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N H Luebke

Publications and source records attributed to N H Luebke.

12 recordsLinked to original sources
PubMed1995

Physical dimensions, torsional performance, bending properties, and metallurgical characteristics of rotary endodontic instruments. VI. Canal Master drills.

A laboratory study was performed on machine-driven Canal Master drills to determine their physical dimensions, torsional performance, bending properties, and metallurgical characteristics in fracture. Physical dimensions were determined for each of the available sizes (#50 to #100) of Canal Master drills from the manufacturer that distributes these instruments in the United States. Samples were also tested in clockwise torsion using a Maillefer memocouple. Bending properties of cantilever specimens were measured with a Tinius Olsen stiffness tester. Bending fatigue testing was performed on a unique laboratory apparatus. Scanning electron microscope examination confirmed visual observations that the stainless steel Canal Master drills exhibited ductile torsional fracture. This study is part of a continuing investigation to establish standards for all machine-driven rotary endodontic instruments.

Dental High-Speed Equipment↗
PubMed1994

Performance of engine-driven rotary endodontic instruments with a superimposed bending deflection: V. Gates Glidden and Peeso drills.

A laboratory study was performed on Gates Glidden and Peeso drills to determine the incidence of shaft fracture when a bending deflection was superimposed on the rotating drills. Samples of sizes #1 to #6 stainless steel Gates Glidden drills, sizes #1 to #6 stainless steel and carbon steel-type P Peeso drills, and sizes #009 to #023 carbon steel-type B-1 Peeso drills from each of two manufacturers were evaluated with a unique apparatus that applied a 2-mm bending deflection while rotating the instruments. The apparatus did not restrict movement of the bur head during rotation. The test drills were rotated at 2500, 4000, and 7000 revolutions per minute, and the number of revolutions at failure was recorded. Scanning electron microscopic observations established that the stainless steel Gates Glidden and Peeso drills failed by ductile fracture, whereas the carbon steel Peeso drills failed by brittle fracture. Instrument fracture was always near the handpiece shank with this test, and the length of the fractured drills was measured from the working tip. It is recommended that this additional test be adopted to determine fatigue properties of engine-driven rotary endodontic instruments in establishing international performance standards.

Dental High-Speed Equipment↗
PubMed1993

Bending and metallurgical properties of rotary endodontic instruments. IV. Gates Glidden and Peeso drills.

A laboratory study was performed on Gates Glidden and Peeso drills to determine the bending characteristics and related metallurgical properties. Sizes #1 to #6 stainless steel Gates Glidden drills, sizes #1 to #6 stainless steel and carbon steel type P Peeso drills, and sizes #009 to #023 carbon steel-type B-1 Peeso drills were evaluated in cantilever bending with a Tinius Olsen stiffness tester. The bending moments were measured for a 12.5-mm test span at deflection angles of 2 to 90 degrees. The mean maximum bending moments in g cm and the corresponding deflection angles in degrees were plotted graphically to ascertain the bending characteristics of the instruments. The stainless steel Gates Glidden and Peeso drills exhibited considerable permanent bending deformation during testing. Some stainless steel drill samples were able to withstand the full bending deflection of 90 degrees without fracturing. In contrast, the carbon steel Peeso drills were able only to undergo bending deflections of less than 20 degrees and exhibited brittle fracture. If the drill fractured during the in vitro testing, the failure site was always located near the handpiece end.

Dental Cavity Preparation↗
PubMed1992

Physical dimensions, torsional performance, and metallurgical properties of rotary endodontic instruments. 3. Peeso drills.

A laboratory study was performed on Peeso drills to determine their physical dimensions, torsional performance, and metallurgical properties. Samples were measured from each of sizes #1 to #6 of Peeso drills (type P) and sizes #009 to #023 of Peeso drills (type B-1) from the two manufacturers that distribute these instruments in the United States. They were also tested in clockwise and counterclockwise torsion using a digital torque meter instrument. It was not possible to evaluate completely some type P drills of size #4 and larger or type B-1 drills of size #016 and larger because the torsional moments exceeded the capacity of the test instrument. Scanning electron microscopic examination confirmed visual observations that the stainless steel Peeso drills exhibited ductile torsional fracture, in contrast to the carbon steel Peeso drills which fractured in a relatively brittle manner. The carbon steel Peeso drills exhibited a much greater tendency for torsional fractures in the bur head, along with considerably smaller values of angular deflection at separation compared to the stainless steel Peeso drills. This study is part of a continuing investigation to establish standards for all rotary endodontic instruments.

Dental Cavity Preparation↗
PubMed1991

Torsional and metallurgical properties of rotary endodontic instruments. 2. Stainless steel Gates Glidden drills.

