PubMed Health⌕ Search

Biomedical subjects

E Lautenschlager

Publications and source records attributed to E Lautenschlager.

13 recordsLinked to original sources
PubMed2001

A biomechanical analysis of the modified Tsuge suture technique for repair of flexor tendon lacerations.

Thirty-six flexor tendons from fresh frozen cadavers were randomized to three types of repairs: a Kessler-Tajima, a 4-strand modified Tsuge, and a 6-strand modified Tsuge. All repairs were accompanied by a standard epitendinous suture. The repaired tendons were then tested to initial gap and ultimate failure in an Instron machine. The average forces to ultimate failure were 31.8 N (SD, 8.8), 48.4 N (SD, 10.7), and 64.2 N (SD, 11.0) respectively. The 6-strand modified Tsuge suture was significantly stronger than the other repairs and the 4-strand modified Tsuge was significantly stronger than the 2-strand Kessler-Tajima. The 6-strand and 4-strand modified Tsuge repairs appear strong enough to withstand the forces generated during early active range of motion flexor tendon rehabilitation protocols. Clinical trials are required to evaluate the usefulness of these repairs.

Biomechanical Phenomena↗
PubMed1994

A comparison of the hardness of different types of titanium and conventional metal ceramics.

This study compared the surface hardness of machine milled titanium and cast titanium, and the surface hardness profile of a gold-palladium alloy, a nickel chromium alloy, milled and cast titanium. For each group, 15 discoid specimens, 10 mm in diameter and 5 mm thick, were fabricated by either casting or milling. Five specimens of each group underwent one of three treatments: (1) no heat treatment, (2) a standard heat treatment, or (3) an extended heat treatment. Knoop hardness values were determined. Results indicated that the Knoop hardness of cast titanium was less than that of the cast titanium standard treatment group, which was less than the Knoop hardness of the cast titanium extended treatment group. Knoop hardness of milled titanium was less than that of the milled titanium standard treatment and milled titanium extended treatment groups. For the surface hardness profile, cast titanium showed a decreasing surface hardness as the distance from the surface of the specimen increased. No such trend was identified for the other groups tested.

Chromium Alloys↗
PubMed1992

Effects of home bleaching preparations on composite resin color.

The lightening of teeth is done professionally by exposure to warm hydrogen peroxide solutions or at home with an active bleaching gel of perhydrol urea or carbamide peroxide. This study compared the effects of two commercial bleaching gels on the color of composite resin with those in a previous study using the dental office technique. Commercial composite resins test specimens were exposed to the bleaching gels or water (control) for 312 hours at 37 degrees C at 100% relative humidity. Color change value was calculated with before-and-after solution exposure L*a*b* color values. ANOVA (alpha = 0.01) revealed no differences in the color of the specimens after use of the test solutions. All color change values were less than 2 or the normal limit of visual acuity. No visual color change was evident for these composite resins. The at-home method recorded no shade-altering effects compared with the professional technique, which created a noticeable color change.

Analysis of Variance↗
PubMed1992

Composite resin color change after vital tooth bleaching.

Color change of composite resin was determined with the Minolta Chroma meter (CR-100) after four sessions of vital bleaching. Specimens of selected composite resin materials were subjected to vital bleaching (37% H3PO4/1 minute, then 30% H2O2/infrared light/30 minutes.) Specimens were stored in water between bleaching. Control specimens were used to determine the effects of water storage alone. Initial L*a*b* color readings were made on 24-hour hydrated specimens. Final L*a*b* readings were made on 24-hour hydrated specimens. Calculations were made for the delta E values for each specimen. Mean delta E values and standard deviations were obtained for each material. Two-way ANOVA and Newman-Keuls analyses showed significant (alpha = 0.05) color change for most bleached materials. Additionally, some materials had delta E values greater than 3. These were visibly lighter compared to their controls. Vital bleaching produced color change in most composites as measured with the Chroma meter. This technique may be used to lighten dark-colored or stained composite resin restorations.

Acrylic Resins↗
PubMed1977

Influence of cations on the electrical activity of neuroblastoma X glioma hybrid cells.

Electrical excitability is one of the various neuronal properties of neuroblastoma X glioma hybrid cells. At a Ca2+ concentration of 1.8 mM the action potential is inhibited by tetrodotoxin, suggesting that the inward current is carried by Na+ ions. In contrast, at a Ca2+ concentration of 20-36 mM and even in the absence of Na+, spikes (sometimes repetitive) with strong hyperpolarizing afterpotential occur, which are no longer affected by tetrodotoxin. They are, however, blocked by antagonists of Ca2+ like La3+, Co2+, Mn2+, and the synthetic compounds D-600 and BAY a-1040. This seems to indicate that at high concentrations of Ca2+, the inward current of the action potential is essentially carried by Ca2+. Sr2+, but not Mg2+ can effectively substitute for Ca2+. It slows down the time course of the action potential. Ba2+ depolarizes the membrane gradually. If Ca2+ is also present, Ba2+ causes a reduced depolarization and spontaneous action potentials with no hyperpolarizing after-potential are observed.

Action Potentials↗
PubMedDate not supplied

The contribution of the glenohumeral ligaments to anterior stability of the shoulder joint.

The purpose of this study was to investigate the ligamentous stabilizing mechanisms preventing anterior instability in the glenohumeral joint. Six freshly thawed, unembalmed cadaveric shoulders were dissected, preserving the joint capsule and glenohumeral ligaments, the coracohumeral ligament, and the subscapularis tendon. Hall-effect strain transducers were placed on the superior, middle, and inferior glenohumeral ligaments. The humerus and scapula were fixed in a specifically designed mounting apparatus that allowed the glenohumeral joint to be placed in 0 degree, 45 degrees, or 90 degrees of abduction. The mounting apparatus was placed in a model TTC Instron Universal Testing Instrument, which applied an external rotation torque to the humerus. Strain produced in the three glenohumeral ligaments was recorded on a three-channel X-Y chart recorder. At 0 degree of abduction, the superior and middle glenohumeral ligaments developed the most strain. At 45 degrees of abduction, the inferior and middle glenohumeral ligaments developed the most strain, with considerable strain also being developed in the superior glenohumeral ligament. At 90 degrees of abduction, the inferior glenohumeral ligament developed the most strain, with strain also seen in the middle glenohumeral ligament.

Biomechanical Phenomena↗
PubMedDate not supplied

The mechanical properties of milled and cast titanium for ceramic veneering.

This study compared the mechanical properties of machine-milled pure titanium and cast titanium. The metals were cast or milled to the dimensions of a standard tensile bar pattern. Each group was treated under three different conditions: as-cast (or as-milled), standard heat, and extended heat. Tensile testing found no difference in the mechanical properties of as-cast and as-milled titanium. Heat treatment significantly increased the ultimate tensile strength and the yield strength of cast titanium but had no such effects on milled titanium. There was no significant difference between the two metals in the modulus of elasticity or the percentage of elongation under the three treatment conditions.

Alloys↗
PubMedDate not supplied

Marginal fit of machine-milled titanium and cast titanium single crowns.

Eighteen type IV dental stone dies were fabricated from a metal master die that replicated a tooth prepared to receive a metal ceramic crown. They were divided into three groups according to the type of crowns to be made: (a) machine-milled, spark-eroded titanium crowns (Procera); (b) cast titanium crowns; and (c) noble alloy crowns (as the control). The control specimens showed the smallest mean marginal openings at 25 microns and were significantly different from both the machine-milled crowns (54 microns) and the cast titanium crowns (60 microns). The two types of titanium crowns were not significantly different from each other.

Analysis of Variance↗