A force-transmitting assembly includes a metal shaft having at least two longitudinally-extending grooves defined in an outer surface, and a metal hub having at least two longitudinally-extending grooves defined in an inner surface that surrounds the outer surface of the shaft. A plurality of discrete parts is disposed in the at least two longitudinally-extending grooves of the shaft and the hub in an interference-fit manner so as to transmit a torque from the shaft to the hub. Each of the discrete parts is composed of at least 50 mass % of technical ceramic selected from Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, ZrO.sub.2, or a mixture of two or more of Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, and ZrO.sub.2.

An attachment mountable to an electric toothbrush handle having a drive shaft comprises a neck member having an elongated body with a principal axis and a cavity; a slide member with an engagement surface; a guide sleeve member having a cavity, a first outer surface with an engagement opening, and a transition surface; and a collar member. The guide sleeve member, with slide member inserted within the engagement opening, is inserted within the neck member cavity. Insertion of the drive shaft into the collar member and guide sleeve member from a first radial position along an axis offset and parallel to the principal axis to a second radial position in-line with the principal axis, via the transition surface, results in the drive shaft being held in frictional contact with the engagement surface of the slide member to enable transfer of force/motion from the drive shaft to the neck member.

A steering shaft assembly includes an outer member and an inner member. The outer member defines a first key way that extends from an outer member first end towards an outer member second end along a first axis. The inner member has a first key that extends along the second axis from an inner member first end towards an inner member second end and is at least partially received within the first key way.

A force-transmitting assembly includes a metal shaft having at least two longitudinally-extending grooves defined in an outer surface, and a metal hub having at least two longitudinally-extending grooves defined in an inner surface that surrounds the outer surface of the shaft. A plurality of discrete parts is disposed in the at least two longitudinally-extending grooves of the shaft and the hub in an interference-fit manner so as to transmit a torque from the shaft to the hub. Each of the discrete parts is composed of at least 50 mass % of technical ceramic selected from Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, ZrO.sub.2, or a mixture of two or more of Si.sub.3N.sub.4, SiAlON, Al.sub.2O.sub.3, and ZrO.sub.2.