bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Bleaching Agents on the Hardness and Morphology of Enamel
Authors: LOPES GUILHERME CARPENA , BONISSONI LEANDRO , BARATIERI LUIZ NARCISO , VIEIRA LUIZ CLÓVIS C. , MONTEIRO SYLVIO 
Published: June 2007

ABSTRACT Purpose: The goal of the present laboratory study was to analyze the effect of two home bleaching agents (Opalescence 10%, Ultradent, and Hi‐Lite II, Shofu) as well as the separate solutions of 10% carbamide peroxide primary components (3% hydrogen peroxide and 7% urea) on enamel microhardness and surface morphology. Materials and Methods: Thirty human molars stored in water for no longer than 3 months were selected. Their facial and lingual surfaces were embedded in acrylic resin, and the specimens were polished with up to 600‐grit sandpaper. The 30 molar sections were divided into five groups as per treatment modality (n = 6); group 1, 10% carbamide peroxide bleach with carbopol (Opalescence, Ultradent); group 2, oxygen‐free gel bleach (Hydroxylite, Hi‐Lite II, Shofu); group 3, 3% hydrogen peroxide with carbopol (Dermus Pharmacy, Florianopolis, SC, Brazil); group 4, 7% urea treatment (Dermus Pharmacy); and control, group 5, artificial saliva (Dermus Pharmacy). Prior to treatment, six indentations (Vickers) were made on each of the six surfaces in each group under a load of 100 g for 30 seconds. Bleaching procedure was conducted for 3 hours per day for 2 weeks, the control group excepted. Following each bleaching session, the specimens were washed with deionized water and kept in artificial saliva at 37°C, this solution being changed daily. Pre‐ and post‐treatment microhardness data were analyzed using a two‐way analysis of variance. In a similar way, 30 other specimens underwent the same procedures. After the bleaching period, the samples were observed under the scanning electron microscope. Results: Specimens submitted to bleaching treatment with 3% hydrogen peroxide gel as described in this study showed a significant reduction of surface microhardness (p < .0001). The other treatment modalities had no effect on surface microhardness. No morphologic alterations were observed on enamel submitted to bleaching gel of 10% carbamide peroxide (Opalescence), oxygen‐free gel (Hi‐Lite II, Shofu), or 7% urea solution compared with the control (artificial saliva). However, the specimens bleached for 3 hours per day for 2 weeks with 3% hydrogen peroxide gel presented areas of mild erosion. The effect, nevertheless, was not uniform, occurring with varying intensity on all samples of enamel bleached with 3% hydrogen peroxide.CLINICAL SIGNIFICANCEBleaching treatment conducted with two home bleaching agents (Opalescence 10%, Ultradent, and Hi‐Lite 11, Shofu) had no adverse effects on enamel microhardness or on surface morphology. Bleaching with 3% hydrogen peroxide can have a negative effect on enamel hardness and surface morphology when performed as described in this study
In vivo Influence of Residual Moisture on Microtensile Bond Strengths of One‐Bottle Adhesives
Authors: PERDIGÃO JORGE , GERALDELI SAULO , CARMO ANDRÉ R.P. , DUTRA HÉLIO R. 
Published: June 2007

ABSTRACT Purpose: This study evaluated the microtensile bond strengths of three dentin adhesives applied on clinically moist dentin or on dentin that was dried with air for 5 seconds. The null hypothesis to test was that the level of residual moisture does not influence bond strengths when restorations are placed in vivo. Materials and Methods: Twenty‐four premolars scheduled to be extracted for orthodontic reasons from patients between the ages of 15 and 23 years were restored with one of the following adhesive systems followed by a mini hybrid composite resin: Excite (Ivoclar/Vivadent), an ethanol‐based dentin adhesive; Prime & Bond NT (Dentsply/Caulk), an acetone‐based dentin adhesive; and Single Bond (3M ESPE), an ethanol and water‐based dentin adhesive. After extraction, the specimens were sectioned with a slow‐speed diamond saw in two perpendicular directions to obtain sticks with a cross‐section of 0.7 ± 0.2 mm2. The specimens were attached to a Geraldeli device and fractured using a universal testing machine at a crosshead speed of 1 mm per minute. Results: For each dentin adhesive, there were no statistical differences between means for dry dentin versus moist dentin. Single Bond and Prime & Bond NT ranked in the same statistical subset regardless of the moisture condition of the substrate. Both Excite, dry, and Excite, moist, resulted in statistically lower bond strengths than Single Bond, moist, but similar to those of Single Bond, dry, Prime & Bond NT, moist, and Prime & Bond NT, dry.CLINICAL SIGNIFICANCEIn this study, the level of residual moisture did not influence microtensile bond strengths. Clinically, the degree of moisture left on the dentin surface upon rinsing off the etching gel may not be as relevant as previously reported in laboratory studies.
Shear Bond Strength of Bis‐acryl Composite Provisional Material Repaired with Flowable Composite
Authors: HAGGE MARK S. , LINDEMUTH JAMES S. , JONES AMMON G. 
Published: June 2007

