Nail biting (onychophagia)

Nail biting (onychophagia) is a common oral habit in children and young adults (1,2,3,4)

• nail biting is rarely noted in children younger than 3-6 years, whereas it is quite common around puberty
• estimated that 20-33% of children between the ages of 7 and 10 years and 45% of adolescents are nail-biters
• aetiologies suggested for nail biting include stress, imitation of other family members, heredity, transference from the thumb-sucking habit, and poorly manicured nails
• nail biting is usually confined to the fingernails and most nail-biters bite all of the fingers equally rather than selectively
• in most cases, it is of cosmetic concern only; however, if not controlled, it can lead to serious morbidity
• complications of nail biting include
  • damage to the cuticles and nails, dermatological problems of fingers such as melanonychia, self-inflicted gingival injuries and gingival swelling, dental problems such as increased incisal wear and apical root resorption. In addition, osteomyelitis has been reported in a phalanx as a result of chronic nail biting (4)
  • secondary bacterial infection can occur from diseases of the nail such as onychomycosis and paronychia, and nailbiting might spread the infection to the mouth. Conversely, a nailbiter with oral herpes can develop herpetic whitlow of the bitten finger

Management:

• some people spontaneously quit previous onychophagia because of fear of developing infections; others quit to imitate friends who have attractive nails
• as a rule, no treatment is needed for mild cases of onychophagia
• for more serious situations, treatment should involve removal of the emotional factors inducing the habit (excitement, overstimulation, unhappiness, idleness, for example)
  • application of a bitter-tasting commercial preparation to the nail is often ineffective
  • use of occlusive dressing on the fingertips and wearing mittens or pajamas that cover both the hands and the feet are a variety of reminders and should only be used with the consent and cooperation of the child
  • keeping the nails well trimmed is another useful measure, so that poorly trimmed corners and cuticles are not temptations
  • an effective alternative to overcome the problem is to ask the patient to use the rubber bite piece when he or she feels the urge for nailbiting or has anxiety (watching films, TV, athletic games, pretest tensions). Chewing sugar-free gum, if not compulsively done, could also be a way to keep the mouth occupied and render the habit difficult or impossible
    • as the patient gets used to the rubber biter or the gum rather than the nail, the professional should ask the patient to let 1 fingernail grow. The nails on the other fingers are free to chew on, if the desire remains. After that, the number of intact nails can be gradually increased

Reference:

• 1) Tanaka OM, Vitral RW, Tanaka GY, Guerrero AP, Camargo ES. Am J Orthod Dentofacial Orthop. 2008 Aug;134(2):305-8
• 2) Tosti A et al. Phalangeal osteomyelitis due to nail biting. Acta Derm Venereol 1994: 74: 206-207
• 3) Vogel LD. When children put their fingers in their mouths. Should parents and dentists care? N Y State Dent J 1998: 64: 48-53
• 4) Waldman BA, Frieden IJ. Osteomyelitis caused by nail biting. Pediatr Dermatol 1990: 7: 189-190.