Which of the following can lead to the development of dental fluorosis?

The development of dental fluorosis is primarily associated with excessive exposure to fluoride during the early years of tooth development. This often occurs when young children consume too much fluoride from sources such as toothpaste, which they may ingest instead of spitting out. Fluorosis is a cosmetic condition that leads to discoloration and mottling of the enamel, and it typically manifests in children whose teeth are still forming, particularly before the age of 8.

While inadequate oral hygiene, consuming sugary foods, and reducing dental visits can negatively impact oral health in general, they do not directly cause dental fluorosis. Inadequate oral hygiene can contribute to cavities and gum disease, sugary foods can lead to tooth decay, and not visiting the dentist may allow existing problems to worsen; however, none of these factors involve an overdose of fluoride. Therefore, the excessive use of fluoride toothpaste during formative years is the primary cause linked to the development of dental fluorosis, making it the correct answer in this context.