bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase Identification and Quantitative Metallographic Procedures for Dental Amalgams
Authors: Mateer Richard S. , Reitz C.D.
Published: November 2010

Identification of microstructural phases discussed in the literature was confirmed by microprobe using visual display. Rigorous point counting techniques yield volume proportions of crystalline phases and porosity, but localized composition variations characteristic of condensed amalgams make it seldom worth the effort. Visual comparison with standards is a simple and effective alternative.
Derivatographic Analysis of Dentin
Authors: Komrska Jiri
Published: November 2010

A new method was used for examination of the organic and inorganic components of human dentin.
Measurement of the Deflection of Dentin Disks Under a Condensation Type of Load
Authors: Schnell Richard J. , Swartz Marjorie L. , Phillips Ralph W.
Published: November 2010

A model was constructed to simulate a one surface cavity preparation. Dentin disks of varying thickness served as the pulpal floor of the model. The deflection of the cavity floor was monitored when forces of the type used in condensing amalgam and gold foil restorations were applied. Deflection of the dentin occurred under this type of loading. The amount depended on the magnitude of the load and thickness of the dentin. A cement base reduced the deflection of the cavity floor.
Sealing of Developmental Pits and Fissures : III. Effects of Fluoride on Adhesion of Rigid and Flexible Sealers
Authors: Lee Henry , Stoffey Donald , Orlowski Jan , Swartz Michael L. , Ocumpaugh David , Neville Kris
Published: November 2010

Bovine teeth that were treated with acidulated fluoride before and after etching with phosphoric acid produced adhesive bonds with fissure sealers that were lower than those of untreated controls. Human teeth from an area of high natural fluoridation were shown to be extremely resistant to etching with citric and phosphoric acids.
Enamel Dissolution: II. Action of Titanium Tetrafluoride
Authors: Mundorff Sheila A. , Little Marguerite F. , Bibby Basil G.
Published: November 2010

Mechanisms by which titanium tetrafluoride (TiF4) reduces enamel solubility were investigated. An association was found between solubility reduction and the formation of a glaze on the enamel surface. Also, TiF4treated enamel had higher levels of fluoride than enamel treated with acidulated phosphate-sodium fluoride. Solubility reductions and fluoride levels decreased slightly with washing but after 48 hours the fluoride level was still 60% of the maximum, and solubility reductions ranged between 64 and 70%.
Further Studies of Resin-Modified Temporary Restorative Materials
Authors: Civjan Simon , Huget Eugene F. , De Simon Laszlo B. , Rapheld Thomas V.
Published: November 2010

Composition and physical properties of a polycarbonate resin-reinforced zinc oxide-eugenol cement and of a formulation based on zinc oxide, eugenol and o-ethoxybenzoic acid (EBA) were determined. Both materials were similar in strength, but the polycarbonate-containing material was tougher and showed less solubility and disintegration. Cementing film thicknesses were obtained with the EBA cement.
Effects of Nutrition on the Composition of Tooth Lipids and Fatty Acids in Rats: II. Effects of Restriction of a Cariogenic Diet on Caries and Lipid Composition of Molars and Incisors
Authors: Alam Syed Q. , Alvarez Celestino J. , Harris Robert S.
Published: November 2010

Weanling rats were maintained on a cariogenic diet for three or six weeks. Two control groups were given this diet ad libitum; the food intake of two other groups was restricted. The restricted groups gained less weight and developed less dental caries. Phospholipids and free fatty acids were the main lipid fractions in molars and incisors. Food restriction altered the amounts of these two fractions in the teeth.
Effects of Changing Body Position on Dental Occlusion
Authors: Mc Lean Lewis F. , Brenman Henry S. , Friedman M.G.F.
Published: November 2010

Graded changes in body position produced no noticeable changes in wax registrations of dental contact patterns resulting from voluntary jaw closure. Occlusal contact patterns that resulted from electrically stimulated jaw closures indicated an increase in closing force and a mesial shift of prime occlusal contact points as the body was raised to an upright position.
Electron Probe Microanalysis of Human Enamel Microstructure
Authors: Wirsing A. , Judd G. , Ansell G.S.
Published: November 2010

An electron probe microanalyzer was used to determine compositional variations of the Ca/P ratio in the core and sheath areas of individual rods in human enamel. The Ca/P ratio in the core is that of a calcium-deficient hydroxyapatite, whereas the ratio in the sheath is that of almost stoichiometric apatite. Treatment with HCl or EDTA alters the Ca/P ratio in the core and the sheath.
Effect of Undernutrition During the Perinatal Period on Caries Development in the Rat: V. Changes in Whole Saliva Volume and Protein Content
Authors: Menaker Lewis , Navia Juan M.
Published: November 2010

Rats malnourished during development show increased susceptibility to caries. During this time molars mineralize and salivary glands undergo rapid development. Nutritional stress could affect either or both of these processes, thus determining caries susceptibility. Present studies show drastically reduced protein content and volume of saliva in rats undernourished during development.
Measurement of Fluoride Uptake and Release in Teeth by Activation Analysis
Authors: Pfeiffer W.C. , Penna-Franca E.
Published: November 2010

High energy photon activation analysis was used as a method by which fluoride uptake and removal in individual whole teeth or tooth structures was followed for long periods of time. Whole tooth fluoridation by topical treatment or after immersion in fluoride solutions can be followed by this method.
Letters to the Editor
Authors: Kamen Alec , Glass R.L.
Published: November 2010

