Mechanical trauma to the oral lining can produce a variety of clinical lesions, depending upon the nature and circumstances of the insult. Three common red, flat lesions in the mouth are (1) the erythematous macule and erosion, (2) the purpuric macule, and (3) the granulomatous stage of the inflammatory hyperplasia.

Traumatic erythematous macules are produced by a low-grade, chronic physical insult. If the trauma is intensified, the lesions may become ulcerated. Common causes include sharp margins of teeth, defective restoration, and ill-fitted dentures. Self-inflicted trauma such as cheek biting or other habits may also cause traumatic erythematous macules.

The red color of the lesion is usually the result of increase blood circulation in the underlying tissue. The loss of part or all of the covering skin also contributes to the measures of color developed; a thick membrane obscures the underlying red color, whereas more color is transmitted through a thin one. The degree of redness is also, in part, a function of the amount of the pigment hemoglobin present in the area and the extent of its oxygenation. Red lesions frequently have a thin skin that covers numerous dilated and engorged vessels, and as a consequence, they bleed heavily after minimal trauma.

A red color can also be imparted to the tissues by another pigment, melanin. This color may vary from light brown to a reddish brown to a bluish black. The reddish brown color is seen infrequently in melanin-producing lesions.

The usual sites for erythematous macules are on the front and the side of the tongue, the floor of the mouth, the back of the palate, the cheek, and the wet surfaces of the lips. The macules may show considerable variation in the intensity of its red color. The size of the red zone corresponds closely to the size of the traumatic agent. The edges of the lesions are not usually well defined. Symptoms may vary from mild tenderness to considerable pain. The causative agent is usually identified, either through the history of the oral examination. The lesion generally resolves quickly after the cause is removed; however, if the lesion is located on the tongue, it may persist for several weeks and heal as a bald pink area. Because this lesion is basically inflammatory, it may blanch when digital pressure is applied.

There are many lesions in the mouth that have the similar clinical presentations. Therefore, when a red lesion occurs in the mouth, you need to see your dentist. Your dentist will help you to determine whether the lesion is a (1) traumatic erythematous macule, (2) purpuric macule of oral sex, (3) palatal bruising because of severe coughing or severe vomiting, (4) macular hemangioma, (5) atropic candidiasis, (6) mononucleosis and histoplasmosis, (7) herpangina, (8) erythroplakia, and (9) squamous cell carcinoma.

Once you are diagnosed with erythematous macule, your dentist should identify and remove the mechanical irritant immediately. The procedures may involve smoothing the sharp edges of broken teeth, replacing defective restorations, straigtening teeth with braces, and adjusting ill-fitted dentures. Your lesion is then kept under close observation until it disappears. Healing normally takes place in 3 or 4 days. If the lesion does not disappear in 10 days, additional workup should be done. A biopsy may be performed then to rule out more serious conditions such as erythroplakia, squamous cell carcinoma, and fungal diseases such as candidiasis and histoplasmosis.