Is tongue/cheek/lip biting a dermatophagia or self injury?

A little of both... Intra-oral biting can be strictly conscious, strictly compulsive or a combination. In any of these cases it could be construed as both dermatophagia and self-injury in varying degrees as technically dermatophagia is self-injury even though it is classified as form of (obsessive-compulsive) disorder. Don't confuse this with accidental intra-oral bites which may be self or externally inflicted.
Biting. If you have broken down dentition, you might cause trauma to your tongue and cheek as well.

Related Questions

I have been constantly upset/crying my self to sleep for no reason, lip biting/cheek biting, no motivation, self harmed. HELP

You need medicalhelp. Based on your description, you need emotional support and medical help. Please share your problem with your parents and ask them to find help for you either from a Conseller or a psychologist. It is not uncommon to have such problem during teen years but there is medical help available. But you must seek help right away and not delay it. Read more...
Get help now.. You seem quite depressed and need to see a mental health professional right away. Please have a parent or a trusted adult come with you for an initial appointment. Write down all meds you take, any alcohol/drug/tobacco/caffeine use, current stresses and about when you started feeling so negative. Your pcp is a good person to ask for a referral. If you feel suicidal, go to the ER. Please get help. Read more...

How can I break a tongue and lip biting habit?

See your dentist. Have your dentist see you to check your bite. Maybe your bite may need adjusting so you won't bite your lip or tongue. Is this a habit you have? Is this something that started happening recently? Read more...
Know your enemy. The more you know about the habit, the easier it is to conquer. Find your trigger: what causes you to bite or start biting your lips/tongue? Is it physical or emotional? When does it happen? How much distraction is needed to keep you away? Knowing that every habit fills some void in your life, what is an alternative to noid the void? Your dds or md should be able to help you explore the details. Read more...

I am getting white patches inside my mouth from lip biting?

Don't bite. In all seriousness it could be related to the biting, but other things need to be considered. A dermatologist dentist or ENT physician might help clarify. Read more...