The ornamental design for a handle for an orthodonticinstrument, as shown and described.
FIG. 1 is a perspective view of an embodiment of a handle for an orthodontic instrument;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a right side view thereof; and,
FIG. 7 is a bottom view thereof.
The dash-dot-dash broken lines illustrates the bounds of the claim. The broken lines showing of various portions, other elements in the Figures are for the purpose of illustrating unclaimed portions and form no part of the claimed design. The claimed design includes two surface textures, namely, polished and brushed surface textures with the stippling indicating a brush surface texture.