bluuebunny/crossref_metadata_2025 huggingface dataset:
Humoral IgG Antibodies to Oral Microbiota in a Population at Risk for Root-surface Caries
Authors: Kent R. , Smith D.J. , Joshipura K. , Soparkar P. , Taubman M.A.
Published: November 2010

Mutans streptococci have been strongly implicated in the initiation of dental caries on coronal surfaces. Their role in development of root-surface caries is less clear. The etiologic agents of both types of dental caries are likely to elicit systemic immune responses. The objective of the present study, therefore, was to study the association of clinical variables of disease with humoral IgG antibodies to nine oral micro-organisms in 314 adult subjects, aged 45-65 years, who were at risk for root-surface caries. Antibody activity to Streptococcus mutans strain Ingbritt, S. mutans / S. sobrinus GTFs, S. faecalis strain 19433, Actinomyces viscosus strain WVU 626, Actinomyces naeslundii strain 12, Lactobacillus casei, Actinobacillus actinomycetemcomitans strain Y4, Porphyromonas gingivalis strain 381, Eikenella corrodens strain 1073, and Wolinella recta strain 371 was measured by ELISA. Pearson correlation coefficients among log10 antibody levels within subjects revealed marked positive correlations among subgingival bacteria, generally weak positive correlations among supragingival micro-organisms, and no correlations between elements of the supragingival battery with the subgingival battery. IgG antibody levels to mutans streptococcal antigens were significantly correlated with subject DMF scores (r = 0.23; p < 0.0001). No significant correlation was seen between DMF scores and antibody to any other supragingival micro-organism tested. Further relationships between levels of S. mutans antibody and individual clinical variables were analyzed by step-wise multiple linear regression, resulting in a model that was highly significant (p = 0.0001), with an r2 = 0.14. Numbers of missing teeth, coronal caries, root-surface caries, and root-surface restorations were each positively associated with antibody levels to mutans streptococci. The model indicated that the associations seen with S. mutans antibody reflected previous encounters with S. mutans antigens, since this model emphasized cumulative caries experience over measures reflecting a subject's current status. These observations strengthen the association between S. mutans and dental caries on coronal surfaces and suggest a further association with caries on root surfaces.
Dental Plaque and Calculus: Risk Indicators for Their Formation
Authors: Christersson L.A. , Grossi S.G. , Dunford R.G. , Machtei E.E. , Genco R.J.
Published: November 2010

The aim of this study was to determine the levels of plaque and subgingival calculus accumulation and to evaluate their correlations with periodontal disease, as well as to evaluate the correlations with race, age, and gender in an attempt to identify risk indicators for plaque and calculus formation. A total of 508 adults 25-73 years of age was examined, and plaque assessment, gingival bleeding assessment, probing pocket depth, and attachment levels were determined. The mean percent visible plaque was 73.5% (range, 8.3-100%), mean percent of bleeding surfaces 38.5% (range, 0-100%), and the mean percent teeth with subgingival calculus 39.6% (range, 0-100%). The mean probing pocket depth in the group was 2.5 ± 0.6 mm (SD), and mean clinical attachment loss was 2.1 ± 1.1 mm. The majority (63%) were classified as having "Moderate" periodontal disease, 7% were "Healthy", and the remaining 30% had "Established" periodontal disease. Plaque and calculus showed statistically significant relationships to the three disease categories (p < 0.001). Multiple step-wise regression analyses on the correlations between plaque and periodontal disease, race, age, and gender resulted in an overall correlation coefficient of r = 0.25 (p < 0.001). Disease status ("Established") contributed most (p = 0.003), followed by race (Blacks; p = 0.015), gender (Males; p = 0.022), and age (55-73 yr; p = 0.022), to the correlation with plaque. For subgingival calculus, the overall correlation coefficient was r = 0.44 (p < 0.001). However, only two of the variables-namely, disease status (p < 0.001) followed by race (p = 0.017)-showed statistically significant correlations. In this population, age, being male, and being Black were risk indicators for supragingival plaque, while race alone was a risk indicator for subgingival calculus. Hence, it is reasonable to test intervention measures which effectively control plaque and subgingival calculus in these target groups to determine their importance in the development of periodontitis.
Effect of Age on the Rate of Tooth Movement in Combination with Local Use of 1,25(OH) 2D3 and Mechanical Force in the Rat
Authors: Takano-Yamamoto T. , Kawakami M. , Yamashiro T.
Published: November 2010

The purpose of this study was to compare the amount and rate of tooth movement in young and mature rats administered 1,25(OH)2D3 simultaneous with application of mechanical force. In 30 seven-week-old and 30 28-week-old male Wistar rats, the right maxillary first molar was moved buccally with a fixed appliance. The appliances delivered forces ranging from 5 to 20 g. Twenty μL of 1,25(OH)2 D3 (10-10 and 10-8 mol/L) was injected locally into the submucosal palatal area of the root bifurcation of the right first molar. The left side was injected with phosphate-buffered saline (PBS). In young rats receiving 10-10 mol/L 1,25(OH)2D3 every three days, tooth movement significantly increased to 126% ofthat in PBS-injected control rats on day 20. In 1,25(OH)2D3-injected mature rats, tooth movement was stimulated markedly and increased with 10-10 mol/L to 245% and with 10-8 mol/L to 154% of the amount of tooth movement seen in the PBS-injected controls by the end of the experiment. PBS-injected rats had a plateau stage where tooth movement did not occur at all, while there was no such lag-time in the 1,25(OH)2D 3-injected group which showed continuous tooth movement. The local injection of 1,25(OH)2D3 did not change serum calcium, phosphate, and alkaline phosphatase activity, and there were no apparent clinical or microscopic side-effects.
Solubilization of Dentin Matrix Collagen in situ
Authors: Van Strijp A.J.P. , Klont B. , Ten Cate J.M.
Published: November 2010

