bluuebunny/crossref_metadata_2025 huggingface dataset:
Molar Efficiency Study of Chlorinated NPG Substitutes in Dentin Bonding
Authors: Miniotis N.J. , Bennett P.S. , Johnston A.D.
Published: November 2010

This study evaluated and compared the contributions to dentin adhesive bonding of three N-phenylglycine analogues with electron-withdrawing substituents on the aromatic ring. These electron-deficient "N-compounds" included: N-(4-chlorophenyl)-glycine (NCPG), N-methyl- N-(4-chlorophenyl)-glycine (NMNCPG), and N-(3,4-dichlorophenyD-glycine (NDCPG). An experimental three-step dentin-bonding protocol that consisted of sequential application of acidic ferric oxalate solution, an N-compound in acetone, and a surface-active comonomer in acetone was used. The first and third steps were held constant throughout the study. Each N-compound (NCPG, NMNCPG, NDCPG) was used in step two at ten concentrations ranging from 0.0 mol/L (pure acetone) to 5 x 10-1 mol/L, depending on solubility. After overnight storage in distilled water, the dentin-to-composite bonds were broken in tension. The data were analyzed with ANOVA, and multiple comparisons were performed with Duncan's Multiple Range test. All statistical tests were controlled at α = 0.05. At 5 x 10-3 mol/L, the relative effectiveness of the three N-compounds (as measured by tensile bond strengths) was NMNCPG > NCPG > NDCPG. Of all concentrations studied, the mean bond strengths produced with NMNCPG were statistically as good as or better than those produced by the other two compounds, and NCPG was always as good as or better than NDCPG. Increased electron-withdrawing from the nitrogen of the amine group by the substituents narrowed the effective concentration range for dentin bonding and, in general, produced lower mean bond strengths between dentin and composite.
Molecular Orientation of Silane at the Surface of Colloidal Silica
Authors: Söderholm K.-J.M. , Shang S.-W.
Published: November 2010

The objective of this study was to investigate the silica-silane bond formation present at the filler interface of dental composites. Diffuse reflectance infrared Fourier transform spectroscopy was used, and the spectra of pyrogenic silica (Cab-O-Sil) treated with different concentrations of γ-methacryloxypropyltrimethoxy-silane (MPS) were analyzed. The outcome of the study suggested that the γ-methacryloxypropyltrimethoxysilane (MPS) molecules oriented parallel to the colloidal silica surface (Cab-O-Sil) and formed two types of bonds. One of these bonds was a siloxane bridge formed by a condensation reaction between the silanol groups of both the silica surface and the hydrolyzed silane. Water formed during this reaction and soon became recaptured by the silanol groups of the silica surface. These water molecules were not available for additional hydrolyzation reactions ofthe unhydrolyzed silane under the experimental conditions. The intensity of the isolated OH-groups decreased because of this reaction. Simultaneous with the condensation reaction, the carbonyl group of the MPS molecule formed hydrogen bonds. This hydrogen bond formation resulted in a peak shift of the carbonyl band from 1718-1720 cm-1 to 1700-1702 cm-1. This hydrogen bond formation also occurred with the isolated OH-groups. After consumption of the isolated OH-groups, no additional surface reaction occurred because no further OH-groups were available for additional condensation reactions or hydrogen bond formation. The findings suggest that the amount of silane needed for filler treatment depends on the number of isolated OH-groups available on the filler surface.
A Multiple Logistic Regression Analysis of the Risk and Relative Odds of Temporomandibular Disorders as a Function of Common Occlusal Features
Authors: Pullinger A.G. , Seligman D.A. , Gornbein J.A.
Published: November 2010

A multiple logistic regression analysis was used to compute the odds ratios for 11 common occlusal features for asymptomatic controls (n = 147) us. five temporomandibular disorder groups: Disc Displacement with Reduction (n = 81), Disc Displacement without Reduction (n = 48), Osteoarthrosis with Disc Displacement History (n = 75), Primary Osteoarthrosis (n = 85), and Myalgia Only (n = 124). Features that did not contribute included: retruded contact position (RCP) to intercuspal position (ICP) occlusal slides < 2 mm, slide asymmetry, unilateral RCP contacts, deep overbite, minimal overjet, dental midline discrepancies, ≤ 4 missing teeth, and maxillo-mandibular first molar relationship or cross-arch asymmetry. Groupings of a minimum of two to at most five occlusal variables contributed to the TMD patient groups. Significant increases in risk occurred selectively with anterior open bite (p < 0.01), unilateral maxillary lingual crossbite (p < 0.05 to p < 0.01), overjets > 6-7 mm (p < 0.05 to p < 0.01), ≥5-6 missing posterior teeth (p < 0.05 to p < 0.01), and RCP-ICP slides > 2 mm (p < 0.05 to p < 0.01). While the contribution of occlusion to the disease groups was not zero, most of the variation in each disease population was not explained by occlusal parameters. Thus, occlusion cannot be considered the unique or dominant factor in defining TMD populations. Certain features such as anterior open bite in osteoarthrosis patients were considered to be a consequence of rather than etiological factors for the disorder.
Effects of Oral Sensory Afferents on Mastication in the Miniature Pig
Authors: Huang X. , Zhang G. , Herring S.W.
Published: November 2010

