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 IV: Clasp pattern dimensions and their influence on clasp behavior.
Harold F. Morris, D.D.S., M.S.,* Kamal Asgar, Ph.D.,** James S. Brudvik, D.D.S.,*** Sheldon Winkler, D.D.S.,**** and Eugenia Popescu Roberts***** Veterans Administration Medical Center, Allen Park, Mich.; University of Michigan, School of Dentistry, Ann Arbor, Mich.; LJniversity of Washington, School of Dentistry, Seattle, Wash.; Temple University, School of Dentistry, Philadelphia, Pa.; and University of Detroit, School of Dentistry, Detroit, Mich.
An analysis of clasp design in partial dentures.
The relation between the design and the behaviour of a clasp can be expressed mathematically in terms of two very simple equations. One of these, the S equation, indicates the strength of the clasp, while the other, the Q equation, measures its performance. Two of the factors in the Q equation, Qc and Qm, are contributions to the performance from the design and the material respectively. They are therefore figures of merit or ` quality factors ' by means of which the adequacy of the design and the material can be judged. Choice of the correct undercut and clasp thickness can be made quickly and easily with the Q and S design charts and two examples are given in the text by way of illustration. The likelihood of fatigue failure is discussed in the light of this analysis and, while it cannot be ruled out with the information at present available, the chief cause of failure would appear to be faulty design.