bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on Chondrocytes from Mandibular Condylar Cartilage, Nasal Septal Cartilage, and Spheno-occipital Synchondrosis in Culture. I. Morphology, Growth, Glycosaminoglycan Synthesis, and Responsiveness to Bovine Parathyroid Hormone (1-34)
Authors: Takigawa M. , Okada M. , Takano T. , Ohmae H. , Sakuda M. , Suzuki F.
Published: November 2010

Methods for isolating chondrocytes from the craniofacial complex and culturing them in vitro were established. Chondrocytes which were isolated by collagenase digestion from mandibular condylar cartilage, nasal septal cartilage, and spheno-occipital synchondrosis grew well in vitro. All three types of chondrocytes actively synthesized glycosaminoglycans, a differentiated phenotype of chondrocytes, and responded well to parathyroid hormone. However, some different characteristics were noted among the three types of chondrocytes in culture.
Skin Graft Rejection After Allogeneic Tooth Transplants in Mice
Authors: Riviere G.R.
Published: November 2010

Three strain combinations of in-bred mice representing strong and moderate histocompatibility barriers were used to determine if tooth allotransplants evoked strong or weak immunologic memory as measured by the second-set donor-strain skin graft technique. At issue was whether the anatomic site of engraftment could influence the outcome of these experiments. Recipients received either 5-mmdiameter skin grafts or one or four adult teeth. Experimental transplants were placed in subcutaneous pouches or in ear pouches. Control mice received only orthotopic skin grafts. Second-set orthotopic skin grafts were placed either one mo, six mo, or 11 mo after primary transplants. Skin grafts were observed daily until rejection occurred. We found that skin provoked strong memory in subcutaneous tissues, but that teeth generated very weak memory in subcutaneous tissues. Conversely, teeth placed in ear pouches were able to generate strong immunologic memory. This occurred whether donor and recipient shared H-2 allo-antigens, or whether one tooth or four teeth were grafted, and the difference persisted for at least six mo. We conclude that teeth are not weak antigens, nor is the subcutaneous site privileged regarding immunologic memory. Rather, there seems to be some critical interaction between teeth and the immune system draining subcutaneous tissues that results in a failure to generate strong anamnestic immunity. Perhaps definition of the processes involved will be of advantage in future human applications.
Auger Chemical Analysis of Oxides on Ni-Cr Alloys
Authors: Baran G.
Published: November 2010

Oxides formed on four Ni-Cr dental casting alloys in three temperature domains and in two different atmospheres were chemically analyzed using the Scanning Auger Microprobe. Distributions of Ni and Cr in the oxide layers varied with the alloy; oxidation in air resulted in apparently thicker oxide layers than did oxidation in a reduced oxygen atmosphere.
Microprobe and SEM Analysis of Surface Coatings on Caries-like Lesions in Enamel after Metal Ion Mordanting and APF Application
Authors: Clarkson B.H. , Wefel J.S. , Miller I. , Edie J.
Published: November 2010

The production of tenacious surface coatings on enamel after metal ion mordanting followed by APF has been reported to prevent caries-like lesion initiation in vitro. In this study, similar surface coatings, which may be responsible for the inhibition of lesion progression, were examined using SEM and microprobe analysis. Relatively thick, even surface coatings which were in intimate contact with the enamel surface of caries-like lesions were seen after zirconium and iron (ferric) pre-treatment, buta thinner and unevenly distributed coating was seen after titanium pre-treatment. This latter coating was similar to that seen after APF treatment alone. Fluoride concentrations on the surface and in the subsurface of caries-like lesions were similar for all treatment groups. The surface coatings after zirconium and iron mordanting may be responsible for the greater inhibition of lesion progression than that seen after both titanium pre-treatment and APF treatment alone.
Tissue Repair After Condylectomy in Growing Macaca fascicularis
Authors: Bakker V.M. , Swartberg P.E. , Heeley J.D.
Published: November 2010

In order to determine the nature of tissue repair after removal of condyles, bilateral condylectomies were performed in seven growing female Macaca fascicularis. Two animals underwent condylectomies only, and five animals were fitted with maxillary and mandibular splints before undergoing condylectomies. One condyle from each condylectomized animal was processed for histologic examination. Four animals, with intact condyles, were available as controls: Two had splints placed, while the other two did not undergo any treatment.

Nine mo after surgery, the histology of 12 resection sites and 12 control condyles (seven removed at condylectomy and five at death) was compared. In the control condyles, hypertrophic cartilage was seen over the entire condylar surface. From the 12 resection sites, five showed hypertrophic cartilage, non-hypertrophic cartilage cells were present in three, and four demonstrated bone apposition and resorption. Cartilage was present only at the medial and central aspects of the surgical site, and in every specimen, bone was seen at the lateral pole.

Two out of 12 fossae overlying surgical sites contained hypertrophic cartilage, while the five control glenoid fossae showed bone, an intermediate zone, and a fibrous capsule.

Because of the variety in tissue response and the small number of animals in each group, the effect of the splints could not be determined.

Based on the results of this study, the following was concluded:

(1) Regeneration of organized hypertrophic cartilage with inherent growth potential can take place after condylectomy, albeit not in every instance and only in the medial aspect of the stump. In the lateral aspect, and also medially if hypertrophic cartilage does not reform, bone is predominant. The original height is not recovered.

