bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Prevalence and Pattern of Distribution of Root Caries in a Scottish Medieval Population
Authors: Kerr N.W. 
Published: November 2010

The prevalence and pattern of distribution of root caries were determined in a Scottish Medieval population. The principal finding was a lower root caries prevalence, compared with that of modern times, with respect to surfaces at risk; this was particularly marked with respect to buccal root caries. A lower intake of refined sugars and the presence of heavy deposits of supragingival calculus are suggested as factors that may be responsible for the observed differences. The common site for the early root caries lesion was just apical to the enamel-cementum junction. Initially, it extended laterally in the form of an elliptical erosion; however, the greater the depth of the lesion, the more circular the outline became.
Depressed Eruption Rate of the Rat Maxillary Incisor in a Drug-induced Uncompensated Hemolytic State Model
Authors: Giglio M.J. , Sanz A.M. , Bozzini C.E. 
Published: November 2010

Female rats weighing about 180 g were separated into two groups. One group (A) received phenylhydrazine (PHZ) every other day during three weeks (for induction of an uncompensated hemolytic state), while the control group (C) received saline. The evidence for the establishment of the uncompensated hemolytic state was obtained by hematocrit value, reticulocyte count, and red-cell-volume-59Fe uptake. Body-weight gain (which is a measure of overall body growth rate), body-length gain (which is a measure of longitudinal skeletal growth rate), food intake, and maxillary incisor eruption rate (ER) were significantly depressed in rats of group A during the PHZ-injection period, in relation to rats of group C. These results indicate that anemia and/or associated factors depress ER, along with body growth and skeletal growth.
The Release of Mercury from Dental Amalgam: The Mechanism and in vitro Testing
Authors: Marek M. 
Published: November 2010

Dissolution of mercury from the Ag-Hg matrix phase of dental amalgam in distilled water and synthetic saliva, and the mercury evaporation from the solutions, were studied in vitro. The main objectives of the study were to evaluate the factors that affect the results of the mercury release tests, and to consider the possible mechanisms of the release in vivo. Specimens were exposed to the liquids in open or closed bottles, and the changes in the mercury concentration were determined by cold-vapor Atomic Absorption Spectrophotometry. Concentration vs. time tests showed the dissolution rate decreasing with time. Tests involving sequences of short and long exposures with solution changes showed higher average rates for short-term dissolution into the fresh solution than for the longer preceding exposures. The differences were attributed to a stifling effect of the concentration of elemental mercury on the dissolution. It is believed that mercury dissolved mainly in the elemental form and that a continuous increase in the concentration was made possible by oxidation in the solution. In open cells, some of the mercury was lost by evaporation. The analysis showed that the results of mercury dissolution tests depend on many test variables, such as time, solution volume, oxidation and evaporation conditions, etc. Evaporation, dissolution, and evaporation/dissolution mechanisms of the mercury release in vivo were considered. It was concluded that the dissolution/evaporation model best described the mercury release from dental amalgam restorations.
The Inorganic Components of Cementum- and Enamel-related Dentin in the Rat Incisor
Authors: Steinfort J. , Deblauwe B.M. , Beertsen W. 
Published: November 2010

Recently, we have shown that, in rodent incisors, the crown- and root-analogue dentin (enamel- and cementum-related dentin) show differences in mineralization rates (Beertsen and Niehof, 1986) and composition of the organic matrices (Steinfort et al. , 1989). It was the aim of the present study to determine whether these differences were accompanied by differences in the inorganic components. Rat incisors were analyzed by means of hardness measurements, microradiography, and the determination of Ca, Mg, and PO4 content. The outer circumpulpal dentin layer of the enamel-related dentin (ERD) was considerably harder and denser than the comparable layer of the cementum-related dentin (CRD). Concomitantly, a higher Ca and P04 content was found for the ERD than for the CRD, while the reverse occurred with respect to Mg. From the apical end of the incisor toward the incisal edge, the Ca/PO4 ratio tended to decrease for both ERD and CRD, while the Mg/PO4 ratio increased. All differences appeared to be statistically significant. It is concluded that differences in the non-collagenous organic matrix were accompanied by differences in the inorganic components. More specifically, a relatively high content of highly phosphorylated phosphoproteins (ERD) was associated with a higher Ca and a lower Mg content.
Plaque Fluid and Diffusion: Study of the Cariogenic Challenge by Computer Modeling
Authors: Dibdin G.H. 
Published: November 2010

