The Mouth and Lupus

Introduction

The mouth can be affected by lupus erythematosus in a variety of ways but the most frequently occurring conditions are mucosal patches which are found in 10-25% of cases and xerostomia, which develops in up to 30% of sufferers. The mucosal lesions usually produce minimal symptoms whilst a lack of saliva causes a number of significant problems.

Mucosal patches

The mucosal lesions of lupus range from ulcerative or erythematous patches to white keratotic plaques (Figure 1). The clinical appearance is similar to both lichen planus and lichenoid reactions. The buccal mucosal is the site most frequently affected although any area of the mouth may be involved. The mucosal lesions are often painless but some patients may complain of pain. Topical steroid mouthwash, in the form of either betamethasone (0.5mg, betnesol) or prednisolone (5mg, prednesol), held in the mouth for five minutes three times daily will resolve any discomfort. The possibility that intra-oral changes represent a lichenoid reaction rather than lupus itself must always be considered since such mucosal lesions are seen relatively frequently with the use of the nonsteroidal anti-inflammatory drugs that patients with lupus may be taking. If the onset of any oral symptoms coincides with the provision of systemic drug therapy then it may be necessary to consider an alternative medication.

Figure 1. White keratotic patch of lupus in the left buccal mucosa.

Xerostomia (Dry mouth)

Saliva is produced by three pairs of major glands (parotid, submandibular and sublingual) and numerous minor glands scattered throughout the mouth. In health, the salivary glands produce approximately 0.75 litre of saliva in 24 hours. Almost a third of lupus patients suffer from a significant reduction in the production of saliva which causes oral symptoms (Table 1) and signs (Table 2). In addition to being dry, the oral mucosa becomes erythematous and the tongue may appear lobulated (Figure 2).

Table 1 - Symptoms of dry mouth Difficulty in talking Difficulty in swallowing Loss of taste Altered taste Generalised oral discomfort Difficulty with dentures Discomfort at the angles of the mouth

Table 2 - Signs of dry mouth Absence of saliva or frothy saliva Erythematous mucosa Lobulated tongue Dental caries, particularly at the cervical margins Fracture and loss of dental restorations Erythematous and pseudomembranous candidosis Angular cheilitis

Figure 2. Lobulated appearance of the tongue as a result of xerostomia.

Investigation of xerostomia

The presence of a dry mouth can be crudely assessed by either simply looking in the patient's mouth to see if saliva is pooling behind the lower incisors or by placing the face of a dental mirror against the buccal mucosa (the mirror will stick to the mucosa if salivary levels are reduced).
In addition to these simple tests, a number of special investigations have been developed to detect reduced salivary production. Such special techniques include measurement of salivary flow rates, sialography, scintiscanning, serology and labial gland biopsy. The extent to which each of these tests is used will depend on an individual patient's history and the availability of the required facilities.

• Salivary flow rates
  The measurement of salivary flow rates is known as sialometry. Flow rates may be assessed either as "resting" or as stimulated. Collection of saliva from the parotid glands is achieved by the use of specifically designed collection devices (Carlsson-Crittenden cups) that are placed over the right and left parotid duct orifices. The cups are held in place by suction and salivary flow collected (resting flow). For the measurement of stimulated flow rates, salivary production is encouraged by placement of 1 ml of 10% citric acid on the dorsum of the tongue. A flow of at least 0.7 mI/min over a period of five minutes would be considered normal, less than this value is indicative of reduced salivary function. Assessment of flow rates from the submandibular gland is more complicated and is usually only used for research purposes.

• Sialography
  Sialography is a method of demonstrating the structure of the salivary duct network of either the submandibular or parotid gland. The technique is based on the infusion of a water-based radio-opaque contrast medium into the main excretory duct. The medium is usually introduced using a syringe and polythene cannula inserted into the excretory duct orifice. Radiographs, consisting of a lateral oblique and antero-posterior view, are taken whilst the patient feels the gland filling.
  Sialography is an invaluable method of demonstrating structural abnormalities within the salivary tissues. A "snow storm effect", known as sialectasis, is a characteristic finding in lupus due to pooling of the medium within the gland. Sialography is basically a safe and simple procedure, the only contra-indications being allergy to iodine or the presence of acute infection in the gland.

• Scintiscanning
  Radioisotopic study of salivary glands is based on the ability of active tissues to selectively uptake radioisotopes from the bloodstream. The isotope is introduced intravenously and the head/neck subsequently scanned by methods which are able to pick up isotopic emissions. This technique allows measurement of uptake and, therefore, provides an assessment of salivary gland function.

• Serology
  Immunological investigation of venous blood can be used to demonstrate the presence of specific autoantibodies associated with salivary gland disease including anti-Ro (SSA), anti-La (SSB) and anti-salivary duct antibody.

