How many letters does the top answer for “a vacant space, or gap, esp. between teeth in a jaw.” have?

The most common answer is diastema (8 letters).

Crossword clue: a vacant space, or gap, esp. between teeth in a jaw.

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

diastema 8 letters web-def

a gap or vacant space between two teeth

a gap or vacant space between two teeth 63% similar → diastema