bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contact Damage as a Failure Mode During In Vitro Testing
Authors: Harvey Charles K. , Kelly J. Robert 
Published: March 2005

PurposeThe purpose of this study was to identify the failure mode(s) for all‐ceramic crowns tested in vitro and to determine whether measured failure loads in this type of testing would be influenced by indenter radii (a classic Hertzian cone‐crack variable) and specimen thickness.Materials & MethodsFracture surfaces and failure probability data from glass‐ceramic cuspids (50 = n) tested in a previous in vitro study were examined to determine their mode of failure. To further evaluate the failure mode identified for the crowns, 100 ceramic platelets (50 glass‐ceramic, 50 feldspathic porcelain) were loaded to failure beneath spherical indenters (radii, 0.75‐94 mm).ResultsGlass‐ceramic cuspids failed from blunt contact damage at the point of loading (with Hertzian stress‐state damage evident). Ceramic platelets exhibited failure from either the indentation surface (Hertzian cone‐cracking present) or from the supported surface (ie, mimicking bending failure). Failure‐loads increased with the indenter radius for both failure modes. Failure from blunt contact damage occurred at markedly higher loads than did failure from support‐surface sites.ConclusionsBlunt indentation damage was identified as being the failure source for the glass‐ceramic cuspid crowns and a major failure mode for both feldspathic porcelain and glass‐ceramic platelets loaded beneath spherical indenters. This failure mode is not similar to that reported for clinically failed glass‐ceramic crowns. Influential testing variables were contact radius, ceramic thickness, and the surface finish of both the ceramic specimen and test platen.
Geometric Analysis of Occlusal Plane Orientation Using Simulated Ear‐Rod Facebow Transfer
Authors: Santos José dos , J. Nelson Stanley , Nummikoski Pirkka 
Published: March 2005

PurposeEar‐rod facebow techniques may position casts high or low between the upper and lower members on the articulator when using orbitale or nasion as anterior reference positions. This study assessed the effect of changing the anterior reference position on simulated mountings utilizing simulated ear‐rod facebow.Materials and MethodsTracings from lateral cephalographs made on seven subjects were superimposed with an outline model of a semiadjustable articulator. Three simulated mountings were performed for each subject in which the plane of occlusion was positioned (1) high, (2) midway, and (3) approaching the lower member (low). Maxillary and mandibular occlusal planes representing intercuspal position were determined from the cephalographs and positioned on the articulator model in a simulated centric relation position for each mounting. Condylar guidance was determined from a simulated protrusive position.ResultsAnalysis of the three mounting positions demonstrated no change in intercuspal position within subjects; however, angles formed between upper member and condylar guidance were 14.9% smaller for the mid‐distance mounting, 42.9% smaller for the high mounting, and 13.4% higher for the low mounting positions when compared with a standard Frankfort horizontal plane reference.ConclusionsThe cephalographs showed extreme variability in the position of the ear piece to bony structures of the skull, but this deviation appeared to be compensated by a change in the horizontal condylar guidance relative to mounting. Results also suggest that casts may be mounted in a convenient mid‐position for routine articulation.
Effect of Firing on the Color Stability of a Light‐Cured Ceramic Stain
Authors: Reis Rodrigo S. , Neiva Gisele F. , Yaman Peter , Razzoog Michael E. 
Published: March 2005

PurposeThis study evaluated the color stability of four stains of a light‐cured porcelain stain system between the light‐cured and fired stages.Materials and MethodsThirty‐six ceramometal discs 20 mm in diameter and 2 mm in thickness were cast to provide the substrate on which Ceramco II porcelain was applied. The porcelain was polished to a uniform thickness of 2 mm, and the samples were divided into four groups and assigned a color (yellow, orange, green, or blue). Orbit LC stain was applied in a thin layer and light‐cured for 40 seconds. After light‐curing, three color readings were made with a Minolta Chroma Meter II. The porcelain discs were then fired in a porcelain oven and three color measurements were again made. The pre‐ and postfired Commission Internationale de I'Eclairage L*a*b* values were recorded and the color difference (ΔDLE) was calculated for each specimen. The clinical significance for the computed ΔDLE ratings was completed according to previously modified criteria.ResultsThe results show that the mean ΔDLE between the light‐cured and fired stages of Orbit LC are clinically acceptable. No statistically significant differences (p < .05) were observed between any of the four groups.ConclusionsA light‐cured porcelain stain system was evaluated for color stability between light‐cured and fired stages. Within the conditions of this study, the following conclusions can be made: (1) There was no clinically significant color difference between light‐cured and fired stages for the stain colors evaluated; and (2) the final color of the restorations altered with light‐cured stains can be predicted before firing.
Comparison of Strains Transferred to a Bone Simulant Between As‐Cast and Postsoldered Implant Frameworks for a Five‐Implant‐Supported Fixed Prosthesis
Authors: Clelland Nancy L. , Carr Alan B. , Gilat Amos 
Published: March 2005