The performance of mastication is presumed to be influenced by afferent stimulation, but little information is available from awake, intact animals. Thirteen experiments were carried out with four miniature pigs. Electromyographic signals from the jaw muscles were recorded simultaneously with jaw movements during natural chewing of foods of differing hardnesses. Harder foods were found to be associated with higher activity levels of jaw-closing muscles and greater lateral deviation, but reduced jaw opening. The sensory supply from one side of the oral cavity was then removed by injected local anesthetic, and the recordings repeated. In addition to decreased activity levels, the jaw-closing muscles showed reduced ability to adjust to different foods. The frequency of mastication fell slightly, and the animals preferred to chew on the uninjected side. Lateral deviation was reduced, but at the same time the jaw-opening muscles usually became more active, and accordingly the jaw opened more widely. These findings provide new information on the role of oral sensory afferents in regulating natural chewing patterns. The decreased activities of the jaw-closing muscles are consistent with, although they do not demonstrate, the existence of a positive feedback from periodontal afferents.
Neural Changes in Periapical Lesions after Systemic Steroids in the Ferret
Authors: Holland G.R.
Published: November 2010

This study was intended to clarify the relationship between the neural changes which occur around the apex of the ferret canine after pulpectomy and the inflammatory process induced by the procedure. In 12 young adult ferrets, under general anesthesia, the pulps in the mandibular canine teeth were removed and replaced with gutta percha and Grossman's sealer. Six of the animals were treated with dexamethasone to reduce the inflammatory response. Three months later, the animals, again under general anesthesia, were perfused with a fixative mixture. Three unoperated animals that had not been treated with dexamethasone were also perfused. The mandibular canine teeth and their supporting tissues were removed, processed, and serially sectioned. Three-dimensional reconstructions of the periapical lesions in each animal were assembled and their volumes measured. The density of innervation in the periapical region was estimated. The mean lesion volume in the pulpectomized animals not treated with dexamethasone was 3.54 (± 2.27) mm3 and in the dexamethasone-treated animals 1.33 (± 1.31) mm 3. The differences were statistically significant when tested by the Mann-Whitney U test (p < 0.01). Bacteria were not seen within any of the lesions. The innervation density beneath the canines in the pulpectomized animals not treated with dexamethasone was 164 units per mm2 (± 80) and in the steroid-treated animals 151±68 units per mm2. In the control, untreated animals, the innervation density was 22 ± 10 units per mm2.The difference between the steroid-treated pulpectomized animals and the untreated pulpectomized animals was not statistically significant (p > 0.5). The difference between both pulpectomized groups and the unoperated controls was significant (p < 0.01). Neural proliferation beneath pulpectomized teeth was not related to the size of the inflammatory lesion.
Protective Effect of Topically Applied Fluoride in Relation to Fluoride Sensitivity of Mutans Streptococci
Authors: Van Loveren C. , Buijs J.F. , Ten Cate J.M.
Published: November 2010

The aim of the present in vitro experiments was to determine whether the protection of enamel by topically applied fluoride against demineralization by bacterial acids would depend on the fluoride sensitivity of the bacteria. Glucose-agarose gel suspensions of fluoride-sensitive and fluoride-resistant mutans streptococci were placed on bovine enamel specimens with different amounts of fluoride. One group of specimens was untreated, a second group had been pretreated with a F-lacquer, and a third group had been pretreated with the F-lacquer and rinsed subsequently with a KOH-solution, to remove deposited CaF2. After 22-hour incubations at 37°C, the amounts of calcium and lactate and the pH of the agarose gels were determined. This procedure was repeated on three consecutive days. Two parent S. mutans strains, one parent S. sobrinus strain, and five fluoride-resistant derivatives were tested. Both pretreatments gave a significant protection to the enamel specimens. For the S. mutans strains, the degree of protection did not depend on the fluoride sensitivity of the strains. For the S. sobrinus strains, the results suggested a reduced protection against demineralization by the fluoride-resistant derivatives. Only from the second group of enamel specimens was enough fluoride released for inhibition of bacterial metabolism. Presumably, it was released by the dissolution of CaF2. It is concluded that a possible adaptation of mutans streptococci in dental plaque to frequent exposures to fluoride will not necessarily decrease the caries-preventive effects caused by topically applied fluoride agents.
Differences in Composition of Cell-attachment Sialoproteins between Dentin and Bone
Authors: Fujisawa R. , Butler W.T. , Brunn J.C. , Zhou H.Y. , Kuboki Y.
Published: November 2010

Matrices of dentin and bone were compared with respect to the content of cell-attachment sialoproteins. The levels of two sialoproteins, osteopontin (OPN) and bone sialoprotein (BSP), were determined in dentin and bone by immunochemical procedures. Polyclonal antibodies against bovine BSP and an antibody against the amino-terminal decapeptide of rat OPN were used. The relative levels of OPN and BSP in dentin were less than one-tenth of the levels in bone. The differences between dentin and bone levels of OPN and BSP were thus larger than those for osteonectin or bone Gla protein in the two tissues. The scarcity of the cell-attachment proteins in dentin may reflect the metabolic inactivity of dentin.
Analysis of Debond Rates of Resin-bonded Prostheses
Authors: Boyer D.B. , Williams V.D. , Thayer K.E. , Denehy G.E. , Diaz-Arnold A.M.
Published: November 2010

