issues have been raised concerning the need for consideration of alternatives to fluoride. The principle reason to do so has been the lack of comprehensive effectiveness of fluoride, which in turn reveals incomplete understanding of the caries process. Included among the topics required for clarification of caries initiation would be quantitative methods for relating plaque pH values to the formation of caries. Thus, methods for assessing the activity of anticaries agents over time would be of considerable assistance in monitoring the effects of these test compounds on bacteria. The use of recombinant oral micro-organisms containing genetic fusions, to provide information on the effects of agents on bacteria growing in model systems, is discussed as a possible means of obtaining relevant data in situ.
Model Investigations of Caries Inhibition by Fluoride-Releasing Dental Materials
Authors: Erickson R.L. , Glasspoole E.A.
Published: January 2009

Fluoride-releasing dental materials are generally believed to reduce or prevent secondary caries. The evidence for this is largely anecdotal and centers on clinical experience with silicate cements and, more recently, with glass-ionomer cements. Unfortunately, corroborating evidence from controlled clinical trials is inadequate to establish precisely how effective these materials are or under what conditions they might be effective. Even less is known about the clinical effectiveness of newer materials that, often, release less fluoride. In vitro model systems have been used to study the effects of dental materials on de/remineralization of surrounding tooth structure. Fluoride-releasing materials have been shown in these models to reduce demineralization of both enamel and dentin compared with a material that does not release fluoride. This is useful from a mechanistic standpoint, but without clinical "standards" to guide model results, it is not possible to define an acceptable level of fluoride release or the length of time such release is required. A limited number of in situ model studies has been conducted, and some fluoride dose-response information has been obtained. These models are closer to the real situation and perhaps provide the best means to define required levels of fluoride release from materials in the absence of adequate clinical information.
Evaluation of Fluoride-Releasing Dental Materials by Means of in Vitro and in Vivo Demineralization Models: Reaction Paper
Authors: Rawls H. Ralph
Published: January 2009

It is essential that we understand the dose-response mechanisms of fluoride delivered intra-orally at sites in intimate contact with dental tissues. Many studies show that extremely low levels of fluoride can inhibit caries. However, few of these studies provide a direct comparison between fluoride release and the inhibition of secondary caries. For this, laboratory, animal, and in situ caries models are required which can predict clinical efficacy. This paper supplements Dr. Erickson's presentation (Erickson and Glasspoole, 1995) by illustrating the adaptation of currently used demineralization and caries models to the development and evaluation of fluoride-containing resin materials. As representative of this class of material, those which release by ion-exchange are reviewed. It is concluded that model systems designed for topical fluorides and non-fluoride dental materials can be adapted for use with fluoride-releasing materials. Further, the use of materials with a long history of clinical efficacy as inhibitors of marginal caries, such as the silicates, is a useful means of determining target values for developing new fluoride-releasing materials. The minimum concentration of F- that must be maintained in the immediate vicinity of a material to provide caries protection at localized sites is not yet known. Nor is it known what combination of release rate, pattern of release, and duration of release is needed to optimize either localized or full-mouth protection. These issues deserve closer examination to aid our understanding of F- action when delivered from dental materials, so that improved caries model systems can be designed for use with dental materials.
Physical and Chemical Aspects Related to Substances Released from Polymer Materials in an Aqueous Environment
Authors: Ruyter I.E.
Published: January 2009

