Which one among the following elements/ions is essential in small quantities for development of healthy teeth but causes mottling of the teeth if consumed in higher quantities?

Fluoride is a naturally occurring mineral essential in small quantities for dental health. It helps prevent cavities by promoting mineralization, making tooth enamel more resistant to acid, and reducing tooth decay. Low levels of fluoride strengthen enamel and are often added to drinking water and toothpaste for this purpose [4]. However, excessive intake of fluoride, particularly during the developmental stages of teeth in childhood, leads to a condition known as dental fluorosis [1]. This condition is characterized by the mottling, staining, and discoloration of the enamel, ranging from opaque white spots to brown disfigurement and pitting in severe cases [4]. While it provides systemic and topical benefits for preventing caries at optimal levels (around 0.7 ppm), chronic overexposure causes structural changes in the teeth and can lead to skeletal fluorosis, affecting joints and bones [3].

Sources

1. [4] https://en.wikipedia.org/wiki/Dental_fluorosis
2. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > ag.l.s.Fluorine > p. 414
3. [3] NCERT. (2022). Contemporary India II: Textbook in Geography for Class X (Revised ed.). NCERT. > Chapter 5: Print Culture and the Modern World > A bright smile from toothpaste and minerals > p. 105