The effects of the oral environment on dentin matrix collagen were studied. In the partial prostheses of 12 participants, two completely demineralized dentin specimens were mounted covered by a Dacron gauze. After an experimental period of seven weeks, the specimens were transferred to a trypsin-containing buffer for determination of the amount of denatured collagen. Subsequently, the specimens were incubated with a bacterial collagenase for assessment of the amount of collagen. After the intra-oral exposure, there was a collagen loss varying between 1 and 47 wt%. This variation might be due to differences in proteolytic activity of the colonizing microflora. After exposure to the oral environment, only about 0.5 wt% of the available collagen was trypsin-degradable. This indicates a rapid solubilization of the denatured collagen from the specimens into the oral cavity. A separate group of specimens was examined by light microscopy and transmission electron microscopy. Various degrees of breakdown could be discerned. Some experimental specimens showed loss of surface integrity and tubules heavily infected with different types of micro-organisms. The lumens of the tubules were enlarged, sometimes creating caverns as a result of the loss of the intertubular collagenous matrix.
Immunolocalization of Integrin α6β4 in Mouse Junctional Epithelium Suggests an Anchoring Function to both the Internal and the External Basal Lamina
Authors: Hormia M. , Virtanen I. , Quaranta V.
Published: November 2010

The localization of the integrin α 6β4, a transmembrane adhesion molecule associated with hemidesmosomes, was studied in mouse junctional epithelium (JE) by the use of monoclonal antibodies in indirect immunofluorescence microscopy. The results showed that the integrin a6 subunit was expressed throughout the JE and was localized to the cell membranes, including the aspects facing the internal and external basal laminae. The β4 subunit had a more restricted distribution. It was expressed only in cells facing the internal and the external basal laminae and had a basally polarized distribution. In other parts of gingival epithelium, both integrin subunits were mainly expressed at the basal aspects of basal epithelial cells. The basement membrane components, type IV collagen and laminin, could be detected only in the external basal lamina and in other basement membranes of gingival epithelium. The results indicate that the a6β4 integrin, expressed in mouse JE, has a role in mediating the attachment of the cells to the basement membranes facing the connective tissue and the tooth.
Immunoglobulins in Milk from Cows Immunized with Oral Strains of Actinomyces, Prevotella, Porphyromonas, and Fusobacterium
Authors: Takahashi N. , Eisenhuth G. , Lee I. , Laible N. , Binion S. , Schachtele C.
Published: November 2010

Immunization of pregnant cows with bacteria leads to the presence of high concentrations of specific antibodies in colostrum and milk. A total of 14 cows was immunized with single strains of heat-killed oral bacteria or pools of strains of Actinomyces, Porphyromonas, Prevotella, and Fusobacterium. Two cows were treated with adjuvant alone. The mean percentages of IgGl, IgG2, IgM, and IgA in all of the milks were 83.8, 3.8, 9.3, and 3.1, respectively. ELISA and whole cell agglutination assays demonstrated high titers in the milks from the cows immunized with either individual strains or the bacterial pools. The highest titers determined by ELISA belonged to the IgGl isotype and in several milks were 64-fold greater than titers in milk from cows treated with adjuvant alone. The concentrations of all antibodies and the titers determined by ELISA and whole cell agglutination assays markedly decreased from the first to the sixth milkings. The functional specificity of the antibodies was demonstrated by agglutination tests against a wide range of bacteria including members of Actinomyces, Fusobacterium, Porphyromonas, Prevotella, Streptococcus, Eubacterium, Propionibacterium,Peptostreptococcus,Bacteroides,Actinobacillus, Haemophilus, Capnocytophaga, and Wolinella. Minimal cross-reactions with bacteria in other genera were observed with all of the milks. High-titer milk preparations have been obtained from immunized cows, and the capacity of the bovine antibodies to agglutinate target bacteria indicates their potential usefulness in oral passive immunization studies.
Chewing Pressure us. Wear of Composites and Opposing Enamel Cusps
Authors: Lutz F. , Krejci I. , Barbakow F.
Published: November 2010

The effects of various chewing pressures on the wear of composites and enamel were assessed in vitro. Standardized composite discs (8 mm in diameter, 2 mm in height) were made of a fine-particle hybrid (FPH), a coarse-particle hybrid (CPH), and ahomogeneous microfilled composite (HMC). The composite specimens were chemically degraded by immersion in 75% ethanol for 24 h, brushed for 30 min, and then thermocycled 300 times (5-55-5°C) while being occlusally loaded 120,000 times at 1.7 Hz, with chewing forces of 25, 50, 75, and 100 N. Standardized human enamel cusps with a uniform contact area of 0.384 mm2 served as antagonists in the chewing machine. Wear of the composites and enamel cusps, their combined wear, and the increase of the enamel contact surfaces were quantified. An increase in chewing pressure significantly enhanced the wear of both composite and enamel in all groups except for the antagonists opposing a HMC. The FPH was most wear-resistant to in vitro chewing pressures in the range of 6.58 to 19.74 MN/m2, the CPH at 26.32 MN/m2, while the HMC was the most enamel-friendly of the three composites tested. The FPH composite had the least disintegration in the occlusal contact area. The ranking of the composites generally varied at the different chewing pressures with respect to the three types of quantified wear-that is, composite wear, enamel wear, and total wear.
Radiometric Classification of Alveolar Bone Health
Authors: Hildebolt C.F. , Zerbolio D.J. , Shrout M.K. , Ritzi S. , Gravier M.J.
Published: November 2010

