What is the problem with children sucking their fingers?

Patient's question:

Month
Detailed medical history and purpose of consultation: Anorexia
Duration of this illness: 1 week
Current general condition: Finger sucking, anorexia
Medical history: None
Previous diagnosis and treatment history and effectiveness: Ineffective
Auxiliary examinations:

Doctor's answer:

Hello, some children have the habit of biting or licking their nails, and some continue to bite their nails even when they grow up, or even fail to control themselves as adults. Generally, the habit of biting nails often starts with the thumb and index finger, and the duration of biting is also short. However, as it develops, not only does the duration increase and the frequency increase, but it also affects all ten fingers. The long-term result of biting nails often leads to varying degrees of damage to the nail plate. Moreover, since the biting area is different, the damage is also different. If the free end of the nail is bitten, the damage is often manifested as the shortening of the nail plate, resulting in a short and bald front edge, with uneven and sawtooth-like edges.