The two letters that Churchill had written in 1952 and 1954 are powerful revelations of his reliance on Sir Wilfred Fish,the most renowned dentist of his generation.
The letters, which have never been seen before, are to be auctioned by Bonhams in London on March 18, and expected to fetch up to 1,400 pounds.
Churchill had lost many of his front teeth in his 20s, prompting the need for an upper set of dentures.
The letters reveal that the fear that problems with his teeth might affect his public speaking, one of the most powerful attributes for a politician, kept haunting Churchill throughout his life.
It was only Fish on whom Churchill relied for the delivery of his dentures.
As a sign of appreciation, Churchill confirmed Fish's nomination for a knighthood in a letter in January 1954.
'I am very glad it fell to me to recommend you for a well-deserved honour. I enclose one set of dentures and I should be so much obliged if you would tighten them up a little for me. The others are working very well,' the Daily Express quoted him as writing in the letter.
Experts believe that it was because of Fish's skill that Churchill's inspiring and uplifting words, such as the 'finest hour' speech during the Second World War, sounded as good as they did.
'Churchill relied on his false teeth to maintain his distinctive public-speaking style,' the Telegraph quoted a Royal College of Surgeons spokesman as saying.