Objective: was to evaluate the retentive force of clasps made from two materials cobalt chromium and nickel titanium.
Material and methods: Each of the fourteen enhanced dental stone models has a missing mandibular 1st, 2nd premolar, and 1st molar. Clasp abutment was utilised on the second molar. According to the materials used, the models were classified into two groups: group I (GI) for nickel titanium (Ni-Ti) and group II (GII) for cobalt chromium (Co-Cr). Each testing model and its clasps were placed within a universal testing machine, and the retention was determined by applying a 5 mm/min withdrawal force to it. Removal and insertion cycling of clasps was carried out for 730, 1460, 2190, and 2,920 cycles (corresponding to 6, 12, 18 and 24 months of simulated clinical use of a RPD) to simulate the retention test.
Results: Retention, after 730, 1460, 2190, and 2,920 cycles totally the difference between Ni-Ti and Co-Cr groups was statistically non-significant (P =0.03575>0.00272) where (Co-Cr > Ni-Ti).
Conclusion: When compared to nickel titanium partial denture clasps, cobalt chromium removable partial denture clasps have larger retentive forces. Nickel titanium removable partial denture clasps may be a good substitute for cobalt chromium removable partial denture clasps.
KEYWORDS: Retention, Fatigue resistance, Deformity, Nickel titanium, Partial Denture.