Debonding rates of 164 resin-bonded prostheses (RBP) placed from 1974 to 1985 were examined at recall. The yearly debond rates were calculated, the cumulative probability of failure was determined for the debonded RBPs, and Weibull distribution parameters were determined. For perforated prostheses, there was a high initial debond rate, followed by slowly decreasing rates for about 5 years. Increasing rates after 5 years indicated the beginning of wearout. The Weibull parameters for the wearout period ofthe perforated prostheses were: characteristic life = 128 (SE = 2) months, modulus = 1.27 (0.06), and threshold parameter = 0. Data were available for etched frameworks for 6 years and showed decreasing debond rates during this time. The characteristic life of the etched bridges was 318 (84) months. The cumulative failure data were also modeled with a cubic polynomial distribution that resulted in a U-shaped hazard function.
Mechanical Performance of a Dental Composite: Probabilistic Failure Prediction
Authors: Van Der Varst P.G.T. , Brekelmans W.A.M. , De Vree J.H.P. , De Groot R.
Published: November 2010

In clinical situations, the mechanical performances of dental structures-for example, composite restorations-depend on many factors. Most of them have a probabilistic character. Because composites are brittle materials, their strength should also be considered as a probabilistic quantity. For successful prediction of mechanical failure of structures consisting of these materials, a probabilistic approach is indispensable, and a suitable definition of equivalent stress must be introduced. An equivalent stress facilitates the transfer of strength data of laboratory specimens to situations where the stress state is much more complicated. The tensile and compressive strengths of composites differ considerably. Of two equivalent stress definitions that potentially describe this experimental fact (the Driicker-Prager and the Modified von Mises equivalent stress), the predictive capacity was investigated for a microfine composite. In a probabilistic approach to failure, use of the Driicker-Prager equivalent stress appeared to be superior, because the average failure load of notched beams was predicted with an error smaller than 8%.
Analysis of the "Shear" Bond Strength of Pretreated Aged Composites Used in Some Indirect Bonding Techniques
Authors: Shiau J.Y. , Rasmussen S.T. , Phelps A.E. , Enlow D.H. , Wolf G.R.
Published: November 2010

Investigations of the repair of composites have shown that bond strengths can be significantly reduced at an interface involving an aged composite. Brackets placed by some indirect bonding techniques also have an interface involving an aged composite. This study investigated some of the properties of sealant-composite interfaces and parameters affecting these properties independent of other regions and interfaces found in the total enamel-sealant-composite-bracket system using a shear bond-strength test and fractographic analysis. The effects of various pretreatments of 7-day-old composite surfaces on the bond strength and contact angle of a mixed sealant on these pretreated surfaces were determined. Fractured specimens with adhesive failure closest to the point of force application had low bond strengths (17.62 MPa), which could be correlated with surface pretreatment. Preliminary tests showed that acetone pretreatment produced the most consistently strong interfaces with the fewest adhesive failures of this type. Specimens with adhesive failure only in other regions had higher bond strengths (23.41 MPa), which showed no dependence on pretreatment. There was no statistical relationship between contact angle and bond strength. The data coupled with fracture path analysis suggest that: first, the critical region for fracture analysis is that part of the adhesive interface which is closest to the point of force application; second, failure during some dental shear bond strength tests probably occurs as a consequence of tensile stress induced by a bending moment rather than by shear stress; and third, specifying bond strength as breaking load/area may he incorrect.
The Effect of the Electrode Potential on the Release of Mercury from Dental Amalgam
Authors: Marek M.
Published: November 2010

The effect of the electrode potential on the rate of mercury dissolution from the matrix phase (γ1) of dental amalgam was investigated. Specimens of the Ag-Hg phase, with and without dissolved tin, were exposed to synthetic saliva and maintained at various potentials by means of a potentiostat. The amount of dissolved mercury was determined after 24 h by cold-vapor Atomic Absorption Spectrophotometry. Anodic polarization curves for the γ1 specimens and pure silver and mercury were also recorded.

The results for the Ag-Hg phase showed a potential-independent dissolution rate between -0.6 and -0.1 V (SCE), followed by a sharp increase. Mercury dissolution from the Ag-Hg-Sn phase was much slower than from the tin-free γ 1 phase, and potential-independent to +0.05 V (SCE); a sharp increase in mercury dissolution was observed at +0.1 V (SCE). The anodic polarization curves for the Ag-Hg-Sn phase indicated passivity between -0.67 V and +0.1 V (SCE), but no clear passivation for the Ag-Hg specimen, silver, or mercury.

The results show that in the potential-independent region, mercury dissolved in the atomic form from both the tin-free and tin-containing γ1 phase. The increase in dissolution in the upper range of potentials was tentatively attributed to selective anodic dissolution of silver and an onset of electrochemical dissolution. The results indicate that the rate of mercury release from the γ 1 phase of dental amalgam was not affected by potential changes due to alloying or galvanic contacts unless the potential exceeded some critical value.
The Resistance and Adaptation of Selected Oral Bacteria to Mercury and Its Impact on Their Growth
Authors: Lyttle H.A. , Bowden G.H.
Published: November 2010

