(a) Except as provided in subsection (b) of this section, enrollment in Children's Medicaid Dental Services is mandatory for clients from birth through age 20. (b) The following clients are not eligible for Children's Medicaid Dental Services provided through managed care: (1) clients age 21 and over; (2) clients, regardless of age, residing in Medicaid-paid facilities such as nursing facilities, state supported living centers, or intermediate care facilities for people with intellectual and developmental disabilities; and (3) STAR Health program recipients.