A palatal obturator is a prosthesis that totally occludes an opening such as an oronasal fistula (in the roof of the mouth). They are similar to dental retainers, but without the front wire. Palatal obturators are typically short-term prosthetics used to close defects of the hard/soft palate that may affect speech production or cause nasal regurgitation during feeding.

Source: https://en.wikipedia.org/wiki/Palatal_obturator