Abstract: A method and apparatus for determining the attachment point of tissue to a tooth are provided. The apparatus comprises a body for insertion into the mouth which includes a datum surface for engagement with a location on a tooth. A probe is also provided on the body, which is moveable relative to the datum surface by way of a motor operable to control the movement of the probe in order to engage the probe with the tissue. A measuring device is also provided to measure the movement of the probe relative to the datum surface and an attitude sensing device is included to inhibit the operation of the measuring means upon movement of the body from a predetermined attitude. Furthermore, the motor includes a force control device to regulate the force applied to the probe so that the force is maintained at a predetermined value.