<https://data.doctorgenius.com/definition/orthodontist/hawley-retainer.rdf>
<http://schema.org/description>
"A Hawley retainer is a type of removable retainer made from wire and acrylic. A thin wire runs on the outside of the front or bottom teeth and is attached to an acrylic or plastic base shaped to fit the roof of the mouth or inside the lower teeth."
<https://omanaortho.com/salt-lake-city-ut/removable-retainers/>