A radiograph-based classifier for discrimination between normal and diseased alveolar bone was developed. The alveolar bone health of dry mandibles was rated, by consensus of two trained observers, as normal or diseased. Bitewing radiographs of mandibular quadrants were digitized and regions of interest (ROIs) of the alveolar bone between the first and second permanent molars outlined. Gray-scale histograms for the ROIs were computed, and a classifier based on these histograms was developed. Two observers (independently) used only the classifier to rate the bone as being normal or diseased. These ratings were compared with the original ratings of trained observers who viewed and scored the actual alveolar bone. The sensitivity (the ability to detect diseased alveolar bone), specificity (the ability to detect normal alveolar bone), and accuracy were 0.90 or greater, indicating good agreement with subjective visual assessments of dry mandibles. These results suggest that this procedure may be applicable for evaluations of bone health in humans.
Demand and Need for Treatment of Craniomandibular Dysfunction in the Dutch Adult Population
Authors: De Kanter R.J.A.M. , Kayser A.F. , Battistuzzi P.G.F.C.M. , Truin G.J. , Van't Hof M.A.
Published: November 2010

A nationwide survey of oral conditions, treatment needs, and attitudes toward dental health care in Dutch adults was carried out in 1986. One of the aims of the study was to investigate the perceived need and demand for treatment of craniomandibular dysfunction (CMD). A sample of 6577 persons (15-74 yrs of age), stratified for gender, age, region, and socio-economic status, was contacted. Of this sample, 4496 persons participated in the behavioral part of the study, of which 3526 were examined clinically.

The CMD-treatment demand was based on (1) CMD complaints in the past, (2) CMD complaints at present, and (3) an anticipated increase of the present complaints. CMD was both anamnestically and clinically assessed, independently by different examiners.

A total of 21.5% of the Dutch adult population reported dysfunction, but 85% of these perceived no need for treatment. With most of the remaining 15% either seeking or intending to seek treatment (or having had it before), a figure of 3.1% can be used to summarize the actual level of treatment need for CMD in the Dutch adult population.
The Dependence of Shrinkage Stress Reduction on Porosity Concentration in Thin Resin Layers
Authors: Alster D. , Feilzer A.J. , De Gee A.J. , Moli A. , Davidson C.L.
Published: November 2010

The development of polymerization contraction stress was determined as a function of the surface area of porosity, so that the contribution of voids in resin composite to stress relief could be investigated. Experiments were carried out on 200-um-thick layers of resin bonded from wall to wall in a restrained condition. The resin samples were divided into three groups: Group A was without porosity, group B contained a small number of pores, and group C contained a large number of pores in comparison with group B. For each group, porosity area, maximal stress, and stress development rate were determined. The mean maximal stress and stress development rate were inversely proportional to the mean porosity surface. These characteristics differed significantly (p < 0.01) between group A and C. For determination of whether shrinkage stress reduction has to be ascribed to flow from the outer surfaces of the voids or to inhibition of the setting reaction by oxygen in the voids, resin containing only nitrogen bubbles was also tested. The results indicated that both aspects contributed substantially to shrinkage stress relief.

Incorporation of pores by the stirring of a luting cement contributes to stress reduction and can therefore be considered as a contribution to the maintenance of marginal integrity.
Heterogeneity of Surfaces of Subgingival Bacteria as Detected by Zeta Potential Measurements
Authors: Cowan M.M. , Van der Mei H.C. , Stokroos I. , Busscher H.J.
Published: November 2010

Porphyromonasgingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans (A.a.) are Gram-negative bacteria which are implicated in various forms of periodontal disease. The Gram-positive Peptostreptococcus micros may also play an important role. For investigation of the possible adhesion and colonization mechanisms of these organisms, the charge properties of the outermost layers of bacterial cell surfaces were studied through the measurement of zeta potentials at various pH values. Eleven fresh clinical isolates, representing the four species, and one laboratory strain, P. gingivalis W83, were examined. Eleven of the 12 strains displayed heterogeneity with respect to pH-dependent zeta potentials. Within single cultures of each of these strains, two distinct populations of cells were found, one which was more negatively charged than the other. For the Gram-negative strains, the more negatively charged subpopulation was in the majority, while the P. micros strains appeared to be composed mainly of a less-negatively-charged subpopulation. Vesicles prepared from two strains displayed the same pH dependence and heterogeneity of zeta potentials as the parent cells. An A.a. strain which was passaged several times in fluid medium had lost its fimbriae and became homogeneous with respect to charge.
Studies on the Adhesion of Glass-ionomer Cements to Dentin
Authors: Lin A. , McIntyre N.S. , Davidson R.D.
Published: November 2010

