The ornamental design for a dental implant, as shown and described.
FIG. 1 is a perspective view of dental implant showing my new design.
FIG. 2 is a top view thereof.
FIG. 3 is a front view thereof.
FIG. 4 is a rear view thereof.
FIG. 5 is a left view thereof; and,
FIG. 6 is a right view thereof.
The dash-dot-dot lines immediately adjacent the claimed area in FIGS. 1 and 2 represent the boundaries of the claimed design, while all other dash-dot-dot lines in the figure drawings are depict environmental subject matter only; the dash-dot-dot lines form no part of the claimed design.