The Journal devotes this section to comment by readers on topics of current interest to dental research. The editor reserves the right to edit all communications to fit available space and requires that all letters be signed. Printed communications do not necessarily reflect the opinion or official policy of the Association. Your participation in this section is invited.
Studies on Ca2+-Stimulated Adenosine Triphosphatase in Rat Submandibular Glands : Its Distribution and Properties
Authors: Furuyama Shunsuke , Negishi Toshie , Tobe Yasumi , Takiguchi Hisashi
Published: November 2010

Intracellular distribution and some characteristics of a Ca2+-stimulated adenosine triphosphatase (ATPase) in rat submandibular glands were investigated. This enzyme was activated by calcium alone, and magnesium was not necessary for its activation. Mg 2+stimulated ATPase also was investigated in the same enzyme preparations.
Some Properties of Uridine 5'-Diphosphogalactose: N-Acetylglucosamine Galactosyltransferase in Human Parotid Saliva
Authors: Nakamura Ryo , Watanabe Tatsuo , Tsunemitsu Akira
Published: November 2010

Uridine 5'-diphospho (UDP)-galactose: N-acetylglucosamine galactosyltransferase was separated from human parotid saliva and partially purified. The optimum pH of the enzyme was 7.5. The enzyme required a specific acceptor, and its activity was activated by manganese and magnesium ions.
Effect of Prior Acid Etch on Rate of Sn3F3PO4 Formation Subsequent to Topical Application of SnF2
Authors: Nordquist William D. , Krutchkoff David J. , Wei Stephen H.Y.
Published: November 2010

The effect of prior acid etch on the rate of Sn3F3PO4 formation subsequent to in vitro SnF2 interaction with human dental mineral has been investigated using light microscopy, surface replicas, and internal reflection spectroscopy. Results showed that Sn3F3PO4 forms more rapidly on etched surfaces as compared with nonetched controls. The observed accelerated rate was attributed to increased reaction surface provided by prior acid etch plus a rougher surface conducive to crystal nidus formation.
Detection of Prostaglandins in Bovine Gingival Tissue
Authors: Das S.K. , Adhikary P.K. , Bhattacharyya D.K.
Published: November 2010

Lipids were extracted from bovine gingival tissues and examined by thin-layer chromatography and ultraviolet absorption spectroscopy for the presence of prostaglandins. Results indicated that these tissues contained a variety of prostaglandins, including PGE1, PGE2, PGF2, and certain of their metabolites.
Cusp Size, Sexual Dimorphism, and the Heritability of Maxillary Molar Cusp Size in Twins
Authors: Biggerstaff Robert H.
Published: November 2010

The quantitative hierarchy for maxillary molar cusp size is established. Sexual dimorphism, not present in measures of individual cusp size, is present when the size contributions of individual cusps and ridges are summed. The twin data analyses show a low level of hereditary variability for these dental traits.
Working Time of Polymeric Restorative Materials
Authors: Jacobsen P.H.
Published: November 2010

The validity of determining the working times of polymeric restorative materials with the use of rheologic methods in the laboratory has been investigated by measuring the adaptation of polymeric restorative materials to artificial cavities when inserted at 30-second time intervals during their setting reactions. There was a significant deterioration in adaptation during the working times which suggests that small changes in viscosity early in the setting reactions radically affect the materials' mobility.
In Vivo Effects of Direct Current in the Mandible
Authors: Zengo A.N. , Bassett C.A.L. , Prountzos G. , Pawluk R.J. , Pilla A.
Published: November 2010

The application of low level direct current with a current density of 50 μa/cm2 within the mandible of mature Beagle dogs results in an increased osteogenesis about the negative electrode (cathode). Significant differences observed between the use of platinum-iridium and stainless-steel electrodes suggest careful consideration of appropriate current density and electrode composition when direct current stimulation is to be used.
Capacity of Buffers to Inhibit Acid Production within Dental Plaque
Authors: Clarke Nigel G. , Dowdell L. Rex
Published: November 2010

An oral radiotelemetric technique was used to determine whether a range of efficient buffers had the capacity to control the levels of hydrogen ions within dental plaque in the presence of sucrose. It was found that the buffers failed to control both the intensity and duration of the acid produced.
Distribution of Streptococcus mutans Biotypes in Five Human Populations
Authors: Keene Harris J. , Shklair Irving L. , Mickel Gerald J. , Wirthlin Milton R.
Published: November 2010

Cultural and biochemical methods were used for the isolation and identification of five different Streptococcus mutans biotypes in samples of dental plaque obtained from human subjects who were living in widely separated geographical areas. Although biotype c was the most prevalent type in each population, distinct geographic differences in biotype distribution were observed.
Proteolipid and Calculus Matrix Calcification In Vitro
Authors: Ennever J. , Vogel J.J. , Riggan L.J. , Paoloski S.B.
Published: November 2010

The initiator of calculus matrix calcification, in vitro, was isolated. Crude phospholipid, known to contain the factor, was separated into five fractions by column chromatography. A single protein-containing fraction induced apatite formation during incubation in a metastable calcium phosphate solution. The nucleating fraction was identified as a proteolipid.
Diffusion Phenomena During Artificial Carious Lesion Formation
Authors: Featherstone J.D.B.
Published: November 2010

Art(ficial carious lesions were produced in human enamel using lactic acid [HL] buffers plus diphosphonate [MHDP]. Surface layer thickness was related to [MHDP], middle zone (body) and inner zone depths to [HL] and pH. Indications are that diffusion in enamel is predominantly by unionised species such as HL and CaHPO4, and dissolution by H+ and L-.
Symphysis Menti of the Rabbit: Anatomy, Histology, and Postnatal Development
Authors: Hirschfeld Z. , Michaeli Y. , Weinreb M.M.
Published: November 2010

