[A study on the reference planes and lines for dental practice]

In prosthetic dentistry, determination of the occlusal plane has a great influence on functional articulation and esthetic aspects. However, we have no means to decide the occlusal plane, because we have too many points for deciding the occlusal plane in the data. The data which we usually use were decided in the past and much of this does not conform to the present changed Japanese physical standards. The author has studied ways to decide the occlusal plane. One of them is based on the points which were decided in the past, the other is based on new points which were decided by the author. The results were as follows. 1. When the posterior points of Camper's plane are at the lower part of the tragions, it is parallel to the occlusal plane within the sagittal plane. 2. There is no difference between Camper's planes whether the frontal points are at the lower part of the alare or the subnasal point. 3. There are few differences between the Frankfort planes whatever 3 points are chosen from both orbital points and both tragions in the sagittal plane. 4. There are few individual differences between the Frankfort planes based on points at the right tragion and the left tragion in the frontal plane. 5. The angle of Dürer's plane towards the occlusal plane tends to be similar to the angle of the Frankfort plane towards the occlusal plane in the sagittal and frontal planes. 6. The HIP plane shows a slight tendency to acclivity towards the occlusal plane in the sagittal plane, but parallel is the occlusal plane closely in the frontal plane. 7. The inclinations toward the occlusal plane in the sagittal plane of the three lines of the nasion to the left alare, the nasion to the right alare, and the nasion to the subnasal point, are similar. 8. The lines from the center of the upper first incisal edge to the left subaurale point, and from the center of the upper first incisal edge to the right subaurale point, are parallel to the occlusal plane in the sagittal plane. 9. The three lines from the left orbital point to the right orbital point, the left alare to the right arale, and the left subaurale point to the right subaurare point parallel the occlusal plane closely in the frontal plane. 10. The line from the nasion to the subnasal point makes a right angle with the occlusal plane in the frontal plane.(ABSTRACT TRUNCATED AT 400 WORDS)