The invention relates to a self-tapping broken-bone threaded retention nail for teeth. The self-tapping broken-bone threaded retention nail comprises a nail handle, a self-breaking neck and a tooth nail body, wherein the self-breaking neck is located between the nail handle and the tooth nail body, the tooth nail body comprises a first threaded rod, a step and a second threaded rod, and the step is located between the first threaded rod and the second threaded rod. The step is a cylindrical self-locked ring and surrounds the peripheries of the threaded rods. When the self-tapping broken-bone threaded retention nail is used, the nail has the good mechanical retention power with various inorganic salt filling materials such as composite resin, light-cured resin and silver amalgam, the repairing body and dentin bonding strength is obviously improved, accordingly the range of a conservation method of tooth defect prosthetics is widened, and more affected teeth or trauma defects are treated. The existing optical repairing method for tooth repairing is performed by adopting the retention nail, and accordingly more affected teeth or trauma defects are treated and repaired perfectly.