Selected strains of oral Streptococcus and Actinomyces have been tested for their ability to grow in the presence of mercury. Strains were tested for growth on a semi-defined medium with low mercury-binding characteristics. Sensitivities were initially measured on agar plates, and subsequently, selected strains were grown in broth so that the impact of mercury on the growth characteristics could be determined. Streptococci were more resistant to mercury (5 μg/mL to 40 μg/mL) than Actinomyces (< 5 μg/ mL to 30 μg/mL). The most resistant streptococci included S. mitis biovar 1, S. salivarius, S. sobrinus, and one strain of S. mutans, all of which grew on agar with 40 μg/mL of mercury. Two other S. mutans strains were more sensitive, being inhibited by 10 and 20 pg/mL mercury. The most resistant Actinomyces was A. naeslundii genospecies 1 (ATCC12104), which grew on medium with 30 ug/mL mercury; two strains of Actinomyces were completely inhibited by 5 ug/mL. Mercury caused increased lag times and reduced cell density in broth cultures. Enrichment cultures of samples of human dental plaque showed that streptococci were the most resistant organisms that could be cultured on the medium and that these strains could adapt to relatively high mercury concentrations. S. oralis and S. mitis biovar 1 were the most resistant organisms isolated from enriched cultures, growing in broth media with 65 ug/mL mercury. Mercury was bound to cell walls and cell cytoplasm of streptococci grown in the presence of mercury. The levels of resistance to mercury of most of the organisms tested indicate that they would be able to grow in the environment of human dental plaque containing mercury.
A Quantitative Enzyme Histochemical Analysis of the Distribution of Alkaline Phosphatase Activity in the Periodontal Ligament of the Rat Incisor
Authors: Groeneveld M.C. , Everts V. , Beertsen W.
Published: November 2010

The spatial distribution of alkaline phosphatase (ALP) activity was examined in the periodontal ligament of the continuously growing rat incisor. With the indoxyl-tetrazolium salt method, enzyme activity was demonstrated in undecalcified cryosections, and the amount of reaction product was quantified. ALP activity appeared to be distributed heterogeneously. Its highest activity was found in the bone-related compartment of the ligament. In the tooth-related compartment and the supracrestal extension of the ligament, enzyme activity was significantly lower, but still higher than in the lamina propria of the gingiva. In the part of the ligament bordering the cementum, highest activity was found in the apical region just occlusal to Hertwig's epithelial root sheath, where formation of acellular cementum begins. From there toward the incisal edge, the activity of the enzyme gradually decreased. It is suggested that differences among the various parts of the periodontal ligament are related to local variations in phosphate metabolism and cementum deposition.Received for publication December 11, 1992 Accepted for publication March 17, 1993
Membrane Protein Expression by Actinobacillus actinomycetemcomitans in Response to Iron Availability
Authors: Winston J.L. , Chen C.-K. , Neiders M.E. , Dyer D.W.
Published: November 2010

Iron-limited growth conditions under anaerobiosis were established for Actinobacillus actinomycetemcomitans strains Y4, JP2, and 75 by use of the ferrous ion chelator 2,2'-dipyridyl. Growth inhibition was reversible with both ferrous and ferric iron sources. Sarcosyl-insoluble membrane fractions of iron-stressed anaerobic A. actinomycetemcomitans cultures revealed a similar iron-repressible protein of -70 kDa in A. actinomycetemcomitans strains Y4, JP2, and 75. This 70-kDa protein was recognized by serum from localized juvenile periodontitis patients and a periodontally healthy subject. This suggested that the 70-kDa iron-repressible protein may be expressed in vivo. When A. actinomycetemcomitans was grown under aerobic conditions, the ferric iron chelator, ethylenediamine di(o-hydroxyphenylacetic acid) (EDDA) was utilized for growth limitation. EDDA inhibition was reversible in strain Y4 with ferrous and ferric iron sources. An iron-repressible protein of -70 kDa was also noted in iron-stressed aerobic cultures. The 70-kDa protein maybe involved in iron transport by A. actinomycetemcomitans. Preliminary experiments were performed to examine potential iron transport systems for A. actinomycetemcomitans. Production of the two most common chemical types of siderophore was not detected in A. actinomycetemcomitans culture supernatants. Iron-starved A. actinomycetemcomitans cells did not bind transferrin or lactoferrin in a dot blot assay.
Comparison of Tooth Surface-specific Dental Caries Attack Patterns in US Schoolchildren from Two National Surveys
Authors: Li S.-H. , Kingman A. , Forthofer R. , Swango P.
Published: November 2010

The 1979-1980 and the 1986-1987 National Institute of Dental Research (NIDR) surveys of school-aged children revealed that virtually all tooth surfaces experienced a decrease in caries prevalence during the inter-survey period. Overall, there was a 28% decrease in the proportion of tooth surfaces attacked by caries for the primary dentition between the two surveys. The decrease for primary incisors was numerically small (5 surfaces per thousand surfaces at risk) and not statistically significant, whereas decreases in the canines and primary molars were considerably larger (23 surfaces per thousand) and statistically significant. For the permanent dentition, the overall decrease in the proportion of surfaces attacked was 35% during the 1979-87 period. Differences between the two surveys in the proportions of surfaces with caries were largest for pit and fissure surfaces (56 surfaces per thousand), followed by those for posterior approximal surfaces (14 surfacesper thousand) and all other smooth surfaces (5 surfaces per thousand). Almost all of these differences were statistically significant, except for some surfaces which experienced very few caries.
Enhanced Chemical Strengthening of Feldspathic Dental Porcelain
Authors: Denry I.L. , Rosenstiel S.F. , Holloway J.A. , Niemiec M.S.
Published: November 2010

Previous studies on ion exchange of dental ceramics have shown that the biaxial flexural strength can be improved by exchanging potassium for sodium ions at temperatures below the strain point.

