Toothbrush with automatic actuation

A brushhead for use in a power toothbrush, wherein the toothbrush includes a driver assembly for the brushhead assembly and a system for measuring the capacitance between a conductive electrode on the brushhead assembly and an electronics ground in a handle portion of the toothbrush, the brushhead comprising:

• a brushhead which is insertable onto and removable from the remainder of the power toothbrush, the brushhead itself having a value of capacitance which is part of a total capacitance between the conductive electrode and the electronics ground which is above such a pre-selected threshold value or within such a pre-selected range for actuation of the toothbrush, indicative that the brushhead is an authorized brushhead for the toothbrush.