Exposure to an aqueous environment will change the physical properties of polymer materials with time. Due to water absorption, surface hardness is reduced and mechanical properties are adversely affected. The composition of polymer dental materials varies greatly. The organic substances are represented by monomers, oligomers, polymers, initiators, activators, inhibitors, anti-oxidants, UV stabilizers, plasticizers, fluorescent compounds, and other additives. The inorganic substances are represented by oxides and glasses (fillers and pigments) of various composition. Both organic and inorganic substances are released into water from composite materials. Combined-HPLC/UVspectroscopy analysis of an aqueous extract from a composite filling material demonstrates that the eluate contains several components. Several inorganic metal-ions released into aqueous solutions have been identified. Only a few of the released organic substances have been identified. Several investigators have determined the quantity of residual monomers in the polymerized materials, and the decrease of such residual monomers with time. Exposure to water, or aqueous salivary enzyme solutions, results in release of degradation products, such as formaldehyde, methacrylic acid, and others.
Advanced Techniques of Micro-Analysis and Confocal Microscopy: Perspectives for Studying Chemical and Structural Changes at the Interface Between Restorative Materials and the Cavity Wall
Authors: Duschner H. , Ernst C.-P. , Götz H. , Rauscher M.
Published: January 2009

Migration of trace amounts of elements and structural changes characterize the interface between immiscible substances. The contact zone among filling materials, saliva, and the cavity wall has the additional function of preventing the progress of leakage and subsequent caries. Difficulties in chemically and structurally analyzing the gradients of composition in an interface of microscopic dimensions characterize the experimental situation. The use of advanced techniques of instrumental micro-analysis and techniques of micro-visualization is our approach to the problem. With confocal laser scanning microscopy (CLSM), effects of the components of the filling material on the structure of the cavity wall can be visualized non-destructively. Surface analysis with electron spectroscopy (XPS) and micro-spot analysis with laser mass analysis (LASMA) give the information on changes of the elemental composition of the cavity wall. The effects of the filling materials on the structure of enamel are correlated with the pre-treatment of the cavity wall. XPS and LASMA give evidence that fluoride does not migrate into the enamel of the cavity wall.
Caries-Preventive Effects of Fluoride-Releasing Materials
Authors: Büyükyilmaz T. , Øgaard B.
Published: January 2009

The plaque-retentive properties of fixed orthodontic appliances result in a severe challenge on surfaces generally not susceptible to caries. Lesions may develop within a month in the absence of fluoride, and clinical studies have shown that from 50 to 75% of orthodontic patients develop decalcifications on labial surfaces during treatment. Fluoride mouthrinses reduce the occurrence, although compliance is often poor. Orthodontic bonding agents and cements releasing fluoride, which reduce the need for cooperation, have been introduced. Few clinical studies have been done to prove the cariostatic properties of fluoride-releasing materials in orthodontics. In short-term caries model studies, glass ionomers and a glass filler containing light-cured adhesive that releases relatively large amounts of fluoride have shown cariostatic properties. However, during severe challenges such as occur with orthodontic appliances, fluoride alone has limited cariostatic properties. The combination of fluoride with antimicrobial agents, and the use of acidic fluoride solutions depositing acid-resistant coatings of calcium fluoride and titanium have shown to give better clinical effects than fluoride alone during extreme conditions. Fluoride-releasing materials may therefore be considered as useful supplements to these procedures.
The Effects of Gic Restorations on Enamel and Dentin Demineralization and Remineralization
Authors: Ten Cate J.M. , Buus M.J. , Damen J.J.M.
Published: January 2009

Glass-ionomer cement (GIC) restorations release fluoride after placement in the oral environment. This is assumed to be one of the reasons for the decreased prevalence of secondary caries. In the current studies, the effects of GIC restorations on demineralization and remineralization of enamel and dentin lesions were studied, in an in vitro and an intra-oral model, respectively. The in vitro pH-cycling study revealed that the excessive fluoride release of the freshly placed restorations upset the (commonly observed) mineral balance between the specimens and the de/remineralizing solutions. Anomalous patterns of calcium uptake by the specimens (with GIC) during the demineralization phase and calcium loss during the remineralization phase were observed. This was hypothetically explained from the behavior of a surface coating on the GIC restorations, which was observed with SEM. The intra-oral studies showed, after three months in situ, hypermineralization of dentin close to or in contact with the restoration. It is concluded that the fluoride released from GIC or the decreased permeability as a result of hypermineralization causes lower susceptibility of the dentin of the cavity walls.
Studies on the Effect of Fluoride Released by Glass Ionomers in the Oral Cavity
Authors: Forss H. , Seppä L.
Published: January 2009

