I don't think he did. His hair style hasn't significantly changed over the years. The picture of his actor, and William Riker in the tenth Star Trek movie, don't differ that much. If it looks like he is wearing a hairpiece, that is likely just product.
He had an excellent "mountain man" beard in the parallel universe in which the Enterprise is "one of the last ships left" being pursued by the Borg, in "Parallels".