Onychophagia (pathological nail biting)is derived from the Greek words Onychos meaning nails and Phagein means to eat. Nail biting is a body focused repetitive behaviour(BFRB) which can be defined as the crossing of any digit from an individuals lips . According to the DSM-5,the Diagnostic and Statistical Manual of Mental Disorders-fifth edition, nail biting is an impulse control disorder and is classified under Obsessive –compulsive disorder(OCD) and related disorders.(APA).

Nail biting falls along a continuum from a mild,occasional behaviour with minimal impact to a frequent,intense and disfiguring clinical manifestation. Visible damage to the cuticles and nails, dermatological problems of fingers melanonychia, paronychia(infection of the nail fold), chronic swollen gums,infected gums and periodontal traumatic injuries. Malocclusions associated with dentoalveolar segment –crowding ,rotations, attrition on the incisal edges of the mandibular incisors. Non physiological forces acting on teeth can speed up resorption or cause apical root resorption. Nail biting is being associated with tempero mandibular dysfunction. Children with poor toilet hygiene, ENTEROBACTERIACAE bacteria can pose threat by penetrating the body through mouth. Bacterial infection can occur from disease of the nail such as onychomyosis and paronychia .Nail biter with oral herpes can develop herpetic whitlow of the bitten finger . Nail biting may also have undesirable psychological effect such as making people more self conscious and hence reluctant to show their hands. Its been noticed finger nail growth is increased by 20 % because frequent manipulation stimulates the circulation to the germinal area in the nail root.

The best treatment is to educate ,stimulate good habits, develop conscious awareness.Habit Reversal Training,Non –removable reminders(wristbands,bracelet that jingles) ,Self monitoring technique(smart watch application that track the positon of users hands),Aversion therapy(Bitter tasting nail polish i.e denatonium benzoate),Medication therapy(selective serotonin reuptake inhibitors,psychotropic agents, N-acetylcysteine )Healthy Nails Program(nail cosmetics ,trimmed nails), Barrier type interventions that block contact between mouth and nails such as gloves ,mittens, retainers or bite plates, dental deterrent device that prevent the front teeth from damaging the nails. Self help technique(movement decoupling),Acceptance & Commitment Therapy(ACT),Hypnotherapy.