Assessing Salivary Gland Hypofunction—Part I
Brian C. Muzyka, DMD, MS, MBA
Xerostomia is a subjective complaint of many dental patients. In fact, a significant proportion of the population routinely reports symptoms of dry mouth or difficulty swallowing. These symptoms are usually transient and related either to medication use, psychological state, viral infection, or dehydration. While xerostomia may be associated with salivary gland hypofunction, this condition alone is not a reliable predicator for salivary gland hypofunction.
Determination of whether the salivary gland hypofunction is the cause of the symptoms of dry mouth is indeed a difficult task. A thorough review of the history and pattern of the complaint, medical history, medications, and a detailed clinical examination are necessary. It is helpful to determine the onset and severity of the symptoms, and the clinician should be aware if the symptoms are transient or chronic in nature, if occurrence patterns (eg, dry mouth on wakening, increased dry mouth as day progresses) are evident, or if liquids are required to swallow foods when eating.
Dry mouth on wakening is normal, as salivary output during sleep is at its lowest’ symptoms as the day progresses may indicate mouth breathing, excessive awareness, or a less severe form of hypofunction. Relatively reliable indicators of gland hypofunction would include difficulty swallowing food, a feeling of dryness while eating, and the need to sip liquids during meals.
Quantifying salivary output is a difficult task, particularly when the procedure is not performed routinely. There are , unfortunately, no standardized, objective evaluations available to determine salivary gland output. Conflicting data on whole, parotid, submandibular, unstimulated, and stimulated salivary output exists. It is generally accepted that patients with whole, unstimulated salivary output of less than 0.12 mL to 0.16 mL/minute have gland hypofunction and are subject to a higher rate of oral hard and soft tissue complications.
Navazesh et al have also established a set of clinical measures that are helpful in determining hypofunction.1 These measures include dryness of the buccal mucosa, the total number decayed, missing or filled teeth, the absence of saliva from duct orifices upon expression, and dryness of the lips.
The determination of the cause of salivary gland hypofunction is difficult and often multifactorial. Prescription medicines (eg, antidepressants, antihistamines, certain antihypertensives, neuroleptics, and parasympatholytics) have often been associated with this condition, and various prescription medications not directly attributed to causing dry mouth can also influence salivary gland output.2 Dry mouth can also be caused by a variety of systemic diseases (eg, poorly controlled diabetes mellitus, sarcoidosis, amyloidosis, HIV, Hepatitis C, Sjogren’s syndrome). Radiation to the head and neck region and graft versus host disease following transplant may also cause dry mouth.
If the medications are not a cause of salivary gland hypofunction, the clinician should refer the patient to a physician for appropriate evaluation. Diagnostic tests are available to determine diabetes, Hepatitis C, HIV, sarcoidosis, and amyloidosis. Sjogren’s syndrome can also be detected using laboratory assays that are helpful in diagnosing the disease, particularly when used in conjunction with labial salivary gland histopathology and results of the opthalmological exam. Sjogren’s in the presence of other rheumatoid type diseases is referred to as a secondary Sjogren’s syndrome; Sjogren’s in the absence of other rheumatological diseases is considered primary Sjogren’s.
Saliva functions as a mucosal lubricant to aid in mastication and phonetics. Saliva protects the oral tissues through provision of antimicrobial activity, maintains a neutral oral pH, and serves as a reservoir for calcium and phosphate, which are required for remineralization. Saliva also enhances taste capacity and aids in the digestive process. Loss of adequate salivary gland function can be devastating to the patient. Moreover, such a loss leads to a very difficult situation for the dental clinician to manage.
*Director of Hospital Dentistry, Division of General Dentistry, East Carolina University School of Dental Medicine, Greenville, NC
- Navazesh M, Christensen C, Brightman V. Clinical criteria for the diagnosis of salivary gland hypofunction. J Dent Res 1992;71(7):1363-1369.
- Wu AJ, Ship JA. A characterization of major salivary gland flow rates in the presence of medications and systemic diseases. Oral Surg Oral Med Oral Pathol 1993;76(3):310-316.