PurposeTo measure and compare the strains transferred by screw‐fastening one‐piece full‐arch prostheses as cast and after sectioning and soldering.Materials and MethodsPhotoelastic resin was applied directly to five 3.75 × 13‐mm Brånemark implants, situated 7 mm apart, in a silicone mold of an edentulous mandible. Four strain gauge rosettes were also incorporated in the resin to allow strain measurements at four locations. Three frameworks were made from a single master cast produced from an impression of the five‐implant model with 4‐mm abutments. These frameworks were sequentially secured to the master model with five gold slot screws tightened to 10 N cm. Strain indicator readings were recorded at a standardized time following the initial fastening of each prosthesis. The test was repeated three times. Each of the three castings were subsequently sectioned and soldered in two locations, mesial to the two terminal fixtures. After soldering, the three superstructures were returned to the master model for measurement of postsolder strains three times each. A one‐way repeated‐measures ANOVA was performed to determine differences between mean principal strains between the as‐cast and postsoldered groups.ResultsA statistically significant difference was found in the principal strains between the as‐cast and soldered frameworks. Overall, there was a decrease in the magnitude of strain for the soldered frameworks.ConclusionsSectioning and soldering improved the as‐cast accuracy as far as the amount of strain transferred to the bone simulant.
An Evaluation of Microwave‐Polymerized Resin Bases for Removable Partial Dentures
Authors: Loh Poey Ling , Munoz Carlos A. , Goodacre Charles J. , Andres Carl J. , Moore B. Keith 
Published: March 2005

Purpose The hardness, porosity, and adaptation of removable partial dentures fabricated with one heat‐polymerized denture base resin and two resins designed for microwave polymerization were evaluated.Materials and Methods Five prostheses were evaluated for each resin. Adaptation of the denture bases to the master cast was evaluated by spatial orientation and mean weight of residual impression material. The prostheses were then embedded in epoxy resin and sectioned for evaluation of resin hardness (Knoop hardness) and microporosity.Results There were no significant differences in the adaptation of the acrylic resin bases for Acron MC and Ch Lucitone. There was no significant difference in the mean Knoop hardness values for any of the resin bases near and away from the metal. None of the denture bases showed porosity greater than 100 μm.Conclusions Both resin bases formulated for microwave polymerization were effectively polymerized around metal frameworks without adverse effects on resin hardness or porosity. Justi Denture Base material had poorer base adaptation than the other two resins.
Transverse Strength, Ductility, and Qualitative Elemental Analysis of Cobalt‐Chromium Alloy After Various Durations of Induction Melting
Authors: Vallittu Pekka K. 
Published: March 2005

Purpose The aim of this study was to compare the transverse strength and ductility of bars cast from cobalt‐chromium alloy that had been melted for various lengths of time (n = 5 per group). To determine its elemental composition, the cobalt‐chromium alloy was also analyzed qualitatively.Materials and Methods Transverse strength and ductility of the cobalt‐chromium bars was measured by a three‐point loading test. Scanning electron microscopy (SEM) and energy‐dispersive spectroscopy (EDS) were used to determine the composition of the samples compared with unmelted cobalt‐chromium alloy.Results The transverse strengths of the test bars cast from the cobalt‐chromium alloy, which had been induction‐melted for various lengths of time, did not differ significantly (p= .056); but the ductility of the test bars was affected by the duration of induction melting of the alloy (p < .001). According to the SEM/EDS analysis, the amount of silicon in the cobalt‐chromium alloy decreased with lengthening duration of induction melting of the alloy.Conclusions This study supports the previous finding that good resistance to deflection fatigue is correlated with increased ductility of cobalt‐chromium alloy and vice versa.
Wear of Visible Light‐Cured Restorative Materials and Removable Partial Denture Direct Retainers
Authors: Latta George H. , Wicks Russell A. , Huget Eugene F. , Murray Granville A. 
Published: March 2005