The rubidium ion is bigger than the potassium ion and can also be considered as a candidate for replacing smaller ions, i.e., sodium or potassium, although it has not been used for dental ceramics. The double-step method uses the exchange of a small ion for a large ion (Li for Na) above the strain point, and the further exchange of a large ion for a small ion (K for Li) below the strain point. The purpose of this study was to compare the effect of rubidium-for-potassium ion exchange with that of potassium-for-sodium exchange (Tuf-Coat, G-C International Corp., Japan) on the flexural strength of a feldspathic dental porcelain and to test the hypothesis that a double-step ion exchange can lead to greater strengthening than potassium ion exchange alone.

Weight measurements were performed before and after treatment. Qualitative chemical analyses allowed the rubidium, potassium, and sodium concentration profiles to be determined along cross-sections of the specimens. The maximum biaxial stresses were calculated after specimens were fractured in water on a ball-on-ring fixture at 0.5 mm/min.

Relative to the untreated control group, the flexural strength of the potassium-exchanged groups was significantly increased, except for those treated at 400 or 500°C. All the groups treated with RbNO3 exhibited a significant increase in flexural strength, with a maximum for the group treated at 450°C. The group submitted to a double-step exchange showed a statistically significant increase in the mean flexural strength compared with the group treated with Tuf-Coat at 450°C.
Co-activation of Sternocleidomastoid Muscles During Maximum Clenching
Authors: Clark G.T. , Browne P.A. , Nakano M. , Yang Q.
Published: November 2010

In an attempt to determine the degree of co-activation present in selected cervical muscles during clenching, we instructed 12 male subjects to produce four brief maximum voluntary contraction (MVC) efforts (clenching) in a position of maximum intercuspation. Surface EMG activity was recorded bilaterally from the masseter and sternocleidomastoid (SCM) muscles. The contraction level for the SCM during clenching was reported as a percentage of the SCM's maximum activity achieved during maximum neck flexion against resistance. All EMG signals for the masseter and SCM were converted to a true RMS voltage signal and digitized at a 100-Hz sampling rate. Mean peak EMG voltage levels were determined for the activity recorded during each brief MVC task. All subjects demonstrated co-activation of the SCM during strong abrupt clenching efforts. The mean levels (± S.D.) of SCM activity were 11.8 ± 9.6% (right) and 14.2 ± 9.4% (left) of the MVC capacity. Fifty percent of masseter activity was required to achieve 5% activity of the SCM bilaterally, and there was a progressive development of the SCM co-activation which paralleled the masseter activation.
Defluoridation of Water at High pH with Use of Brushite, Calcium Hydroxide, and Bone Char
Authors: Larsen M.J. , Pearce E.I.F. , Jensen S.J.
Published: November 2010

The aim of this study was to improve the efficiency of the bone-char method of water defluoridation by pre-treating the water with brushite and calcium hydroxide. Various amounts of brushite, calcium hydroxide, and bone char were suspended batchwise in 100 mL of distilled water containing 0.53 mmol/L fluoride for 24 h under gentle agitation. At suitable intervals, pH and the concentrations of fluoride, calcium, and phosphate in the water were determined and, when possible, the degrees of saturation with respect to brushite, hydroxyapatite, and fluorapatite calculated. Bone char used alone took up fluoride slowly and inefficiently. The addition of brushite and calcium hydroxide resulted in high concentrations of calcium and phosphate, making the solutions highly supersaturated with respect to fluorapatite, and led to a 20-fold increase in fluoride removal from the water. The combined use of all three salts left low concentrations of phosphate in solution and optimized the fluoride uptake capacity. Repeated use of the same bone char for 18 consecutive runs demonstrated that uptake of fluoride by the bone char was improved by repeated use, provided that brushite and calcium hydroxide were added. Therefore, addition of the two salts to the water may prolong the life of the bone char indefinitely, ensure the removal of fluoride, and thus avoid the problem of determining when the bone char is exhausted. In conclusion, we show that the bone-char defluoridation technique can be improved by addition of brushite and calcium hydroxide to the water. The problem of high terminal pH remains, however, and further work is required to improve potability.
Deformation of the Human Mandible During Simulated Tooth Clenching
Authors: Korioth T.W.P. , Hannam A.G.
Published: November 2010

Localized corpus and dental arch distortions measured directly on human and animal mandibles suggest complex deformation patterns at other mandibular sites during functional loading. To describe these, we simulated selected static bites on a three-dimensional finite element computer model of the human jaw. Five clenching tasks were modeled: intercuspal position, left group function, left group function plus balancing contact, incisal clenching, and right molar clenching. Under conditions of static equilibrium and within the limitations of the current modeling approach, the human jaw deforms elastically during symmetrical and asymmetrical clenching tasks. This deformation is complex, and includes the rotational distortion of the corpora around their axes. In addition, the jaw also deforms parasagittally and transversely. The degree of distortion depended on each clenching task, with actual deformations being relatively small and ranging from 0.46 mm to 1.06 mm for the tasks modeled when all sites were taken into account. The predicted overall narrowing of the dental arch is consistent with clinical reports in the literature during similar, although not identical, static jaw function. The predicted regional deformations of the upper condylar surfaces imply differential loading at their upper surfaces. Although still constrained to forceful static biting conditions, the simulated mandibular and dental arch distortions should be taken into consideration in the design and testing of prosthetic devices in the lower jaw.
The Multidivisional Structure: Organizational Fossil or Source of Value?
Authors: Hoskisson Robert E. , Hill Charles W.L. , Kim Hicheon
Published: November 2010