(2) The cartilage of the glenoid fossa is capable of adaptive changes similar to those seen in condylar cartilage.
Tear Strength of Non-aqueous Impression Materials
Authors: Keck S.C. , Douglas W.H.
Published: November 2010

Examples from each of the four major groups of dental impression materials (polysulfides, polyethers, condensation polysiloxanes, and addition polysiloxanes) were subjected to a trouser-leg tear test. Tear energies were determined, and materials were ranked with respect to each other. Polysulfides displayed the highest tear energy, while condensation polysiloxanes were the lowest, with the addition polysiloxanes occupying an intermediate position.
Anticariogenic Effects of Tea in Rats
Authors: Rosen S. , Elvin-Lewis M. , Beck F.M. , Beck E.X.
Published: November 2010

Teas varying in fluoride and tannin concentration were evaluated in rats for anticariogenic activity. There was a direct correlation between fluoride in tea and the inhibition of sulcal caries in rats, whereas no relationship was observed between tannin and this type of lesion. Teas also had a significant effect on caries progression and imparted a black stain to the teeth.
Basic Biological Sciences Relationship between Concentration of Human Salivary Statherin and Inhibition of Calcium Phosphate Precipitation in Stimulated Human Parotid Saliva
Authors: Hay D.I. , Smith D.J. , Schluckebier S.K. , Moreno E.C.
Published: November 2010

Human salivary secretions are supersaturated with respect to the calcium phosphate salts which form dental enamel, a property which provides important protection for the teeth. We previously proposed that statherin, a 43-residue phosphopeptide, plays a key role in this protective system by inhibiting or delaying potentially harmful precipitation of calcium phosphate salts in the salivary glands and mouth. The purpose of the present study was to determine if the concentrations of statherin in saliva, despite their wide normal range, are high enough to fulfill this function. Concentrations of statherin in stimulated human parotid saliva samples from 36 female and 32 male subjects, aged from 17 to 30 years, were determined by a single radial immunodiffusion method. Values found ranged from 3.0 to >27.3 μM, with a mean value of 12.8 (S.D. ± 5.46) μM.

At concentrations below these values, statherin inhibited spontaneous precipitation of calcium phosphate salts from an assay system which was more supersaturated with respect to dicalcium phosphate dihydrate, and comparably supersaturated with respect to hydroxyapatite, than were human saliva samples.

The inhibitory activities of five of the 65 stimulated parotid saliva samples assayed were greater than would be anticipated from their statherin concentrations. This unexplained discrepancy is not associated with the presence of the acidic proline-rich proteins in saliva, although these proteins also affect calcium phosphate precipitation.

The results of this study show that statherin is present in stimulated human parotid saliva at concentrations and levels of activity which are consistent with its proposed biological function, and support the proposal that statherin plays a significant role in a system which provides a protective and reparative but stable environment for the teeth.
The Formation and Remineralization of Artificial White Spot Lesions: A Constant Composition Approach
Authors: De Rooij J.F. , Nancollas G.H.
Published: November 2010

Artificial white spot lesions have been prepared on bovine enamel surfaces by the controlled addition of lactate buffer containing methylhydroxydiphosphonate ions. The rates of remineralization have been measured using a constant composition method in solutions of calcium phosphate of low supersaturation. Deposition of new hydroxyapatite solid phase takes place exclusively within the white spot lesion at a rate appreciably slower than that of an acid-etched enamel surface, probably due to the presence of methylhydroxydiphosphonate located within the intact surface region of the lesion.
Masking Power of Dental Opaque Porcelains
Authors: Woolsey G.D. , Johnson W.M. , O'Brien W.J.
Published: November 2010

A technique was developed to qualify the masking power of undiluted opaque dental porcelain by dilution of opaque powder with a clear glaze powder and by extrapolation of quantitative data gathered by reflectance spectrophotometry. Quantification of reflectance data was made on dilute opaque porcelains using the scattering and absorption coefficients in the Kubelka-Munk equation. Qualitative comparisons of undiluted opaque porcelains were made from quantitative data gathered from diluted opaque porcelains.
Computer Correction of Projective Distortions in Dental Radiographs
Authors: Webber R.L. , Ruttimann U.E. , Groenhuis R.A.J.
Published: November 2010

Distortions in radiographic images caused by changes in shape and position of the film relative to the x-ray beam can result in registration artifacts which interfere with interpretation of subtracted images.

A warping transformation is described which maps known points of reference in one image into homologous points in another. The corrected image pair can then be superimposed and subtracted with significantly-reduced differences in registration to facilitate the detection of localized changes of diagnostic interest.
Fourier Transform Infrared Analysis of Degree of Polymerization in Unfilled Resins—Methods Comparison
Authors: Ferracane J.L. , Greener E.H.
Published: November 2010

Two methods of transmission Fourier Transform Infrared analysis were compared to determine the degree of polymerization (DP) in unfilled Bis-GMA-based dental resins. Diluent concentration, curing mode, and activator type were investigated. DP ranged from 55-72% and was highest for the most diluted resins. The effects of polymerization activation mode and type were insignificant. DP was slightly enhanced in the bulk of the resin, as determined by a KBr-pellet technique, in comparison with results from a thin film method, but both techniques seem to provide useful and reproducible results for dental resins.
Local Immunoglobulin Synthesis in Juvenile Periodontitis: Initial Findings
Authors: Mason J.D. , Thompson J.J. , Yukna R.A.
Published: November 2010