Purpose This study measured the in vitro wear of visible light‐cured restorative materials and removable partial denture direct retainers.Materials and Methods An aluminum test die was produced by replicating the facial contours of an extracted human molar (model). The replica's cervical contour was modified by placement of a restorable Class V cavity preparation. The test die became a fixed component of a testing apparatus. The restorative materials tested were Z100 (fine particle filled resin composite), Silux Plus (microfilled resin composite), and Photac‐Fil (hybrid glass ionomer). Cast round, half round, I bar, and wrought‐wire retainers were designed to engage a 0.254‐mm undercut. Caliper measurements of the wear of restorative materials were made at intervals during testing, and after 7,500 retainer placements and removals. The measurements of material‐ and retainer‐wear were subjected to ANOVA and Tukey tests.Results Generally, retainers with round profiles caused less wear of the restorative materials than those featuring flat contact surfaces. Wear of the materials ranged from 14 ± 5.5 μm (Silux Plus by cast round) to 70 ± 10.0 μm (Photac‐Fil by cast half round). Mean wear of retainers, however, ranged only from 2 ± 4.5 μm for six of 12 possible retainer‐material pairings up to 12 ± 4.5 μm (cast half round by Z100).Conclusions Regardless of their design features, the direct retainers of this study exhibited little wear when paired with any of the restorative materials. Overall, material wear appeared to be greater than retainer wear by a factor of five. When paired with practically any retainer type, the hybrid glass ionomer (Photac‐Fil) exhibited more wear than either of the two resin composites (Z100 or Silux Plus). Although not established clearly, retainers with round profiles (wrought‐wire and cast round) appeared to produce less wear of restorative materials than their I bar and cast half round counterparts.
Effectiveness of Computer‐Aided Removable Partial Denture Design
Authors: Lindquist Terry J. , Clancy James M. S. , Johnson Lynn A. , Wiebelt Frank J. 
Published: March 2005

Purpose Computer programs have been developed for removable partial denture (RPD) design, but their educational impact has never been investigated. This study measured the effectiveness of computer‐based RPD design simulations in a traditional RPD design course for second‐year dental students.Materials and Methods Thirty‐six students were randomly assigned to four groups, two simulation and two control groups, at the beginning of the RPD design module. A cross‐over design compared the two strategies during laboratory exercises. First, the simulation group worked with the simulation, while the control group met in small‐group seminars with faculty. Post‐test 1 was given, and then students switched teaching methods and post‐test 2 was given. Each post‐test had two parts. Part 1 involved designing an RPD based on specific patient criteria. Part 2 involved choosing the more correct of the two designs.Results Results showed a significant difference (p= .0072) in two of four test groups. Although it was an initial evaluation, the computer simulation was shown to be equivalent to faculty‐led small‐group seminars. Students also responded positively to a questionnaire on their perceived effectiveness of the simulations.Conclusions The results suggest that RPD design can be taught as effectively with computer‐based simulations as with faculty‐led seminars.
TASTE COMPONENTS OF CHEDDAR CHEESE: FRACTIONATION AND OPTIMIZATION OF CHEDDAR CHEESE TASTE IN WATER
Authors: YANG BIN , VICKERS ZATA 
Published: March 2005

ABSTRACT To determine the taste components of Cheddar cheese, we fractionated one mild Cheddar cheese and one aged Cheddar cheese by water extraction, freeze‐drying and gel filtration. Salty, sour and umami were the three predominant tastes present in the fractions. Neither trigeminal sensations nor astringency was perceived. We used response surface methodology to reconstruct a mild Cheddar cheese taste and an aged Cheddar cheese taste in water. Less salt and less acid were needed to simulate the taste of mild Cheddar cheese, compared with aged Cheddar cheese. Our optimized water solutions (containing sodium chloride, lactic acid and monosodium glutamate) were as similar to the real cheese samples as were the water extracts of the standard cheeses. However, neither our optimized solutions nor the water extracts matched the taste of the actual cheeses.
Functional Analysis of All Nonribosomal Peptide Synthetases in
Cochliobolus heterostrophus
Reveals a Factor, NPS6, Involved in Virulence and Resistance to Oxidative Stress
Authors: Lee Bee-Na , Kroken Scott , Chou David Y. T. , Robbertse Barbara , Yoder O. C. , Turgeon B. Gillian 
Published: March 2005

