Fellow 135-pound contender Anthony Leone has agreed to replace Silva. The fight is scheduled to headline Bellator 111 at Winstar World Casino in Thackerville, Okla.
The promotion originally offered the opportunity to recent tournament winner and former featherweight champion Joe Warren, who ultimately turned it down due to injury.
"After we heard the news on Silva, we immediately made the call to our other bantamweight tournament winner, Joe Warren," Bellator CEO Bjorn Rebney said. "Joe informed us he was still rehabbing a previous knee injury and would be unable to compete on the March 7 card."
Leone (13-6) is coming off a unanimous decision loss to Silva in a tournament final in October. The loss snapped a four-fight winning streak for Leone.
Dantas (15-3) hasn't fought since winning the Bellator title with a second-round knockout of Marcos Galvao last February. The Brazilian is 5-0 in Bellator but did suffer a loss outside the promotion to Tyson Nam in August 2012.