Definition Lichenoid reactions are a heterogeneous group of lesions of the oral mucosa that show clinical and histopathological similarities to lichen planus, but have a different course.
Etiology Hypersensitivity to dental restorative materials, amalgam, composite resins and dental plaque accumulation are the most common causative factors. Rarely, a reaction to drugs may be responsible.
Clinical features Clinically, they appear as white and/or erythematous lesions, usually associated with peripheral delicate white striae (Fig. 8).
Erosions are also common (Fig. 9). The lesions mimic erosive lichen planus. Characteristically, the lesions are strictly confined to the mucosa directly in contact with the restorative materials, and do not migrate to other sites. The lesions disappear after removal of the adjacent material.
The diagnosis is usually made clinically.
Laboratory tests A skin punch test may be helpful in some cases.
Differential diagnosis Lichen planus, fixed drug eruption, discoid lupus erythematosus, cicatricial pemphigoid, cinnamon contact stomatitis.
Treatment Replacement of the restorative material, polishing and smoothing, and good oral hygiene are recommended.
Topical steroid treatment for a short time is also helpful.
Fig. 8 Lichenoid reaction to dental amalgam and cold – white and erythematous
Fig. 9 Lichenoid drug reaction to allopurinol – white hyperkeratotic lesions and superficial