An electro-immunoassay technique was used to determine simultaneously immunoglobulin G (IgG) and albumin concentrations in serum and extracts of gingival tissue comprising the pocket wall. Assays of samples obtained from seven patients with juvenile periodontitis (mean age, 18 years) indicated that local synthesis accounted for 72% of the IgG found in the gingiva.
Somatotopic Organization and Transmedian Pathways of the Rat Trigeminal Ganglion
Authors: Shellhammer S.B. , Gowgiel J.M. , Gaik G.C. , Weine F.S.
Published: November 2010

The localization of neuronal cell bodies in the trigeminal ganglion for the pulpal nerves of incisors and first and second molars in the rat was determined by utilization of retrograde axonal transport of horseradish peroxidase. Transmedian labeling was found with all teeth, but labeling was greater in the ipsilateral ganglion.
The Effects of Epinephrine, Norepinephrine, and Carbachol on Oxygen Consumption in Rat Sublingual Gland Slices
Authors: Terzic M. , Stojic D.
Published: November 2010

Epinephrine and carbachol, but not norepinephrine, significantly stimulated oxygen consumption in rat sublingual gland slices. The response to epinephrine was blocked by phentolamine and yohimbine, while propranolol and prazosin did not affect it. The response to carbachol was blocked by atropine. Also, oxygen consumption induced by both epinephrine and carbachol was inhibited by verapamil. These findings suggest that epinephrine enhanced oxygen consumption in sublingual gland slices by activation of alpha 2-adrenergic receptors, while carbachol activated muscarinic receptors; activation of both receptors mediated the respiratory response by facilitating the entry of extracellular Ca.
Materials Science Cement Distribution and Bond Strength in Cemented Posts
Authors: Goldman M. , DeVitre R. , Tenca J.
Published: November 2010

Rods of lucite were drilled to receive a #5 parapost to a depth of 4 mm and 7 mm. Posts were fitted and cemented either by coating the post with cement or by placing the cement in the prepared hole with a lentulo spiral in a low-speed hand-piece and then inserting the pre-coated post. Photographs were taken to determine the distribution of the cement. The lentulo spiral distributed the cement along the entire length of the preparation, but coating alone did not distribute the cement evenly.

The tensile strength with these two methods of post cementation was also compared in four groups of extracted teeth. In Groups IA and IIA, the post preparation was rinsed with 2 ml of 5.25% NaOCl and dried with paper points and blasts of air. In Group IA, the post was coated with zinc phosphate cement and seated. In Group IIA, the cement was placed into the post space with a lentulo spiral in a slowly rotating hand-piece; the post was then coated and seated. In Groups IB and IIB, the post preparation was rinsed with 1 ml of 17% Na2 EDTA followed by 1 ml of 5.25% NaOCl to remove the smeared layer at the dentin-cement interface. The posts were then cemented as in IA and IIA. Under the conditions of this experiment, the following conclusions can be drawn:

(1) Placing cement into the preparation with a lentulo spiral increased the tensile strength and the overall cement distribution.

(2) Removing the smeared layer increased the tensile strength, whether the post was simply coated with cement or cemented into place using a lentulo spiral.

(3) The greatest tensile strength occurred when the smeared layer was removed and the post was cemented into place using a lentulo spiral and coating combination.
Shear Testing of the Porcelain-Metal Bond
Authors: Drummond J.L. , Randolph R.G. , Jekkals V.J. , Lenke J.W.
Published: November 2010

A simple shear test was employed to determine the bonding strength of porcelain to a gold metal substrate and to a non-precious metal substrate after they had been aged in double-distilled water at 37°C for four and 12 months. A 7.4% and 18.1 % decrease in bond strength after four months and 12 months, respectively, was observed for the porcelain-gold system, and a decrease of 21.2% and 21.4% after four and 12 months, respectively, for the non-precious-porcelain system. A significant difference was observed between the bond strengths of the porcelain-metal composites: 51.17 ± 11.29 MPa for the porcelain-gold system and 31.83 ± 3.65 MPa for the porcelain-non-precious system.
Effect of Some Salts of Calcium, Sodium, Potassium, and Strontium on Intra-oral Enamel Demineralization
Authors: Brudevold F. , Tehrani A. , Attarzadeh F. , Goulet D. , Van Houte J.
Published: November 2010

A newly-developed intra-oral enamel demineralization test was used to evaluate the effect of supplementation of a 10% sucrose solution with various components on enamel demineralization induced by the sucrose. Five human subjects wore a palatal prosthesis holding eight blocks of subsurface bovine enamel covered with a layer of S. mutans cells. The test involved rinsing with sucrose solution or with sucrose solution supplemented with 0.162 mol/l of different calcium salts or equivalent concentrations of Na-, K-, and Sr salts; rinsing was for one min at times zero and 45 min of the 90-minute test period. Ca-propionate, Ca-acetate, and Ca-levulinate completely inhibited sucrose-induced enamel demineralization; Ca-chloride, Ca-lactate, and Ca-ascorbate gave from 65-75%, and K-acetate, Nalactate, and Sr-lactate 39, 25, and 18% inhibition, respectively. Consideration of the anion dissociation constants and the Ca-anion association constants of the salts suggests that the observed inhibition is caused mainly by common ion effects and, to a lesser extent, by buffer effects.
Analysis of Covariance in Caries Clinical Trials using Groupings of Teeth
Authors: Worthington H.V. , Adkins B.L.
Published: November 2010

An empirical investigation was carried out on data from four caries clinical trials of subjects who were initially 11 to 12 years old. The three baseline variables suggested by Adkins (1977), as possibly being related to caries increment, were each calculated on specific groupings of teeth, and these were then considered as predictor variables for the dependent variable, caries increment.