This study investigated the bonding mechanisms of glass-ionomer cement to dentin. The approaches included mechanical determination of bond strengths, analysis of surface morphology by means of scanning electron microscopy (SEM) and confocal microscopy, and measurement of chemical changes of fracture bond sites by means of x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The highest bond strengths were obtained with light-cured glass-ionomer cement. SEM and confocal images showed evidence of mechanical interlocking of cement in dentinal tubules. SIMS depth profiles confirmed the ion-exchange process between the light-cured glass-ionomer cement and the dentin surface. From corresponding XPS results, it was clear that the adhesion characteristics were significantly affected by light-curing and the chemical structure of the polymer.
Effects of Cement-curing Modes on Dentin Bonding of Inlays
Authors: Zuellig-Singer R. , Krejci I. , Lutz F.
Published: November 2010

The aim of this in vitro study was to evaluate dentin adhesion after cementation of immediate direct "All Purpose" Hybrid (AP.H) composite inlays (Dentsply) and Cerec Dicor-MGC (Dentsply) inlays with the dentin adhesive Prisma Universal Bond 2 (Dentsply) and the dual-curing Dicor-MGC luting composite (Dentsply).

In 24 extracted human molars, standard MOD cavities were prepared with one approximal margin located in enamel and the other one located in dentin. They were divided into four groups: (I) AP.H inlays, luting composite only, chemically cured; (II) AP.H inlays, luting composite, immediately-light-cured; (III) AP.H inlays, luting composite, initially chemically and delayed-light-cured (15 min); and (IV) MGC inlays, luting composite, initially chemically and delayed-light-cured (15 min). In vitro load cycles corresponding to five years of clinical stress followed. Initially and after specimens were loaded, the margins were analyzed quantitatively by SEM. The tooth/cement and cement/inlay interfaces were scored separately.

The initial percentages of "continuous margin"—at both the tooth/luting composite and luting composite/inlay interfaces-were higher than 94% for all groups. At the end of the load cycles, the quality of the margins at the tooth/luting composite interface significantly decreased for all groups. The highest decrease was found for the cervical margins located in dentin, where only 37%-61% were scored as "continuous margin". The AP.H inlay/luting composite interface showed almost no change. At the MGC inlay/ luting composite interface, the percentage of "continuous margin" decreased to 74%.

After specimens were loaded, the percentage of "continuous margin" in dentin was lower than in enamel, despite the use of a dentin bonding agent (PUB 2). Chemical curing alone and immediate- and delayed-light-curing modes of the dual-cured luting composite showed "continuous margin" scorings which were not statistically different from each other.
Association Between Salivary Flow Rate and the Use of Systemic Medication Among 76-, 81-, and 86-year-old Inhabitants in Helsinki, Finland
Authors: Narhi T.O. , Meurman J.H. , Ainamo A. , Nevalainen J.M. , Schmidt-Kaunisaho K.G. , Siukosaari P. , Valvanne J. , Erkinjuntti T. , Tilvis R. , Makila E.
Published: November 2010

The aim of this study was to examine salivary flow rate and its association with the use of medication in a representative sample of 76-, 81-, and 86-year-old subjects, totaling 368.

In this study, 23% (n = 80) of the subjects were unmedicated. From one to three daily medications were used by 47% (n = 168) and more than four medications by 30% (n = 104). The most commonly used medications were nitrates, digitalis or anti-arrhythmic drugs (47.7%), analgesics and antipyretics (32.6%), and diuretics (29.5%). The mean number used daily was significantly higher in 86-year-olds than in the two younger age groups (p < 0.01). No significant differences in this respect were found between genders.

Among the unmedicated subjects, 76-year-olds had significantly higher stimulated salivary flow rates than did the 81-year-olds (p < 0.05). Unmedicated women showed significantly lower unstimulated (p < 0.01) and stimulated flow rates than did men (p < 0.05).

Stimulated salivary flow rate was also significantly higher in the 76-year-old medicated subjects than in the medicated 86-year-old subjects (p < 0.05). No statistically significant differences were found in unstimulated salivary flow rates among the three age groups. Medicated women showed significantly lower unstimulated salivary flow rates than men (p < 0.001), although the difference in stimulated saliva flow was not significant. A statistically significant difference in unstimulated and stimulated salivary flow rates was found between unmedicated persons and those who took from four to six, or more than seven, prescribed medications daily.
Immunocytochemical Localization of Cathepsins B and G in Odontoclasts of Human Deciduous Teeth
Authors: Sasaki T. , Ueno-Matsuda E.
Published: November 2010

For clarification of the mechanisms by which odontoclasts resorb deciduous teeth during physiological root resorption, cysteine-proteinases such as cathepsins B and G were immunocytochemically localized in odontoclasts at the ultrastructural level. Extracted human deciduous teeth undergoing root resorption were fixed with a mixture of formaldehyde and glutaraldehyde and processed for immunocytochemical detection of these enzymes. Sheep antisera, raised against either human cathepsin B or G, were used as primary antibodies. In odontoclasts, specific immunogold labeling of both anti-cathepsin B and G was clearly localized in lysosomes and pale vacuoles of various sizes, and in a portion of the extracellular canals of odontoclastic ruffled borders. In the presence of either antibody, the cytoplasmic matrix, mitochondria, and nuclei were minimally labeled by immunogold particles. The presence of these proteolytic enzymes in odontoclasts suggests that, during odontoclastic root resorption, these enzymes are involved in the formation of resorption lacunae by means of intra/extracellular degradation of collagen and other non-collagenous matrix proteins of deciduous teeth.
Histomorphometric Study of the Periodontal Vasculature of the Rat Incisor
Authors: Blaushild N. , Michaeli Y. , Steigman S.
Published: November 2010

