The above is a 7 year old girl. Notice in the photo that she has a chipped lateral incisor (damage from clenching).
The four tooth anterior deprogrammer (in the lower photo) was use every-other night for several weeks before the kid stopped clenching. This type of clenching is rare, but treatable when the upper incisors have fully erupted.
Anterior deprogrammers are described in “A Guide For TMJ-Type problems”, a book about treatment for occlusomuscular problems.