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Instrument Types (instrument + type)
Selected AbstractsRoot canal preparation with FlexMaster: asessment of torque and force in relation to canal anatomyINTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2003W. Hübscher Abstract Aim, To investigate physical parameters of FlexMaster nickel-titanium instruments while preparing curved canals in maxillary molars in vitro. Methodology, A torque-testing platform was used to prepare root canals in 11 extracted human maxillary molars with FlexMaster rotary instruments. Peak torque and force was registered along with numbers of rotations required to shape the canals. Canals were divided into ,wide' and ,constricted' groups depending on canal volumes assessed by microcomputed tomography. Resistance to cyclic fatigue was also tested. Mean scores for each instrument type were calculated and statistically compared using anova and Scheffé post hoc tests. Results, Mean torque varied between 0.1 ± 0.1 and 0.8 ± 0.5 N cm while mean force ranged from 4.2 ± 2.0 to 7.3 ± 3.5 N. Mean numbers of rotations totalled up to 18. All three variables registered showed weak correlations to preoperative canal volumes (P < 0.01) and differed significantly between ,wide' and ,constricted' canals (P < 0.001). Numbers of rotations to fracture in a cyclic fatigue test were between 348 and 1362. Conclusion, FlexMaster instruments generated low torque scores and were highly resistant to cyclic fatigue, whilst three instruments fractured in extremely narrow canals. Consequently, more research is required to limit fracture incidence and to optimize instrumentation guidelines. [source] Subgingival polishing with a teflon-coated sonic scaler insert in comparison to conventional instruments as assessed on extracted teethJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 8 2001(II). Subgingival roughness Abstract Aim: To assess the root surface roughness and topography on extracted teeth using different instruments. Material and Methods: In the present study, laser profilometry was used to examine the 3-D roughness values Ra and Rz and topography of root surfaces of periodontally-involved teeth instrumented in vivo with curette, conventional ultrasonic device, conventional or teflon-coated sonic scaler insert, or the Periotor instrument (12 teeth per instrument type), and compare these with uninstrumented cementum surfaces. Results: The roughness values Ra and Rz of the roots treated with the different instruments showed a similar pattern: curettes and the Periotor instrument produced the smoothest surfaces (Ra about 1.5 ,m, Rz 30 ,m); the 4 other instruments created similar Ra values of approximately 2,3 ,m and Rz roughness of about 50,70 ,m, which equals the untreated root surface. For Ra, the difference between the curette or the Periotor instrument and the teflon-coated sonic insert or ultrasonic insert was significant, and for Rz, a significant difference was found between the curette or the Periotor instrument and ultrasonic insert. As opposed to surfaces debrided with the Periotor and teflon-coated sonic scaler, it appears that hand instruments markedly reconfigure surfaces. Conclusion: The lowest root-surface roughness values were obtained with hand instruments. The teflon tubing on the sonic scaler insert effected no change of topography or roughness as compared to uninstrumented, control surfaces. However, it must be pointed out that hard-tissue removal was not investigated. Zusammenfassung Einführung: Wir wollten die Rauhigkeit und die Topographie der Wurzeloberfläche an extrahierten Zähnen infolge unterschiedlicher Instrumentation einschätzen. Material und Methoden: In der vorliegenden Studie wurde die Laserprofilometrie genutzt, um die 3D Rauhigkeitswerte Ra und Rz sowie die Topographie der Wurzeloberfläche von parodontal erkrankten Zähnen, die in vivo mit Küretten, konventionellen Ultraschallgeräten, konventionellen oder mit Teflon beschichteten Schallscalereinsätzen oder mit dem Periotorgerät (12 Zähne pro Instrumentenart) bearbeitet worden waren, zu überprüfen und dies mit unbehandelten Zementoberflächen zu vergleichen. Ergebnisse: Die Rauhigkeitswerte Ra und Rz der Wurzeln, die mit verschiedenen Instrumenten behandelt worden waren, zeigten ein ähnliches Muster: Küretten und das Periotorinstrument erbrachten die glattesten Oberflächen (Ra ungefähr 1.5 ,m, Rz 30 ,m); die 4 anderen Instrumente schufen gleiche Ra-Werte von ungefähr 2,3 ,m und Rz-Rauhigkeit von ungefähr 50,70 ,m, was den unbehandelten Wurzeloberflächen glich. Für Ra war die Differenz zwischen Kürette oder Periotorinstrument und mit Teflon beschichteten Schalleinsätzen oder Ultraschalleinsätzen signifikant, und für Rz wurde eine signifikante Differenz zwischen der Kürette oder dem Periotorinstrument und dem Ultraschalleinsatz gefunden. Im Gegensatz zu Oberflächen, die mit Periotor und mit Teflon beschichteten Schallscalern bearbeitet wurden, scheint es, daß Handinstrumente die Oberflächen deutlich rekonfigurieren. Schlußfolgerung: Die geringsten Wurzeloberflächenrauhigkeitwerte wurden mit Handinstrumenten