I know of oral motor problems with sensory integration disorder which is also a nervous system disorder that looks like ADD/ADHD in behavior but is a little different. Sensory can be by itself and it can also be a secondary problem to ADD/ADHD.
Oral motor issues make speaking tough as it takes lots of coordination to make those mouth muscles work. Also, chewing can be tough especially on items like meat. It can be as extreme as a child drooling. Also, kids with sensory soothe themselves orally. They like to suck and chew on things like sleeves, collars, anything they can get in their mouths.
An occupational therapist usually can help with this issue.