Salivary Gland Disease
Saliva serves multiple and important functions and is essential for speech and swallowing. Saliva plays an important role in maintaining oral health by maintaining the integrity of the oral mucosa. It contains a variety of proteins which have anti-bacterial activity and salts and minerals including fluoride and acts as a buffer and is, therefore, important in the control of dental caries (decay) and periodontal disease.
Saliva is produced by the three pairs of major salivary glands which are – the parotid glands in front of the ear, the submandibular glands (under lower jaw bone) and the sublingual glands (under the tongue in the floor of the mouth). In addition, there are another 600-1,000 minor salivary glands distributed widely just below the mucosal lining of the mouth and on the hard and soft palate, cheeks, lips and floor of mouth.
Salivary glands can be involved in many pathological processes, including infections, inflammatory disorders, obstruction, tumours and degenerative disorders. The most frequent problems seen due to infections, obstruction from stones, benign tumours and destructive auto-immune disease.
Specialist knowledge of dental and oral diseases is necessary for the proper management of these patients.
The mumps virus is the most frequent cause of salivary gland infection. Bacterial infection of the major glands usually arises from the mouth and is often a recurrent problem especially in a gland previously damaged by stones or irradiation or in debilitated patients.
Calculi or stones can form in the major salivary glands and their ducts. These stones may cause obstruction of salivary outflow typically with pain and swelling at meal times. If the obstruction is not relieved the gland becomes chronically inflamed and damaged and often requires an operation to remove the gland. If the stones are small, a small camera may be passed up the duct to visualize the stone and the stone may be then removed with a grasper or basket. Sometimes it may not be possible to remove the stone with this technique and an operation to remove the effected gland is required.
Obstruction of minor salivary glands also occurs resulting in cyst like swellings in the lips and cheeks.
Tumours are lumps or swellings in the gland. Lumps occur in the glands due to abnormal overgrowth of part of the salivary glands. They are not necessary cancer. The vast majority of tumours in salivary gland are benign which means that they are not cancerous and do not spread to other parts of the body. Although the majority are benign they grow relentlessly and can reach large proportions if left untreated. These lumps should be removed as there is a risk that after many years a benign lump can turn malignant. The management of salivary gland tumours requires specialised surgical skills due to the proximity of important cranial nerves and the often aggressive nature of the disease.
The salivary and lacrimal glands are subject to an auto-immune destructive condition (Sjögren’s syndrome) which results in dry eyes and a dry mouth. Sjögren’s syndrome is often accompanied by other systemic diseases such as rheumatoid arthritis, systemic lupus erythematosis or primary biliary sclerosis. Patients develop severe oral symptoms relating to failure of salivary production and approximately 10% of patients with Sjögren’s syndrome will develop a non-Hodgkin’s lymphoma. These patients require meticulous follow-up in order to detect the onset of lymphoma at an early stage when treatment is still effective.