• Labial gland biopsy
  Sjögren's syndrome comprises of dry mouth and/or dry eyes in combination with a connective tissue disorder, such as lupus. Histopathological examination of the minor salivary glands within the lower lip is the single most specific diagnostic test for confirmation of Sjögren's syndrome and, therefore, can be used to confirm a diagnosis of lupus. The minor glands lie superficially behind the lower lip and can be collected simply under local anaesthesia by making a linear excision through the labial mucosa. At least five lobules of salivary tissue should be obtained since not all minor glands show the histopathological features of the condition.

Treatment of xerostomia

Treatment of dry mouth must not only involve attempts to replace the lack of saliva by the use of salivary substitutes or stimulants but should also include measures to minimise secondary problems, in particular dental caries (Figure 3).

Figure 3. Fracture of dental restorations and caries due to xerostomia.

• Salivary substitutes
  A number of salivary substitutes, based on either methylcellulose or gastric mucin, are available in the British National Formulary (Table 3).

  Table 3 Substitute Base Comments Artificial saliva BNF Methylcellulose Cheap Glandosane Methylcellulose Low pH, not suitable for dentate patients Luborant Methylcellulose Good pH, contains fluoride Saliva Orthana Mucin Good pH, contains fluoride

  Although the use of salivary substitutes may appear to offer a simple answer to the problem of dry mouth, any benefit gained is usually short-lived and, consequently, patients often resort to the use of salivary stimulants as an alternative.

• Salivary stimulants
  A number of methods of stimulating secretion of saliva have been suggested. Many sufferers of xerostomia resort to eating traditional boiled sweets in an attempt to relieve the dryness. However, it is important to tell such patients to stop this habit since the sugar intake will dramatically encourage dental caries. Saliva flow can be safely encouraged by the use of sugar-free chewing gum or diabetic sweets. Pilocarpine is a drug that has been recommended for the treatment of dry mouth following radiotherapy and has also been used in patients with lupus. Pilocarpine can be given in tablet form at a dose of 5mg two or three times a day. However, although pilocarpine does increase salivary flow it also results in excretion by other exocrine glands and patients complain of excessive sweating or tear production. Such unwanted side effects combined with a number of medical contraindications or other side effects limit the usefulness of pilocarpine. A glycerine and lemon based mouthwash can be effective in edentulous patients although it must not be given to sufferers who have natural teeth since the low pH will encourage dental caries.

• Oral hygiene
  Rigorous oral hygiene measures and preventive regimens, especially topical fluoride therapy, should be instituted as reduced amounts of saliva will predispose to an increased incidence of caries. In addition, it is essential that patients remove any dentures at night and clean them daily with soap using a small soft brush to dislodge food debris.

• Fluoride mouthwash
  The use of a daily mouthwash containing sodium fluoride 0.05% will help reduce dental caries.

• Dietary advice
  The patient should be asked to complete a diet diary over a four-day period (including a weekend). Subsequent dietary advice must concentrate on minimising cariogenic items, particularly sweetened drinks including tea and coffee.

• Other measures
  Dry or cracked lips can be improved by use of a petroleum-based ointment such as vaseline. Patients who complain of thick or sticky saliva may gain some relief from the regular use of a mouthwash consisting of baking soda (1 teaspoon) and salt (1/2 teaspoon) in water (1 litre). Interestingly, symptoms of dry mouth have been anecdotally reported to respond to the provision of evening primrose oil at a dose of 1000mg daily.
  The use of drugs that are known to reduce salivary flow, in particular tricyclic antidepressants, such as dothiepin and amytriptyline, should be avoided in patients with dry mouth.

Infection

Approximately 40% of the adult population harbour candida in their mouths as part of the commensal oral flora. Reduced salivary flow can lead to an increase in the numbers of candida resulting in opportunistic oral candidoses. The clinical presentation may be either white pseudomembranes (thrush) or erythematous atrophic areas of mucosa. Candidal infections are particularly frequent if the patient wears dentures. Topical antifungal agents are of little or no benefit in the management of oral candidosis and, therefore, it is preferable to provide a seven-day course of systemic fluconazole (50mg daily). The need for denture hygiene should be stressed if there is evidence of candidal infection. Full dentures should be placed in a dilute solution of hypochlorite at night for approximately three weeks. Partial dentures with metal components should be placed in chlorhexidine.

Opportunistic bacterial infection may develop in the salivary glands, particularly the parotid glands, due to reduced flow of saliva down the excretory duct. Acute infection presents as a painful swelling of the affected gland accompanied by a discharge of pus at the main duct orifice. Oral amoxycillin is the antibiotic therapy of choice whilst erythromycin should be used in patients with a hypersensitivity to penicillins.

Dr. Michael A. O. Lewis
Reader and Consultant in Oral Medicine
Dental School
University of Wales College of Medicine
Heath Park, Cardiff, CF44XY