A gain in efficiency of approximately 20% was obtained when an analysis of covariance was used with these predictor variables, over a straightforward analysis of variance. However, this was only slightly more efficient than using baseline DMFS as a covariable. This investigation did not support the results of initial work done by Adkins (1977).
Tarnishing in vivo and in vitro of a Low-gold Alloy Related to Its Structure
Authors: Herø H. , Valderhaug J.
Published: November 2010

Studies on tarnishing of a low-gold alloy, both as-cast and solid-solution-annealed, have been carried out in vivo and compared with that of a type III gold alloy. Small polished samples were partly embedded in complete dentures for nine months. Generally, the low-gold alloy in the as-cast state was found to be more prone to tarnishing than were the other two materials, followed by the same alloy, solid-solution-annealed. These results are in agreement with both previous and present in vitro studies using 2% solutions of Na2S. The tarnish attacks followed the pattern of Cu segregations in vitro, and frequently also in vivo. Previous findings in vitro, on the other hand, show that tarnishing occurs predominantly on Agrich phases. The link is to be sought in the structural details. In the Cu-rich regions along grain boundaries and in interdendritic positions, eutectic particles with thin lamellae (~0.05 μm) of alternating Ag and Cu enrichments occurred. In these areas, we found a more unstable matrix with increased tendency to splitting into similar, but even thinner, lamellae. Most likely, these lamellae of alternating compositions act as galvanic cells. The cathodic reduction of oxygen probably takes place mainly on the Cu-rich lamellae, which are Au-enriched on the surface due to initial selective dissolution of Cu. With increasing time, attacks up to several μm in depth comprising both kinds of lamellae tend to occur at the grain boundary regions in an in vivo test, probably by a fretting corrosion mechanism.
Basic Biological Sciences
Authors: Hong Y.C. , Chow L.C. , Brown W.E.
Published: November 2010

It has been shown in laboratory and animal studies that tooth enamel becomes considerably more reactive toward low levels of fluoride after receiving pre-treatment which forms dicalcium phosphate dihydrate (DCPD) in the enamel as an intermediate. This in vitro study was undertaken to determine the effect on human enamel fluoride uptake of incorporating DCPD-forming rinses into a conventional fluoride rinsing program. In one group, enamel samples received a one-minute rinse with 0.2% NaF each day for 20 days. Samples in the second group were treated identically, except that they were also given a one-minute DCPD-forming rinse prior to the first, sixth, eleventh, and sixteenth fluoride rinses. At the end of the rinsing program, all samples were washed in 1 M KOH to remove labile fluorides. The enamel biopsy data showed that the fluoride uptake resulting from 0.2% NaF alone was not statistically significant, whereas uptake produced by the DCPD-forming plus NaF rinses was signiftcant. The results suggest that the DCPD-forming rinse may improve the efficacy of fluoride rinse programs.
Effect of Environmental Conditions on the Fluoride Sensitivity of Acid Production by S. sanguis NCTC 7865
Authors: Marsh P.D. , McDermid A.S. , Keevil C.W. , Ellwood D.C.
Published: November 2010

Growth and environmental conditions affected the fluoride (F) sensitivity of acid production by Streptococcus sanguis NCTC 7865. Cells grown glucose-limited in a chemostat were generally more sensitive than those harvested from cultures in which there was an excess of glucose (amino acid-limited). There was no consistent relationship between the growth rate of cells and their F sensitivity. Slower-growing cells (mean generation time = 14 hr) were more sensitive than those growing quickly when glucose was the limiting nutrient, whereas the faster growing cells from the glucose-excess culture were most susceptible. The pH of the environment markedly affected the F sensitivity of cells: 2 mM F- was sufficient to abolish acid production by cells incubated at pH 5.0, whereas 24 mM F-did not totally inhibit glycolysis at pH 7.0 or 8.0. Regardless of pH and growth conditions, the cationic composition of the environment had the most pronounced effect on acid production and fluoride sensitivity. Cells washed and re-suspended in KCl were more acidogenic and more sensitive to F than the same cells treated with saline. At pH 7.0 and 8.0, saline-washed cells were comparatively unaffected by F, while glycolysis by the same cells at the same pH but washed in KCl could be inhibited by up to 80%. These results suggested that F inhibition could not be explained merely on the basis of HF uptake at low pH values. Since it has been shown previously that the activity of the energized membrane is maintained by K+ and dissipated in the presence of Na+, it was proposed that proton motive force (pmf) might be involved in the uptake of F-.
Sugar Clearance from Saliva and Intra-oral Spaces
Authors: Goulet D. , Brudevold F. , Tehrani A. , Attarzadeh F.
Published: November 2010

The clearance of glucose from saliva was compared with that from spaces located in an intra-oral appliance. The spaces (N = 8) were similar in shape and size to posterior interdental spaces and could be sampled with a microsyringe without removing the appliance from the mouth. The subjects (N = 5) rinsed their mouths with solutions of 5, 10, or 25% glucose. Samples were obtained from a pair of spaces and from saliva at standard intervals and were analyzed for glucose. The rate of glucose clearance was consistently slower from the spaces than from bulk saliva, as shown by higher concentrations and longer clearance times for the spaces. The clearance curves were similar in shape and were rectilinear when the logarithms of the concentrations were plotted against time. The rate of clearance from the spaces appears to be characteristic for an individual, as was also true of salivary clearance.
Effects of a Fusobacterium nucleatum Extract on Immunoregulation in Mice
Authors: Yoshie H. , Mitsuma T. , Kozima K. , Hara K.
Published: November 2010

The purpose of this study was to examine the effect of an extract of Fusobacterium nucleatum on humoral and cell-mediated immunity and phagocyte functions in mice.