erzielt. Die Teflonröhrchen auf den Schallscalereinsätzen erbrachten keine Veränderungen der Topographie oder der Rauhigkeit im Vergleich zu unbehandelten Kontrolloberflächen. Jedoch muß ausgeführt werden, daß die Entfernung des Hartgewebes nicht untersucht wurde. Résumé Nous voulions mettre en évidence la rugosité de la surface radiculaire et sa topographie sur des dents extraites à la suite de polissage avec différents instruments. Dans cette étude, la profilométrie par laser a été utilisée pour examiner les valeurs Ra et Rz de rugosité tridimensionnelle et la topographie des surfaces radiculaires de dents atteintes de maladies parodontales instrumentées in vivo à l'aide de curettes, d'un appareil ultrasonique conventionnel, d'insert de détargrage sonique recouvert de téflon ou du Periotor (12 dents par type d'instrument) et de les comparer avec les valeurs des surfaces cémentaires non-instrumentées. Les valeurs Ra et Rz de rugosité des racines traitées avec les différents instruments montraient des caractéristiques similaires: les curettes et le Periotor produisait les surfaces les plus lisses (Ra environ 1.5 ,m, Rz 30 ,m); les 4 autres instruments donnaient des valeurs Ra de 2,3 ,m approximativement et une rugosité Rz d'environ 50,70 ,m, équilavent aux surfaces non traitées. Pour Ra, la différence entre les curettes ou le Periotor et les inserts soniques recouverts de téflon ou l'insert ultrasonique étaient significatifs, et pour Rz, une différence significative apparaissait entre les curettes ou le priotor et les inserts ultrasoniques. Contrairement aux surfaces débridées avec le periotor et le détartreur sonique recouvert de téflon, il apparaissait que les instruments manuels reconfiguraient la surface remarquablement. Les valeurs les plus basses de rugosité de la surface radiculaire étaient obtenues avec les instruments à mains. Le revètement de téflon sur l'insert sonique n'entrainait pas de modifications de topographie ni de rugosité par rapport au surfaces controles non-instrumentées. Cependant, il faut signaller que l'élimination des tissus durs n'a pas étéétudiée. [source] Temperature changes in dental pulp associated with use of power grinding equipment on equine teethAUSTRALIAN VETERINARY JOURNAL, Issue 1-2 2005GJ WILSON Objective To quantify the temperature changes in the dental pulp associated with equine dental procedures using power grinding equipment. Design A matrix experimental design with replication on the same sample was followed to allow the following independent variables to be assessed: horse age (young or old), tooth type (premolar or molar), powered grinding instrument (rotating disc or die grinder), grinding time (15 or 20 seconds) and the presence or absence of water coolant. Procedure Sound premolar and molar teeth from a 6-year-old horse and a 15-year-old horse, which had been removed postmortem, were sectioned parallel to the occlusal plane to allow placement of a miniature thermocouple at the level of the dental pulp. The maximum temperature increase, the time taken to reach this maximum and the cooling time were measured (n=10 in each study). The teeth were placed in a vice and the instrument used on the tooth as per clinical situation. Results Significant differences were recorded for horse age (P < 0.001), instrument type (P < 0.001), grinding time (P < 0.001) and presence or absence of coolant (P < 0.001). There was no significant difference for tooth type. Conclusion Thermal insult to the dental pulp from the use of power instruments poses a significant risk to the tooth. This risk can be reduced or eliminated by appropriate selection of treatment time and by the use of water irrigation as a coolant. The increased dentine thickness in older horses appears to mitigate against thermal injury from frictional heat. [source] Comparative investigation of two rotary nickel,titanium instruments: ProTaper versus RaCe.INTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2004Part 2. Abstract Aim, To determine the cleaning effectiveness and shaping ability of ProTaper and RaCe nickel,titanium rotary instruments during the preparation of curved root canals in extracted human teeth. Methodology, A total of 48 root canals of mandibular and maxillary molars with curvatures ranging between 25° and 35° were divided into two groups of 24 canals each. Based on radiographs taken prior to instrumentation with the initial instrument inserted into the canal, the groups were balanced with respect to the angle and the radius of canal curvature. Canals were prepared using a crown-down preparation technique. After each instrument, the root canals were flushed with a 2.5% NaOCl solution and at the end of instrumentation with NaCl. