Douglas Harper's Etymology Dictionary
"having crooked, projecting teeth," 1580s) from snag (n.), perhaps a frequentative formation, + toothed "having teeth" (of a certain kind); see tooth (n.). Alternative snaggle-tooth (adj.) is from 1650s; snaggle-tooth (n.) is from 1820.
Wiktionary
a. (alternative spelling of snaggletoothed English)
Usage examples of "snaggle-toothed".
He stood firmly planted on the lowest steps of his palace, arms outspread, grinning a great snaggle-toothed grin that conveyed complete and absolute delight at the idea that the Coronal of Majipoor was to be his guest at dinner tonight.
Ten-dollar bags of heroin that turned folk into snaggle-toothed grey scarecrows with wobbly heads and dead eyes, their bodies split open with crusty scabs and running sores, scratching all over like flea-bit dogs, dreaming in their vomit, waking long enough to beg change and stumble into traffic.