Surprising this is not available on the Web: I've burrowed around and cannot find it. It is probably Hollywood slang from the 1940s, when it was common to travel across the US / Mexican border to get excellent dental work for a quarter of what you'd pay in California - remembering that anybody with aspirations to go before a movie camera must have a better-than-perfect smile.

"Tijuana Dentist" is a euphemism for crossing the border to get a quick abortion, if you happen to be an aspiring starlet who gets knocked up. In that era there was no easy path to a legal pulling of the rabbit. So if you were expecting and did not expect to expect you would tell everyone you were going to Tijuana to get your teeth fixed.
If you say "She's taken a week off to go see a Tijuana Dentist" it means the young lady in question has made a quick trip South of the Border to get a fetus yanked.
by SpeedyBB April 4, 2022
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