Nail biting

Nail biting
Fingers of a nail-biter.
Classification and external resources
Specialty	Pediatrics
ICD-10	F98.8 (ILDS F98.810)
ICD-9-CM	307.9
DiseasesDB	31465
MeSH	D009259
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Nail biting, also known as onychophagy or onychophagia, is an oral compulsive habit. It is sometimes described as a parafunctional activity, the common use of the mouth for an activity other than speaking, eating, or drinking.

Nail biting is very common, especially amongst children. Less innocent forms of nails biting are considered an impulse control disorder in the DSM-IV-R and are classified under obsessive-compulsive and related disorders in the DSM-5. The ICD-10 classifies the practice as "other specified behavioral and emotional disorders with onset usually occurring in childhood and adolescence." However, not all nail biting is pathological, and the difference between harmful obsession and normal behavior is not always clear.

Nail biting usually leads to deleterious effects in fingers, but also mouth and more generally the digestive system. These consequences are directly derived from the physical damage of biting or from the hands becoming an infection vector. Moreover, it can also have a social impact.

The ten fingernails are usually equally bitten to approximately the same degree. Biting nails can lead to broken skin on the cuticle. When cuticles are improperly removed, they are susceptible to microbial and viral infections such as paronychia. Saliva may then redden and infect the skin. In rare cases, fingernails may become severely deformed after years of nail biting due to the destruction of the nail bed.

Nail biting may have an association with oral problems, such as gingival injury, and malocclusion of the anterior teeth. It can also transfer pinworms or bacteria buried under the surface of the nail from the anus region to the mouth. If the bitten-off nails are swallowed, stomach problems can occasionally develop.

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