Prisoner is a legal term for a person who is imprisoned. In section 1 of the Prison Security Act 1992, the word prisoner means any person for the time being in a prison as a result of any requirement imposed by a court or otherwise that he be detained in legal custody.
To qualify for insurance coverage under the medically necessary definition, one would have to practically be skeletally deformed...in essence, one would need a whole lot more than just braces for correction. Please read the link below to read what conditions qualify for medically necessary.
To be considered medically necessary (needed to treat, correct or ameliorate a medical defect or condition,) orthodontic services must be an essential part of an overall treatment plan developed by both the physician and the dentist in consultation with each other.