ABSTRACT Background: Time and expense are considerable when refabrication of a bis‐acryl composite provisional prosthesis is required, so an effective method of repair is desirable. Attempts at self‐repair have been ineffective, and no reports of repair specific to bis‐acryl composites were found in the literature. Purpose: To investigate the strength of a bis‐acryl composite repair using flowable composite after two surface treatments and three storage conditions. Materials and Methods: Thirty specimens of bis‐acryl composite were made and divided into six groups. Half of the specimens received air abrasion only, and half received air abrasion followed by application of an intermediate bonding resin. A flowable composite was then applied to all specimens. Following three different storage conditions, the flowable composite was debonded using a universal testing machine in tensile mode. Results: All specimens failed cohesively within the bis‐acryl composite rather than at the repair interface. Surface treatment with air abrasion alone resulted in significantly higher shear bond strength values than when air abrasion and intermediate bonding resin were combined. Bond strength values were significantly higher in thermocycled specimens than in air‐dried specimens. Conclusions: Use of air abrasion followed by application of flowable composite proved to be a successful technique for bis‐acryl composite repair.
Effects of Four Prophylaxis Pastes on Surface Roughness of a Composite, a Hybrid Ionomer, and a Compomer Restorative Material
Authors: WARREN DONNA P. , COLESCOTT TARA DEBNER , HENSON HAROLD A. , POWERS JOHN M. 
Published: June 2007

ABSTRACT Purpose: This study was undertaken to compare the effects of three prophylaxis pastes (Nupro with coarse, medium, or fine pumice) with a new paste (Clinpro with perlite) on the surface roughness of a resin composite (Dyract AP), a hybrid ionomer (Fuji II LC), and a compomer (TPH Spectrum). Materials and Methods: Twenty disks (2 mm thick ± 10 mm in diameter) of each material were prepared in split molds and stored for 24 hours at 37°C in a 100% relative humidity humidistat. Baseline Mylar surface roughness values were determined. A single operator polished each specimen for 10 seconds with each paste. Five tracings of each specimen of surface roughness (Ra, μm) were made using a surface profilometer. Means and standard deviations were calculated, and analyzed by two‐way analysis of variance (three restorative materials and four prophylaxis pastes as factors) and compared using Tukey‐Kramer intervals calculated at the 0.05 level of significance. Results: Analysis of variance showed significant differences among restorative materials (after polishing) and prophylaxis polishing agents. Tukey‐Kramer intervals for comparisons were 0.04 and 0.05 μm, respectively. All polishing agents produced significant increased roughness compared with baseline, yielding the following results (X + SD, μm) for the three restorative materials (Fuji II LC, TPH Spectrum, Dyract AP): perlite, 0.16 ± 0.07, 0.28 ± 0.26, 0.79 ± 0.64; course pumice, 0.36 ± 0.17, 0.48 ± 0.25, 0.88 ± 0.46; medium pumice, 0.26 ± 0.10, 0.35 ± 0.30, 0.46 ± 0.21; and fine pumice, 0.16 ± 0.06, 0.34 ± 0.30, 0.42 ± 0.24). Fine pumice and perlite produced the least roughness on the hybrid ionomer, medium and fine pumice on the resin composite, and perlite on the compomer.CLINICAL SIGNIFICANCESince prophylaxis pastes have the potential to increase the surface roughness of resin composite, hybrid ionomer, and compomer restorative materials, routine polishing during prophylaxis should be avoided.
Safety Issues When Using a 16% Carbamide Peroxide Whitening Solution
Authors: LEONARD RALPH H. , GARLAND GLENN K. , EAGLE JAMES C. , CAIMAN DANIEL J. 
Published: June 2007