The extract was obtained from the heat-inactivated supernatant of sonicated F. nucleatum. Mouse splenocytes were cultured with sheep red blood cells (SRBC), and antibody formation was assayed by counting the plaque-forming cells (PFC). After C3H mouse skin was grafted onto the BALB/c mouse, cytotoxicity of BALB/c mouse splenocytes to L-cells was enumerated, T- and B-cell blastogenesis was determined by the uptake of 3H-thymidine. In vivo phagocyte functions were measured using carbon clearance test, bactericidal, and acid phosphatase activity assays.

The number of SRBC-specific and non-specific PFC in splenocytes stimulated with the extract increased 2.5-8. 7-fold over that of unstimulated splenocytes. Cytotoxicity of splenocytes from the extract-injected mice decreased in a dose-dependent fashion at 12 days after grafting. T cell mitogenicity of the extract was observed. The carbon clearance rate was reduced, and bactericidal and acid phosphatase activities were elevated by the extract injection of the mice.

In conclusion, F. nucleatum extract has an adjuvant effect on humoral immunity, and a suppressive effect on cell-mediated immunity and activated phagocyte functions.
Dental Caries and Tetracycline-stained Dentition in an American Indian Population
Authors: Rebich T. , Kumar J. , Brustman B.
Published: November 2010

Complaints of enamel defects in American Indian children residing on the St. Regis reservation in New York State prompted an epidemiological study. The results of that study, reported earlier (Rebich et al., 1983), indicated that over one-fifth of the American Indian children had discoloration of the dentition due to ingestion of tetracycline during the years of tooth formation. These data also provided an ideal opportunity to examine the link between tetracycline staining and caries which has been postulated by previous authors. American Indian children, ages 7-18, were found to have a higher caries experience than other children and a lower rate of dental service utilization, as evidenced by the filled component of the DMFS index (FS/DMFS). Within the American Indian population, however, no indication was found of any association between tetracycline staining and dental caries.
Basic Biological Sciences Importance of High pKA Acids in Cariogenic Potential of Plaque
Authors: Margolis H.C. , Moreno E.C. , Murphy B.J.
Published: November 2010

Through the use of computer simulation, it is shown that anions of high pKA acids (e.g., acetic, propionic, butyric), present in resting plaque fluid, act as effective buffers during the production of stronger acids (e.g., lactic) by oral micro-organisms. Using reported organic acid compositions for plaque, obtained from caries-resistant and caries-susceptible individuals, analyzed at various times following sucrose exposure, it is shown that the calculated pH values of the aqueous phase of plaque describe typical Stephan curves. Furthermore, it is shown that for higher acid anion contents in resting plaque, a higher degree of saturation of the aqueous plaque phase with respect to enamel is maintained during acid production, resulting in a lower demineralization potential of plaque. Enamel demineralization experiments conducted in vitro confirmed the significance of the results of the computer simulations, thus providing evidence for a correlation between the known metabolic activity of plaque (organic acid composition), physical chemistry of plaque, and caries susceptibility.
Microstructures of Duplex (β + γ) Silver-Tin Alloys
Authors: Abbott J.R. , Miller D.R. , Netherway D.J.
Published: November 2010

The microstructures of (β + γ) silver-tin alloys are especially influenced by both homogenization temperature and subsequent heat treatment. When the alloy is cooled from homogenization temperatures above approximately 200°C, lenticular regions of the ordered orthorhombic γ phase precipitate from within the disordered h.c.p. β_phase on three structurally equivalent planes, (1210), (1120), and (2110), to form a Widmanstatten structure. When the duplex alloys were homogenized at temperatures below approximately 200°C, where the β/ (β + γ) phase boundary is vertical, these structures were not observed.
Ultrastructural Study of Epithelial Cell Attachment to Implant Materials
Authors: Jansen J.A. , De Wijn J.R. , Wolters-Lutgerhorst J.M.L. , Van Mullem P.J.
Published: November 2010

Attachment of gingival tissues to the protruding post of an endosseous dental implant is of great importance for the prognosis of its clinical success. Little is known about the requirements an implant material must meet to secure a durable permucosal seal. The objective of this study, therefore, was to gain insight into the morphology of epithelial cell-implant interfaces for a number of well-known or potential implant materials.

Guinea pig epithelial cells were cultured on gold, titanium, carbon, hydroxylapatite, carbonate apatite, and modified polystyrene substrates. The metallic and carbon substrates were obtained by vapor-phase deposition of thin films on polystyrene carriers. This technique allowed for the preparation of ultra-thin sections for transmission electron microscopy containing substrate as well as the cells adhering to it. The cultures on apatite were decalcified prior to sectioning.

The results revealed that as attachment structures, focal contacts, extracellular matrix contacts, and hemidesmosome-like contacts could be distinguished. Hemidesmosome-like contacts were only observed on apatite and polystyrene and not on the metallic or carbon surfaces.

