Accuracy and mechanical properties of denture clasps fabricated utilizing pre-sintered Co-Cr alloy discs

This study evaluated the use of pre-sintered cobalt-chromium (Co-Cr) alloy discs in the fabrication of clasps for removable partial dentures, comparing their accuracy and mechanical properties, as determined via tensile testing, with those of conventional fabrication methods.

Accuracy of the clasps was assessed by obtaining three-dimensional (3D) data (design data) of the Akers clasp. The clasps were fabricated under three conditions: (1) pre-sintered, fabricated from pre-sintered Co-Cr alloy discs; (2) fully sintered, fabricated from fully sintered Co-Cr alloy discs; and (3) cast, fabricated via casting. For each method, 3D data were collected (fabrication data). The design and fabrication data were subsequently superimposed, and the accuracy of the clasps was investigated based on their inner surfaces. The mechanical properties were assessed via tensile testing of dumbbell-shaped Co-Cr alloy specimens fabricated under the same conditions used for accuracy testing (pre-sintered, fully sintered, and cast).

Cast clasps typically exhibited the highest trueness values and fully sintered clasps exhibited the highest precision values. The pre-sintered clasps exhibited high trueness in every part of the rest area; however, the accuracy at the clasp tip was low. In terms of mechanical properties, the pre-sintered clasps exhibited the highest elongation, meeting the standards for Type 4 metals as specified by ISO 22674:2022.

The present study demonstrates that pre-sintered Co-Cr alloy discs are suitable for fabrication of clasps with good fit and mechanical properties, provided that the accuracy of the clasp tip is improved.