Amelia shows Dexter the brush chart that you completed and he is sad.

Hi… Sometimes I feel so blessed that together we are defeating the tooth demon. I am so proud of you for completing the chart like a champ. You have become one of my favorite kids, and I can’t congratulate you enough for performing so well. I sent a picture of your chart to the tooth demon, and do you know what happened? He lost a tooth!….
The more charts you complete perfectly, the more teeth he will lose —and if he loses all his teeth, he will get so weak, he won’t even be able to visit anyone. You have no idea how important it is for you to do well on this chart. I love you so much, my smart, kind, and intelligent friend. My unicorn wishes you well for completing the chart too. Hope to see you soon, darling.