This study assessed quantitatively the vascular system in the cementum-related periodontal ligament (PDL) along the rat incisor. The lower left incisors of six rats (± 200 g) were subjected to routine histological procedures and cross-sectioned serially (2 μm), and the distance between each section and the apex was computed. The PDL of five sections at different levels along the tooth was divided into mesial, lingual, and lateral parts. The number and area of small and terminal arterioles, capillaries (C), sinusoids (S), post-capillary venules (PCV), and connecting venules, as well as the area of the PDL, were established. Blood vessels (BV) occupied 47 ± 2% of the PDL area in the apical half and 4 ± 2% at the incisal end. Of the total BV area, 41%, 32%, and 27% were located on the lingual, mesial, and lateral tooth sides, respectively. The majority of BV belonged to the venous system (98.5 ± 0.6% and 82.5 ± 3.0% in the apical and incisal parts, respectively). The apical venous system comprised 95.4 ± 1.6% S and 3.2 ± 1.0% PCV, reversing to 27.2 ± 14.2% S and 55.2 ± 11.3% PCV in the incisal half. The number of arterial profiles increased gradually from 6.8 ± 1.5 at the apex to 25.3±2.4 in the incisal part and that of C from 9.0 ± 1.18 to 25.0 ± 4.3. The extensive vascularization in the apical half of the PDL is consistent with the high metabolic demands and with the need for protective cushioning of the constantly growing dental and periodontal tissues. The paucity of blood supply and the presence of numerous small BVs in the incisal end equate with the metabolic needs of the highly organized supporting tissue in this region.
New Aspects of the Setting of Glass-ionomer Cements
Authors: Wasson E.A. , Nicholson J.W.
Published: November 2010

For many years, glass-ionomer cements have been described as setting by the formation of a poly(acrylate) matrix. Recent research has suggested that a second reaction may be involved, namely, the formation of a silica matrix. So that this hypothesis could be tested, non-polymer cements, based on an ionomer glass plus acetic acid, were prepared and stored for up to six months. They were insoluble in water, and their compressive strength was found to increase rapidly over the period of storage. By contrast, the product of the reaction between ZnO and acetic acid was soluble in water. These results support the idea that there is a secondary setting reaction in glass ionomers and suggest that it is responsible for the increase in strength observed.
Immunocytochemical Localization of Cathepsin D in Rat Junctional Epithelium
Authors: Ayasaka N. , Goto T. , Tsukuba T. , Kido M.A. , Nagata E. , Kondo T. , Yamamoto K. , Tanaka T.
Published: November 2010

Localization of cathepsin D was studied in the junctional epithelium (JE) of healthy rat gingivae by immuno-light and -electron microscopy, by means of both the avidin-biotin-peroxidase complex method and a colloidal gold IgG method. At the light-microscopic level, cathepsin D was demonstrated in the JE and oral sulcular epithelium (OSE). Cathepsin D immunoreactivity was remarkable in the coronal portion of the JE and decreased toward its apical portion. However, cathepsin D immunoreactivity in the basal cell layer of the JE was negligible or negative. In the OSE, the granular layer was positive for cathepsin D. In the adjacent connective tissue, many macrophage-like cells (not clear at this level) close to the basal cell layer showed strong immunoreactivity. At the electron microscopic level, cathepsin D was found in the primary lysosomes and trans-cisternae of Golgi apparatus in the JE cells. These lysosomes were often fused together or were fused with cathepsin D-negative intracytoplasmic vacuoles to form secondary lysosomes, which indicated that intracellular digestion may have been in progress. However, neutrophils contained few gold particles based on cathepsin D. It is likely that the amounts of cathepsin D contained in the JE cells and macrophages are larger than those of cathepsin D contained in the neutrophils.

These findings provided morphological evidence that JE cells have the same endocytotic capacity as macrophages and neutrophils, and that JE cells participate in the intracellular digestion that is carried out by lysosomal enzymes such as cathepsin D. It is suggested, in addition, that maximum intracellular digestion occurs in the coronal portion of the JE.
In vitro Antimicrobial Activity of the Human Neutrophil Cytosolic S-100 Protein Complex, Calprotectin, Against Capnocytophaga sputigena
Authors: Miyasaki K.T. , Bodeau A.L. , Murthy A.R.K. , Lehrer R.I.
Published: November 2010