The multidivisional (M-form) structure has been variously characterized as the most significant organizational innovation in the twentieth century (Williamson, 1985) and as an organizational fossil that is increasingly irrelevant in the modern world (Bettis, 1991). Against this background, the purpose of this paper is threefold. First, to critically evaluate three perspectives, including transaction cost, strategic management and sociological, relating to the M-form firm. Second, to examine what the empirical evidence finds about relationships proposed by these perspectives. Finally, to develop a model that summarizes the relationships proposed among these perspectives and make suggestions about future theory building and areas where further empirical work is needed.
Forming, Adapting, and Terminating the Employment Relationship: A Review of the Literature from Individual, Organizational, & Interactionist Perspectives
Authors: Taylor M. Susan , Giannantonio Cristina M.
Published: November 2010

This article reviews research published in the last five years (1988- 1992) on three employment status activities-formation, adaptation, and termination-from three perspectives-individual, organizational, and interactionist. It to integrates these findings into a common body of knowledge, in order to show what might be gained from a consideration of all three perspectives. The article concludes with recommendations for the requirements of models used to guide future research on the employment relationship and with the identification of fruitful directions for new research.
Top Management Influence on Innovations: Effects of Executive Characteristics and Social Culture
Authors: Hoffman Richard C. , Hegarty W. Harvey
Published: November 2010

Innovation is a growing source of strategic advantage across a variety of industrialized cultures. Top managers often seek to influence or champion strategic innovations. This study examined the extent to which executive characteristics explains top management influence on product/market (PM) and administrative (A DM) innovations in four Western cultures. The results support the proposition that different executive characteristics explain influence on each type of innovation. The influence process differed across cultures for A DM but not for PM innovations. The implications of this study for practice and research are discussed.
Relating Porter’s Configuration/Coordination Framework to Competitive Strategy and Structural Mechanisms: Analysis and Implications
Authors: Morrison Allen , Roth Kendall
Published: November 2010

This article examines the categorization of business strategy in global industries according to Porter’s (1986) configuration/coordination framework. In particular; the relationships between cost/differentiation-based competitive strategies and configuration/coordination-based international strategy types are evaluated. The article also examines the relationship between patterns of configuration/coordination and the structural mechanisms of centralization, formalization and specialization. By examining patterns across 77 businesses, the article raises important questions about the interpretation and application of the configuration/coordination framework in determining broad organizational responses to globalization. In particular, the relationship between competitive strategy and international strategy is re-examined and extensions to the framework are proposed.
Relationship between Job and Family Satisfaction: Causal or Noncausal Covariation?
Authors: Frone Michael R. , Russell Marcia , Cooper M. Lyme
Published: November 2010

Prior research supports a positive relationship between job and family satisfaction. Although this relationship has been taken as support for the spillover hypothesis, it is also consistent with an alternate hypothesis that has received little attention. The congruence hypothesis states that job and family satisfaction are positively related because they share a common cause or causes. Thus, the distinction between the spillover and congruence hypotheses reflects the broader distinction between causal and noncausal (i.e., spurious) covariation. The goal of this study was to determine which hypothesis best reflects the relationship between job and family satisfaction. Data were obtained through household interviews with a random sample of 631 individuals. Structural equation modeling techniques were used to estimate simultaneously a reciprocal relationship between job and family satisfaction and a noncausal correlation between their disturbance terms. Results supported the congruence hypothesis, indicating that the relationship between job and family satisfaction is characterized best as noncausal.
Relationships Among Value Congruence, Perceived Victimization, and Retaliation Against Whistle-blowers
Authors: Miceli Marcia P. , Near Janet P.
Published: November 2010

Previous research on organizational members who report perceived wrongdoing has been conducted primarily in public sector organizations. The present study examined survey data from directors of internal auditing in a variety of North American organizations. Because retaliation occurred infrequently, data were analyzed with the case-control method, which is relatively unknown in the organizational literature but is frequently used in medical research to examine the occurrence of rare diseases. Managerial retaliation w’as more likely when: (1) the whistle-blower perceived that stopping the wrongdoing would harm the organization; (2) the wrongdoing harmed the organizations climate or culture: (3) the whistle-blower tried unsuccessfully to remain anonymous, when the wrongdoing continued; (4) the wrongdoing harmed the public; and (5) low value congruence existed between whistle-blowers and their organizations.
The influence of General Perceptions of the Training Environment on Pretraining Motivation and Perceived Training Transfer
Authors: Facteau Jeffrey D. , Dobbins Gregory H. , Russell Joyce E.A. , Ladd Robert T. , Kudisch Jeffrey D.
Published: November 2010