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. After splitting the roots longitudinally, the amount of debris and smear layer was quantified on the basis of a numerical evaluation scale, using a scanning electron microscope (SEM). The data established for scoring the debris and the smear layer were separately recorded and analysed statistically using the Wilcoxon test. Results, Two ProTaper and three RaCe instruments fractured; there was no significant difference between instrument types (P > 0.05). Completely clean root canals were never observed. For debris removal, RaCe files achieved significantly better results (P < 0.001) than ProTaper instruments. The results for remaining smear layer were similar and not significantly different (P > 0.05). RaCe instruments maintained the original canal curvature significantly better (P < 0.05) than ProTaper instruments. No significant differences were detected between the instruments (P > 0.05) for the time taken to prepare the canals. Conclusions, Under the conditions of this study, RaCe instruments resulted in relatively good cleaning and maintained the original curvature significantly better than ProTaper did. [source] The Rise of ,New' Policy Instruments in Comparative Perspective: Has Governance Eclipsed Government?POLITICAL STUDIES, Issue 3 2005Andrew Jordan Governance is a term in good currency, but there are still too few detailed empirical analyses of the precise extent to which it has or has not eclipsed government. This article explores the temporal and spatial characteristics of the governance transition by charting the deployment of new policy instruments in eight industrialised states and the European Union. The adoption and implementation of (,old' and ,new') policy instruments offer a useful analytical touchstone because governance theory argues that regulation is the quintessence of government. Although there are many ,new' environmental policy instruments in these nine jurisdictions, this article finds that the change from government to governance is highly differentiated across political jurisdictions, policy sectors and even the main instrument types. Crucially, many of the new policy instruments used require some state involvement (that is, ,government'), and very few are entirely devoid of state involvement (that is, pure ,governance'). Far from eclipsing government, governance therefore often complements and, on some occasions, even competes with it, although there are some cases of fusion. Future research should thus explore the many complex and varied ways in which government and governance interact in public policy-making. [source] Towards a universal product ion mass spectral library , reproducibility of product ion spectra across eleven different mass spectrometersRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2008Chris Hopley Product ion spectra produced by collision-induced dissociation (CID) in tandem mass spectrometry experiments can differ markedly between instruments. There have been a number of attempts to standardise the production of product ion spectra; however, a consensus on the most appropriate approach to the reproducible production of spectra has yet to be reached. We have previously reported the comparison of product ion spectra on a number of different types of instruments , a triple quadrupole, two ion traps and a Fourier transform ion cyclotron resonance mass spectrometer (Bristow AWT, Webb KS, Lubben AT, Halket JM. Rapid Commun. Mass Spectrom. 2004; 18: 1). The study showed that a high degree of reproducibility was achievable. The goal of this study was to improve the comparability and reproducibility of CID product ion mass spectra produced in different laboratories and using different instruments. This was carried out experimentally by defining a spectral calibration point on each mass spectrometer for product ion formation. The long-term goal is the development of a universal (instrument independent) product ion mass spectral library for the identification of unknowns. The spectra of 48 compounds have been recorded on eleven mass spectrometers: six ion traps, two triple quadrupoles, a hybrid triple quadrupole, and two quadrupole time-of-flight instruments. Initially, 4371 spectral comparisons were carried out using the data from eleven instruments and the degree of reproducibility was evaluated. A blind trial has also been carried out to assess the reproducibility of spectra obtained during LC/MS/MS. The results suggest a degree of reproducibility across all instrument types using the tuning point technique. The reproducibility of the product ion spectra is increased when comparing the tandem in time type instruments and the tandem in space instruments as two separate groups. This may allow the production of a more limited, yet useful, screening library for LC/MS/MS identification using instruments of the same type from different manufacturers. Copyright © 2008 John Wiley & Sons, Ltd. [source] Mass measurement accuracy comparisons between a double-focusing magnetic sector and a time-of-flight mass analyzerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 10 2008Michael S. Bereman We report a direct comparison of the mass measurement accuracies (MMAs) obtained on different mass spectrometry instrument types; a magnetic sector as the ,gold standard' and an electrospray ionization time-of-flight (ESI-TOF) instrument. Sixty samples, obtained from the Department of Chemistry at North Carolina State University, were analyzed on each instrument. Data are presented and