上顎小臼歯の彎曲徴について
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概要
- 論文の詳細を見る
Muhlreiter (1928) pointed out the curve symbol, root symbol and angle symbol as the components to identify the rightness or leftness of the tooth. The curve symbol, one of these three symbols, is an importante element in the plaster sculpture, yet the matters relating to the curve symbol such as the angle to compose it, its position or the relationship with the adjacent tooth have not been explained. These have been reviewed in this laboratory to get effective guides for dental anatomy, and Mizuki (1977) has already made the matters clear concerning the right maxillary anterior teeth in this respect. The author followed the method employed by Mizuki and investigated the extracted maxillar right premolars. Their crown lengths were transversally separated into 12 sections of even space, the contour of each separating line recorded by the contracer, and the angles formed by the curvatures from the buccal to the mesial direction and that from the buccal to the distal direction were also measured. Detailed study of the data thus obtained was made from various view points, and the following conclusions have been reached in due consideration : 1. In the observation of the contours by the occulsal aspect of the maxillar right first premolar, the portion visible from the occulsal side is the area from the 5th separating line toward the occulsal surface. This is the area where the curve symbol is usually observed to identify the rightness or leftness of the tooth. The portion observed for such identification at this time is not the outermost contour, but where the difference between the mesial and distal curvature angles is most peculiar near the outermost contour, or the area around the 9th separating line. 2. Also in the maxillar right first premolar, it is learned that the mesial curvature angle is greater than the distal one at the two separating lines of the 8th and 9th, and an apparent curve symbol exists here contrary to the anterior teeth. Since the 9th separating line is where the curve symbol is most significatntly great, if the curve symbol is to be observed by the cut off surface of the tooth, it may be cut off at the 9th separating line after 12 separating lines were marked on. 3. In the case of the maxillar right second premolar, no curve symbol is observed at all as noted by the text book. If the comparison of the mesial and distal curvature angles is needed, it may be done by cutting off the tooth at the 7th separating line where the angle difference is greater by the same 12 separating lines method. As observed above the curve symbol may be studied by obtainining the 12 separating contours by the use of contracer.
- 九州歯科学会の論文
- 1977-03-31