Deficiency of fluoride leads to which one of the following health

Deficiency of fluoride leads to which one of the following health problems?

Tooth caries
Mottling of tooth
Bending of bones
Stiffening of joints
This question was previously asked in
UPSC CDS-2 – 2016
Fluoride plays a crucial role in dental health. It strengthens tooth enamel by incorporating into the crystal structure, forming fluorapatite, which is more resistant to acid dissolution than hydroxyapatite.
A deficiency of fluoride weakens tooth enamel, making teeth more susceptible to demineralization by acids produced by bacteria in the mouth. This process leads to the formation of cavities, known as tooth caries or tooth decay.
Mottling of teeth (dental fluorosis) is caused by *excessive* intake of fluoride during tooth development. Bending of bones (rickets) is typically due to Vitamin D, calcium, or phosphate deficiency. Stiffening of joints can be caused by various conditions like arthritis.