A child resorts to lip biting habit without primary involvement of mentalis muscle, the differential diagnosis is:
An important consideration is the necessity for making a differential diagnosis before attempting to break the lip habits. If there is class II div 1 malocclusion or an excessive overjet problem, the abnormal lip activity may be purely compensatory or adaptive to the dentoalveolar morphology. Abnormal lip activity is almost always associated with Class II div 1 malocclusion and open bite problems, and the elimination of the malocclusion usually restores normal muscle function.
Learned habit
Lack of parental care
Class II div I malocclusion
Patient is suffering from xerostomia resulting in cracked lips