SpongeBob and Patrick are having fun chewing on some salt water taffy at the Bikini Bottom Fair. Patrick pulls some sweets in his mouth when suddenly, he begins to feel pain and assumes that it has something to do with his teeth. SpongeBob suggests that Patrick should go to the dentist. Although Patrick doesn't want to because he's afraid of the dentist, he reluctantly goes.
At the dentist office, Dr. Mundane checks Patrick's teeth and finds that he still has a baby tooth. He tells Patrick that to make the pain stop; he needs to extract the tooth so the adult tooth can grow in its place. But Patrick refuses to let his tooth go. As they head home, SpongeBob tells Patrick about Tooth Island, a place where the Tooth Fairy sends baby teeth after being extracted from someone's mouth. Patrick still refuses to leave his baby tooth and claims that he knows what's best for it.
As time went by, Patrick continues to suffer pain in his mouth and finally decides to get his tooth to the Tooth Fairy. Squidward, who doesn't believe in the Tooth Fairy, rants that there is no such thing. He bets that if SpongeBob and Patrick could prove that if there is a Tooth Fairy, he will eat a bucket of raw chum meat, which disgusts them. SpongeBob suggests to have Patrick's tooth removed, but Patrick doesn't want to and runs away. SpongeBob pursues Patrick in a chase and finally catches him. When SpongeBob showed him photos of how SpongeBob's teeth were handled, Patrick finally decides that it's time to have his tooth removed.
Dr. Mundane successfully extracts the tooth, and at night, Patrick puts his tooth under the pillow so he can go to Tooth Island. While Patrick is sleeping, SpongeBob sneaks in to take Patrick's tooth. However, he got caught by Squidward, thinking that he proved the Tooth Fairy isn't real. Patrick was disappointed and believed that SpongeBob had betrayed him. But SpongeBob doesn't believe that and takes Patrick and Squidward to the docks. There, he shows them the real Tooth Ferry, which turned out to be a cruise ship. Patrick is overjoyed and says good-bye to his tooth. After the ship had departed, SpongeBob and Patrick punished Squidward for trying to ruin their friendship and forces him to eat a bucket of chum meat, which resulted from him in losing his teeth.
This episode aired approximetaly exactly 1 month after it's US air in Greece, on January 2, 2017 and it marked the first new episode to air in that country for the new year.
Both the final title and the original title reference the phrase "The truth, the whole truth, and nothing but the truth."
On DirecTV, this episode listed as Season 9, Episode 30 instead of Season 9, Episode 26 due to an error with "Whirly Brains" and "Mermaid Pants" was being listed as Season 9, Episode 29. Its sister episode "Mutiny on the Krusty" shares this trait.
Squidward is shown to have eight teeth when they break apart from him mouth, yet more than eight go into the ocean.