Numerous in vitro studies have shown that fluoride released by glass ionomers can have effects on enamel, dentin, and plaque adjacent to the material. However, the action of fluoride in vivo may be different from that found in vitro. The aim of the present series of studies was to investigate the effects of glass ionomers in oral conditions. This was tested in clinical experiments conducted on adults who had freshly made or old glass ionomers in their mouths. The results of the studies showed that fluoride released by glass ionomers may increase the fluoride content of plaque close to the material. Fluoride content decreased rapidly with decreasing fluoride release from glass ionomer, but it was increased slightly even in plaque growing on three-year-old fillings. However, the effect appeared to be very local, and no increase in salivary fluoride content due to glass-ionomer fillings was found. Although the growth of plaque was not inhibited, the proportion of mutans streptococci was significantly reduced in plaque growing on glass ionomer during the six weeks after placement of the material. No such effect, however, could be seen in the case of three-year-old glass-ionomer fillings. Although in vitro studies have shown that glass ionomers can take up fluoride and subsequently release it, applying fluoride gel to old glass-ionomer fillings did not result in an increased fluoride concentration of plaque growing on the fillings in vivo. Further studies are needed to find out whether the recharging of glass ionomers with fluoride has clinical significance.
The Role of the Acquired Enamel Pellicle in Calculus Formation
Authors: Rølla G. , Rykke M. , Gaare D.
Published: January 2009

This article reviews a new concept of pellicle formation based on recently published data, and some experiments concerning the role of the pellicle in relation to calculus formation. There are strong indications that the pellicle consists of a multilayer of globules with a diameter of from 20 to 300 nm. These globules have a raspberry-like surface with clusters of smaller globules which are bound together by calcium, probably by bridging. The globules have negatively charged surfaces and hydrophobic interiors and are very similar to the micelles present in milk. It was shown in the present experiments that the pellicle inhibited seeded precipitation of calcium phosphates on enamel in a saturated solution. It was further shown that several proteolytic enzymes were able to release peptides from both milk micelles and from salivary globules, and that this treatment eliminated or reduced the inhibiting effect of the pellicles with regard to precipitation of calcium phosphates on enamel. It is suggested that this may be related to calculus formation in vivo, and that the pellicle normally inhibits calculus formation, but that proteolytic enzymes from bacteria in the oral cavity degrade the pellicle and cause it to lose its inhibiting effect.
Inhibition of Formation of Calcium Phosphate Deposits on Teeth and Dental Materials: Recent Advances
Authors: Gaffar A. , Legeros R.Z. , Gambogi R.J. , Affutto J.
Published: January 2009

The inorganic composition of dental calculi from teeth and dentures has been characterized by x-ray diffraction, electron microprobe, and infrared absorption spectroscopy. They consist of carbonated hydroxylapatite (CHA), dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP), and magnesium-substituted beta-tricalcium phosphate (6-TCMP). The calculi on denture surfaces are principally CHA. Formulations have been developed to inhibit formation of these calculi in humans. The active inhibitors are pyrophosphate, pyrophosphate plus polymer, and zinc salts. These agents inhibit calculus formation in humans by preventing the formation of hydroxyapatite crystals. The new formulations include multiple-benefits products containing fluoride and antimicrobial and/or desensitizing agents. These provide not only reduction in calculus formation in humans but also reduced plaque, gingivitis, and/or dentinal hypersensitivity. Recent studies have also indicated a relationship between gingival recession and supragingival calculus in the Thai population, and the use of an anticalculus formulation has shown significant improvement in gingival recession in this population.
Deposit Formation on Prosthetic Materials in Vivo After One Year: a Quantitative Study of Twelve Materials
Authors: Zanghellini G. , Dykman A.G. , Rheinberger V. , Arends J.
Published: January 2009

In vivo-formed deposits on prosthetic materials are of considerable interest. Deposit quantification is important to gain insight into the mechanisms of formation and removal.

