Sir, my15year old has habit of bitting inner surface of mouth.does it cause small mouth infection...???

Could: This is certainly possible, as any break in the skin is at risk for infection. I would not say it is typical, however. If there is any fever, or increased swelling in the area, pain to touch, then he should be examined and potentially prescribed antibiotics. I would ask about the underlying issues causing the biting? Is this a nervous habit? Does he feel relief after biting?

It can...: If the teeth puncture the soft tissues, then bacteria from the mouth may be introduced into the mucosa, causing an infection.

If this continues: it may be a symptom of anxiety or an obsessive habit. Consider speaking with a psychologist to help her stop this behavior.

Mouth biting: Very unusual to get mouth infection unless from tooth infection . Try to distract him with chewing gum to try and stop chewing his inner mouth.