The present study was conducted to determine whether trainees’ general beliefs about training affect pretraining motivation and transfer of training in a large-scale training curriculum. In addition, the influence of social support for training from four organizational constituents (top management, supervisors, peers, and subordinates) and task constraints in the work environment on pretraining motivation and training transfer were evaluated. Nine hundred sixty-seven managers and supervisors completed a questionnaire that assessed 14 constructs. Structural equations analysis with LISREL VII indicated that the overall reputation of training, intrinsic and compliance incentives, organizational commitment, and three social support variables (subordinate, supervisor, and top management support) were predictive of pretraining motivation. In addition, pretraining motivation and subordinate, peer, and supervisor support were predictive of managers’ perceived training transfer. These findings suggests that previous theory and research (e.g., Noe, 1986; Noe & Schmitt, 1986) serve as a useful heuristic for predicting the effects of general beliefs about training on training effectiveness. Implications of the-findings for future research and practice are discussed.
The Impact of Method Effects on Structural Parameters in Validation Research
Authors: Schmitt Neal , Nason Earl , Whitney David J. , Pulakos Elaine D.
Published: November 2010

Use of a structural equations analysis to estimate the degree of predictor-related criterion bias in selection research is illustrated. For the hypothetical data considered in this paper, a likability methods factor produced significant changes in estimates of the structural parameters relating the predictors to the criterion. Regression analyses using two methods factors as covariates yielded similar results. The advantages of employing the more complicated LISREL analysis versus more familiar regression analysis are discussed and some suggestions for future research using the structural equations approach are presented.
Is the Past Prologue?: A Test of Ghiselli’s Hobo Syndrome
Authors: Judge Timothy A. , Watanabe Shinichiro
Published: November 2010

Ghiselli (1974) observed that some workers possess internal impulses to migrate from one job to another irrespective of better alternatives or other apparently rational motives. Ghiselli labeled this tendency the “hobo syndrome.” The present study tested the validity of the hobo syndrome using a national longitudinal sample of young workers. Results of event history analyses indicated support for the hypothesis that turnover depends on the number of times an individual has left his or her job in the past. The meaning and implications of the results in light of recent dispositional research are discussed.
When We Don’t See Eye to Eye: Discrepancies between Supervisors and Subordinates in Absence Disciplinary Decisions
Authors: Martocchio Joseph J. , Judge Timothy A.
Published: November 2010

The present study provided a within-subjects assessment of the factors associated with absence disciplinary decisions for both supervisors and subordinates. In addition, this study examined discrepancies in disciplinary decisions between supervisors and their subordinates based on differences in psychological and demographic attributes. A sample of non-academic employees from 19 intact triads (one supervisor; two subordinates) at a large Midwest university responded to hypothetical scenarios describing factors that might contribute to absence disciplinary decisions. The results demonstrated that both supervisors and subordinates generally place similar weights on factors that are relevant to disciplinary decisions. Perhaps more importantly, a number of psychological and demographic differences between supervisors and subordinates related positively to discrepancies in disciplinary decisions.
Commentary on ‘Resveratrol commonly displays hormesis: Occurrence and biomedical significance’
Authors: Hayes Daniel P
Published: November 2010

The plan of attack for this Commentary is threefold. First: to consider, place in perspective and judge some of the claims that have been advanced for resveratrol’s utility. Second: to evaluate and judge the scientific basis and validity of the paper being commented upon. The judgment is very positive. Third: to place in perspective the importance of hormesis in being a major factor determining resveratrol’s ultimate efficacy.
Flickr’s potential as an academic image resource: An exploratory study
Authors: Angus Emma , Stuart David , Thelwall Mike
Published: November 2010

Many web 2.0 sites are extremely popular and contain vast amounts of content, but how much of this content is useful in academia? This exploratory paper investigates the potential use of the popular web 2.0 image site Flickr as an academic image resource. The study identified images tagged with any one of 12 subject names derived from recognized academic subject categories in the three main Institute for Scientific Information (ISI) citation indexes. Image content analysis was used to determine the types of images found, and term-frequency analysis of associated tags was carried out to provide additional insights into the context behind image placement. The results show that Flickr can be used as a resource for subject-specific images in some subject areas; and that non subject-specific images can also prove to be of value for individual academics.
‘It can be a religion if you want’: Wing Chun Kung Fu as a secular religion
Authors: Jennings George , Brown David , Sparkes Andrew C.
Published: November 2010

Drawing on data generated from a six-year ethnographic study of one Wing Chun Kung Fu Association in England, this article explores the ways in which this martial art is constructed as a form of religion and functions as a secular religious practice for core members of this association. Two key features of this process are identified. The first involves the ways in which Wing Chun evolves from an everyday secular practice into something that takes on sacralized meanings for participants while the second focuses on the development of a Wing Chun habitus over time. The article closes with a discussion of how the findings relate to broader discussions of martial arts practices, religion and spirituality in Western cultures.
Possible sites of action of the new calcitonin gene-related peptide receptor antagonists
Authors: Eftekhari Sajedeh , Edvinsson Lars
Published: November 2010