A histologic and anatomic investigation of the symphyseal region in rabbits did not reveal a bony fusion between the two halves of the mandible; these two bones are united in the anterior part by a synchrondrosis, and a definite histologic suture with interdigitating bony rugosities and interposed connective tissue, in the posterior part. Functionally, the two parts are immobile and thus constitute one bone.
Be, Li, and Na Redistribution Near a Porcelain/Ni Alloy Interface Shown by Ion Microprobe Mass Analysis
Authors: Williams T.R. Peter , Johnson C.E. , Winchell P.G. , Philips R.W.
Published: November 2010

During porcelainization the non-preoxidized alloy develops a Be-rich reaction zone in the interface which separates a Be-depleted alloy from a Li and (to a lesser extent Na) depleted region of the ceramic. Thus, Be diffuses to the interface through the alloy Be° → Be++ + 2 e- occurs at the interface; some of the electrons are electronically conducted to the porcelain-air interface where they are consumed as 2 e-+ ½ Oo2 → O=, and the resulting negatively charged porcelain surface attracts Li+ (and Na+).
Objective Evaluation of Surface Microreplication by Dental Impression Materials
Authors: Schoen F.J. , Mohammed H. , Fischlschweiger W. , Going R.E.
Published: November 2010

Twenty-two materials, including 19 dental impression elastomers, were compared in their ability to replicate microscopic detail. Some polysulfide, silicone, and polyether materials performed well. Curiously, microscopic replication ability generally correlated inversely with that expected from the nominal consistency. The test method developed appears to be a suitable microreplication evaluation standard.
An Evaluation of Primary Enamel Pretreatments and Their Effects on Resin Retention
Authors: Smutka Steven , Jedrychowski Joseph , Caputo Angelo
Published: November 2010

The effects of various enamel pretreatments on bond strengths between primary enamel and resin were investigated. Pretreatments included: removal of the outer enamel surface, varied exposure to phosphorie acid, and the use of an organic coupling agent. Results indicated highest bond strengths utilizing acid pretreatments and an organic coupling agent.
Cellular Regulation of the Metabolism of Androgens in Rat Oral Mucosa: I. Effect of Medroxyprogesterone Acetate (MPA) on the Soluble Supernatant (Cytosol) Activating Microsomal Δ4-3-Ketosteroid-5α-Reductase and 17β -Hydroxysteroid Oxidoreductase Enzyme Systems
Authors: Vittek Jozef , Rappaport Sydney C. , Gordon Gary G. , Southren A. Louis
Published: November 2010

Soluble supernatant (cytosol) of rat oral mucosa was found to contain a factor accelerating the activity of microsomal Δ4-3-ketosteroid-5α-reductase and 17β-hydroxysteroid oxidoreductase enzymes metabolizing testosterone. Systemic administration of medroxyprogesterone acetate further increased this cytosolic activity.
Normal Mature Human Enamel Protein
Authors: Belcourt A.
Published: November 2010

Pure enamel was prepared using an original microdissection technic. Protein concentration was 375 μg per gram of enamel. Polyacrylamide gel electrophoresis showed a single fast-migrating zone containing a thin double band. Ultracentrifugation studies suggested that the proteins were of low molecular weight or of weak density. Absorption spectra showed a strong absorbance at 260nm. Amino acid analyses yielded a composition of 25% Gly, 13.5% Glu, 11% Ser, 11% Pro, 2% Cys and 2% Hyp. A glucidic content of 15% was estimated and glucose, galactose, mannose and fucose were identified. The organic matrix of enamel seemed to be constituted of two major glycoproteins probably fibrous but different from keratin.
Cellular Responses to the Dispersion Amalgams in vitro
Authors: Nakamura M. , Kawahara H.
Published: November 2010

Three dispersion amalgams were tested in vitro. Spherical-D and Dialloy showed very similar effects on the cells as did the Spherical and fine cut amalgams. The other dispersion amalgam, Dispersalloy, had intense and persistent cytotoxicity even 24 hours after trituration. Difference of the results was presumed to result from different alloy composition.
Electromyographic Correlates of Experimentally Induced Stress in Diurnal Bruxists and Normals
Authors: Rao Stephen M. , Glaros Alan G.
Published: November 2010

Diurnal bruxists and normals were compared in responsiveness to stress and on psychological status. Results indicated that masseter EMG activity was significantly higher at rest for bruxists than normals, that bruxists responded differentially more to stress than normals, and that no significant differences were present between bruxists and normals on the psychological measures.
Adhesive Bonding of Various Materials to Hard Tooth Tissues. XXII. The Effects of a Cleanser, Mordant, and PolySAC on Adhesion Between a Composite Resin and Dentin
Authors: Bowen R.L.
Published: November 2010

Preliminary evaluations on the effects of a cleanser, mordant, and polyfunctional surface-active comonomer on adhesion between a composite resin and dentin evinced that the ferric chloride mordant significantly improved bonding. The effects of the cleanser and coupling agent were also favorable, as were all of their interactions.
Basic Biological Sciences
Authors: Fitzgerald Robert J. , Fitzgerald Dorothea B. , Adams Beatrice O. , Duany Luis F.
Published: November 2010