Calprotectin is a complex of two anionic proteins found in abundance in the cytosol of neutrophils, certain macrophages, and oral epithelial keratinocytes. Bacteria of the genus Capnocytophaga are pathogens of periodontal origin which can cause systemic infection in neutropenic subjects. Recently, it has been observed that Capnocytophaga may be internalized by neutrophils within the cytosol rather than within a membrane-delimited phagosome. The purpose of this study was to test the in vitro antibacterial effect of the cytosolic complex, calprotectin, against Capnocytophaga sputigena. Calprotectin was purified from the cytosol of human neutrophils by gel filtration and anion exchange FPLC, and it exerted potent in vitro antimicrobial effects against C. sputigena. Net bacteriostatic activity was exerted up to 18 h, after which bactericidal effects were observed. Both net bacteriostatic and bactericidal activity occurred at concentrations above 20 μg/mL and exhibited identical dose-response characteristics. Particle counts increased in the presence of calprotectin, despite net bacteriostasis as assessed by changes in colony-forming units (CFU). Dose-response characteristics and direct particle counts suggested that net bacteriostatic effects were the result of balanced cell division and death, rather than suspension of cell division. We conclude that calprotectin can be a significant contributor to host defense against infection by Capnocytophaga.
Caries Risk Assessment by a Cross-sectional Discrimination Model
Authors: Leverett D.H. , Featherstone J.D.B. , Proskin H.M. , Adair S.M. , Eisenberg A.D. , Mundorff-Shrestha S.A. , Shields C.P. , Shaffer C.L. , Billings R.J.
Published: November 2010

Although the prevalence of dental caries is continuing to decline, it still affects a majority of the US population and can be a serious problem for those afflicted. The objective of this project was to develop and perfect a model for assessment of risk of dental caries onset in children. In the first study, reported herein, a set of clinical, microbiological, biochemical, and socio-demographic variables was identified that distinguished, with an acceptable level of sensitivity and specificity, between children who had no previous caries experience and children who had high caries levels. A total of 313 children-age 12-15 years, 140 from a fluoridated community and 173 from a fluoride-deficient community-was selected on the basis of previous caries experience, either zero DMFS or high DMFS (> 6 in the fluoridated or ≥ 8 in the fluoride-deficient community). Clinical exams for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride concentration. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of discriminant analyses, with use of seven key clinical and laboratory variables, it was possible for zero-DMFS subjects to e classified correctly (specificity) in 77.6% of cases in the fluoridated community and in 86.1% of cases in the fluoride-deficient community. High-caries subjects were classified as such (sensitivity) in 79.3% and 88.1% of cases, respectively.
Caries Risk Assessment in a Longitudinal Discrimination Study
Authors: Leverett D.H. , Proskin H.M. , Featherstone J.D.B. , Adair S.M. , Eisenberg A.D. , Mundorff-Shrestha S.A. , Shields C.P. , Shaffer C.L. , Billings R.J.
Published: November 2010

Our objective was to develop and perfect a model for the assessment of risk of dental caries onset in children. Even though dental caries prevalence in children is continuing to decline, there is still a significant minority for whom it is a problem. In this study, we sought to ascertain whether a set of variables selected in a previous cross-sectional study could be used to differentiate between caries-free six-year-olds who would or would not subsequently present with clinically-detectable caries. A total of 472 caries-free six-year-olds—286 from a fluoridated community and 186 from a fluoride-deficient community-was selected. Clinical examinations for DMFS, dental fluorosis, and plaque were conducted. Stimulated whole saliva was collected for analysis of mutans streptococci, lactobacilli, total viable flora, and fluoride, calcium, and phosphate concentrations. A questionnaire was used for collection of demographic data as well as information on prior fluoride exposure, dietary habits, and oral hygiene practices. By means of linear discriminant analyses, it was possible to predict correctly which children would develop caries within six to 12 months (sensitivity) in 82.8% of cases and which children would not develop caries during that period (specificity) in 82.4% of cases.
Effects of Initial Temperature and Tempering Medium on Thermal Tempering of Dental Porcelains
Authors: Hojjatie B. , Anusavice K.J.
Published: November 2010

The objective of this study was to test the hypothesis that quenching of porcelain in silicone oil rather than in compressed air will significantly increase the flexure strength by reducing the potential for crack formation during transient cooling. A secondary hypothesis to be tested is that the initial tempering temperature can be reduced significantly below the porcelain maturing temperature of 982°C but well above Tg without a decrease in strength. Opaque-body porcelain disks, 16 mm in diameter and 2 mm in thickness, with a thermal contraction mismatch (Δα) of -1.5,0, and +3.2 ppm/°C were tempered from initial temperatures of 650, 750, 850, and 982°C in silicone oil with kinematic viscosities of 50,1000, and 5000 centistokes. Porcelain disks were also subjected to three cooling procedures in air: slow cooling in a furnace (SC), free convective cooling in a laboratory bench (FC), and tempering (T) by blasting the surface of body porcelain with air.

The crack size induced by a Vickers microhardness indenter was measured within one minute after crack development. For determination of the influence of initial cooling temperature on biaxial flexure strength, six body porcelain disks (Δα = 0) were tempered in air from initial temperatures of 650, 750, 850, and 982°C. The mean crack size of specimens tempered in oil was significantly smaller (p ≤ 0.001) than that of specimens that were slowly-cooled or fast-cooled in air for all thermal contraction mismatch cases. For the same initial temperature, the compatible system (Δα = 0) yielded a smaller crack size compared with the other mismatch levels. For specimens tempered in air, an increase in initial tempering temperature from 650°C to 850°C produced a 34% increase in flexure strength (80.2 MPa to 107.6 MPa). However, increasing the initial tempering temperature from 850°C to 982°C resulted in only a 7% increase in the mean flexure strength. The results of this study indicate that tempering of dental porcelains in air or in silicone oil from an initial temperature ranging from 650 to 850°C improved the resistance to crack initiation and failure. However, compared with oil quenching, tempering in air was associated with a smaller risk of thermal shock failure.
Kinetic Aspects of Gingival and Periodontal Ligament Fibroblast Attachment to Surface-conditioned Dentin
Authors: Rompen E.H. , Kohl J. , Nusgens B. , Lapiere C.M.
Published: November 2010

