W.R. Grace has signed a definitive agreement to acquire dental silica businesses from Evonik Industries. The European Commission required Evonik to sell the businesses as a condition for approving the firm’s just completed $630 million purchase of J.M. Huber Corp.’s specialty silica operations. Set to close on Sept. 5, Grace’s deal brings a license to produce and sell Evonik’s Sident dental precipitated silica and Huber’s defoamer and anticaking agents. Grace says the transaction will strengthen its sales to toothpaste makers.