1) In the group of normal occlusal subjects, the canine showed a tendency of mesial inclination to FH plane and, moreover, there was observed a gradual or incremental distal inclination from the first premolar to second molar in the mandible. In the maxilla, on the other hand, the second premolar approximated to a right angle to X axis, the first premolar showing the largest distal inclination followed by the canine. Inversely, the first and second molars revealed a heavy mesial inclination.
In the group of overbite patients, on the other hand, axial inclination of the canine was found to be more or less at a right angle as compared with normal occlusal subjects and, further, the tendency of a slight distal inclination was observed from the maxillary first premolar to first molar.
In the mandible, both the canine and first premolar gave more pronounced inclinations distally, whereas noticeable mesial inclinations were observed from the second premolar to second molar.
2) As for the axial cross angles of upper and lower jaws, the second premolar cross angle was found to be the largest, those of the canine and second molar tending to be smaller. In the group of overbite patients, on the other hand, the first premolar cross angle was the largest and even the canine cross angle was larger than that of normal occlusal subjects.
3) Various crown heights (cuspid in the case of canine, buccal cusp tip in the case of premolar, buccal surface groove in the case of molar, distance to FH plane for the upper teeth and distance to X axis for the lower teeth) of the normal occlusal subjects were observed to be more or less the same concerning the canine and first premolar in the maxilla, accompanied by a trend that a distance to FH plane became smaller as it went from the second premolar to second molar.
As compared with normal subjects, respective distances from the first premolar and first molar to FH plane were considerably shorter. With the mandible, in particular, distance from the left second premolar to X axis was observed to have been reduced.
4) Various crown depths (cuspid in the case of canine, buccal cusp tip in the case of premolar, buccal surface groove in the case of molar and respective distances of the upper and lower teeth to Y axis) were found to be deeper bilaterally in the overbite patients than in normal occlusal subjects.
5) In all the normal occlusal subjects under study, there was observed no statistical difference between the right and left sides in common to the both jaws on all the measurement items.
There existed a statistical difference, however, for the axial inclination angle of the maxillary second molar in the group of overbite patients.
6) The mandibular angle in overbite patients was generally smaller than in normal occlusal subjects, being indicative of the fact that the inclination of their mandibular basal planes tended to be rendered flat.
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