ABSTRACT OF THE DISCLOSURE [Problem] Disclosed is a method for manufacturing a spherical brush having highly dense brush bristles for easy cleaning of periodontal pockets and a cylindrical brush having the brush bristles highly dense brush bristles at a ball portion of a tip thereof and a brush manufactured by the manufacturing method. [Solution means] A fiber bundle, which is composed of a number of short fibers prepared by cutting long fibers and is gripped between a set of U-shaped wires arranged to crisscross with each other to form a loop. The open ends of the U-shaped wires are pulled and twisted in opposite directions and so that the fibers at the portion gripped by the U-shaped wires are compressed to reduction the size of their bundled areas. Elastic repulsion is established between the fiber bundles near a wire-gripped portion by the size differences of the cross sectional areas of the free end fibers at both ends of the wire-gripped portion and is utilized so that the free end fibers diverge radially to the circumference from the wire-gripped portion.
