There are both central and peripheral causes of masticatory dysfunction. First, the central factors. It is caused by the nerves in the skull, the nerves in the human skull innervate all physical activities, the lesion of the nerves in the skull will lead to the mastication function can not be carried out properly. Second, then there are peripheral factors, peripheral factors there are many kinds of factors. 1, is the dental factors. 2, is the temporomandibular joint factors, these two factors can also lead to chewing dysfunction. 3, psychological factors, psychological factors are also very common, because of psychological problems lead to their own will not eat, will not chew.