Every cariogenic challenge involves a mixture of convective transport, diffusive transport, and biochemical reactions, plus physico-chemical reactions (including charge-coupling of diffusion), all of which together require numerical methods for their analysis. This presentation describes a one-dimensional finite-difference computer model of the cariogenic process, and some conclusions obtained from it. Sugar clearance from the mouth, together with site-dependent exchange between the bulk saliva and plaque surface via a salivary film, is combined with a finite-difference model of events occurring within the dental plaque. The latter includes: sugar diffusion and pH-dependent acid production; diffusion and dissociation equilibria for two acid end-products of fermentation and their anions (acetate and lactate); diffusion and dissociation equilibria of phosphate buffer; diffusion of potassium and chloride; diffusion of protons and simultaneous equilibration with fixed and mobile buffers. So that proper concentration distributions consistent with local charge neutrality can be ensured, an algorithm called Q-couple is used to impose charge-coupling between the fluxes of different ions including fixed charges. Mineral dissolution and precipitation are modeled as part of the same equilibrium calculations. The predictions of the model are compared with those of an earlier, much simpler one, in which fixed buffers were not included. It is shown that the known concentration of fixed buffer greatly extends the low pH of a Stephan curve. The isoelectric point of the plaque bacteria also appears to be of importance. The effects of various concentrations of mobile buffers, including acetate, are investigated. It is also shown that varying plaque/saliva contact over the known range derived from published studies has a profound effect on the modeled cariogenic challenge.
Plaque Fluid as a Bacterial Milieu
Authors: Edgar W.M. , Higham S.M. 
Published: November 2010

Studies of the extracellular, free concentrations of substrates, growth factors, inhibitors, and end-products of metabolism to which the intact plaque microflora is exposed in situ can assist in the understanding of factors controlling plaque pathogenicity. Information is becoming increasingly available from analysis of fluid separated by centrifugation of plaques collected at various intervals after an intra-oral pulse of dietary or experimental substrate, or different procedures or treatments having cariostatic potential. Such analytical results give more information than those obtained by analysis of aqueous or other extracts, because they yield values of substrate concentration representing those occurring at the bacterial cell surface. The largest body of information concerns extracellular levels of acid end-products of sugar catabolism in relation to food quality or sequence, and of amino acids and other products of nitrogen metabolism, in relation to studies of the detailed metabolic events of the Stephan curve, and of the demineralizing effect of the plaque environment. Areas where little information is available and which merit further study include plaque clearance of salivary and other components with anti-caries activity (e.g., antibodies, enzymes, fluorides, cations, other antimicrobials, etc.), and substrate concentrations to determine gradients for diffusion into and out of plaque.
Mutans Streptococci, Oral Hygiene, and Caries in an Adult Swedish Population
Authors: Salonen L. , Allander L. , Bratthall D. , Hellden L. 
Published: November 2010

The objective of the present study was to describe the distribution of salivary mutans streptococci in a randomly selected adult population and to relate the distribution to the prevalence of caries. The aim was also to study the association between caries and different levels of oral hygiene (OH). The results were based on the assessment of caries, dental plaque, and concentration of salivary mutans streptococci in 914 subjects who represented 95% of an age- and gender-stratified population sample of 967 individuals, randomly selected from the total adult population living in Alvsborg County, Sweden. The results showed that the distribution of mutans streptococci among dentate adults not wearing any kind of removable denture(s) was similar to that previously reported from studies on Swedish schoolchildren, while a comparably higher proportion of subjects with high levels of mutans streptococci was found among the dentate individuals wearing some kind of removable denture(s). Even higher proportions were found among edentulous individuals with complete denture(s). There was a correlation between mutans streptococci concentration in saliva and caries. The subjects with lower concentrations showed a significantly lower mean number of decayed surfaces, compared with the individuals with higher concentrations of mutans streptococci in their saliva. The median OH standard was lower in the older age groups, and there was a higher ratio of decayed surfaces per remaining tooth in those age groups, in comparison with the younger groups. However, for individuals without mutans streptococci, no relation between OH standard and caries could be found and, regardless of OH standard, higher numbers of decayed surfaces were found with an increasing concentration of mutans streptococci in saliva.
In vitro Evaluation of a Fluoride-releasing Orthodontic Resin
Authors: Chan D.C.N. , Swift E.J. , Bishara S.E. 
Published: November 2010

