A dental medicament applicator is disclosed. In one embodiment, a retention device is sized for insertion at a dental site, such as an interproximal site. The retention device includes a body and at least one matrix within the body containing a topical substance, such as a fluoride-containing chemical agent, silver diamine fluoride, or a peptide-based chemical agent, for example. One or two wings may be selectively separably coupled to respective ends of the body. The body, in response to being physically affixed to the dental site, delivers the topical substance at a controlled rate to the dental site.