A new method is presented for the quantitative investigation of deposit formation in vivo on 12 experimental materials after one year. The parameter assessed is the deposition parameter, D, the fraction of the surface covered by deposits. The materials were arranged in a given sequence in the prosthesis flanges and carried in two investigations by 11 and 20 participants for one year.

The results show that the parameter D is strongly material-, participant-, and site-dependent. Differences between materials varied by a factor of at least 25; PMMA (Polymethylmethacrylate) was always lowest in D value. The D values in the upper prosthesis were always larger than in the lower prosthesis; the ratio Dupper /D lower was 2.3 ± 0.5.

The material parameters strongly influencing the deposit formation were of both the monomer and the filler type. Attempts were made to correlate D with surface hardness, surface roughness, and water absorption. Only the last parameter was clearly linearly related to D.

LASMA (Laser Mass Spectrometry) studies showed that the chemical nature of the deposits formed in vivo on prosthetic materials is. in general, initially different from that of calculus.
Mechanisms of Stain Formation on Teeth, in Particular Associated with Metal Ions and Antiseptics
Authors: Addy M. , Moran J.
Published: January 2009

Much has been written on the subject of extrinsic tooth discoloration, but, except when the pigment is intentionally applied, the etiologies and mechanisms are poorly understood. Extrinsic stains have been classified as non-metallic or metallic. The pigment usually lies not on or in the dental tissues, but in surface deposits, particularly the acquired pellicle layer and at sites receiving limited cleaning. Whether pigments absorb, adsorb, or chemically interact with dental surfaces is unclear. Some stains merely seem to reflect the color of the apparent source, whereas others have been ascribed to a secondary chemical alteration of a substance at the tooth or pellicle surface. Theories of chromogenic bacteria and formation of metal sulfides are frequently propounded but without clear supportive evidence. Staining by cationic antiseptics and, to a lesser extent, metal salts has attracted research interest. Chlorhexidine and other cationic antiseptics, it is hypothesized, may catalyze browning reactions or facilitate metal sulfide formation in pellicle. Controlled clinical studies have repeatedly shown that dental and mucosal staining associated with the use of chlorhexidine and some metal salts is dependent upon volunteers' imbibing reasonable quantities of chromogenic beverages, such as tea. However, it must be appreciated that cationic antiseptics and polyvalent metals can precipitate chromogenic material from a large range of dietary compounds. The control of dental staining, at least that associated with chlorhexidine, can be achieved both in vitro and in vivo by the use of oxidizing agents which appear to remove the stain physically from the surfaces.
Stain and Subsurface Degradation of Dental Composites as a Function of Structure and Permeability: a Clinical and Laboratory Study
Authors: Mair L.H.
Published: January 2009

Staining and subsurface degradation of dental composites were studied in a clinical trial and associated laboratory experiments. The materials in the clinical trial were Clearfil Posterior, Occlusin, and P-30. A significantly higher proportion of Occlusin restorations exhibited marginal stain. An in vitro study indicated that the clinical practice of curing the unfilled bonding resin prior to placing the composite caused the formation of a resin interface with the potential to stain. Bonding resins containing hydrophilic monomers such as HEMA stained more than resins based on BIS-GMA/TEGDMA.

In restorations which had been removed for replacement, P-30 exhibited a significantly higher depth of subsurface degradation as assessed by silver nitrate staining. In vitro studies indicated that this material was more permeable and leached more inorganic ions than the other materials. It is suggested that, in clinical practice, the thickness of the bonding resin should be kept to a minimum, and that modem materials with soluble glass fillers should be investigated so that the effects of these fillers on permeability and degradation can be observed.