Decalcification around brackets is sometimes observed following orthodontic treatment. Fluoride-releasing orthodontic adhesives have been developed and used for reduction of the frequency and severity of decalcification. This study evaluated a light-activated, fluoride-releasing resin composite adhesive, FluorEver OBA. Our findings indicate that FluorEver OBA released small concentrations of fluoride ions over time. However, the adhesive had significantly lower tensile bond strengths than a conventional composite cement. Microhardness testing indicated that the resin underneath metal orthodontic brackets was not thoroughly polymerized, which may have contributed to cohesive failures of the resin composite. Despite its lower tensile bond strength, FluorEver OBA may be indicated for cases where decalcification is expected.
Oral Induction of Immunological Tolerance to Chromium in the Guinea Pig
Authors: Vreeburg K.J.J. , Van Hoogstraten I.M.W. , Von Blomberg B.M.E. , De Groot K. , Scheper R.J. 
Published: November 2010

Metal alloys used in dentistry may elicit adverse side-effects. Contact allergic reactions to metals released from such alloys are among the most frequently encountered problems. In an earlier study, we observed that oral contacts with nickel or chromium salts did not sensitize, but rather decreased the risk of subsequent sensitization to these metals. In the present study, we focused on chromium allergy and extended our earlier observations by further dose-response studies. In addition, we compared different chromium valencies as to their potential oral tolerogenic effects. Development of immunological tolerance in chromium-fed guinea pigs was demonstrated by their inability to develop chromium hypersensitivity after a subsequent immunization attempt. For these studies, the techniques of immunization and skin testing were first improved. One feeding with a high dose of K2Cr2O7, (containing hexavalent chromium) was effective in full tolerance induction. In contrast, trivalent chromium (CrCl3) induced a distinctly lower degree of tolerance, whereas metallic chromium powder was not detectably tolerogenic after a limited number of feedings. Dose-frequency-response studies with K2Cr2O 7, showed that full tolerance could also be induced by an increase in the number of feedings with sub-optimal tolerogenic doses. The present results therefore support our hypothesis that long-lasting oral contact with chromium-releasing metal alloys may ultimately result in strong immune tolerance to this metal in subjects without previous skin contact with it. This view is further supported by recent insights into the unique tolerogenicity of oral, as compared with gastro-intestinal, allergenic contacts.
An Intra-oral Appliance Study of the Plaque Microflora Associated with Early Enamel Demineralization
Authors: Macpherson L.M.D. , MacFarlane T.W. , Stephen K.W. 
Published: November 2010

An intra-oral appliance model was used to investigate the composition of the plaque microflora associated with early enamel demineralization. Enamel sections, with exposed windows, were mounted on lower removable appliances, and the devices were worn by volunteers for three-week periods under three experimental conditions. These were: (1) "normal" plaque conditions, (2) extra-oral sucrose applications nine times daily, and (3) inoculation of each volunteer's own mutans streptococci onto the test sites and sucrose applications as described for (2). After 21 days, the plaque overlying each window was removed, and the bacterial composition was determined. Changes in mineral content of the associated enamel were measured by microradiography and microdensitometry, and the total mineral loss (Az) that had occurred at each site was calculated. The 144 sites studied were divided into four demineralization groups by Az value, with an increase in mineral loss from group 1 to group 4. A progressive and significant increase in the isolation frequency of mutans streptococci occurred from Az group 1 to group 4 sites. These organisms were isolated from the plaque of every location with enamel mineral loss of over 1000 Az units, but were not detected in 27% of the group 3 sites. Lactobacilli comprised 2% to 3% of the total cultivable microflora in groups 1-3 sites, but were found in significantly higher proportions (18%) at those enamel sites experiencing the most extensive mineral loss (group 4). No significant relationship was found between demineralization and the levels of Actinomyces species or Veillonella. This model allows plaque bacterial composition to be related to the very early stages of enamel demineralization, and the results support the view that lactobacilli are associated with the more established lesions.
A 24-month Clinical Study of the Incidence and Progression of Dental Caries in Relation to Consumption of Chewing Gum Containing Xylitol in School Preventive Programs
Authors: Kandelman D. , Gagnon G. 
Published: November 2010

