OREANDA-NEWS. A.M. Best has affirmed the financial strength rating (FSR) of A (Excellent) and the issuer credit ratings of “a” of Delta Dental Plan of Michigan, Inc. (DDMI) (Okemos, MI) and its affiliated group of Delta Dental plans, Delta Dental Plan of Ohio, Inc. (DDOH) (Dublin, OH) and Delta Dental Plan of Indiana, Inc. (DDIN) (Indianapolis, IN).