Of 50 strains of lactobacilli isolated from dental plaque of school children, two strains, provisionally identified as Lactobacillus salivarius, and one strain, provisionally identified as Lactobacillus fermentum, induced significant caries activity in conventional hamsters. Sucrose was a required dietary cariogenic substrate and could not be replaced with glucose or starch. In contrast to cariogenic strains of Streptococcus mutans the active lactobacilli did not form adherent sucrose-mediated plaques in vitro, did not form intracellular iodophilic polysaccharides and did not form detectable insoluble extracellular polyglucans.
Handling of Calcium by the Ferret Submandibular Gland
Authors: Mangos J.A. , Boyd R.L. , Loughlin G.M. , Cockrell A. , Fucci R.
Published: November 2010

The handling of Ca by the submandibular gland of the ferret during stimulation of salivation with pilocarpine was studied using micropuncture and microanalytical, as well as standard, physiological techniques. Concentrations of ionized Ca were measured in the fluid from the intercalated, lobular, and main ducts of the gland. The net transductal fluxes of this divalent ion were calculated.
A Study of in vivo Fluoride Uptake by Dental Tissues from Fluoride-containing Silver Amalgams
Authors: Souganidis D.J. , Athanassouli T.M.N. , Papastathopoulos D.S.
Published: November 2010

Teeth to be extracted for orthodontic reasons were filled in vivo with regular and fine-cut silver amalgams containing 1% and 5% SnF2. The teeth were extracted after 15 or 30 d, and the in vivo fluoride release and uptake by the dental tissues were studied using an electron microprobe analysis technique. The obtained results show that the use of SnF2 silver amalgams can be of potential value for minimizing caries adjacent to dental restorations.
Effect of Moisture Contamination on High-Copper Amalgam
Authors: Yamada Toshimoto , Fusayama Takao
Published: November 2010

Moisture contamination caused delayed excessive expansion and deterioration of the physical properties only with the non-high-copper lathe-cut alloy amalgam containing zinc, but not with the new high-copper amalgam and the non-high-copper spherical alloy amalgam containing zinc. It affected the compressive strength and creep but not the hardness. The setting dimensional change of all amalgams containing zinc was slightly affected by it.
The Effect of Rotary Instrumentation on the Permeability of Dentin
Authors: Boyer D.B. , Svare C.W.
Published: November 2010

The filtration and diffusion of tritiated water through dentin disks were measured in a split-chamber diffusion cell. The dentin had been cut with a diamond disk and the surfaces modified with a carbide fissure bur or diamond bur. Disks were given a secondary burnishing treatment with a blank bur or a modified blank bur. Burnishing reduced the permeability of dentin cut with a fissure bur.
TEM Study of the Central Dark Line in Enamel Crystallites
Authors: Marshall A.F. , Lawless K.R.
Published: November 2010

The central dark line observed in enamel crystallites has been studied by transmission electron microscopy. Lattice images and microdiffraction show it to be a single 100 plane of the hydroxyapatite structure whose appearance depends on specific diffraction conditions. The nature and significance of the central dark line as indicated by these studies are discussed.
Oral Flora of Children with "Nursing Bottle Caries"
Authors: van Houte J. , Gibbs G. , Butera C.
Published: November 2010

Plaque from carious and sound tooth surfaces, as well as saliva from children with "nursing bottle caries," contained unusually high levels of Streptococcus mutans; the levels of Streptococcus sanguis in plaque on anterior teeth and Streptococcus salivarius in saliva were unusually low. Lactobacilli were detected in nearly all plaque samples. The findings are discussed in relation to the role of S. mutans and lactobacilli in the initiation of human dental caries and diet-plaque interactions.
Carbonate Apatites from Aqueous and Non-aqueous Media Studied by ESR, IR, and X-ray Diffraction: Effect of NH4+ Ions on Crystallographic Parameters
Authors: Doi Y. , Moriwaki Y. , Aoba T. , Okazaki M. , Takahashi J. , Joshin K.
Published: November 2010

Carbonate-containing apatites prepared from aqueous and non-aqueous media were investigated by ESR, IR, and X-ray diffraction. A typical asymmetric signal at g=2.0, which many workers have observed in irradiated calcified tissues, is interpreted in terms of CO3-3 and CO-2 and the trapped electron center. The CO3-3 and CO- 2 ions originated from the carbonate which substitutes for the phosphate ion in the apatite crystalline structure.

From the comparison of the data between the carbonate apatites prepared under the presence of Na + and NH4+ ions, it is suggested that NH 4+ ions contribute to the crystallographic parameters, either by substituting in the structure or by suppressing the CO3 incorporation into the structure, or by both. The production of the C02 radical ion could be accounted for based on the concept of hydrogen bond between the oxygen atom of CO2-3 and the hydrogen atom of NH4 +.
The Use of Additives to Improve the Mechanical Properties of Gypsum Products
Authors: Sanad M.E.E. , Combe E.C. , Grant A.A.
Published: November 2010

The effects of adding a combination of calcium oxide and gum arabic additives to calcium sulfate hemihydrate have been determined. It has been found possible to produce gypsum products with properties superior for dental applications. In particular, formulations are suggested for die, model, and flasking materials.
Clinical Science
Authors: Yoshida K. , Takada K. , Adachi S. , Sakuda M.
Published: November 2010

Miniature surface electrodes were developed to examine the EMG activity of the tongue during various functions under normal physiological conditions with minimal fear and discomfort to human subjects. An outline of the electrodes, which consist of electrically high-conductive silver paste, small rubber caps, and fine wires, is introduced, and the practicability of their clinical application is discussed.
Materials Science
Authors: Powis D.R. , Follerås T. , Merson S.A. , Wilson A.D.
Published: November 2010

