Oral maxillofacial pathology or oral pathology is a branch of dental science concerning the identification, diagnosis and management of diseases affecting the mouth, jaw or face. In this field of science, the causes, processes, and effects of these diseases are investigated.
Types of lesion
The different types of oral lesions include:
These are raised above the plane of the oral mucosa and may be fluid filled (blister) or solid. If a blister is 5 mm or less in diameter, it is called a vesicle and if it is more than 5 mm in diameter, it is called a bulla. Lesions filled with pus are called pustules regardless of the diameter. Elevated solid lesions are called papules if they are 5 mm or less in diameter and if they are more than 5 mm but no more than 2 cm in diameter, they are called nodules. If the elevated lesion is over 2 cm in diameter, it is called a tumour.
Depressed or pitted lesions
Depressed or pitted lesions are those found below the plane of the oral mucosa and are usually ulcers. They may have a ragged or a smooth edge and vary in diameter and depth. More than one lesion may be present or there may be a single lesion.
A flat lesions presents as a discoloured area known of as a macule. Flat lesions of the tongue are marked by areas of lost lingual papillae.
Oral cancers and pre-malignant lesions
Squamous cell carcinoma or malignant cancer is most commonly found in the lower lip, the tongue, the floor of the mouth and the soft palate. A common pre-cancer is leukoplakia. This presents as a white patch that cannot be "wiped off," as might be the case with oral candida for example. Around 85% of oral cancers begin as leukoplakia. Estimates vary according to population group, but suggest that the risk of leukoplakia developing into cancer can be as much as 20%. Leukoplakia is seen most commonly in smokers and heavy alcohol drinkers. The most common sites for leukoplakia are the lips, floor or roof of the mouth, inside of the cheek, the gums and tongue.
Erythroplakia is also a lesion that does not wipe away, only the lesion is red in colour. In more than 90% of cases, erythroplakia proves to be severe dysplasia or invasive cancer. The most common sites of the lesions are the tongue, floor of the mouth and the soft palate.