A dental implant assembly comprises an elongated tubular body adapted for securement within a bore in a jaw bone of a patient. The body has an expandable bottom portion. The expandable bottom portion has an outer thread on an outer surface. The outer thread has a major diameter that gradually increases from a first major diameter near a bottom end of the body to a second major diameter near a top end of the bottom portion. The top end of the bottom portion is located between the bottom top ends of the body. An expander at least partially extends into the bottom end of the tubular body. The expander is configured to be advanced from a first position in which the bottom portion of the body is not expanded to a second position in which the expander forces the bottom portion of the body to expand.