ABSTRACT

Nonribosomal peptides, made by nonribosomal peptide synthetases, have diverse biological activities, including roles as fungal virulence effectors. Inspection of the genome of
Cochliobolus heterostrophus
, a fungal pathogen of maize and a member of a genus noted for secondary metabolite production, revealed eight multimodular nonribosomal peptide synthase (
NPS
) genes and three monomodular
NPS
-like genes, one of which encodes a nonribosomal peptide synthetase/polyketide synthase hybrid enzyme presumed to be involved in synthesis of a peptide/polyketide molecule. Deletion of each
NPS
gene and phenotypic analyses showed that the product of only one of these genes,
NPS6
, is required for normal virulence on maize. NPS6 is also required for resistance to hydrogen peroxide, suggesting it may protect the fungus from oxidative stress. This and all other
nps
mutants had normal growth, mating ability, and appressoria. Real-time PCR analysis showed that expression of all
NPS
genes is low (relative to that of actin), that all (except possibly
NPS2
) are expressed during vegetative growth, and that expression is induced by nitrogen starvation. Only
NPS6
is unfailingly conserved among euascomycete fungi, including plant and human pathogens and saprobes, suggesting the possibility that NPS6 activity provides oxidative stress protection during both saprobic and parasitic growth.
Mutator
-Like Element in the Yeast
Yarrowia lipolytica
Displays Multiple Alternative Splicings
Authors: Neuvéglise Cécile , Chalvet Fabienne , Wincker Patrick , Gaillardin Claude , Casaregola Serge 
Published: March 2005

ABSTRACT

A new type of DNA transposon,
Mutyl
, has been identified in the sequenced genome of the yeast
Yarrowia lipolytica
. This transposon is 7,413 bp long and carries two open reading frames (ORFs) which potentially encode proteins of 459 and 1,178 amino acids, respectively. Whereas the first ORF shows no significant homology to previously described proteins, the second ORF shows sequence similarities with various
Mutator
-like element (MULE)-encoded transposases, including the bacterial transposase signature sequence. Other MULE features shared by
Mutyl
include a zinc finger motif in the putative transposase, a 22-bp-long imperfect inverted repeat at each end, and a 9- to 10-bp duplication of its target site in the chromosome. Of the five copies of
Mutyl
present in the genome, one has a deletion of the first 8 bases, and the others are full length with a single base change in one element. The first potential gene of
Mutyl
,
mutB
, was shown to be expressed in exponentially growing cells. Its sequence contains a predicted intron with two 5′ splice sites, a single branch point, and two 3′ splice sites. Its mRNA is alternatively spliced, as judged by reverse transcription-PCR, and generates four mRNAs corresponding to protein-coding sequences of 128, 156, 161, and 190 amino acids. Of the three distinct lineages characterized in
Y. lipolytica
, strains from the German lineage and the French lineage do not carry
Mutyl
. A study of the distribution of
Mutyl
in strains of the French lineage evidenced a recent transposition event. Taken together, these results indicate that
Mutyl
is still active.
Synthesis and some reactivity studies of germanium, tin and lead analogues of alkynes
Authors: Power Philip P. 
Published: March 2005

AbstractRecently published work on the syntheses and reactivity of the germanium, tin, and lead analogues of alkynes is summarized. The heavier Group 14 ‘alkynes’ are stabilized by bulky terphenyl ligands and are thermally robust crystalline solids. However, they are extremely reactive and their reactivity decreases in the order Ge > Sn > Pb. Their spectroscopy and reactivity patterns suggest that the germanium species, in particular, has considerable diradical character. This hypothesis is also supported by preliminary density functional theory calculations. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis and photochemical reactions of 1,2,7‐chalcogenadistannacycloheptanes
Authors: Saito Masaichi , Iso Kaori , Yamada Katsuhiko , Nakano Susumu , Yoshioka Michikazu 
Published: March 2005

