OLDWICK, N.J.--(BUSINESS WIRE)--A.M. Best has upgraded the financial strength rating (FSR) to A (Excellent) from A- (Excellent) and the issuer credit rating (ICR) to “a” from “a-” of Renaissance Life & Health Insurance Company of America (RLHICA) (Indianapolis, IN), an affiliate of Delta Dental Plan of Michigan, Inc. (DDMI) (Okemos, MI). Concurrently, A.M. Best has affirmed the FSR of A (Excellent) and the ICR of “a” for DDMI and its affiliates, Delta Dental Plan of Ohio, Inc. (DDOH) (Dubli