An in vitro model has been developed for measurement of initial attachment of 3H-labeled human gingival fibroblasts (HGF) and periodontal ligament cells (HPDL cells) to sieved dentin powder. Reproducible attachment was obtained and was closely related to the number of plated cells, the amount of dentin powder, the temperature, and the time (from 0 to 6 h) of incubation. HGF and HPDL cells had a high affinity for untreated dentin. Heat-denatured BSA coating of the dentin fully inhibited cell attachment, while a fibronectin coating had no significant effect. A surface conditioning of the dentin grains by 3% citric acid or by 2.5% minocycline-HCl increased the initial attachment of HPDL cells significantly (p < 0.05). Minocycline-HCl was more efficient than citric acid in that respect. In addition, HGF attachment to untreated dentin was highly significantly improved (p < 0.005) by a pre-incubation of the cells with 50 μg/mL of minocycline, and there was also indication (p = 0.067) of improvement by the presence of minocycline in the attachment medium, with a maximum of efficacy at 110 μg/mL. These results suggest that minocycline-HCl directly influenced the attachment properties of fibroblastic cells and that citric acid and minocycline-HCl could act by different mechanisms. HGF and HPDL cells originating from the same patient displayed no significant difference in their attachment to dentin in this model.
A Microbiological Study of Primary Root-caries Lesions with Different Treatment Needs
Authors: Beighton D. , Lynch E. , Heath M.R.
Published: November 2010

Samples of altered or carious dentin for microbiological culture were obtained from 301 primary root-caries lesions in 59 patients by means of a standardized sampling procedure. This involved the cleansing of each root surface of extraneous supragingival plaque by means of a hand-held toothbrush and distilled water and the collection of the sample with a sterile dental excavator passed through the entire vertical dimension of each lesion. The total number of colony-forming units (cfu) in each sample and the numbers of mutans streptococci (primarily Streptococcus mutans), lactobacilli, yeasts, and Gram-positive pleomorphic rods (GPPR) were determined. Individual bacterial counts were expressed as log10 (cfu per sample), as a percentage of the total number of bacteria per sample, and as a frequency of isolation from lesions with different clinical diagnostic criteria. Clinical measurements of each lesion were made for color, texture, position relative to the gingival margin, and treatment need. Lesions classified as soft yielded significantly more bacteria, mutans streptococci, lactobacilli, and GPPR than leathery lesions, which yielded more bacteria than hard lesions. Lesions were classified into 5 treatment categories: soft and restore, leathery and restore, leathery and debride of caries; leathery and treat therapeutically; and hard no treatment. The total numbers of bacteria, mutans streptococci, lactobacilli, GPPR, and yeasts decreased significantly with decreasing treatment need. The frequency of isolation of mutans streptococci, lactobacilli, and yeasts was significantly greater from lesions requiring restoration and from lesions situated within 1 mm of the gingival margin. We suggest that the majority of root caries is initiated adjacent to the gingival margin.
A Histological Study of the Exfoliation of Human Deciduous Teeth
Authors: Sahara N. , Okafuji N. , Toyoki A. , Ashizawa Y. , Yagasaki H. , Deguchi T. , Suzuki K.
Published: November 2010

For clarification of the histological details of the shedding of human deciduous teeth, exfoliated and extracted deciduous teeth were examined by light and electron microscopy. After the roots were completely resorbed, the dento-gingival junction migrated along the inner resorbing surface and finally reached the pulpal surface of the crown. At the same time, the gingival epithelium also proliferated and migrated under the crown of the deciduous tooth in such a way that part of it lined the residue of the pulp and another part lined the surface overlying the erupting successional tooth.

This phenomenon took place from various sides of the tooth surface. Therefore, just before exfoliation, the migrated gingival epithelium formed narrow necks of tissue, and the crown was only superficially attached to the gingiva by them. The final shedding of the tooth appeared to occur by a tearing of these narrow tissue regions. The results of the present study suggest that the dento-gingival junction as well as gingival epithelium play important roles in the process of exfoliation of human deciduous teeth.
Simultaneous Caries Induction and Calculus Formation in Rats
Authors: Tanzer J.M. , Grant L.P. , McMahon T. , Clinton D. , Eanes E.D.
Published: November 2010

