Oral lichen planus (OLP) is a chronic inflammatory oral mucosal disease of unknown cause. The literature includes many reports on the possible association between allergic reactions and dental restorative materials. We investigated the association of OLP and oral lichenoid lesions (OLL) with amalgam filling, metal inlay or metal crown and found that the proportion of amalgam-associated lesions in lesions of patients with amalgam filling was the highest. The proportion of crown-associated lesions in lesions of patients with metal crown was higher than that in lesions of patients with metal inlay. Histopathological examination revealed spongiosis in the lesions adjacent to amalgam filling or metal crown, suggesting that spongiosis is a helpful marker to suspect the association with dental metal. These results indicate that local allergic reaction to metal restorations may be involved in the development of OLP and OLL.