ABSTRACT Background: The scientific literature is lacking on the occurrence of side effects and other safety issues when using carbamide peroxide whitening solutions of concentrations greater than 10%. This double‐blind nightguard vital bleaching study compares safety issues when using 16% carbamide peroxide against a placebo or 10% carbamide peroxide (Nite White Classic by Discus Dental Inc.). Evaluated were changes in gingival index, plaque index, nonmarginal gingival index, nongingival oral mucosal index, tooth vitality, and the patients' perceptions of tooth sensitivity and gingival irritation. Materials and Methods: Twenty female dental hygiene students participated in the study. Each participant wore a maxillary treatment tray for 1 week without any solution and then for 8 to 10 hours per night for 14 nights, filling each quadrant with placebo, 10% carbamide peroxide, or 16% carbamide peroxide, using a split tray design. Results: With respect to gingival index, plaque index, nonmarginal gingival index, nongingival oral mucosa index, tooth vitality, and tooth sensitivity, there were no statistically significant differences between the 16% carbamide peroxide solution and the other two solutions (p > .05). Quadrants receiving the 16% carbamide peroxide solution experienced more gingival irritation than quadrants receiving placebo or 10% carbamide peroxide solution (p > .05). Conclusions: When evaluating the above‐mentioned safety issues, except for gingival irritation, there were no statistically significant differences between a 16% carbamide peroxide solution and 10% carbamide peroxide solution or a placebo when used as described here.CLINICAL SIGNIFICANCEAmong the 20 participants whose data were analyzed, it was found that a 16% carbamide peroxide whitening solution (Nite White Classic), when used as described in this study, can be effective in nightguard vital bleaching with no statistical differences in gingival index, plaque index, nonmarginal gingival index, nongingival oral mucosa changes, tooth vitality, or tooth sensitivity, compared with a 10% whitening solution (Nite White Classic). More gingival irritation was experienced with 16% carbamide peroxide. Additionally, 20% of the participants in this study self‐reported sensitivity when wearing their treatment tray without any solution, and 36% of the participants reported sensitivity to the placebo solution.
Dynesthetic and Dentogenic Concept Revisited
Authors: JAMESON WILLIAM S. 
Published: June 2007

ABSTRACT:The dynesthetic and dentogenic concept, when applied, provides a more natural, harmonious prosthesis, which not only is desired by patients, but also is a quality of care they deserve. Outstanding esthetics can be achieved by simple guidelines, using tooth molds specifically sculpted for males and females, arranging prosthetic teeth to correspond with personality and age and sculpting the matrix (visible denture base) with more natural contours. There is no reason for edentulous individuals to be provided with care of any less quality than that available with other procedures, such as crowns, bridges, veneers, or implant restorations. Providing this upscale product can be rewarding and satisfying to patient and operator alike. This concept produces superior results no matter what posterior occlusal scheme is employed but, in the opinion of the author, works best when used in conjunction with a noninterceptive linear occlusion approach (not to be confused with lingualized occlusion), which precludes anterior contact.CLINICAL SIGNIFICANCE:Dentogenics provides an approach to esthetics in prosthodontics that enables the dentist to create a restoration in harmony with the patient's objective personality. This concept considers gender, I age, and personality to restore the patient's dignity and unique individuality that has been missing in far too many prostheses.
Polymerization Efficiency of LED Curing Lights
Authors: LEONARD DANIEL L. , CHARLTON DAVID G. , ROBERTS HOWARD W. , COHEN MARK E. 
Published: June 2007

