Biomedical subjects

H F Morris

Publications and source records attributed to H F Morris.

81 records · Page 5Linked to original sources

PubMed1981

Stress-relaxation testing. Part III: Influence of wire alloys, gauges, and lengths on clasp behavior.

Commonly used, commercially available dental wires have been evaluated and ranked through stress-relaxation testing to given the clinician a basis for determining their use as retentive clasp arms. Clinical laboratory principles relative to the use of wire clasp arms have been discussed. Clinical experience with the cobalt-chrome-nickel wire retentive clasp arms used in the infrabulge approach over the last 8 years has been rewarding. These wire clasps have been every bit as effective as the cast bar clasps and have proven to be superior in terms of adjustability and resistance to fracture. The relation of active clasp length to retention and permanent deformation is a crucial one and should be a component of every philosophy of design and construction of removable partial dentures.

Dental Alloys↗

PubMed1979

The influence of heat treatments on several types of base-metal removable partial denture alloys.

Four removable partial denture alloys, Vitallium (Co-Cr alloy), Dentillium P.D. (Fe-Cr alloy), Durallium L.G. (Co-Cr-Ni alloy), and Ticonium 100 (Ni-Cr alloy), were evaluated in the as-cast condition and after heat treatment for 15 minutes at 1,300 degrees, 1,600 degrees, 1,900 degrees, and 2,200 degrees F followed by quenching in water. The following properties were determined and compared for each alloy at each heat treatment condition: the yield strengths at 0.01%, 0.1%, and 0.2% offsets, the ultimate tensile strength, the percent elongation, the modulus of elasticity, and the Knoop microhardness. The results were statistically analyzed. Photomicrographs were examined for each alloy and test condition. The following conclusions were made: 1. The "highest values" were exhibited by the as-cast alloy. 2. Heat treatment of the partial denture alloys tested resulted in reductions in strength, while the elongations varied. This study demonstrates that, in practice, one should avoid (a) prolonged "heat-soaking" while soldering and (b) grinding or polishing of the casting until the alloy is "red hot". 3. Durallium L.G. was the least affected by the various heat treatment conditions. 4. Conventional reporting of the yield strength at 0.2% offset, the ultimate tensile strength, and percent elongation are not adequate to completely describe and compare the mechanical behavior of alloys. The reporting of the yield strength at 0.01% offset, in addition to the other reported properties, will provide a more complete description of the behavior of the dental alloys.

Chromium↗

PubMed1979