Migraine is considered a neurovascular disease affecting more than 10% of the general population. Currently available drugs for the acute treatment of migraine are vasoconstrictors, which have limitations in their therapeutic use. The calcitonin gene-related peptide (CGRP) has a key role in migraine, where levels of CGRP are increased during acute migraine attacks. CGRP is expressed throughout the central and peripheral nervous system, consistent with control of vasodilatation and transmission of nociceptive information. In migraine, CGRP is released from the trigeminal system. At peripheral synapses CGRP results in vasodilatation via receptors on the smooth muscle cells. At central synapses, CGRP acts postjunctionally on second-order neurons to transmit pain centrally via the brainstem and midbrain to higher cortical pain regions. The recently developed CGRP-receptor antagonists have demonstrated clinical efficacy in the treatment of acute migraine attacks. A remaining question is their site of action. The CGRP-receptor components (calcitonin receptor-like receptor, receptor activity modifying protein 1 and receptor component protein) are found to colocalize in the smooth muscle cells of intracranial arteries and in large-sized neurons in the trigeminal ganglion. The CGRP receptor has also been localized within parts of the brain and the brainstem. The aim of this paper is to review recent localization studies of CGRP and its receptor components within the nervous system and to discuss whether these sites could be possible targets for the CGRP-receptor antagonists.
Electronic Structures of Tungsten and Molybdenum Carbides as a Fuel Cell Anode Catalyst
Authors: Tominaga Hiroyuki , Nagai Masatoshi
Published: November 2010

The band structures of W2C(001), WC(001), β-Mo2C(001), and Pt(111) slabs as an anode catalyst with two adsorbed hydrogen molecules using periodic DFT calculations revealed the anode performance of the carbides.
Cyclic and Linear Structures Constructed by Ionic Bonds between Alkali Ion and Pinwheel Pentanuclear [GdIII(CuIIL)4] Core of M[GdIII(CuIIL)4] (M+ = Na+, K+, and Cs+; H3L = N-(4-Methyl-6-oxo-3-azahept-4-enyl)oxamic Acid)
Authors: Maruno Yuji , Yabe Kazuya , Hagiwara Hiroaki , Fujinami Takeshi , Matsumoto Naohide , Re Nazzareno , Mrozinski Jerzy
Published: November 2010

Three copper(II)–gadolinium(III) complexes M[Gd(CuL)4] with M+ = Na+, K+, and Cs+ have been synthesized, where H3L denotes N-(4-methyl-6-oxo-3-azahept-4-enyl)oxamic acid. The anionic part [Gd(CuL)4]− assumes a pinwheel-like pentanuclear GdCu4 core and the central GdIII ion is coordinated by eight oxygen atoms of four “(CuL),” where each “(CuL)” assumes a square-planar N2O2 coordination geometry and functions as a bidentate chelate ligand to GdIII ion. The sodium and potassium salts assume a one-dimensional (1D) chain structure bridged by Na+ or K+ ions, while the cesium salt assumes a cyclic dimeric structure bridged by Cs+ ions. For the assembly structures, the cation acts as a connector between adjacent [Ln(CuL)4]− cores. The magnetic data demonstrated an intracluster ferromagnetic interaction between GdIII and CuII ions within a GdCu4 core and an intercluster antiferromagnetic interaction through the cation. The magnetic susceptibilities can be reproduced by the spin Hamiltonian based on the pentanuclear GdCu4 structure, = βH(4gCuSCu + gGdSGd) − 2JSGd(SCu1 + SCu2 + SCu3 + SCu4). The best-fit parameters are gGd = 2.00, gCu = 2.12, JGd–Cu = +1.11 cm−1, zJ′ = −0.065 cm−1, and 0.4% of monomeric CuII impurity for the Na+ salt,; gGd = 2.00, gCu = 2.13, JGd–Cu = +1.03 cm−1, zJ′ = −0.038 cm−1, and 0.2% of monomeric CuII impurity for the K+ salt,; and gGd = 2.00, gCu = 2.14, JGd–Cu = +0.67 cm−1, zJ′ = −0.025 cm−1, 0.2% of monomeric CuII impurity for the Cs+ salt. The Gd–Cu coupling constant J is very similar in the Na+ and K+ salts (+1.11 and +1.03 cm−1) but is slightly smaller for the Cs+ salt (+0.67 cm−1), probably due to the different packing of the GdCu4 clusters in the latter salt (cyclic dimers instead of an infinite chain); (2) the intercluster antiferromagnetic interaction, responsible for the low temperature decrease of χMT, significantly decreases when the ionic radius of the alkali cation increases (Na+ < K+ < Cs+) thus keeping the pentanuclear units further apart.
Development of Highly Selective Organic Reactions Catalyzed by Designed Amine Organocatalysts
Authors: Kano Taichi , Maruoka Keiji
Published: November 2010

A series of chiral amines with conceptually new design have been developed as chiral organocatalysts. These chiral amine organocatalysts have been successfully applied to several asymmetric reactions via iminium and enamine intermediates and exhibited unique reactivity and selectivity in comparison with previous amine organocatalysts derived from naturally occurring amino acids. The synthetic utility of these asymmetric organocatalytic reactions has also been demonstrated in their application to the synthesis of versatile chiral building blocks.
Eine fluidisch angetriebene anthropomorphe Roboterhand
Authors: Werner Tino , Kargov Artem , Gaiser Immanuel , Bierbaum Alexander , Schill Julian , Schulz Stefan , Bretthauer Georg
Published: November 2010

In diesem Artikel wird eine fluidisch angetriebene Roboterhand vorgestellt, deren flexible Aktuatoren adaptives Greifen sowie die weiche Handhabung von Gegenständen ermöglichen. Der mechanische Aufbau vereinigt die anthropomorphe Erscheinung mit einer präzisen DreiPunkt-Kinematik eines Greifers. Es werden Designmerkmale, das Antriebskonzept, die Steuerungskomponenten, technische Eigenschaften und ein Anwendungsbeispiel für die Service-Robotik beschrieben.