The results of this study suggest the existence of some, as yet unknown, property of the substrate that determines the nature and the structure of the contact site with epithelial cells.
In situ Fluoride Uptake from Fluoride Dentifrices by Carious Enamel
Authors: Stookey G.K. , Schemehorn B.R. , Cheetham B.L. , Wood G.D. , Walton G.V.
Published: November 2010

A series of studies was performed to measure fluoride deposition in incipient caries-like lesions in enamel specimens contained in functional partial dentures in panelists who used fluoride dentifrices for periods ranging from two to nine weeks. The studies demonstrated the ability of the model to replicate the fluoride-uptake results obtained with a series of three dentifrices in two different panels of subjects. All fluoride dentifrices resulted in significant fluoride deposition, although significantly greater deposition was observed with a NaF-SiO 2 dentifrice.
The Stimulation of Human Peripheral Blood Lymphocytes by Oral Bacteria: Macrophage and T-Cell Dependence
Authors: Baker J.J. , Tondreau S.P.
Published: November 2010

Human peripheral blood mononuclear lymphocytes from individuals with moderate periodontitis were separated into purified subpopulations of T lymphocytes and B lymphocytes by rosetting with sheep red blood cells (E). All three lymphocyte subpopulations were compared for proliferative responses to cell walls from seven oral bacteria, phytohemagglutinin (PHA), pokeweed mitogen (PWM), lipopolysaccharide (LPS), and streptolysin-O (SLO). Mononuclear cells and are-combined subpopulation consisting of four parts purified T lymphocytes and one part B lymphocytes responded significantly to all of the stimulants. Purified T lymphocytes by themselves responded significantly to PHA and PWM, but were unresponsive to oral bacteria and SLO; however, T lymphocytes cultured with 2% autologous macrophages responded significantly to all seven oral bacterial cell walls and to SLO, which indicates that T-cell responses to oral bacteria are macrophage-dependent. T-cell-depleted non-E-rosette-forming B cells by themselves were poorly responsive to all of the tested stimulants; however, the responses of these cells to oral bacteria, PWM, LPS, and SLO increased significantly in the presence of 10% mitomycin-C-treated T cells, demonstrating that B cell proliferation to these stimulants is T-cell dependent.
Adjusting Craniofacial Correlations for Technical Error
Authors: Buschang P.H. , Tanguay R. , La Palme L. , Demirjian A.
Published: November 2010

Reliability estimates provide a means of adjusting observed correlations for technical error. The results show that the true correlations among 11 craniofacial landmarks are consistently higher than observed values. Consequently, the regression slopes defining these relationships are also increased. The less reliable two measures are, and the closer their joint reliability approximates the observed correlation, the greater the expected change in true correlation. Adjusting craniofacial relationships for technical error may substantially increase the proportion of variation explained, and thereby alter statistical inferences drawn from results.
Double-layer Color Effects in Porcelain Systems
Authors: O'Brien W.J. , Johnston W.M. , Fanian F.
Published: November 2010

The color of an unshaded body porcelain was determined at three thicknesses on white, gray, and three chromatic backings. Spectral absorption and scattering coefficients of the porcelain were determined from the diffuse reflectance at one thickness on the white and gray backings. These optical coefficients, when utilized with the Kubelka-Munk reflectance theory, accurately predicted the color of the other sample configurations studied. The scattering of the body porcelain was found to decrease with increasing wavelength within the visible spectrum, in accordance with scattering theory for particles not substantially less than the wavelength of the scattered light. For the filtering effects of a translucent material in optical contact with a backing, the Kubelka-Munk reflectance theory described the interaction between the optical absorption and scattering within the translucent material and the reflectance of the backing.
Appearance of Dentin γ-Carboxyglutamic Acid-containing Proteins in Developing Rat Molars in vitro
Authors: Finkelman R.D. , Butler W.T.
Published: November 2010

An in vitro model of mineralization was devised in order to study the developmental appearance of dentin γ-carboxyglutamic acid-containing proteins (DGPs) in relation to the onset of mineralization. Maxillary third molars from 11-day-old rats were cultured with or without fetal calf serum (FCS) as modified from Navia et al. (1984).- Molars were incubated without radiolabel, or with either 45CaCl2 (5 μCi/ml) for 24 hr at various stages of a ten-day culture period or [3H]-leucine (10 μCi/ml) for 24 hr at the eighth day of culture. Molars were lyophilized and extracted with 10% formic acid overnight at 4°C. DGPs in extracts were detected by immunologic and chromatographic techniques; DGPs in molar sections were detected by immunolocalization using indirect immunofluorescence. Molar development was evaluated histologically using the Von Kossa staining technique.

Molars cultured with FCS showed histologic evidence for mineralized dentin and enamel and a significant increase in 45Ca uptake after the sixth day in vitro. Eleven-day-old molars in vivo and molars cultured without FCS showed no evidence of the presence of mineralized tissues. [3H]-Leucine-labeled DGPs were isolated and identified by affinity and reversed-phase high-performance liquid chromatography and by gel electrophoresis from both mineralized and unmineralized molars. DGP antigens were localized immunohistochemically using rabbit anti-rat antibodies raised against a highly purified DGP preparation. In the unmineralized molar, antigenicity was seen in odontoblasts but not in predentin matrix, pre-odontoblasts, or in any other cell type. Antigens in the mineralized molar were localized to odontoblasts and dentin. Analysis of these data indicates that rat molars cultured with FCS show de novo mineralization in vitro and suggests that rat molar odontoblasts synthesize DGPs concurrently with the elaboration of predentin matrix but independently of mineral deposition.
Basic Biological Sciences Isolation and Growth of Human Periodontal Ligament Cells in vitro
Authors: Ragnarsson B. , Carr G. , Daniel J.C.
Published: November 2010