Weanling specific pathogen-free Osborne-Mendel rats were fed a high-calcium, high-phosphorus diet with various levels of sucrose and inoculated with Streptococcus sobrinus strain 6715-13WT and Actinomyces viscosus strain OMZ-105 in order to determine whether calculus and caries could develop simultaneously. Rats consumed diets designated RC-16-5, RC-16-25, or RC-16-50 which partially replaced the corn starch component with progressively higher levels of sucrose, thus, to 5, 25, or 50% sucrose. In general, bacterial recoveries of A. viscosus declined with higher sucrose content of the diet, but a pattern of recovery for S. sobrinus was less clear with respect to dietary sucrose. S. sobrinus, however, was recovered at higher percentages from the tooth surface flora at the later two of three sampling dates. Most calculus-identified by the brittle quality, staining characteristics, and apatitic x-ray diffraction patterns of tooth surface deposits-was formed on the maxillary molars, and most carious lesions occurred on mandibular molars. While there was minimal association of the calculus score with the amount of sucrose in the diet, calculus scores increased greatly from 23 to 43 days after infectious challenge. Caries scores, of both fissure and smooth surfaces, by contrast, increased in a dose-response fashion with increasing dietary sucrose and with time. It is thus possible to induce calculus formation and caries simultaneously in specific pathogen-free Osborne-Mendel rats consuming a high-calcium and -phosphorus diet conducive to calculus formation and containing sucrose. This model appears to be well-suited for simultaneous evaluation of the putative calculus-inhibitory and caries-inhibitory effects of oral therapeutic agents.
Cytotoxicity and Dentin Permeability of Carbamide Peroxide and Hydrogen Peroxide Vital Bleaching Materials, in vitro
Authors: Hanks C.T. , Fat J.C. , Wataha J.C. , Corcoran J.F.
Published: November 2010

There has been recent concern about the inadvertent exposure of dentin with patent tubules as well as gingiva to bleaching systems containing 10-15% carbamide peroxide or 2-10% hydrogen peroxide for more than a few minutes. The aims of the present study were: (1) to determine the cytotoxicity of dilutions of hydrogen peroxide in cell culture; (2) to measure hydrogen peroxide diffusion from bleaching agents through dentin in vitro; and (3) to determine the risk of hydrogen peroxide-induced cytotoxicity from exposure of dentin to these vital bleaching agents. The 50% inhibitory dose (ID50) of hydrogen peroxide to succinyl dehydrogenase activity in cultured cells was found to be 0.58 mmol/L after 1 h. All bleaching materials demonstrated diffusion of hydrogen peroxide through dentin in an "in vitro pulp chamber" device. The one- and six-hour diffusates of all bleaching agents through 0.5-mm dentin exceeded the ID50 in monolayer cultures. Inhibition of succinyl dehydrogenase activity corresponded to the amount of hydrogen peroxide that can rapidly diffuse through dentin in vitro and reach concentrations which are toxic to cultured cells in less than 1 h.
An in vitro and in vivo Study of the Release of Mercury Vapor from Different Types of Amalgam Alloys
Authors: Berglund A.
Published: November 2010

The aim of the in vitro part of the study was to measure the rate of release of mercury vapor from different types of dental amalgam in air, and in air during cyclic dipping into isotonic saline solution or Fusayama solution. The measurements were carried out by means of the Mercollector/Mercometer system, based on atomic absorption spectrophotometry. Both new (age ∼ 2 months) and old (age ∼ 1.5 years) amalgam specimens were studied. The variations in the rate of release of mercury vapor in air during cyclic dipping into aqueous media were most pronounced during the first day of the 10-day period studied. In air during cyclic dipping into the aqueous media, the conventional amalgam specimens released mercury vapor at lower rates over the whole period than did the dispersed and single-composition types studied.

The aim of the in vivo part of the study was to determine the daily release of mercury vapor from amalgam restorations made of alloys of the same types and batches as those used in the in vitro part of the study. A series of measurements was carried out on each of eight subjects before and after amalgam therapy. None of the subjects was occupationally exposed to mercury. The subjects had to follow a standardized schedule for 24 h, where they ate, drank, and brushed their teeth at predetermined times (Berglund, 1990). The amount of mercury vapor released per time unit was measured at intervals of 30-45 min. Samples of urine and saliva were analyzed for mercury. The average frequency of fish meals per month was noted. The amalgam therapy— i.e ., from 3 to 6 occlusal amalgam surfaces and from 3 to 10 surfaces in total-had very little influence on the intra-oral release of mercury vapor, regardless of amalgam type used, nor were any effects found on mercury levels in urine and saliva.
An in vitro and in vivo Study of Toothbrush Bristle Splaying
Authors: Rawls H.R. , Casella R. , Mkwayi-Tulloch N.J.
Published: November 2010

The extent to which a toothbrush is worn out, as evidenced by bristle splaying, is an important determinant of cleaning efficacy. In order for this aspect of oral hygiene to be studied, an accelerated means of producing a life-like pattern of bristle splaying was investigated and compared with splaying induced by a human test-panel. Porcelain denture teeth were brushed under a static applied load in a slurry of dentifrice, by means of a revolving "figure 8" motion, for up to 12,000 revolutions. This was found to induce an increase in the degree of splaying (as measured by "wear index") that was well-fitted (R2 = 0.96) by a second-order expression of the form:

where WI = wear index, WIi = initial wear index, Ri = initial rate of increase in WI, tj = brushing time measured in either machine revolutions (tr) or weeks of human use (tw), and C = a separate constant for each brushing mode (machine or human panel). The rate of splaying was found to be strongly influenced by the quality of the bristle filament, but not by small differences in toothbrush design. The splaying pattern induced by the machine could not be distinguished visually from that in a set of brushes used at home by human volunteers. A strong correlation was found between the splaying produced by machine-brushing and by a panel who brushed free-style at home for 13 weeks. The data fit a linear correlation function:

These results demonstrate that an accelerated brushing method can mimic the human process involved in toothbrush splaying, that a quantitative relationship exists between the two, and that it is sensitive to brush-construction factors known to affect splaying. This method is therefore suitable for use in investigations concerning toothbrush durability and the effects of toothbrush design and use on various aspects of oral health.