A study has been made on improving the adhesion of a glass-ionomer cement by the chemical treatment of dentin and enamel surfaces. The most effective surface conditioners were high molecular weight substances containing a multiplicity of functional groups capable of hydrogen bonding. Low molecular weight chelating agents which dissolve calciferous material and dramatically alter the surfaces of enamel and dentin are less effective.
Solvent Effects on Bonding Organo-silane to Silica Surfaces
Authors: Chen T.M. , Brauer G.M.
Published: November 2010

Interfacial bonding and stability of γ-methacryloxypropyltrimethoxysilane with silica surfaces have been studied by means of infrared spectroscopy. The addition of n-propylamine enhances silanization of γ-methacryloxypropyltrimethoxysilane to silica surfaces in normal aliphatic hydrocarbons, and cyclohexane yields a more water-resistant silica-silane bond, and improves the diametral tensile strength of the composite.
Basic Biological Sciences
Authors: Quissell D.O. , Lafferty J.L. , Barzen K.A.
Published: November 2010

The inter-relationship between cellular calcium and cAMP in the regulation of amylase secretion in dispersed rat parotid cells was evaluated. α- adrenergic stimulation augmented β-adrenergic receptor-mediated amylase release. Cellular calcium depletion was unable to completely block amylase secretion.
The Effect of Prolonged Stimulation of Salivary Flow on Bacterial Reactive Factors
Authors: Kashket S. , Guilmette K.M. , Ebersole J.L.
Published: November 2010

Prolonged stimulation of salivary flow leads to major changes in the concentrations of certain bacterial aggregating factors and strain- specific antibodies. Aggregating activity for a strain of Streptococcus sanguis was reduced rapidly, while activities for three strains of S. mutans remained unchanged, and activities for two other strains increased several-fold. The results were independent of changes in salivary protein and calcium. Concentrations of IgA and specific IgA antibodies for three S. mutans strains decreased progressively with continued stimulation. Similar results were obtained with parotid, submandibular, and whole saliva. These findings indicate that the rates of release of the different bacterial reactive substances from the salivary glands often follow independent courses and, furthermore, that the spectrum of reactivities of these substances changes with flow rate. Such changes may be reflected in the bacterial composition of plaque.
Materials Science
Authors: Shen C. , Tsutsumi S.
Published: November 2010

A microleakage model based on the diffusion phenomenon of a radio tracer from the cavity floor of a restoration to the outside medium was discussed and was solved numerically by the finite element method. The simulation results and laboratory data showed that quantitation of microleakage could be achieved and expressed by a new term named Microleakage Coefficient, which reflected the changes of micro gaps by time.
Occlusal Forces in Normal- and Long-face Adults
Authors: Proffit W.R. , Fields H.W. , Nixon W.L.
Published: November 2010

Using both quartz- and foil-based piezo-electric force transducers, occlusal forces during swallow, simulated chewing, and maximum effort were evaluated in 19 long-face and 21 normal individuals. Forces were measured at 2.5 mm and 6.0 mm molar separation. Longface individuals have significantly less occlusal force during maximum effort, simulated chewing, and swallowing than do individuals with normal vertical facial dimensions. No differences in forces between 2.5- and 6.0-mm jaw separation were observed for either group.
In vitro Effect of APF Gel on Three Composite Resins
Authors: Kula K. , Nelson S. , Thompson V.
Published: November 2010

A laboratory study was conducted to determine effects of 1.23% APF gel on three composite resins. All composite resins immersed in APF gel lost significantly more weight than did their controls with significantly different weight losses among the APF-treated composites. Surfaces of all resins exposed to APF gel, as viewed in SEM's, exhibited degradation of filler particles.
Effect of Eugenol on Constrictor Responses in Blood Vessels of the Rabbit Ear
Authors: Hume W.R.
Published: November 2010

Aqueous solutions of eugenol depressed vasoconstrictor responses to exogenous norepinephrine (NE), histamine, and peri-arterial sympathetic nerve stimulation in the isolated central artery of the rabbit ear and in the isolated perfused whole rabbit ear. The depression was dose- and time-dependent, and was slowly reversible. Eugenol appeared to act as an inhibitor of smooth muscle contractility.
Materials Science Thermal Shock Resistance of Porcelain Discs
Authors: Anusavice K.J. , Dehoff P.H. , Twiggs S.W. , Lockwood P.C.
Published: November 2010

Thermal shock testing of opaque porcelain-body porcelain discs and body porcelain discs was performed on three porcelain products. Significant differences exist between the mean failure temperature differentials, ΔT, for the composite opaque-body porcelain discs. The residual tensile stress and the transient tensile stress distribution are more severe for one of the three porcelains tested.
Oral Fluoride Retention with Thixotropic and APF Gels and Foam-lined and Unlined Trays
Authors: LeCompte E.J. , Rubenstein L.K.
Published: November 2010

Ten child volunteers each received four topical fluoride applications using different techniques. The amounts of fluoride applied, recovered from the mouth, and retained in the mouth were calculated for each treatment. The value of patient expectoration following topical F treatment was also evaluated. The tray system with an absorptive liner significantly reduced the amount of gross oral-retained fluoride (p < 0.01). Expectoration following topical treatment with either an APF or thixotropic gel was a significant adjunct in reducing the net oral-retained F dose (p < 0.01). When expectoration is done following a topical F treatment, a thixotropic gel may be an added advantage in reducing oral F retention and ingestion. We recommend that suction devices be used during a topical F treatment, but most importantly that the patient be requested to expectorate thoroughly following topical treatment.
Effect of Long-term Administration of Fluoride on the Levels of EDTA-soluble Protein and γ-Carboxyglutamic Acid in Rat Incisor Teeth
Authors: Smid J.R. , DeJersey J. , Kruger B.J.
Published: November 2010

