When Rarity notices the sorry state of Pinkie Pie's teeth, she drags the pink pony kicking and screaming to see a dentist. During the check-up, a shocking discovery is made: Pinkie has developed an unstoppable culture of plaque that threatens to take her life! The only known cure is a legendary element spoken of in the ancient diary of an early pony dentist. So begins an adventure in search of the element needed to save Pinkie's life!