Is Burning Mouth Syndrome Associated with Extraoral Dryness? A Systematic Review

Burning mouth syndrome (BMS) is characterized by a persistent intraoral burning sensation, often experienced by postmenopausal women. The etiology of BMS remains partially understood, and consequently, treatments remain suboptimal. Extraoral manifestations of BMS, such as extraoral dryness, are less studied. However, it has been suggested that the identification of the frequency and patterns of extraoral dryness and potential underlying mechanisms are essential to optimize treatment strategies and reduce the burden of disease. Therefore, we conducted this systematic review to provide existing evidence about extraoral dryness in BMS. The guidelines for the conduction and reporting of systematic reviews were followed. An electronic search was conducted in four major databases-PubMed, Web of Science, COCHRANE Library, and EBSCOhost-and the grey literature was assessed through Google Scholar. From each included article, information on extraoral dryness in BMS was extracted, and odds ratios were calculated for extraoral dryness among BMS patients compared with non-BMS controls. The findings demonstrated higher odds of the prevalence of extraoral dryness in BMS, which was found to a high degree in the lips, eyes, skin, and genitalia. The pattern of spread and locations of extraoral dryness propose a potential central mechanism. Based on our findings, we encourage the standardization of the assessment, recording, and reporting of the extraoral characteristics of BMS, including extraoral dryness, which can lead to better management strategies and enhance the quality of life of the affected patients.