The effect of chewing gum containing xylitol on the incidence and progression of dental caries was tested in a sample of 274 children, aged eight and nine years, of low socio-economic status and high caries rate. They were divided into two experimental groups (15% and 65% xylitol chewing gum distributed three times a day at school) and one control group (without chewing gum). The three groups were exposed to the same basic preventive program. Children who chewed gum had a significantly lower net progression of decay (progressions-reversals) over a 24-month period than did the controls. Results for the two groups chewing gum were similar. Chewing xylitol gum had a beneficial effect on the caries process for all types of tooth surfaces, and especially for bucco-lingual surfaces. The two experimental groups had a DMF(S) increment of 2.24 surfaces, compared with 6.06 surfaces for the control group. For this indicator, there was no difference between the two experimental groups. Results for the plaque index were in agreement with those of the DMF(S) increment and the net progression of decay.
Immunohistochemical Localization of the Matrix Glycoproteins-Tenascin and the ED-sequence-containing Form of Cellular Fibronectin—in Human Permanent Teeth and Periodontal Ligament
Authors: Lukinmaa P.-L. , Mackie E.J. , Thesleff I. 
Published: November 2010

The expression of two matrix glycoproteins, tenascin and cellular fibronectin (cFN), has been studied in fully developed human permanent teeth, periodontal ligament, and alveolar bone, in both frozen and paraffin-processed material. Polyclonal antibodies to tenascin and a monoclonal antibody recognizing the ED sequence specific to at least some forms of cFN were usedStaining for both tenascin and cFN was positive in the dental pulp, odontoblastic layer, cementoblast-pre-cementum zone, and on the periosteal as well as endosteal surfaces of the alveolar bone. In the periodontal ligament, cFN was evenly distributed, whereas tenascin was accumulated in the attachment zones. Pre-dentin stained for tenascin but not for cFN. Mineralized dentin and cementum were tenascin- and cFN-nega- tive. The relative staining intensity for tenascin was greater than that for cFN in the cementoblast-pre-cementum layer and in the attachment zones of the periodontal ligament, whereas cFN stained more intensely in the pulp. In frozen material, antigenicities were well-preserved. Paraffin processing facilitated precise recognition of tissue morphology, but the antigenicity of cFN was lostThe co-expression of tenascin and cFN in the dental pulp, cementogenic zone, and on the surfaces of the alveolar bone may reflect the ability of the cells to deposit mineralized tissue matrices. The pronounced expression of tenascin in the interfaces between mineralized and non-mineralized tissues suggests that it is functionally associated with mechanical stress and may thus have at least two distinct functions. The relative amounts of the two matrix glycoproteins may contribute to regulation of tissue structure.
Biosynthesis and Secretion of Rat Salivary Proteins by Xenopus laevis Oocytes
Authors: Apekin V. , Goldberger G. , Oppenheim F.G. , Paz M.A. 
Published: November 2010

