Approx how long does it take for a health insurance company to pre-approve an oral surgery?

I'm waiting for my moms health insurance company to pre-approve the surgery to remove my wisdom teeth (they hurt, dang it) and I'm wondering about how long it should take
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Health insurance usually doesn't cover the cost of wisdom tooth extraction. That goes threw your dental insurance... and it is either approves or not approved. I Just recently got my wisdom teeth taken out under general anesthesia. It was completely covered. Mt insurance told me it was a $25 co pay but when i left they said there wasn't a co pay? good luck!!!
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