@cappyx, your coin is exhibiting normal, albeit heavy wear from circulation. If you compare your coin to images with similar amounts of wear, you will see that as the amount of wear increases, the rim gets so broad as to start to obscure the tops of the letters.
"The danger we all now face is distinguishing between what is authentic and what is performed." -----King Adz
You have a normal Mercury dime that just shows heavy circulation wear from being in circulation for a long time. It caused the devices on your coin to flattened. It's Post Strike Damage (it happened after it left the U.S. Mint).