Abstract: A toothbrush includes an anisotropic deformation portion (70) on a rear end side from the bristle tufting surface (11), and a bending strength in a first direction orthogonal to the bristle tufting surface that is smaller than a bending strength in a second direction orthogonal to the long axis direction and the first direction. The anisotropic deformation portion includes an elastic deformation portion (90) that connects a first region on the tip end side from the anisotropic deformation portion and a second region on the rear end side from the anisotropic deformation portion. The elastic deformation portion is elastically deformable in the first direction and the second direction, and bending load when the head portion is displaced in the first direction is lower than a bending load when the head portion is displaced in the second direction.

Abstract: A toothbrush includes a head portion (10) having a bristle tufting surface; a grip portion (30) disposed on a rear end side from the head portion; a neck portion (20) disposed between the bristle tufting surface (11) and the grip portion; and a sensing portion (70) for sensing that an external force in a first direction orthogonal to the bristle tufting surface exceeds a threshold value. A reversal portion (80) connects a first region and a second region, and snaps, buckles, and reverses as the head portion is displaced on a rear surface side due to the external force exceeding the threshold value. An elastic deformation portion (90) connects the first region and the second region, and elastically deforms at least up to the external force at which the reversal portion snaps, buckles, and reverses.

Abstract: A toothbrush capable of inhibiting damage of an oral cavity of a user that includes: a head section that has a bristle implanting surface on a front end side; a handle section that is disposed on a rear end side from the head section and has a handle section main body; and a neck section that is disposed between the bristle implanting surface and the handle section. The toothbrush has a deforming portion that is located on the rear end side from the bristle implanting surface and is deformed, while stress characteristics associated with bending due to an external force acting on the head section are in a plane stress condition.

Abstract: A toothbrush capable of inhibiting damage of an oral cavity of a user that includes: a head section that has a bristle implanting surface on a front end side; a handle section that is disposed on a rear end side from the head section and has a handle section main body; and a neck section that is disposed between the bristle implanting surface and the handle section. The toothbrush has a deforming portion that is located on the rear end side from the bristle implanting surface and is deformed, while stress characteristics associated with bending due to an external force acting on the head section are in a plane stress condition.