My teenage son hangs around with a young lady, "Berta," who seems interested in him. She is a little on the quiet side but seems pleasant and would be pretty if she would only brush her teeth. She has not brushed them in over a year.

Berta's parents have talked to her, my son has talked to her, her girlfriends and sisters have all talked to her, too, but Berta says she does not want to brush and has decided she is just not going to.

I would like to know if there is a type of mental illness that would make her toothbrush phobic. So far, my son is keeping his distance, and he would be embarrassed to have her as a girlfriend. Does she hate herself or feel like she doesn't deserve to have nice teeth? － Seeing GreenDear Seeing Green:

There are myriad dental phobias. Berta might once have gagged while brushing, she might fear the dentist or worry about damaging her teeth. It's also possible she is deliberately trying to repulse an abuser. Someone (a parent, preferably) should discuss this to determine the cause of her reluctance and, if it's a phobia, work on techniques to overcome it. If it's abuse, Berta will need to see a therapist. And the police.