'Phossy jaw' is seen in chronic poisoning with

PHOSPHORUS(P4 ) Chronic Poisoning: The frequent inhalation of fumes over a period of years causes necrosis of the lower jaw in the region of a decayed tooth. The vapours act on the jaw through a carious tooth or an interspace due to missing tooth where suppurative microorganisms are already present. At first there is toothache, which is followed by swelling of the jaw, loosening of the teeth, necrosis of gums, and sequestration of bone in the mandible. This condition is known as &;phossy jaw&; (glass jaw) in which osteomyelitis and necrosis of the jaw occurs, with multiple sinuses discharging foul-smelling pus. Ref:- k s narayan reddy; pg num:-551