A large dental carrier has simplified its corporate structure.

Delta Dental of California, San Francisco, has merged with a major subsidiary, PMI Dental Health Plan, Cerritos, Calif.

Delta Dental acquired PMI, which underwrites and administers prepaid dental coverage in California and other states, in 1985.

PMI has been running DeltaCare USA dental plans with 1.2 million enrollees.

Another Delta Dental subsidiary, Delta Dental Insurance Company, now will run Delta Dental’s DeltaCare USA prepaid dental coverage program throughout the United States, Delta Dental says.

Delta Dental is part of a holding company system that provides or administers dental coverage for a total of 21 million U.S. residents.

Because Delta Dental and PMI combined operations long ago, the corporate merger will not require any staffing or administration changes, according to Delta Dental.