I could find no specific mention of Edward V having had a diseased jaw or having serious health problems in searching through contemporary documentation. The one mention I did find is from Mancini’s Usurpation: “...the young king, Edward V, felt himself to be awaiting death in the Tower.” Mancini mentions Argentine (Edward V’s physician) by name but doesn’t claim to have received this information directly from Argentine.
Edward may well have feared for his life since the important members of his entourage (Rivers, Grey, and Vaughan) had been arrested, held for treason and later executed.
The next account is found in More’s History of King Richard the Third (not contemporary, but he did have access to people who were Richard III’s contemporaries). The dowager Queen, Elizabeth protested that the younger prince “...nedeth good loking to, hath a while ben so sore diseased vexed with sicknes, and is so newly rather a lyttle amended then well recouered...” While this is hearsay, she may well have protested in this manner in an attempt to keep Richard of York with her in sanctuary rather than give him up to their uncle. In any case, even More’s account doesn’t say that Edward was ill.
Another factor may be from the excavation and examination of bones from a cousin, Anne Mowbray. The bones showed she had a rare congenital absence of both left second molars. According the to the 1965 article on Anne Mowbray’s teeth, the older of the tower bones shows the distal maxillary premolars had failed to develop and the younger of the bones had a suppressed second milk molar.
In the absence of DNA evidence that would match the bones’ DNA to Elizabeth Woodville and Edward IV, and facial reconstruction using the skulls and then seeing if either skull matches up with portraits of Edward V, this, for me, is the most convincing argument that the bones could be those of the princes.
C. A. J. Armstrong, ed., The Usurpation of Richard III, Oxford, Oxford University Press, 1936.
Bertram Fields, Royal Blood, New York, ReganBooks, 2000.
Thomas More, The History of King Richard the Third, online at University of Oregon, read here.
Article on Anne Mowbray’s teeth from Br Med J, v.2(5477); Dec 25, 1965, link to PDF excerpt