Dentics were small creatures, comparable in shape and size to leeches on Earth. Unlike leeches, dentics did not consume blood; rather they fed off the food remnants and bacteria in the mouths of larger species.
As such, a practical and symbiotic use was found for them. Putting one in the mouth acted to clean teeth, within a similar final effect as toothpaste, as they ate all food remnants and bacteria, prevent gum disease, and even give a minty breath, thanks to the mint-smelling urine of the creature. ("Exodus From Genesis")
There were more than one species of dentic; there was also one variety that bore a strong resemblance to beetle larvae from Earth.
They were inedible raw, and possibly poisonous or internally harmful when ingested (Ka D'Argo told John Crichton to never swallow a dentic. ("Exodus From Genesis") They could be eaten when heavily fried, but even then they had an unpleasant taste. ("Home on the Remains")
- It is possible the admonition by D'Argo was to preserve a limited supply of the creatures.