The medical term is onychophagia but it is more widely simply called nail biting and it is a habit that an estimated 50% of children and young teenagers indulge in. Most will grow out of the habit while for others it can last a lifetime -- and can have a negative impact on oral health, leading to problems such as:
Damaged tooth enamel. Fingernails are composed of a hard substance called keratin and constant nail biting can chip away at tooth enamel and cause teeth to shift.
Increased plaque and oral bacteria. Germs on the fingernails adds to the level of bacteria in the oral cavity and nail- biters also have higher amounts of plaque than those who do not indulge in the habit.
Temporomandibular joint problems. The additional stress on the temporomandibular joint (TMJ) can lead to a range of TMJ disorders, including jaw pain and headaches.
Nail biting is a medical or mental disorder and not one that can be treated by a dentist. However, it can lead to dental issues and should be discussed with your dentist. Learn how to quit the habit to support your oral health and prevent unnecessary damage to the teeth or TMJ.
Read more at https://yourdentalhealthresource.com/does-biting-your-nails-hurt-your-teeth/