The effect of disinfecting solutions on bending properties and weight changes of Co–Cr and Ti–6Al–7Nb alloys for dentures

We aimed to evaluate the effect of a denture cleanser and NaOCl 5.25% solution on the modulus of elasticity, the ultimate stress, and the weight changes of Co–Cr and Ti–6Al–7Nb alloys. To evaluate the modulus of elasticity and ultimate stress, 24 Co–Cr and 24 Ti–6Al–7Nb castings were fabricated, immersed in Corega Extradent, NaOCl 5.25%, or water in subgroups of six each. Thirty-six castings were produced to evaluate weight changes, 18 Co–Cr and 18 Ti–6Al–7Nb, and immersed in Corega Extradent, NaOCl 5.25%, or water in subgroups of six each. Changes in the modulus of elasticity, ultimate stress, and weight were calculated before and after immersion in the cleanser or NaOCl 5.25% solution for 45 cycles of 10 min each. Two-way analysis of variance ANOVA and Tukey’s test at ل = 0.05 were used to analyze the data. The modulus of elasticity and the ultimate stress of Co–Cr decreased after immersion in the solutions. The same properties of Ti–6Al–7Nb decreased in NaOCl 5.25% and increased in the other solutions. Weight loss was observed in Co–Cr alloy in both Corega Extradent and NaOCl 5.25%. A weight increase was observed in Co–Cr in water. An increase was observed in Ti–6Al–7Nb in Corega Extradent, NaOCl 5.25%, and water. The highest decrease (P = 0.05) in the modulus of elasticity and ultimate stress in Co–Cr were observed in NaOCl 5.25%, whereas no statistically signifi cant differences (P > 0.05) were observed in Ti–6Al–7Nb in any of the solutions. A statistically signifi cant weight loss (P < 0.05) was observed when Co–Cr was immersed in NaOCl 5.25%, and a statistically signifi cant weight increase (P > 0.05) was observed when Ti–6Al–7Nb was immersed in Corega Extradent. The Co–Cr alloy bending properties after immersion fulfi lled ADA Specifi cation No. 14 for satisfactory clinical performance.