Morsicatio buccarum


Morsicatio buccarum is a condition characterized by chronic irritation or injury to the buccal mucosa, caused by repetitive chewing, biting or nibbling. At times, the term is used interchangeably with its major cause, lip-cheek biting or cavitadaxia.

Signs and symptoms

The lesions are located on the mucosa, usually bilaterally in the central part of the anterior buccal mucosa and along the level of the occlusal plane. Sometimes the tongue or the labial mucosa is affected by a similarly produced lesion, termed morsicatio linguarum and morsicatio labiorum respectively. There may be a coexistent linea alba, which corresponds to the occlusal plane, or crenated tongue. The lesions are white with thickening and shredding of mucosa commonly combined with intervening zones of erythema or ulceration. The surface is irregular, and people may occasionally have loose sections of mucosa that comes away.

Causes

The cause is chronic parafunctional activity of the masticatory system, which produces frictional, crushing and incisive damage to the mucosal surface and over time the characteristic lesions develop. Most people are aware of a cheek chewing habit, although it may be performed subconsciously. Sometimes poorly constructed prosthetic teeth may be the cause if the original bite is altered. Usually the teeth are placed too far facially, outside the "neutral zone", which is the term for the area where the dental arch is usually situated, where lateral forces between the tongue and cheek musculature are in balance. Glassblowing involves chronic suction and may produce similar irritation of the buccal mucosa. Identical, or more severe damage may be caused by self-mutilation in people with psychiatric disorders, learning disabilities or rare syndromes.

Diagnosis

The diagnosis is usually made on the clinical appearance alone, and biopsy is not usually indicated. The histologic appearance is one of marked hyperparakeratosis producing a ragged surface with many projections of keratin. Typically there is superficial colonization by bacteria. There may be vacuolated cells in the upper portion of the prickle cell layer. There is a similarity between this appearance and that of hairy leukoplakia, linea alba and leukoedema. In people with human immunodeficiency virus, who are at higher risk of oral hairy leukoplakia, a tissue biopsy may be required to differentiate between this and frictional keratosis from cheek and tongue chewing.

Classification

Morsicatio buccarum is a type of frictional keratosis. The term is derived from the Latin words, morusus meaning "bite" and bucca meaning "cheek". This term has been described as "a classic example of medical terminology gone astray".
The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition states that cheek biting may be a manifestation of body-focused repetitive behavior disorder.

Treatment

The lesions are harmless, and no treatment is indicated beyond reassurance, unless the person requests it. The most common and simple treatment is construction of a specially made acrylic prosthesis that covers the biting surfaces of the teeth and protects the cheek, tongue and labial mucosa. This is either employed in the short term as a habit breaking intention, or more permanently. Psychological intervention is also reported, but does not appear to be beneficial. A self-help technique, termed decoupling, has shown benefits in a single case study.

Epidemiology

This phenomenon is fairly common, with one in every 800 adults showing evidence of active lesions at any one time. It is more common in people who are experiencing stress or psychological conditions. The prevalence in females is double the prevalence in males, and it is two or three times more prevalent in people over the age of thirty-five.