compared between the different instruments. The average absolute MMAs achieved for the magnetic sector and Agilent ESI-TOF mass spectrometers were 3.0 and 1.1,ppm, respectively. Copyright © 2008 John Wiley & Sons, Ltd. [source] Instrument-, age- and site-dependent variations of dermoscopic patterns of congenital melanocytic naevi: a multicentre studyBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2006S. Seidenari Summary Background, Recently, we identified and described dermoscopic aspects, present with a higher frequency in congenital melanocytic lesions with respect to acquired naevi. We also classified small- and medium-sized congenital naevi (CN) into nine subtypes according to their macroscopic and dermoscopic aspects. Objectives, Because the recognition of dermoscopic features may be instrument dependent, in this study, we wanted to check whether dermoscopic patterns specific for CN can be identified in digital images acquired by means of different instruments. We also wanted to check the validity of our previously proposed classification and assess possible age- and site-dependent variations of dermoscopic patterns and naevus subtypes. Patients/methods, Images corresponding to 384 small- or medium-sized CN were collected in eight different centres employing four different instruments. Lesion images were evaluated and checked for the presence of specific dermoscopic criteria, classified, and compared with a database of 350 acquired naevi. Results, Specific and unspecific dermoscopic features were identifiable in images acquired by means of all four instrument types. The mean number of identified features per lesion did not vary according to the instrument employed for the acquisition of the images; however, it was lower for lesions recorded employing low magnifications. The previously proposed classification was easily applied to the whole image database. The variegated naevus type was identified as a highly specific clinical/dermoscopic pattern. Dermoscopic features varied according to age and location. The globular type prevailed in subjects under 11 years of age and on the trunk, whereas the majority of reticular lesions were located on the limbs. Conclusions, Because definite clinical and histological criteria for the diagnosis of the congenital nature of naevi are lacking, the use of dermoscopy can be of great help in identifying those lesions where the presence of specific dermoscopic features makes the diagnosis of CN more likely. Moreover, dermoscopy can be useful both for the classification of lesions already identified as congenital according to definite clinical and anamnestic data and for a possible correlation of naevus phenotype and dermoscopic patterns to the risk of developing a malignant melanoma in prospective studies. [source] Managing the "hollow state": procedural policy instruments and modern governanceCANADIAN PUBLIC ADMINISTRATION/ADMINISTRATION PUBLIQUE DU CANADA, Issue 4 2000Michael Howlett Recent works by Canadian, Dutch, American, British and French scholars have begun to describe a common set of policy instruments contemporary governments now use to indirectly steer social actors towards their preferred policy options. Unlike traditional "substantive" instruments, which directly affect the delivery of goods and services in society, these "procedural" policy instruments are intended to manage state-societal interactions in order to assure general support for government aims and initiatives. Used on an ad hoc basis in the past, these tools have become an essential feature of modern governance. This article advances the study of these procedural policy instruments by developing a taxonomy and outlining the rationale for choosing between particular instrument types. Sommaire: Les gouvernements se trouvent aujourd'hui face à un paradoxe: d'une part, leur pouvoir d'intervention est en principe important au niveau des connais-sances, de I'expertise, des budgets et du personnel; d'autre part, les phénomènes tels que la mondialisation et la démocratisation ont fortement sapé leur capacité d'influer directement sur les résultats sociaux. Des travaux récents d'auteurs canadiens, néer-landais, américains, britanniques et français amorcent la description d'un ensemble commun d'instruments directifs dont se servent actuellement les gouvernements pour orienter indirectement les intervenants sociaux vers les options politiques que les gouvernements préfèrent. À I'encontre des instruments classiques « substantifs » influant directement sur la prestation de biens et services au sein de la société, ces instruments « procéduraux » visent é gkrer l'interaction État-société de manière à ce que les initiatives et objectifs gouvernementaux reçoivent l'appui de tous. Utilisés de manière ponctuelle dans le passé, ces outils sont devenus un éléments essentiel de la gouvemance moderne. Cet article fait progresser l'étude de ces instruments de procédure pour l'élaboration des politiques, en définissant une taxonomie et en pré-cisant les raisons pour lesquelles un type d'instrument particulier serait préférable à un autre. [source] | ||||||||||