A worker made a claim to the UK Atomic Energy Authority for teeth he lost after he sneezed inside a Scottish nuclear reactor building.
The story about the dentures have been revealed by a former engineer at the Dounreay plant in Caithness.
Don Ryan, who worked at the site from 1961 to 1994, has contributed to an oral history of Dounreay.
He said his colleague's claim was rejected and he suggested the teeth may turn up during the site's clean up.
Mr Ryan has told of the lost dentures in an interview with Dounreay's heritage officer James Gunn carried in the site's newspaper, Dounreay News.
The false teeth disappeared inside the experimental nuclear power plant's landmark sphere, also known as the dome.
It and other buildings on the site are being cleaned up and taken apart in a £2.6bn decommission project.
Mr Ryan said: "There was usually a 'watch-keeping' presence in the reactor sphere during runs.
"One of the duty team just happened to be leaning on rails beside the instrument panels, facing outwards towards the spherical steel 'wall' when he sneezed - quite energetically.
"Half a set of teeth, under the influence of gravity and the internal sphere slope, disappeared from view, rattling down to the, never visited, bottom sphere skirt."
He added: "The lost teeth were the subject of a claim on UKAEA but this was rebuffed in firm administrative terms."
Mr Ryan said the dentures may have been recovered by a later shift, or could eventually be found during the demolition of the sphere.