Abstract1,2,7‐Chalcogenadistannacycloheptanes were synthesized by the reactions of 1,4‐bis(bromostannyl) butane with appropriate chalcogenation reagents. Irradiation of the 1,2,7‐thiadistannacycloheptane with a low‐pressure mercury lamp (254 nm) gave 1,3,5,2,4,6‐trithiatristannin. Irradiation of 1,3,5,2,4,6‐trithiatristannin with a low‐pressure mercury lamp in the presence of either cyclotrisiloxane or 2,3‐dimethyl‐1,3‐butadiene gave a complex mixture. Copyright © 2005 John Wiley & Sons, Ltd.
Association of common ATM polymorphism with bilateral breast cancer
Authors: Heikkinen Katri , Rapakko Katrin , Karppinen Sanna‐Maria , Erkko Hannele , Nieminen Pentti , Winqvist Robert 
Published: March 2005

AbstractThe ATM kinase has an essential role in maintaining genomic integrity. Loss of both ATM alleles results in ataxia‐telangiectasia (A‐T), a rare autosomal recessive neuroimmunologic disorder associated with cancer susceptibility. Individuals heterozygous for germline ATM mutations have been reported to have an increased risk for malignancy, in particular, female breast cancer. In the current study, a full mutation analysis of the ATM gene was carried out in patients from 121 breast or breast‐ovarian cancer families. We discovered that the combination of 5557G→A in cis position with IVS38‐8 T→C was associated with bilateral breast cancer (OR = 10.2; 95% CI = 3.1–33.8; p = 0.001). As the 5557G→A change has been reported to affect an exonic splicing enhancer, we hypothesized that the observed composite allele could have some effect on the correct splicing of exon 39. However, no aberrant transcripts were detected, but ATM expression levels of lymphoblast cell lines from heterozygous carriers of this combination allele were lower than from noncarriers (p = 0.09). Lowered gene expression levels may have direct influence on the activities in DNA damage recognition and response pathways, as well as other genome integrity maintenance functions. Based on the results, we propose a cancer risk‐modifying effect for the ATM 5557G→A, IVS38‐8T→C composite allele. © 2005 Wiley‐Liss, Inc.
Dietary patterns and the risk of postmenopausal breast cancer
Authors: Fung Teresa T. , Hu Frank B. , Holmes Michelle D. , Rosner Bernard A. , Hunter David J. , Colditz Graham A. , Willett Walter C. 
Published: March 2005

AbstractThe association between individual foods and breast cancer has been inconsistent. Therefore, we examined the association between diet and risk of postmenopausal breast cancer by the alternative approach of dietary patterns. Dietary patterns were identified with factor analysis from food consumption data collected from a food frequency questionnaire in 1984. Relative risks were computed using proportional hazard models and adjusted for known risk factors for breast cancer. Between 1984 and 2000, we ascertained 3,026 incident cases of postmenopausal breast cancer. We identified 2 major dietary patterns. The prudent pattern is characterized by higher intake of fruits, vegetables, whole grains, low‐fat dairy products, fish and poultry, while the Western pattern is characterized by higher intake of red and processed meats, refined grains, sweets and desserts and high‐fat dairy products. Neither of the patterns was associated with overall risk of postmenopausal breast cancer. However, a positive association between the Western pattern score was observed among smokers at baseline (relative risk = 1.44, comparing top to bottom quintiles; 95% CI = 1.02–2.03; p for trend = 0.03). An inverse association was observed between the prudent pattern and estrogen receptor‐negative cancer (relative risk = 0.62; 95% CI = 0.45–0.88; p for trend = 0.006). Among the major food groups, higher consumptions of fruits (relative risk for 1 serving/day increase = 0.88; 95% CI = 0.80–0.97; p = 0.009) and vegetables (relative risk = 0.94; 95% CI = 0.88–0.99; p = 0.03) were significantly associated with decreased risk for ER− breast cancer. In conclusion, we did not observe an overall association between the prudent or Western pattern and overall breast cancer risk. However, a Western‐type diet may elevate risk of breast cancer among smokers, and a prudent diet may protect against estrogen receptive‐negative tumors. © 2005 Wiley‐Liss, Inc.