all but flaunting his ruined dentition

[suprunp]

After one more smile, all but flaunting his ruined dentition, Ushikawa turned and left the reception room.
(H. Murakami; 1Q84)

I suppose that it should mean something like "which could mean anything but/the purpose of which could be anything but".

Am I right?

Thanks.

[J&K Tutoring]

all but = practically

[Preceptor]

"Since he showed her one more smile, he seemed to be proudly showing his bad teeth..."

That is how the sentence would be rendered in conversational American usage.

[5jj]

all but = practically

I agree, to an extent.

There is a very slight ambiguity in the original sentence (as there would be with 'practically').

I think Preceptor's paraphrase is the more likely, but, In my opinion, it is not clear whether he did not show his teeth, but came close to doing so (in a flaunting manner) or he did show his teeth - in a manner that was close to flaunting.