Megalodon's teeth were up to 17cm long. Like most sharks, Megalodon's teeth were probably located in rows which rotated into use as they were needed. Most sharks have about 5 rows of teeth at any time. The front set does most of the work. The first two rows are used for obtaining prey, the other rows rotate into place as they are needed. As teeth are lost, broken, or worn down, they are replaced by new teeth. Megalodon may have had hundreds of teeth at one time. They did not chew their food like we do, but gulped it down whole in very large chunks.
The jaws were big enough for the Megalodon shark to be able to swallow a whole Rhinoceros! (Source: "W H AL E E C H O E S - From South African Shores", Official Newsletter of the Whale Mark Organisation, September 2009)