New inmates at Woodhill Prison claim that they were told to share toothbrushes last week, because the Milton Keynes prison had run out.
Prisoners are usually issued with a standard set of items when they are admitted, including a toothbrush, toothpaste, soap and plastic razors.
But convicts were told that supplies had run dry last week, and although the Prison Service denies that prisoners were told to share they could not say what advice was given instead.
The mother of one inmate said: “They were simply told that Woodhill had run out, and they had to either go without or borrow from someone else.
“Nobody wants to borrow a stranger’s toothbrush, and nobody wants to loan their toothbrush to a stranger. It’s not hygienic, and if you are in prison rightly or wrongly it is not how you want to introduce yourself.
“My son went in on Sunday and couldn’t brush his teeth for five days.”
Woodhill is a Category A male prison, with a population of 819.
The last inspection of Woodhill by Her Majesty’s Inspectorate of Prisons, in January 2014, found that the number of prisoner complaints was more than twice that of comparator prisons.
The Prison Service admitted that there was a shortage but could not confirm how many prisoners were affected or whether this had happened previously.
A spokesman said: “It is totally untrue to suggest prisoners were told to share toothbrushes.
“There was a shortage for two days, which was quickly rectified, and the supply is now back to normal.”