A laboratory study was performed on stainless steel Gates Glidden drills to determine their torsional and metallurgical properties. Samples of #1 to #6 drills from the two manufacturers that distribute these instruments in the United States were tested in incremental and continuous clockwise torsional loading by using a digital torque meter. The values of mean torque at fracture obtained with these tests generally showed no statistically significant differences for the same drill size and a given manufacturer. However, it was not possible to completely evaluate drill sizes #5 and #6 because the torsional moments developed during testing exceeded the capacity of the test instrument. Scanning electron microscope examination confirmed the occurrence of ductile torsional fracture processes, which were evident from visual observation of the instruments after fracture. This study is part of a continuing investigation to establish standards for all rotary endodontic instruments.

Dental Instruments↗
PubMed1990

Physical dimensions and torsional properties of rotary endodontic instruments. 1. Gates Glidden drills.

A laboratory study was performed on Gates Glidden drills to determine their physical dimensions and torsional properties. Five samples of sizes #1 to #6 drills from two brands distributed in the United States were measured for physical dimensions. Five samples of the most commonly used sizes #1, #2, and #3 drills from these two brands were tested at failure in both the clockwise and counterclockwise directions using an analog torque meter. The values for the bur head dimensions of both brands correspond closely to those established by the ISO. The mean values for torque at failure for both the clockwise and counterclockwise directions showed no statistically significant difference for each brand-size combination. However, some instrument groups had separation or fracture sites near the bur head, while other groups underwent failure near the hand-piece end. This study is the first part of a continuing investigation to establish standards for rotary endodontic instruments.

Dental Instruments↗
PubMed1984

Spatial perception testing in diagnostic radiology.

A test predictive of ultimate radiologic expertise could be of great value in the selection of individuals entering the field. Some individuals have an aptitude superior to others to perceive three-dimensional spatial relations from two-dimensional data. This may enhance their ability to draw radiologic conclusions from clinical images and may favorably affect their performance as radiologists. To test cognitive perceptual ability, a three-dimensional Visual Form Reconstruction Test (form test) was developed and administered to residents and faculty members. All subjects also completed the Thurstone Surface Development Test, a standardized test of spatial visualization ability. The form test results correlated well with resident performance, as measured by overall faculty ratings (predictive validity). Although form test and Thurstone test performance were highly correlated with each other (concurrent validity), the form test was better correlated with resident performance. Intercorrelations among the three subsections of the form test demonstrated high split-part reliability. Performance on the form test was unaffected by level of training. This suggests that an underlying aptitude was measured. These preliminary results indicate that testing of spatial visualization aptitude is predictive of resident performance in radiology. A test such as this could be useful in selection and self-selection of resident candidates.

Aptitude↗
PubMed1980

The cutting effectiveness of carbide fissure burs on teeth.

The cutting effectiveness of the burs decreased with time. While the multivariate analysis of variance showed an overall difference among the three groups, these differences appeared to be due to the shape of the curves (the linear and quadratic components) rather than to their average location (the mean). Therefore there were no significant differences in cutting among the three types of burs tested. The SEM photomicrographs showed that there was no gross bur damage after the burs were used for cutting tooth structure. The cutting mechanism of a carbide bur on tooth structure needs further investigation.

Carbon↗
PubMed1979

Q factor analysis applied to describe attitudes toward dental care.

This study used a modified form of Q factor analysis to introduce students to methods to identify and describe patient and provider attitudes toward dental care. Factor analysis of questionnaire results and a person by person correlation matrix allowed students to compare their own attitudes with those of their patients, faculty, and significant people in their lives. Results indicate certain issues regarding dental care on which all subjects agree. Subjects grouped themselves along different factors according to the relative importance each issue had for them. By identifying these issues and groupings, students had a systematic description of their specific "dentist-patient relationship." By including clusters of people significant in their own lives, students became personally involved in the purpose, methods, and results of the analysis.

Attitude↗
PubMed1978

Discussion of sensitivity to preservatives in anesthetics.

A 23-year-old woman with reported sensitivities to several drugs, including anesthetics, requested dental care. Because of the lack of evidence of allergic reactions to lidocaine, it was used in a dental emergency procedure. The patient had an allergic response. In an evaluation by an allergist, an allergy to methyl paraben was detected. The dental practitioner should be aware of possible allergies to preservative agents when a patient has a history of sensitivity to anesthetics. The practitioner's choice of anesthetics and OTC drugs for this type of patient is crucial.

Adult↗
PubMed1976

Systematic procedure for determining criterion scores.

The present study describes a systematic method for determining a criterion score in criterion-referenced measurement. Reliable estimates were obtained by using only three judges who were subject matter experts. This demonstrates that the method can be applied to the test performance levels of individuals who are required to meet the objectives for a subject matter area. The present study showed that reliable judgments could be made even on subject matter of an advanced nature.

Education, Dental↗