Wiktionary
gumline
n. The line along the top of the gums, where they meet the surface of the tooth
Usage examples of "gumline".
I took out my hand mirror and gave myself a ten-second scan: lower gumline, left eyelash count.
All of his teeth feel as though they have been crisply sheared off at the gumline with cold chisels.
Its long, dirty claws helped in this regard, digging in and inscribing short, jagged marks into the glossy wax as it backed up with its teeth buried to the gumlines in Gerald's flabby upper arm.