EDTA-soluble material, extracted from incisor teeth of rats given 50 ppm fluoride (NaF) in drinking water ad libitum from conception to age nine wk, contained significantly higher levels of protein (P<0.01) and γ-carboxyglutamic acid (P<0.01) than did similar material from control rats. Tooth fluoride levels indicated that the incisors were mildly fluorosed. Analysis of these data indicates that mild fluorosis of rat incisor teeth involves not only the characteristic disturbances of pigmentation and mineral structure but also some alteration of the matrix protein.
Relationships between Masticatory Muscle Cross-section and Skull Shape
Authors: Weijs W.A. , Hillen B.
Published: November 2010

Cross-sectional areas of the masseter, temporalis and medial, and lateral pterygoid muscles were determined in 16 subjects by means of computer tomography. In each subject three scans were made, intersecting the thickest part of the muscles at right angles to the fiber direction. The masseter and medial pterygoid muscles are large in persons with brachycephalic skulls, short faces, and a small jaw angle. The cross-sectional areas of the temporalis and lateral pterygoid muscles showed no correlation with facial dimensions.
Frequency-dependent Modulation of Rhythmic Human Jaw Movements
Authors: Morimoto T. , Inoue T. , Nakamura T. , Kawamura Y.
Published: November 2010

Modulation of jaw movement patterns by alteration of the chewing rhythm was analyzed in nine subjects. Jaw movements were monitored by an electronic transducer system. The subjects were asked to chew gum either at voluntarily determined rates or at rates guided by a light flash that varied from 2 to 7 Hz at 1-Hz intervals. The results can be summarized as follows: (1) Chewing was generally conducted at rates below 3 Hz when the rhythm was voluntarily determined. When the rhythm was guided, however, the maximum chewing rate could occasionally be raised up to 6 Hz; (2) the duration of the chewing cycle was more closely related to changes in the duration of the opening and occlusion phases than to that of the closing phase; (3) at chewing rates below 3 Hz, the maximum gape did not appreciably change with the chewing rhythm, while it decreased linearly at rates above 3 Hz; and (4) at chewing rates below 3 Hz, the jaw opening velocity increased with speed of chewing, whereas it decreased or sometimes fluctuated over a wide range at rates above 3 Hz. It is concluded that, during normal mastication at rates below 3 Hz, chewing rhythm is altered by changing both the velocity of jaw opening and the duration of the occlusion phase.
Spectrometric Analysis of the Influence of Metal Substrates on the Color of Metal-Ceramic Restorations
Authors: Brewer J.D. , Akers C.K. , Garlapo D.A. , Sorensen S.E.
Published: November 2010

The development and use of ceramic alloys have created the potential for variation in the color of dental porcelain. In order to define the nature of the alterations, it is necessary to examine quantitatively the color of dental porcelain baked onto ceramic alloys. The purpose of this study was to examine spectrometrically where color differences occur in the fabrication process. One shade of Vita porcelain was baked onto coupons of three ceramic alloys (high gold, palladium-silver, base metal). Eight replications were made in each alloy at seven fabrication steps: prepared metal, oxide, first opaque, second opaque, first dentin, second dentin, and glaze. Spectrometric analyses were performed for each replication at each step. Data were tabulated every 10 nm over the recorded 380-750-nm range, for conversion to the CIE color measurement system. Tristimulus values X, Y, and Z and chromaticity coordinates x and y were calculated. Differences from spectrographic inspection were seen among the metal substrate series. The greatest variation appeared at the first dentin step between the palladium-silver and high-gold alloys and between the palladium-silver and base metal alloys. Mean tristimulus values were significantly different (p < 0.0001) for all steps and alloys. The distribution of plotted values followed the same pattern of spectral changes throughout the seven fabrication steps. Analysis of these data shows that color differences of metal-ceramic coupons based on dissimilar metal substrates can be quantified, and that spectral reflectance values can be converted to CIE notation. As depicted spectrally, notable color differences appeared with the first dentin porcelain layer.
Histopathology of the Initial Lesion of the Root Surface: an in vitro Study
Authors: Phankosol P. , Ettinger R.L. , Hicks M.J. , Wefel J.S.
Published: November 2010

An acidified gel system was used to produce artificial caries lesions in root surfaces. Radiopaque surface layers were found with 47% of the lesions. Demineralized bodies of the lesion and mineralized zones of banding were seen in all lesions when examined by microradiography. Cementum and dentin seemed to respond to the acid attack in a similar manner. Although artificial root lesions did not simulate natural root caries entirely, the acidified gel system resulted in a reproducible method that might give insight into initial lesion formation on root surfaces. This technique may be used for studying the physico-chemical process involved in the demineralization of root surfaces and for testing the effects of various agents in the prevention of root caries.
Materials Science
Authors: Sutow E.J. , Jones D.W. , Milne E.L.
Published: November 2010