ABSTRACT: Purpose: The purpose of this study was to compare the curing efficiency of three commercially available light‐emitting diode (LED)‐based curing lights with that of a quartz tungsten halogen (QTH) curing light by means of hardness testing. In addition, the power density (intensity) and spectral emission of each LED light was compared with the QTH curing light in both the 380‐to 520‐nm and the 450‐ to 500‐nm spectral ranges. Materials and Methods: A polytetrafluoroethylene mold 2 mm high and 8 mm in diameter was used to prepare five depth‐of‐cure test specimens for each combination of exposure duration, composite type (Silux Plus [microfill], Z‐100 [hybrid]), and curing light (ZAP Dual Curing™ Light, LumaCure™, VersaLux™, Optilux 401™). After 24 hours, Knoop hardness measurements were made for each side of the specimen, means were calculated, and a bottom/top Knoop hardness (B/T KH) percentage was determined. A value of at least 80% was used to indicate satisfactory polymerization. A linear regression of B/T KH percentage versus exposure duration was performed, and the resulting equation was used to predict the exposure duration required to produce a B/T KH percentage of 80% for the test conditions. The power densities (power/unit area) of the LED curing lights and the QTH curing light (Optilux 401™) were measured 1 mm from the target using a laboratory‐grade, laser power meter in both the full visible light spectrum range (380–780 nm) and the spectral range (between 450 and 500 nm), using a combination of long‐ and short‐wave edge filters. Results: The emission spectra of the LED lights more closely mirrored the absorption spectrum of the commonly used photoinitiator camphorquinone. Specifically, 95% of the emission spectrum of the VersaLux, 87% of the LumaCure, 84% of the ZAP LED, and 78% of the ZAP combination LED and QTH fell between 450 and 500 nm. In contrast, only 56% of the emission spectrum of the Optilux 401™ halogen lamp fell within this range. However, the power density between 450 and 500 nm was at least four times greater for the halogen lamp than for the purely LED lights. As I a result, the LED‐based curing lights required from 39 to 61 seconds to cure a 2‐mm thick hybrid I resin composite and between 83 and 131 seconds to adequately cure a microfill resin composite. By I comparison, the QTH light required only 21 and 42 seconds to cure the hybrid and microfill resin I composites, respectively.
Why patients attend emergency departments for conditions potentially appropriate for primary care: Reasons given by patients and clinicians differ
Authors: Masso Malcolm , Bezzina Andrew J , Siminski Peter , Middleton Rebekkah , Eagar Kathy 
Published: June 2007

AbstractObjectives:  To compare reasons identified by clinical staff for potential primary care attendances to the ED with those previously identified by patients.Methods:  Survey of staff and primary care patients in five ED in New South Wales, Australia using questionnaire based on reasons identified in published studies.Results:  Clinicians in the survey identify a broader spectrum of reasons for potential primary care cases presenting to the ED than the patients themselves report. Doctors reported on average 4.1 very important reasons and nurses 4.8 compared with patients 2.4 very important reasons. The main reasons identified by both doctors and nurses were similar and quite different to those identified by patients. Clinicians were more likely to emphasize cost and access issues rather than acuity and complexity issues. There was no difference within the clinician group between doctors and nurses nor by varying levels of experience. Furthermore doctors with significant experience in both primary care and emergency medicine did not differ from the overall clinicians' pattern.Conclusions:  These data confirm that clinician perspectives on reasons for potential primary care patients' use of ED differ quite markedly from the perspectives of patients themselves. Those differences do not necessarily represent a punitive or blaming philosophy but will stem from the very different paradigms from which the two protagonists approach the interactions, reflecting the standard tension in a provider – consumer relationship. If policy is to be developed to improve system use and access, it must take both perspectives into account with respect to redesign, expectations and education.
Treatment of extradural haemorrhage in Queensland: Interhospital transfer, preoperative delay and clinical outcome
Authors: Deverill Jo , Aitken Leanne M 
Published: June 2007

AbstractObjectives:  To measure preoperative delays and clinical outcomes of patients with extradural haemorrhage, comparing patients presenting to hospitals with no neurosurgical facilities, with those presenting directly to neurosurgical centres.Methods:  Retrospective case study with data collected from 10 centres. Patients were identified with a search of the Queensland Trauma Registry database. A total of 315 charts were reviewed, of patients presenting or referred to Queensland's public hospitals between 2002 and 2004 inclusive.Results:  A total of 261 patients were included in the study. One hundred and fifty‐nine patients presented to hospitals with no neurosurgical facilities; 102 presented directly to neurosurgical centres. Forty‐six patients underwent interhospital transfer (IHT) before decompressive craniotomy; their median time interval from presentation to operation was 8 h 5 min. This delay was significantly greater than that for 25 patients admitted directly to neurosurgical centres (median 4 h 19 min; P = 0.0006). After excluding patients who had sustained hypoxic or hypotensive insults or serious extracranial injuries, all deaths (five) occurred in patients undergoing IHT before craniotomy.Conclusions:  IHT of patients with extradural haemorrhage causes significant preoperative delay.
Evidence for a large fraction of Compton-thick quasars at high redshift
Authors: Martínez-Sansigre Alejo , Rawlings Steve , Bonfield David G. , Mateos Silvia , Simpson Chris , Watson Mike , Almaini Omar , Foucaud Sébastien , Sekiguchi Kazuhiro , Ueda Yoshihiro 
Published: June 2007

