Final answer:
Excess fluoride can cause dental fluorosis, which leads to white spots, streaks, or stains on the teeth.
Step-by-step explanation:
Excess fluoride can damage the teeth, causing dental fluorosis. Dental fluorosis is a condition that occurs when excess fluoride is ingested during tooth development. It can result in white spots or streaks on the teeth, or in more severe cases, brown stains, pitting, and enamel loss.