Dentists and doctors are trying to figure out how a baby grew a razor-sharp tooth at mind-boggling speed.

Tara O'Byrne knew that she would be in for sleepless nights when her baby started teething, but this is next level. Her eleven-week-old son Oscar woke up with a fully formed fang this weekend.

"I went in to him around 7am. I usually give him a soother and he goes back asleep for an hour, but he kept crying," the baffled mum told the Irish Mirror.

“So I took him out and changed him but when I went to feed him, I found the tooth in his mouth. It had grown overnight.”

She immediately took him to Our Lady of Lourdes Hospital near their home in Drogheda, County Louth.

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Baby Oscar (Image via Facebook)

Baby Oscar (Image via Facebook)

At the hospital, doctors were dumbfounded.

“They were debating whether it was a tooth or not. They kept calling other doctors in - they didn’t know what to do.” 

Eventually, a specialist in Drogheda was summoned.

“We got an appointment and brought him in. I had to hold him and hold his arms down while she took the tooth out.”

But you won't believe what happened next. 

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The O'Byrne family (Image via Facebook)

The O'Byrne family (Image via Facebook)

“Whatever way the suction was caused the tooth to go up his nose. I had to wind him to get it out, but he was okay," the mum-of-two revealed.

“There were dentists coming in to take pictures of the tooth and everything. We took it home to show Oscar when he gets older.  We were terrified at first but now we’re seeing the funny side. Me and my husband were laughing about it, it’s mad - especially at this time of the year!”

Certainly not your average "trick or treat!"