The invention relates to a motor for surgical instruments, such as dental instruments, comprising an interface (2) for connecting the motor to a power source. The interface (2) comprises conduits for the transport of fluids (22, 24) and electric contacts (25-29) which are disposed essentially one the same arc of circle around the centre of the interface (2) and which are spaced apart at regular intervals. The invention also includes an attachment (7) comprising conduits for the transport of fluids (62-64) and electric contacts (65-69) which are disposed in a corresponding manner, and a pipe (8) which is equipped with one such attachment (7). The regular arrangement of all of the electric contacts (25-29; 65-69) around the centre of the interface (2) of the inventive motor, respectively around the centre of the connector (6) of the attachment (7), ensures that: (i) the same distance is provided between each electric contact (25-29) and the generally-metallic case (1) of the motor, and (ii) production costs are reduced and use of the motor is facilitated owing to the symmetrical arrangement of the connection elements on the interface (2).