so glad I found more information on this topic. My 3 year old daughter has this obsession with licking/chewing everything. Her latest object..... the case for my reading glasses. yuck!!! She loves fabric especially. Here I was thinking "what is wrong with my girl?" apparently it is very common. Thank you.
I teach kindergarten and of the 20 kids i have this year 6 of them chew on every thing. Pretty normal stuff for that age. Don't worry
I realize your son is only five, but have you ever asked him why he feels inclined to chew on everything? Perhaps it is simply a bad habit.
Another possibility is Sensory Integration Dysfunction. If your son feels overstimulated by his environment, he may crave a certain sensory stimulation (such as chewing), that is in his control. You also mentioned him having difficulty concentrating in class, this diagnosis can often be found in combination with Attention Deficit Disorder.
`Kestra
This is an anxiety behaviour. It does not mean that your son suffers from anxiety - perhaps he is of a nervous or cautious or sensitive nature. Our son did this until he started high school - paper, pens, books, clothes, furniture, anything and everything. It is a comforting behaviour for the child. Will the school allow gum or some other chewable during class time? I would suggest that you not draw too much attention to the behaviour but instead, try to substitute the "chewing" behaviour with another comforting habit.