The periodontal ligaments from single human teeth were dissected free of the root surface and plated into culture dishes. In each case two populations of cells were obtained: fibroblasts and epithelial cells. These two populations were separated and grown in culture. The epithelial nature of the epithelioid-appearing cells was confirmed by staining for keratin, exclusively an epithelial cell protein.
Dental Pulp Response to Bacterial Cell Wall Material
Authors: Warfvinge J. , Dahlen G. , Bergenholtz G.
Published: November 2010

Lipopolysaccharides (LPS) from Bacteroides oralis and Veillonella parvula and cell wall material from Lactobacillus casei were studied for their capacity to induce leukocyte migration in the dental pulp and in an implanted wound chamber. Three adult monkeys were challenged using lyophilized material sealed into buccal Class V cavities prepared in dentin. Pulp tissue responses were observed histologically eight and 72 hours after initiation of the experiment. Subjacent to cut dentinal tubules, bacterial materials induced polymorphonuclear leukocyte (PMN's) infiltration in the pulp tissue of the majority of test teeth examined. Responses were similar for the three bacterial test materials at both time periods. Topical applications of bovine serum albumin (BSA), used as a control, induced significantly less accumulation of PMN's. Assessments of induced exudate volumes and leukocyte densities in chambers implanted in rats showed comparable rankings with pulpal experiment between test (i.e., bacterial) and control (BSA) materials. Analysis of the data indicates that high-molecular-weight complexes of bacterial cell walls may adversely affect pulpal tissue across freshly exposed dentin.
Enamel Microhardness Change and Plaque pH Measurements in an Intra-oral Model in Humans
Authors: Essig M.E. , Bodden W.R. , Bradley E.L. , Koulourides T. , Housch T.
Published: November 2010

Changes in plaque pH and microhardness of bovine enamel slabs were evaluated with a seven-day intra-oral cariogenicity test (ICT). The test enamel slabs were mounted in prosthetic appliances with a Dacron mesh cover for enhancement of microbial colonization. Three percent solutions of sucrose, sorbitol, and xylitol were evaluated as four daily extra-oral immersions of 10 min each, for seven days, and the results were compared with baseline experiments (no daily immersions). The pH was measured with antimony electrodes on one-day and seven-day ICT plaque samples that were challenged with a one-minute immersion in the studied substrates. Plaque samples in the baseline experiments were challenged with 3% sucrose. The enamel softening was assessed with measurements of microhardness. Sucrose challenge caused pH depression with both the baseline and the sucrose-immersed plaque. Sorbitol and xylitol challenge did not depress the plaque pH. Compared with the baseline, sucrose immersions caused enamel softening; sorbitol and xylitol did not.
Effect of Inflammation on the of Collagen Types, I, III, IV, and V and Type I Trimer and Fibronectin in Human Gingivae
Authors: Narayanan A.S. , Clagett J.A. , Page R.C.
Published: November 2010

The effect of inflammation on the distribution of collagen types I, III, IV, and V and type I trimer and fibronectin in human gingivae was studied after staining them with antibodies to these proteins, Gingival tissues were obtained after periodontal surgery and incubated with antibodies, and staining was visualized by indirect immunofluorescence using FITC- or rhodamine-conjugated second antibodies. The results showed that antibody to type I collagen stained normal gingival connective tissue uniformly and revealed the presence of thick fiber bundles, The staining was sparse at areas of inflammation and leukocytic infiltration. Anti-type-III antibody revealed a fine fibrillar netWork in the normal gingivae, especially near the epithelium; the type III was also lost at sites of inflammation. Type V collagen antibody also stained the gingival connective tissue intensely but, unlike the types I and III staining, it was retained in inflamed areas. Normal gingivae were not stained by the type I trimer antibody; however, staining occurred at inflamed sites. Both normal and inflamed tissues were stained by type IV collagen antibody. and the staining was restricted to basement membrane structures, The normal and inflamed gingivae contained a thick fiber network which bound unti-fibronectin antibody. We conclude that the various ginglvai collagen fibers are made up of collagen types I, III, and V, that the types I and III collagens are preferentially lost during inflammation, and that type I trimer appears at Inflamed sites.
Effect of NaF on Rat Parotid Gland Amylase Activity and cAMP Concentration in vitro and in vivo
Authors: Shahed A.R. , Bondi J. , Allmann D.W.
Published: November 2010

The effect of NaF on the cAMP concentration in and amylase secretion from rat parotid glands in vitro and in vivo was investigated. In vitro, NaF (0.05 to 10 mmol/1 ) was found to increase significantly amylase secretion and cAMP concentration in parotid gland slices. In vivo, male rats injected intraperitoneally with 15 mg Flkg body weight as NaF had a significantly lower glandular amylase activity and higher plasma amylase activity than did the control rats injected with 0.9% NaCl. The fluoride concentration both in the parotid gland and plasma was highest at 30 min after injection and decreased with time in the fluoride-injected group. The concentration of the parotid gland cAMP in the fluoride-injected group was significantly higher than that in the control group. On the basis of these results, it is suggested that NaF, both in vitro and in vivo, increases the cAMP concentration, which subsequently stimulates amylase secretion from rat parotid glands.
Changes in Plaque pH in vitro by Sweeteners
Authors: Bibby B.G. , Fu J.
Published: November 2010

