NCT03386643.

Trial name or title	Effect of probiotic Bifidobacterium animalis subsp. lactis HN019 on clinical, histopathological and immunophenotypic features of oral lichen planus
Methods	Parallel, double‐blind RCT Brazil
Participants	22 adults Inclusion criteria: men and women aged ≥ 18 years old, consented to participate; with symptomatic reticular lesion or white‐grey papules (or both). In afro‐descendent people, reticular lesions may be associated with hyperpigmented lesions; additional clinical features such as ulcerative, erythematous, plaque and bullous lesions will be accepted in the presence of bilateral and symmetrical reticular lesions. Histopathological inclusion criteria: presence of subepithelial infiltrate predominantly lymphocytic, in band and confined to the subepithelial area; liquefaction degeneration of the basal cells layer.
Interventions	Group A: probiotic (Bifidobacterium animalis subsp. lactis HN019) Group B: clobetasol propionate 0.05% mouthwash twice daily for 4 weeks
Outcomes	Primary: change in symptom intensity (VAS) at baseline, 15–30 days Secondary: histopathological analysis, immunohistochemical analysis, venous blood collection Quality of life (SF‐36 form) at baseline and 1 month
Starting date	6 November 2017
Contact information	Ana Carolina Fragoso Motta
Notes	Sponsor: University of Sao Paulo, Brazil