The crevice corrosion susceptibility of cold-worked Type 316LVM stainless steel, cast Co-Cr-Mo, wrought Co-Cr-W-Ni, non-nitrided and nitrided Ti-6Al-4V ELI, and c.p. Ti, Grades 1 and 4, was studied in vitro by means of a crevice cell. Occlusion was created by interfacing a disc specimen and a Teflon bar. Specimens were mechanically prepared through 2-4 μm Al2O3 and passivated in 30% HNO3, followed by steam sterilization. Tests were performed in a deaerated Ringer's solution, maintained at pH = 7 and 37°C. Anodic polarization was conducted potentiostatically at pre-selected levels, and resultant currents were monitored: stainless steel, 50 and 100 mV (S.C.E.), 450 min; non-stainless materials, 600 mV, 1000 min. Results for the stainless steel demonstrated that a HNO3 passivation treatment reduced its crevice corrosion susceptibility. For the non-stainless steel materials, no crevice corrosion susceptibility was observed, although a dulling and discoloration of c.p. Ti was evident. Recognizing that 600 mV is in excess of the O2 reduction potential in vivo, it was concluded that, in the absence of fretting, implants of these non-stainless steel materials would not experience significant corrosion loss under crevice conditions.
Changes in Dentin Appositional Rates During Pregnancy and Lactation in Rats
Authors: Miller S.C. , Omura T.H. , Smith L.J.
Published: November 2010

Dentin appositional rates were determined in pregnant and lactating rats and compared with those in non-pregnant, age-matched controls. Appositional rates were calculated from measurements of distance between fluorescent mineralized tissue markers. There were significant increases in dentin apposition during pregnancy, with the greatest increases seen in the first two weeks. Dentin appositional rates decreased significantly during mid-lactation. These results indicate that homeostatic changes during pregnancy and lactation affect mineralized tissue accretion.
Dietary Fluoride Intake of 15-19-year-old Male Adults Residing in the United States
Authors: Singer L. , Ophaug R.H. , Harland B.F.
Published: November 2010

The average daily dietary fluoride intakes of 15-to-19-year-old males were estimated from the analysis of 24 FDA "market basket" food collections made from 1975 to 1982. The data indicate that 15-to-19-year-old males residing in fluoridated (>0.7 ppm) cities had an average daily dietary fluoride intake of 1.85 mg/day when the diet provided an estimated caloric intake of 11.72 megajoules (2800 calories). In non-fluoridated cities, with <0.3 ppm in the drinking water, the average dietary fluoride intake was 0.86 mg/day. The beverages and drinking water contributed an average of 75 ± 2% of the daily dietary fluoride intake.
A Study of Factors Associated with Changes in Dental Anxiety
Authors: Kent G. , Warren P.
Published: November 2010

Patients were given the Dental Anxiety Scale (DAS) to complete and asked to indicate the degree of pain they expected to feel on that day's visit to a dentist. After the appointment, they indicated the degree of pain actually experienced. Three months later, the patients were contacted by mail and asked about the amount of pain they remembered having experienced and to complete the DAS again. There was considerable stability in DAS scores over the two administrations, but some of the change in scores was associated with the discrepancy between the degree of pain the patients expected and the degree of pain they actually experienced.
Tarnishing in vivo of Ag-Pd-Cu-Zn Alloys
Authors: Herø H. , Niemi L.
Published: November 2010

Pre-polished specimens of four Ag-Pd-Cu-Zn alloys have been tested for tarnishing while embedded in full acrylic dentures for from six to eight months in vivo. The results have been compared with those from previous immersion tests using 2% Na 2S Solutions. In both types of tests, a multiphase allo consisting of a Pd-Cu-Zn-rich compound in a Ag-rich matrix displayed less corrosion and tarnish resistance than did alloys with compositions similar to the Pd-Cu-Zn-rich compound or the Ag-rich matrix. It is suggested that the presence of local micro-galvanic cells due to chemical inhomogeneities caused the observed susceptibility, to tarnishing, Sulfur was detected by a microprebe in the tarnish layer developed in the oral cavity. The discoloration on this multiphase alloy covered the interdendritic, areas with short distances between the chemical inhomogeneities. This microstructural location was somewhat different from the many dark spots created predominantly on Ag-rich areas during in vitro testing. This difference. is most likely due to dissimilar conditions with regard to sulfide ion concentrations, the presence of protein films, and the length af exposure time,
Rates of Epithelial Cell Proliferation in the Oral Mucosa and Skin of the Tamarin Monkey (Saguinus fuscicollis)
Authors: Rowat J.S. , Squier C.A.
Published: November 2010

Epithelial cell proliferation was determined in skin and various regions of the oral cavity of the tamarin monkey and was expressed by means of two mitotic indices: the number of metaphases per mm of epithelial surface, and the number of metaphases per mm basement membrane. A significant correlation was obtained between the rank ordering of the different regions according to each index. Generally, the non-keratinized tissues of the oral cavity had mitotic rates higher than those of the keratinized oral regions, with the epidermis having the lowest value. The mitotic index also correlated significantly with epithelial thickness, with the thicker regions showing a higher rate of proliferation. These results represent the first comprehensive set of values for a primate and are in general agreement with data obtained from non-primate species; the values support the concept that the oral lining tissue turns over more rapidly than does the masticatory mucosa (Bhaskar, 1980).
A High-copper Amalgam Evaluated after Three Years in City and Country Practices
Authors: Smales R.J. , Gerke D.C.
Published: November 2010

The objective of the study was to compare the condition of Sybraloy restorations placed by the same operator in two different practice locations.

