ST. LOUIS — A St. Louis-based Catholic health care provider has finalized its merger with a Wisconsin health company. SSM Health Care announced its purchase of the Dean Health Systems group of Madison, Wis., in April. The merger took effect on Sept. 1 after receiving regulatory and shareholder approval The nonprofit SSM operates 18 hospitals in Missouri, Illinois, Wisconsin and Oklahoma. Dean Health Systems is a physician-owned organization with more than 60 clinics, plus eye care and pharmacy operations.