No, those are definitely her teeth. She's got the snaggletooth thing going really bad. In this larger photo, it looks like she might be sucking in her bottom lip a bit which enhances the effect.
http://www.sungsblog.com/images/kirsten-dunst.jpg
In this photo, you can see the two teeth on either side of the two middle upper's stick out a bit further.
http://rosasacidas.files.wordpress.c...00a0718071.jpg