A method of making an absorbent insert for absorbing fluid in a root canal. Forming a body in a pre-compressed state prior to use, having a matrix of absorbent material. The matrix of absorbent material swells upon absorbing fluid after the body in the pre-compressed state has been inserted into the root canal. In the forming process, a sheet of absorbent material is compressed to form a compressed sheet, which is cut and shaped to form an insert. Cutting and shaping is by using complementary split mold halves which together define a cavity corresponding to the body of the insert and stamping the compressed sheet with the split mold halves to form the body of the insert.