Escaping the mouth-trap: Recovery from long-term pathological lip/cheek biting (morsicatio buccarum, cavitadaxia) using decoupling

Morsicatio buccarum or lip/cheek biting (LCB) is a body-focused repetitive behavior characterized by repetitive biting or chewing of the mucous membrane of the buccal cavity, including the cheeks, the lips, and sometimes the tongue. According to the DSM–5, LCB is classified as a body-focused repetitive disorder, which in turn is a subcategory of obsessive-compulsive and related disorders. We present a case report of a 52-year-old female (henceforth referred to as AO), who started LCB approximately 40 years ago. In search of a treatment, she downloaded a self-help technique, “decoupling”, from the internet that was initially developed for trichotillomania and nail biting; for these two disorders, decoupling had yielded significant improvement in two randomized controlled trials compared to control conditions. AO modified the technique to her LCB and was able to completely stop the behavior after two days. AO's score on the Skin Picking Scale-Revised, modified for LCB, dropped from 28 points (maximum score: 36) to 0 points. We recommend relabeling the disorder cavitadaxia; the terms lip/cheek biting and morsicatio buccarum are misleading as the disorder may also involve the tongue and morsicatio buccarum relates to the somatic consequences of biting rather than the underlying disorder.