[Reconsideration of anterior reference point in prosthodontics. Orbital point, Inner Canthus of the eye and alae of the nose].

With the aim of designing more aesthetic prosthetic replacements, a series of experiments was conducted to obtain the points of reference for determining the postures (sitting and standing postures) and horizontal reference plane when patients assume the natural head position. The results thus obtained are as follows: 1. Measuring points in the sitting and standing postures were located about 15.0mm below the orbital point respectively. 2. The natural head position tended to shift upward significantly more frequently in the standing posture than in the sitting posture. 3. The natural head position in the standing posture varied less and was more restorable than in the sitting posture. 4. Between the three reference points in both postures, there was no significant difference in the degree of variation, but measurements based on the inner canthus of the eye showed the least variance. 5. In the standing posture, the measurements based on the inner canthus of the eye showed a little, but significant, variance from the measurements based on the three reference points in the sitting posture. From the above, it can be said that the point 25.6mm below the inner canthus of the eye, which was the average of the measurements taken in the standing posture, may be appropriate for use the anterior point of reference for transferring the natural head position onto the articulator.