Phossy jaw, formally known as phosphorus necrosis of the jaw, was an occupational disease affecting those who worked with white phosphorus (also known as yellow phosphorus) without proper safeguards. It was most commonly seen in workers in the matchstick industry in the 19th and early 20th centuries. It was caused by white phosphorus vapour, which destroys the bones of the jaw. Modern occupational hygiene practices have since eliminated the working conditions that caused this disease. Those with phossy jaw would usually begin suffering painful toothaches and swelling of the gums. The pain was characterized as "persistent yet progressive ... spreading to neighboring teeth and jawbone". Over time, pus formation developed penetrating the oral mucosa with the formation of fistula, teeth loss, and recurrent abscesses. Further progression led to the formation of sequestrum (dead bone that has separated from living bone) after three months and necrosis of the jaw within six months. The distinguishing feature of this disease was the eventual separation of the sequestrum which was described as porous and light in weight. The lower jaw was more commonly affected than the upper jaw.[3] Affected bones glowed a greenish-white colour in the dark. The condition also affected the brain, provoking seizures in some chronic cases. Treatments included topical antimicrobials, conservative debridement of sequestra and surgery. Surgical removal of the afflicted jaw bones could save the patient; otherwise, death from organ failure would follow. The disease was extremely painful and disfiguring to the patient, with dying bone tissue rotting away accompanied by a foul-smelling discharge. However, removal of the jaw bone had serious effects on patients' ability to eat, leading to further health concerns including malnutrition.

Το Phossy jaw, επίσημα γνωστό ως νέκρωση φωσφόρου της γνάθου, ήταν μια επαγγελματική ασθένεια που πλήττει αυτούς που δούλεψαν με τον λευκό φωσφόρο (επίσης γνωστός ως κίτρινος φωσφόρος) χωρίς κατάλληλες συνθήκες εργασίας.