(Adds details on industry, FTC complaint)
WASHINGTON, Feb 12 (Reuters) - The U.S. Federal Trade Commission said on Monday it had filed a complaint against the three largest U.S. dental supply companies, saying they had broken antitrust law.
The FTC said that Benco Dental Supply, Henry Schein Inc and Patterson Companies had conspired to refuse to serve or give discounts to dental buying groups.
The three companies sell more than 85 percent of the $10 billion in gloves, cements, chairs and other products that U.S. dentists purchase each year, the FTC said.
Buying groups representing small dental practices had asked the big dental product suppliers to aggregate sales to them and to negotiate prices, the FTC said.
Benco and Henry Schein initially entered into an agreement to refuse to compete for the buying groups' business, and Patterson joined later. Benco invited a fourth group, Burkhart Dental Supply, to join but was rebuffed, the FTC said.
"The complaint details communications between executives of the two companies evidencing the agreement, as well as attempts to monitor and ensure compliance with the agreement," the FTC said in a statement.
A complaint was filed with an FTC internal court, with a trial set to begin on Oct. 12.
Attempts to reach spokespeople for the three companies were not immediately successful. (Reporting by Diane Bartz; Editing by Susan Thomas and Sandra Maler)