Did you check out this link for SPD? http://www.sensory-processing-disorder.com/
Thank you for your input. We are on a waiting list to see a specialist. Unfortunately, it's a very long list. The school is also concerned, but we have not been able to speed things up. I don't recall hearing of a child this age doing this. She is an emotional 12 year old. Perhaps this has to do with our moving out of province away from family. It's the only other thing I can think of, as she did not always chew on wood. If so, I 'm not sure how to help her. We visit as often as we can, however it's very expensive. It feels good to have someone to talk to. I just want to help her.
This sounds like fairly odd behavior for a 12 year old. Chewing on wood is not a criteria of ADHD. You might want to get her evaluated by a mental health professional or the school counselor to rule out emotional problems that might be contributing to this behavior.