Table 1.

Characteristics of prevalence studies.

References (location)	Study type & description	Sample size	Oral lesions in total	Aphthous lesions	Xerostomia	Risk of bias
Abubakr et al. (18) (Egypt)	Questionnaire; oral complaints	573	117	N/A	273	Moderate
Askin et al. (19) (Turkey)	Prospective observational; cutaneous manifestations	210	N/A	3	N/A	High
Biadsee et al. (20) (Israel)	Questionnaire; olfactory and oral manifestation	140	N/A	N/A	72	Moderate
Fantozzi et al. (21) (Italy)	Questionnaire; xerostomia	111	N/A	N/A	51	Moderate
Fidan et al. (22) (Turkey)	Prospective observational; oral lesions	74	58	27	N/A	Low
Gherlone et al. (23) (Italy)	Retrospective and prospective cohort study; salivary gland ectasia and oral disease	122	N/A	N/A	37	Low
Khabadze et al. (24) (Russia)	Retrospective study; Changes in oral mucosa	90	N/A	N/A	N/A	High
Nuno-Gonzalez et al. (25) (Spain)	Cross-sectional study; mucocutaneous manifestations and oral and palmoplantar findings	666	78	46	N/A	Moderate
Rekhtman et al. (26) (USA)	Prospective cohort study; eruptions	296	N/A	N/A	N/A	High
Riad et al. (27) (Czech Republic)	Retrospective	1,237	N/A	21	N/A	Moderate