A health insurance giant is building its ancillary benefits operation.

WellPoint Inc., Indianapolis, has acquired DeCare Dental L.L.C., Eagan, Minn., a dental plan administrator that runs dental plans for 21,000 groups with about 4 million plan members.

DeCare already has been running the dental plan marketed by Empire Blue Cross Blue Shield, New York, which is now part of WellPoint, according to DeCare.

The price of the deal was not immediately available.

WellPoint is acquiring DeCare in part because of growing interest in programs that seek to improve employees’ overall health by improving their oral health, according to WellPoint executives.