Instrument (1) for measuring the position of the lower jaw provided with a top (2) and a bottom (4) bite fork, that are individually adapted to the upper (19) and lower (20) tooth arch of a patient, that are optionally individually adjustable through the use of attachment pieces that adjust the thickness of the bottom and/or top bite fork to the needs of the examination and/or the characteristics of the patient, whereby the top (2) and bottom (4) bite fork are each provided with an extension (5, 11) that extends in a horizontal plane in front of the teeth of the patient with the instrument (1) in the mouth, so that the extensions (5, 11) are outside the mouth of the patient, and whereby these extensions enable the bite forks (2, 4) to move with respect to one another in the horizontal movement plane, while the instrument is placed in the mouth of the patient, and enables the relative position of the bite forks and thus the relative position of the upper and lower tooth arch (19, 20) to be registered outside the mouth of the patient.
