Simulated furcation perforations were repaired with and without blood contamination utilizing tooth-colored mineral trioxide aggegrate (MTA) mixed with either MTA liquid (sterile water), lidocaine, or saline. Samples underwent Instron testing at either 24 or 72 hours and at 7 days. Data were analyzed using a 3-way ANOVA and post-hoc testing using Tukey's true test for significance. All of the 72-hour samples displayed significantly greater resistance to displacement than the 24-hour samples. All of the 7-day samples displayed significantly greater resistance to displacement than the 24-hour and 72-hour samples. Non-contaminated samples displayed significantly greater resistance to displacement than their blood-contaminated counterparts at 7 days. Non-contaminated samples mixed with sterile water, lidocaine, or saline performed similarly at all time periods. Allowing tooth-colored MTA to set undisturbed for 72 hours or longer prior to placement of a coronal restoration may decrease the chance of MTA displacement in furcation perforation repairs.