Xenopus laevis oocytes injected with poly (A+) RNA isolated from rat parotid and submandibular glands synthesize and secrete salivary proteins. Amylase was identified in the media of cultured oocytes injected with rat parotid mRNA by size and immunoprecipitation with anti-human amylase serum. Secretion of the salivary proteins was detectable in the medium eight h following the parotid mRNA injection and continued in a time-dependent fashion for up to 96 h. In contrast to rat parotid slices in culture, which demonstrate a regulated pathway of secretion highly responsive to the secretagogue isoproterenol, secretion of salivary proteins by oocytes did not respond to the stimulation by isoproterenol. Though parotid mRNA is presumed to contain the templates encoding the regulated pathway of secretion, reconstitution of this pathway of secretion in oocytes was not observed in our experiments. Since Xenopus laevis oocytes secrete constitutively significant amounts of proteins when injected with salivary gland mRNA, they are a useful biological system for the analysis of secretion, processing, and function of salivary proteins.
Tensile Fatigue Limits of Prosthodontic Adhesives
Authors: Aquilino S.A. , Diaz-Arnold A.M. , Piotrowskp T.J. 
Published: November 2010

Tensile fatigue limits and ultimate tensile strengths of some prosthodontic adhesive systems were determined. Ni-Cr-Be cylinders were: electro-etched, chemically etched, and sandblasted prior to being bonded end-to-end with BIS-GMA and 4-META adhesives. Bonded specimens were stored in distilled de-ionized water for three days prior to being tested. Fifteen paired specimens per group were subjected to a cyclic tensile load for 1000 cycles. Tensile fatigue limits were determined by the staircase method. Five specimens per group were tested for ultimate tensile strength. In addition, those specimens which survived the 1000 cycles during fatigue testing were also tested for ultimate tensile strength. Statistical evaluations to compare tensile fatigue limits and ultimate tensile strengths for fatigued and non-fatigued specimens were then performed. The results indicated that the tensile fatigue limit and the ratio of fatigue limit to ultimate tensile strength of the sandblasted, 4-META adhesive system were significantly lower than those of the other systems tested. The application of a cyclic load significantly decreased the ultimate tensile bond strength of the 4-META adhesive. Application of a cyclic load had no significant effect on the ultimate tensile bond strengths of the BIS-GMA systems tested.
Draft Results of a Workshop to Develop Guidelines for Studies Involving Microbial Incidence or Populations in the Oral Cavity
Authors: Krichevsky M.I. 
Published: November 2010

The following five outlines are the results to date of the Workshop held in Rockville, Maryland, in January, 1990. The topics considered in these outlines are: (1) validation of immunological and/or nucleic acid identification probes, (2) cross-calibration of methods and/or laboratories for multi-laboratory cooperative studies, (3) choosing methods for identifying or describing microbial populations appropriate to the scientific question asked, (4) microbial ecology methods (e.g., population dynamics) for the oral cavity studies, and (5) epidemiological methods (e.g., incidence, risk factor analysis) for oral microbial studies. Each topic was considered by two independent groups of participants and later rationalized into one. These outlines are meant to be working outlines for evolution of a set of guidelines to advise on designing studies with microbial incidence and/or population components. We are publishing this preliminary version to elicit comment and criticism from people who did not attend the Workshop. (Attendance at the Workshop was necessarily limited by both space and funds.) Some of the topic outlines have been condensed to save Journal space. The full document is available on request. The next stage will be an open forum to gather and discuss further amplification of the "Guidelines", planned for April 17, 1991, Acapulco, Mexico, in conjunction with the IADR/ AADR Meeting. Written comments and requests for further information should be sent to the Workshop organizer (MIK) at the above address. Within each topic, the editing was done in two phases. The basic outlines were prepared by the "break-out" groups during the Workshop. The second stage was to annotate the outlines with the organizer's editorial comments and suggestions. The annotations are set off by brackets. In the main, these consist of requests for amplification and clarification. In a few cases, there may well need to be a fresh look at some of the concepts presented. Three come to mind immediately: (1) the use of diversity measures, (2) "gold standards", and (3) the use of community structure analysis as presented herein. Others may occur to the reader. You are invited to make any and all comments on the material presented in these outlines. Please let your comments range from syntax and format through detailed and broad observations on content and omission. Especially welcome will be your comments on the annotated remarks and any annotations you feel should be added. For example, should reprints be attached to the guidelines, or should the contents of relevant papers be synthesized (or some combination thereof)?