Evaluations of the restorations were based on assessments for marginal fracture and staining, and for surface discoloration and roughness. Sybraloy restorations placed in a city practice were more satisfactory than those placed in a country practice. Surface discoloration proved to be unsatisfactory, especially in the country practice, but could be removed with light polishing.
The Growth of Oral Bacteria on Saliva
Authors: De Jong M.H. , Van Der Hoeven J.S.
Published: November 2010

The present experiments were aimed at studying the degradation of salivary glycoproteins by the oral microflora. To this end, S. sanguis I strain Ny476 and S. sanguis II (S. mitior) strain Ny581 were grown continuously in human-whole saliva. Under these conditions, the strains produced a variety of cell-associated hydrolytic activities, including glycosidases, exo- and endopeptidases, and esterases. S. sanguis II generally exhibited higher levels of enzyme activity than did S. sanguis I, in particular of neuraminidase that was produced only by S. sanguis II. In accordance, S. sanguis II had a higher cell yield and consumed a higher proportion of the sugars and sialic acid in the glycoproteins than did S. sanguis I. Interestinglv, S. sanguis I, which is devoid of neuraminidase, is known to have a lectin with specificity for sialic acid, whereas S. sanguis II has affinity for galactose residues in the glycoproteins. We propose that specific binding of glycoproteins by oral bacteria constitutes a mechanism to collect nutrients in the vicinity of the cell. The special ability of S. sanguis II to utilize saliva for growth was further exemplified by its selection in batch-wise enrichments of dental plaque on saliva. The microflora in these enrichment cultures always consisted of Peptostreptococcus micros, S. sanguis II, and Fusobacterium nucleatum as the dominant organisms. Further, S. mitis and Gemella hæmolysans were generally found to be present. The enrichment cultures produced a wide variety of mainly cell-bound hydrolytic enzymes. This resulted in almost complete breakdown of salivary glycoproteins in the culture.
Antigenic Heterogeneity of Non-pigmented Bacteroides Species Isolated from the Human Oral Cavity
Authors: Kato T. , Okuda K. , Takazoe I. , Fujisawa T. , Mitsuoka T.
Published: November 2010

Serological studies on 27 strains of non-pigmented Bacteroides isolated from the human oral cavity revealed multiple serotypes within B. buccae. B. capillus (= B. buccae) and B. pentosaceus (= B. buccae) were found to be serogroups within B. buccae. B. denticola possessed cross-reactive antigens with B. buccae. Tested strains of B. oralis, B. veroralis, B. oris, and B. heparinolyticus were clearly differentiated from each other.
Characterization of Plasminogen Activators in Unstimulated and Stimulated Human Whole Saliva
Authors: Sindet-Pedersen S. , Gram J. , Jespersen J.
Published: November 2010

The fibrinolytic activity of saliva from healthy males was studied on plasminogen-free and plasminogen-rich fibrin plates. A cell-bound plasminogen activator in human unstimulated and stimulated whole saliva was demonstrated. The assessed fibrinolytic activities could always be quenched by incorporation into the fibrin plates of IgG antibodies raised against human two-chain tissue-plasminogen activator (t-PA), while additional experiments indicated the absence in normal human saliva of urokinase-like and factor XII-dependent plasminogen activators as well as the absence of inhibitors of fibrinolysis. Thus, t-PA is the only type of plasminogen activator in normal human saliva.

The present findings seem to support our recent clinical observations of a decrease in the incidence of bleeding complications and need for replacement therapy in hemophiliacs undergoing oral surgery during local antifibrinolytic therapy with tranexamic acid. Whether the findings might also be of importance in other pathological conditions of the oral cavity, such as impaired wound healing, remains to be elucidated.
Stress Distribution in Metal-Ceramic Crowns with a Facial Porcelain Margin
Authors: Anusavice K.J. , Hojjatie B.
Published: November 2010

The use of metal-ceramic restorations with porcelain butt-joint facial margins has increased in the past several years. Although these crowns exhibit improved esthetics compared with metal-ceramic crowns which display a metal gingival collar or metal knife-edge margin, the effectiveness of this design in resisting intra-oral forces is not known. The objective of this study was to analyze the stress distribution induced by simulated intra-oral loads on crowns with variable coping configurations. The copings, with a thickness of either 0. 1 or 0.3 mm, were modeled with a facial termination of metal at three locations: at the gingival floor, 0.9 mm above the gingival floor, and 4.2 mm above the gingival floor. The coping and crown dimensions were based on a prepared maxillary central incisor with a facial shoulder and a lingual chamfer. Both Ni-Cr and Au-Pd alloy copings were employed in the crown models. Finite element stress analyses were performed on crowns which were subjected to several loading conditions. A cement film thickness of 0.030 mm was assumed.

For all cases, the stresses which developed in porcelain and cement near the facial and lingual margins due to a vertical load of 200 N were predominately compressive in nature. For the crowns with Ni-Cr copings, the tensile stress in porcelain ranged from 11.0 MPa (for crowns with a facial metal thickness of 0.3 mm) to 12.5 MPa (for a metal thickness of 0.1 mm). The corresponding stresses for crowns with Au-Pd alloy copings were 8.3 MPa and 8.6 MPa, respectively. Maximum compressive stresses in cement near the lingual margin were 22.3 MPa for the Ni-Cr crowns and 30.0 MPa for the Au-Pd crowns. The maximum tensile stress in porcelain was 29.0 MPa and occurred near the area of loading for the Au-Pd case. The maximum tensile stress in the facial porcelain region (8.3 MPa) developed within the incisal third of the facial surface. Under the conditions assumed in this study, the alloy type, coping thickness, and coping termination point have a negligibly small effect on the stresses induced in porcelain or cement near the facial margin.