As of April 2015, only children are guaranteed coverage under Medicaid. States are free to determine their own coverage requirements for adults, but there are no minimum requirements.
Minimal coverage requirements for children include relief of pain and infections, maintenance of dental health and restoration of teeth. States are free to determine what treatments are medically necessary. States that provide CHIP coverage to children through a program that is separate from Medicaid can develop their own benefits packages within certain requirements.
Most states provide emergency coverage for adults who are on Medicaid. Less than half the states provide comprehensive dental coverage, however.