Root canal instrument with an in-built measurement body e for measurement of the canal depth and with a stop for preparation of the canal with auxiliary instruments adapted for the purpose. A calibrated drilling and grinding body is used to produce the access to the canal and the stop surface, the canal depth is measured with the measurement body attached to the shaft of the root canal instrument, and the canal is prepared, the measurement body delimiting the penetration by stopping at the reference surface. Adjustment of the measurement body is made with a special adjustment device. <IMAGE>
