That's a tough message for any 8-year-old to hear-and the tooth fairy's grievances about the tooth got pretty specific.
Just ask Sam Warren, an 8-year-old boy who almost lost out on some cash because of his weak brushing habits.
After losing one of his teeth, Sam did the usual thing of sticking it under his pillow for the tooth fairy to collect - hopefully in return for some money.
It said that if the child doesn't start taking better care of his teeth the Tooth Fairy would "withold payment." .
"We expect a certain amount of wear and tear on the teeth we appraise. However in this case your tooth had to be referred up to the committee for further analysis", the letter reads.
The eight-year-old's dad Henry Warren took the opportunity to address his son's poor brushing technique and dental hygiene, in the form of a typed letter.
Barry T. Tooth Fairy says the tooth will be accepted on this occasion, but payment may be withheld in the future should the condition of the next tooth not be "significantly better".
As for the tooth in question, Warren tweeted that sadly there are no photos available, as "Barry has that now".
"The tooth was substandard, what would you have done?" he argued.
But one dad figured out the flawless solution: his son woke up to find a letter from the "tooth fairy" about dental hygiene, and we are certain all parents will applaud.
Henry Warren said he and his wife of almost 10 years Emma encourage their two oldest children - 8-year-old Sam and 5-year-old Alexa-Mae - to practice good dental hygiene.
Mr Warren's letter has since gone viral with more than 5100 re-tweets and 15,000 likes with many praising his parenting skills. But Barry said the response he's received has been "appalling". "Mr. Warren, I have to inform you that this is due to the condition in which we found said tooth".
He said the pay is bad and the hours, long and lonely.