In this task, you're given the title of a story consisting of five sentences, numbered 1 through 5. Your job is to determine which two sentences need to be swapped sentences in order to make a story that makes complete sense and is befittingly titled. Indicate your answer using the numbers of the two sentences in order, such as '34' or '25'. The first digit refers to the sentence which should come first in the story.

Title: Kevin's teeth. Sentence 1: Then Kevin went to the dentist and found out he had cavities. Sentence 2: He simply thought it was a chore he only had to do occasionally. Sentence 3: Kevin never liked to brush his teeth. Sentence 4: The many awful cavities were extremely painful to fix. Sentence 5: Now Kevin brushes his teeth regularly, every night and day.
13