+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

A new design for partial denture circumferential clasp arms

A new design for partial denture circumferential clasp arms

Australian Dental Journal 41(5): 317-323

Partial dentures made from cast cobalt chromium alloys suffer from inadequacies of the retentive spring members. With similar devices made from Type 4 gold alloy, the retentive members are considered satisfactory. Analyses of the combined modulus and strength properties of the alloys show that the lower modulus of elasticity of the gold doubles its overall effectiveness in spring members such as retentive clasp arms. To match this, the strength of cobalt chromium alloys must be doubled. Since this appears unlikely, improvement to the design of the spring members is the only way to rectify this problem. Retentive clasp arms are required to have adequate elasticity to deflect out of the retentive undercut, adequate stiffness to produce retention and adequate strength to resist accidental damage. Current designs have no published rational basis to meet these requirements, and appear far from ideal. An analysis of the forces applying to clasp arms and design for uniform stress along the arm produced a shape which differs substantially from the currently used conical taper. The cross-section dimensions are related to the angular distance from the tip of the clasp. A theoretical comparison of the difference between the theoretical and current designs cannot be made as the current design for tapered clasps is not specific. It is proposed that improved performance over present clasp designs can be obtained by using clasps of the derived shape. However, the manufacture of clasps of the required complex shape and variable size is impractical, and the next best alternative of clasps of constant cross section along their length was examined. Deflection calculations for this form showed that the loss of deflection in using a clasp of constant cross section instead of the ideal was only 23 per cent. It is proposed that clasps of constant cross section along their length, with a thickness chosen according to the size of the tooth used for the undercut, will present a significant improvement in clasp performance. Further, it will provide a systematic method of selecting clasp thickness which is not presently available.

Please choose payment method:

(PDF emailed within 0-6 h: $19.90)

Accession: 045079855

Download citation: RISBibTeXText

PMID: 8961605

DOI: 10.1111/j.1834-7819.1996.tb03140.x

Related references

Clasp design for distal extension removable partial denture by the application of R.P.I. clasp and cingulum clasp. Taehan Ch'ikkwa Uisa Hyophoe Chi 11(9): 587-590, 1973

Flexible partial denture variations. The use of circumferential, combination, and continuous clasp designs. Dentistry Today 31(10): 138-141, 2012

Clasp design for partial denture. Hellenika Stomatologika Chronika. Hellenic Stomatological Annals 23(5): 27-30, 1979

Finite element analysis in defining the optimal shape and safety factor of retentive clasp arms of a removable partial denture. Vojnosanitetski Pregled 70(11): 999-1005, 2014

Clasp design for the protection of the partial denture. Nihon Shika Ishikai Zasshi 37(3): 232-238, 1984

The hinge clasp in removable partial denture design. Dental Update 22(3): 100-102, 1995

The effect of partial denture clasp design on abutment tooth movement. Journal of Prosthetic Dentistry 25(1): 44-56, 1971

Extracoronal clasp design for the distal extension removable partial denture. Florida Dental Journal 58(2 Spec No): 23-6, 58, 1987

Mechanical principles of removable partial denture design. 10. A classification of clasp dentures. Tic 25(6): 10-13, 1966

Mechanical principles of removable partial denture design. 12. A classification of clasp dentures. Tic 25(8): 13-15, 1966

Clasp design and rest placement for the distal extension removable partial denture. Dental Clinics of North America 14(3): 583-594, 1970

Mechanical principles of removable partial denture design. II. A classification of clasp dentures. Tic 25(7): 14-6 Contd, 1966

Stress distribution within circumferential clasp arms. Journal of Oral Rehabilitation 3(4): 387-394, 1976

Assessment of clasp design and flexural properties of acrylic denture base materials for use in non-metal clasp dentures. Journal of Prosthodontic Research 60(2): 114-122, 2016

An investigation of preferable taper and thickness ratios for cast circumferential clasp arms using finite element analysis. International Journal of Prosthodontics 8(4): 392-397, 1995