Influence of polishing on cast clasp properties.
During the polishing of clasps, two possible changes that could affect their properties are thinning of the clasp and work hardening of the alloy. Two distinctly different clasp pattern forms were selected and 20 samples of each were cast. They were then divided into two groups, polished and unpolished, in an effort to determine the total influence of the polishing procedure on clasp behavior. The results indicate that polishing produces a slightly more flexible clasp. Any influence resulting from possible work hardening is offset by the reduction of clasp thickness. Effects of width/thickness ratios and magnitude of deflections on finishing and polishing techniques may also alter clasp flexibility in the polished clasp.
Stress-relaxation testing. Part II: comparison of bending profiles, microstructures, microhardnesses, and surface characteristics of several wrought wires.
1 h d 1 l’t t e enta I era ure fails to provide the profession with a thorough understanding of the wrought wires used as clasp materials in dentistry. All information currently available has largely been obtained through the use of tensile testing. In tensile testing, the atoms within the alloy are subjected to tensile stresses at a constant rate of loading. This is not representative of the type of stress present in clasp arms during clinical use. Since clasp arms are required to undergo repeated bending, both tensile and compressive stresses are developed within the material. The extent and rate of any clasp deflection vary. To provide data which can be analyzed to obtain results which can be applied to clinical situations, it is imperative that the test methods approach the conditions present during clinical function as much as possible. During stress-relaxation testing, the test specimen is deflected by the instrument and released. The resiliency of the material returns the test specimen to its original position in the same manner as a clasp arm, after it has passed beyond the curvature of the tooth. As the clasp is deflected, both the tensile and compressive stresses
Construction techniques for wrought-wire retentive clasp arms as related to clasp flexibility.
Abstract The three standard means of attachment of circumferential wrought-wire retentive arms to removable partial denture frameworks were tested for their influence on component flexibility. A wire retentive arm, adapted after framework construction and soldered to the frame on the base retentive meshwork well away from the minor connector was found to be more flexible than the other common methods of wire attachment. Wire components, attached in this manner, appear to have the same degree of flexibility as unattached wire.