Xerostomia in Patients With Oral Lichen Planus: A Review

Oral lichen planus (OLP) is a chronic mucocutaneous disease that commonly involve oral mucosa. In this disease, frequent lesions in different areas of the mouth can be seen bilaterally and mostly with a similar pattern. The World Health Organization (WHO) classifies OLP as a potentially premalignant disorder with an uncertain risk of malignant transformation, and recommends that patients should be carefully examined. Xerostomia and hyposalivation are common complications of OLP. Saliva composed of water, electrolytes and organic micro and macro molecules and plays many roles. It is one of the main factors in maintaining the health and integrity of the oral mucosa and teeth. Helping to digest food and have a sense of taste, mechanical protection of the oral mucosa, and eliminating oral microbes are other important roles of saliva. The symptoms of xerostomia and hyposalivation include bad breath, burning feeling in the mouth, trouble swallowing or speaking, and altered sense of taste. As a result, xerostomia and hyposalivation can significantly reduce the quality of life of people with OLP. The main mechanism of xerostomia in OLP patients is still unknown, and there is scant research in this field. This study aims to review the studies related to xerostomia in patients with OLP and its related possible mechanisms.

 To find articles related to OLP, a search was conducted in Medline, Scopus, Embase and Web of Science databases on studies related published from 1965 to 2021 using the keywords oral lichen planus, xerostomia, hyposalivation, salivary gland hypofunction, and Oral dryness. include articles were clinical studies on the relationship between OLP and dry mouth/xerostomia with well defined study design and methodology (e.g. diagnosis of OLP by clinical and histopathological studies, use of age- and gender-matched case and control groups since they can affect the characteristics of saliva, and correct saliva extraction).

In this study, 8 articles were finally selected based on entry criteria. These articles were about the histopathological examination of salivary glands, evaluation of salivary compositions, saliva flow rate assessment, and feeling of dry mouth using a questionnaire. Their specifications are presented in Table 1.

Discussion :

The relationship between OLP and xerostomia has been shown in many studies. Various mechanisms have been proposed in this regard. The mentioned mechanisms were the inflammatory and autoimmune disorders of the sensory nervous system, changes in saliva composition, and changes in saliva flow rate. The changes in the surface characteristics of the oral mucosa due to the presence of inflammation cause the sensation of dry mouth in patients with OLP. It was shown that the presence of inflammation in the oral mucosa causes xerostomia even with normal saliva flow rate in patients with OLP. Chronic mucosal inflammation in OLP can endanger the integrity and function of the oral mucosa by affecting the normal absorption and secretion of mucous fluid and electrolytes, which is effective in the occurrence of xerostomia. The loss of the epithelium of the oral mucosa, which is observed in the wounds, causes disturbance in the formation of oral mucosal pellicle, which has a role in making the oral mucosa slippery. The heat associated with the inflammatory response can increase the surface evaporation of mucus and eventually cause xerostomia. Therefore, patients with OLP experience some degree of xerostomia. The control of xerostomia in patients with OLP should be taken into consideration by the clinicians; it can greatly help relieve the symptoms of OLP.