A 45-year-old farmer from a village where the borewell water supply contains fluoride presents with pain and stiffness of the back and knee joints, restricted spinal movements, and radiographic evidence of osteosclerosis of the spine and pelvis. Dental examination shows brown mottled enamel. His symptoms began years after the dental changes. This presentation is best described as:

• A Osteomalacia secondary to vitamin D deficiency
• B Renal osteodystrophy from chronic kidney disease
• C Ankylosing spondylitis with incidental enamel hypoplasia
• D Skeletal fluorosis superimposed on endemic dental fluorosis ✓

Explanation

Chronic ingestion of excess fluoride in drinking water causes dental fluorosis in children during tooth development, while skeletal fluorosis develops later in life with joint stiffness, spinal rigidity and osteosclerosis on X-ray. Dental mottling appearing years before skeletal involvement is the classic sequence of endemic fluorosis seen in Indian villages with water fluoride above about 1.5 mg/L. Osteosclerosis distinguishes it from osteomalacia, which shows osteopenia and Looser zones.

Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.