Supplementary Material for: Onychotillomania Dentata: A Newly Defined Oral-Induced Pattern of Repetitive Nail Trauma

Introduction:
Onychotillomania is a body-focused repetitive behavior characterized by compulsive trauma to the nail unit. While manual manipulation is well recognized, oral-induced mechanisms remain largely undocumented. We describe a novel behavioral subset involving frictional trauma from the teeth, which we term onychotillomania dentata.
Case Presentation:
An 11-year-old female presented with a one-year history of progressive thumbnail dystrophy. She reported a nighttime habit of inserting her thumbs into her mouth and rubbing the nail plates against her lower incisors in a soothing, unconscious anteroposterior motion. Signs of onychophagia were also present. Examination revealed central concavity, roughness, absent cuticle, chronic paronychia, and a macrolunula of the right thumbnail. Dermoscopy showed linear furrows and compact subungual debris. Behavioral counseling, thumb guards, and oral N-acetylcysteine (600 mg every 12 hours) were initiated. Referral to pediatric psychodermatology was made for habit-reversal training.
Discussion/Conclusion:
Onychotillomania dentata represents an oral-induced subset of onychotillomania characterized by repetitive friction. Diagnosis relies on clinical and dermoscopic findings, especially when behavioral admission is lacking. Early identification is critical to avoid misdiagnosis. Management requires behavioral interventions, pharmacologic support, and multidisciplinary care.