Abstract
Using mid-infrared and radio selection criteria, we pre-select a sample of candidate high-redshift type 2 quasars in the Subaru XMM–Newton Deep Field (SXDF). To filter out starburst contaminants, we use a Bayesian method to fit the spectral energy distributions (SEDs) between 24-μm and the B-band, obtain photometric redshifts, and identify the best candidates for high-z type 2 quasars. This leaves us with 12 zphot≥ 1.7 type 2 quasar candidates in an area ∼0.8 deg2, of which only two have secure X-ray detections. The two detected sources have estimated column densities NH∼ 2 & 3 × 1027 m−2, i.e. heavily obscured but Compton-thin quasars. Given the large bolometric luminosities and redshifts of the undetected objects, the lack of X-ray detections suggests extreme absorbing columns NH≳ 1028 m−2 are typical. We have found evidence for a population of ‘Compton-thick’ high-redshift type 2 quasars, at least comparable to, and probably larger than, the type 1 quasar population, although spectroscopic confirmation of their active galactic nuclei nature is important.
Variation of the Amati relation with cosmological redshift: a selection effect or an evolution effect?
Authors: Li Li-Xin 
Published: June 2007

Abstract
Because of the limit in the number of gamma-ray bursts (GRBs) with available redshifts and spectra, all current investigations on the correlation among GRB variables use burst samples with redshifts that span a very large range. Evolution and selection effects have thus been ignored, which might have an important influence on the results. In this Letter, we divide the 48 long-duration GRBs studied by Amati into four groups with redshift from low to high, each group containing 12 GRBs. Then we fit each group with the Amati relation log Eiso=a+b log Epeak, and check whether the parameters a and b evolve with the GRB redshift. We find that a and b vary with the mean redshift of the GRBs in each group systematically and significantly. Monte Carlo simulations show that there is only a ∼4 per cent chance that the variation is caused by the selection effect arising from the fluence limit. Hence our results may indicate that GRBs evolve strongly with cosmological redshift.
EFFECTS OF BITE SIZE ON THE SENSORY PROPERTIES OF VANILLA CUSTARD DESSERTS
Authors: PRINZ JON F. , DE WIJK RENE A. 
Published: June 2007

ABSTRACT A trained panel of 19 subjects were asked to rate a number of sensory attributes of commercially available vanilla custard desserts. Stimuli were placed in plastic cups and were sampled using 11‐mm‐diameter straws. In total, 304 samples were weighed before and after sampling and the volume ingested was calculated. The subjects were categorized into two groups on the basis of the mean volume ingested per sample (< and >10.6 mL). There were significant differences in the ratings between the two groups for temperature, creamy, astringent, melting and airy mouthfeels and rough and fatty after‐feel. We suggest that in sensory testing, it is important to either control or measure bite size to reduce intersubject variability. Manufacturers and caterers may also be able to modify the perception of their products by providing cues to the appropriate bite size by controlling the size of the spoon or container provided.
CONSUMER ACCEPTABILITY AND SHELF LIFE OF “FLOR DE INVIERNO” PEARS (Pyrus communis L.) UNDER DIFFERENT STORAGE CONDITIONS
Authors: SALVADOR ANA , VARELA PAULA , FISZMAN SUSANA M. 
Published: June 2007

ABSTRACT Two groups of “Flor de Invierno” pears (Pyrus communis L.), one recently harvested and another stored in a refrigerated controlled atmosphere for 7 months, were studied after storage at 20C in a normal atmosphere. Survival analysis was used to estimate sensory shelf life, which was 29 and 15 days for a 50% rejection probability, or 13 and 7 days for a 25% rejection probability for recently harvested and stored pears, respectively. A consumer panel evaluated the overall acceptability of the pears on a 9‐point hedonic scale. Recently harvested pears obtained higher acceptability scores throughout the 20C storage time. Instrumental firmness measurements were performed with a texture analyzer through a compression test. The results obtained showed that prolonged storage in a controlled atmosphere causes changes in the fruit that lead to lower firmness, lower acceptance scores and, consequently, a shorter sensory shelf life.PRACTICAL APPLICATIONSThe use of survival analysis to study the shelf life of foods is quite a novel technique in which the key concept is to focus the shelf life estimation on consumer rejection. In this study, survival analysis was applied to pears, but can be applied to other fruits or foods. This approach is useful to know the adequate storage time of food without detrimental sensory quality changes that would conduct to the consumer rejection. Normally, loss in sensory quality appears before microbiological spoilage in many food, so this methodology could be used to predict sensory shelf life.