Clean Slate is the sixteenth episode of the third season of Braceface
During her visit, Petra rather casually admits to the long past "crime" of ripping all the heads off of Nina's dolls, the blame for which had fallen upon Sharon Spitz, despite having had no proof that Sharon did it. Now realizing what really happened and that she had been mean to Sharon for nothing all those years ago, Nina makes an effort to renew her friendship with Sharon. Initially, Sharon was reluctant but tried to go along with it if it could have meant the end of Nina's abuse towards her and her friends. However, Sharon soon learned the only thing potentially worse than being Nina's enemy was being her friend.
During the course of their time spent together, Sharon realized she and Nina have grown too far apart and just could no longer be compatible friends anymore, and in the end Sharon chose Maria, Connor, Alyson, and Brock as her friends over renewing her friendship with Nina.
Nina gets mad at Sharon for choosing the others over her, and they went back to being enemies again, which no longer bothered Sharon as she actually preferred it over being "friends" with Nina.
CLAIRE: I'm sorry. Do...you...exist?
SHARON: I'm Sharon. Nina invited me.
CLAIRE: Yeah, right!
LANIE: I think the dentist cranked her braces too tight! (Giggles)
NINA: Sharon! Claire and Lainie are such kidders!
LANIE: Of course I'm kidding! (Giggling). I love braces.
CLAIRE: (Laughing) I want braces!
NINA: Come on, girls. Let's get Petra and head to the movies.
- This is the only appearance of Nina's cousin, Petra, the true culprit behind the doll incident.
- Petra reveals that she had done it simply because Nina's dolls were better dressed than her own dolls.