A gold tooth a golden tooth

[ROBINDESBOIS]

what´s the slight difference in meaning?

[JPablo]

Yo diría que uno es "un diente de oro" y el otro "un diente dorado"...

Mmmmm...,

A ver que dicen los nativos.

Saludos, Robin.

[Rusty]

There is no difference between a gold tooth and a golden tooth.
Gold, when used as an adjective, means the same thing as the adjective golden.

consisting or made of gold
like gold
of the color of gold
(These meanings encompass 'un diente de oro' and 'un diente dorado'.)

Besides the meanings above, gold also means 'pertaining to gold' when it is used as an adjective.

Golden has several other meanings that the adjective gold does not have.

If you're using golden to mean something other than the meanings given above, you can't use gold as an interchangeable adjective, with one exception; gold or golden can be used to indicate 'the fiftieth in a series' (like a golden anniversary, or a gold anniversary).