Final answer:
Tooth discoloration in a child can be related to the intake of tetracycline antibiotics, which bind to calcium in developing teeth and cause staining.
Step-by-step explanation:
When a nurse observes discoloration of a child's teeth, the group of medications of particular concern are the tetracyclines. These antibiotics are known to bind to calcium in teeth, causing staining or discoloration when given to children during tooth development. Specifically, discoloration can occur when tetracyclines are taken by pregnant women during the second and third trimesters, or by children up to the age of 8 years, which can affect both deciduous (baby) teeth and permanent teeth as they develop.