A new in vitro pH method was used to compare the ability of natural dental plaque to convert nine sweeteners to acid. Tests made in 0.1, 1.0, and 10.0% concentration, or sucrose sweetener equivalents, showed that isomaltulose gave the lowest pH, followed in order by Lycasin, mannitol, palatinit, sorbitol, sorbose, and then, with negligible acid production, aspartame, saccharine, and xylitol. Unlike the other sweeteners, xylitol and saccharine gave smaller pH depressions in higher concentrations of test solutions. At the concentrations tested, none of the sweeteners interfered with acid production from sucrose.
Effects of Dietary Carbohydrates on the Numbers of Streptococcus mutans and Actinomyces viscosus in Dental Plaque of Mono-infected Gnotobiotic Rats
Authors: De Jong M.H. , Van den Kieboom C.W.A. , Lukassen J.A.M. , Van der Hoeven J.S.
Published: November 2010

Dietary sucrose and glucose are known to promote the accumulation of, respectively, Streptococcus mutans and Actinomyces viscosus in complex dental plaque microflora. In this study, we have investigated the effects of these carbohydrates on the numbers of S. mutans and A. viscosus colonizing the teeth of mono-infected gnotobiotic rats. Sucrose at a dietary concentration of between 0.25 and 0.5 percent (corresponding with 7-15 mM in the drinking water) caused an increase in the numbers of S. mutans. This result strongly suggested that the increase was due to extracellular polysaccharide (EPS) synthesis by glucosyltransferase, whose Km value (1.0-7.0 mM) is in the same concentration range.

The numbers of A. viscosus increased three-fold when 10% glucose was added to the basal diet. It seems plausible that this was due to extracellular heteropolysaccharide produced by A. viscosus in the presence of excess glucose. Although in most microbial ecosystems provision of additional substrates leads to an increase in biomass, glucose had only a small effect on the numbers of S. mutans. Mechanical dislodging forces could be limiting the accumulation of dental plaque. EPS synthesis from dietary carbohydrates seems to enable the population to withstand mechanical dislodging at least partially by providing a matrix wherein cells are entrapped or to which the cells are firmly attached.
Histologic Evaluation of Tissue Response to Hydroxylapatite Implanted on Human Mandibles
Authors: Beirne O.R. , Greenspan J.S.
Published: November 2010

The tissue response to hydroxylapatite implants was examined histologically in samples taken from four patients three to six months after the material had been used to augment deficient mandibular alveolar ridges. Minimal inflammation was found, but the implants had not induced new hone formation and were instead surrounded by a fibrous connective tissue scar.
Ultrathinning Dental Porcelain for Transmitted Light Microscopy
Authors: Mackert J.R. , Butts M.B. , Beaudreau G.M. , Fairhurst C.W. , Beauchamp R.H.
Published: November 2010

A technique for ultrathinning brittle materials, originally developed at Battelle Pacific Northwest Labs for examination of lunar materials, has been successfully adapted for the preparation of dental porcelain specimens. A commercial dental porcelain and "Component No. 1" of the Weinstein et al. patent were ultrathinned using this technique. Each material was examined in the unfired powder form, after one firing, and after five firings. The sections were typically from 2 to 6 μ m thick. The ultrathinned specimens were then examined using transmitted light microscopy. Identical areas of fired porcelain specimens were also examined by reflected light microscopy, scanning electron microscopy, and transmitted light microscopy of ultrathinned specimens in order to compare the three techniques. The porcelain powder and each frit were analyzed by x-ray diffractometry (XRD). Leucite (K2O·Al2O3·4SiO2) was detected by XRD in the commercial porcelain and the Component No. 1 frit. Optical micrographs of the ultrathinned specimens revealed a second phase within the glassy frit particles of the commercial porcelain and the Component No. 1 material. No phase changes between unfired and fired specimens were detected by XRD. This success in ultrathinning dental porcelains provides a significant improvement in the ability to resolve the constituent phases of these materials relative to standard petrographic techniques and a useful addition to the techniques available for microstructural examination of dental porcelain.
Lactate Dehydrogenase-deficient Mutants of Serotype g Streptococcus mutans
Authors: Salem H.H.H. , Sandham H.J. , Chan K.H.
Published: November 2010

Three LDH-deficient mutants of a serotype g strain of Streptococcus mutans were produced essentially as described by Hillman (1978): They were produced using ethylmethane sulfonate, and isolated using triphenyltetrazolium-glucose agar. Similar attempts to obtain mutants from a serotype c strain were unsuccessful. The g mutants did not revert during 12 weeks of daily transfer in broth, and, when grown in glucose-containing broth, they reached pH values of 4.9 to 5.0, compared with 4.4 for the parent strain. The efficiency of conversion of glucose to cell mass (Yg) was at least as great with the mutants as with the parent strain. The LDH activities of the mutants were less than 1% of that of the parent strain. Like Hillman' (1978) mutants, ethanol, acetic acid, and acetoin were the major products resulting from the metabolism of glucose. Although at pH 7.0 the mutants grew more slowly than did the parent, at pH 5 and pH 6 one of the mutants grew as rapidly as did the parent. The stability, serotype, and ability of these mutants to grow at low pH suggest their potential usefulness for replacement therapy.