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 beloved fashion dolls. Nina's shocked to hear this, as she had always assumed that friend-turned-nemesis, Sharon Spitz, had done it (despite never having any actual evidence to prove it). Now realizing the truth, and the fact that she's wasted so many years being mean to Sharon for nothing, Nina decides to try and reconcile with Sharon. Hesitant but realizing that it could mean the end of Heather's abuse towards herself and her friends, Sharon decides to go along with it. However, Sharon soon realizes that the only thing potentially worse than being Nina's enemy is being her friend.
In the end, Sharon decides that a friendship with Nina just isn't going to work--at this point, they've grown too far apart to make truly compatible friends. Sharon also realizes that she'd much rather be friends with people like Maria, Connor, Alyson, and Brock, who, as it would seem, were afraid that Sharon was going to choose Nina over them.
Sharon's decision, of course, makes Nina mad, but Sharon doesn't care--in fact, Sharon figures that, at this point, she and Nina are probably better off as enemies than friends. The episode ends with Sharon admitting in voiceover (after Nina gave her the head of one of her old dolls as revenge), "Even though I hadn't decapitated Nina's dolls when we were little, a part of me kind of wishes I had."
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.
- It's revealed that at least part of the reason why Petra had decapitated Nina's dolls was because she was jealous that Nina's dolls were better-dressed than her own dolls.