A cephalometric study of the relationship between the maxillary first permanent molar and the key ridge
Date
1970
DOI
Authors
Tichler, Howard M.
Version
OA Version
Citation
Abstract
The maxillary first molar and the key ridge were investigated cephalometrically. The purpose of the study was to propose a guide for determining where to reposition the molar during orthodontic therapy. One hundred and eighty-twoindividuals (mean age, 10.2 years) with "normal occlusion" were used as a control group. This group was compared statistically to an experimental group of one hundred and fifty-nine patients (mean age, ll.0 years) with malocclusions. These individuals were primarily divided into Class I nonextraction and extraction groups and Class II, division 1 nonextraction and extraction groups. Each of these groups was statistically compared before treatment and at the end of active treatment. Four linear and four angular measurements were made on each tracing. In addition, the path of eruption of the molar was followed in a cross-sectional sample to illustrate the relative position of the molar to the key ridge during its eruption.
The results showed that the key ridge can be identified and reproduced on a cephalometric tracing. The stability of the structure in relation to certain cranial landmarks is questionable. That is, changes in the position of the molar during treatment were accompanied by changes in the position of the key ridge. However, it was established, according to the method employed, that the angular relationship between the molar and the key ridge does not differ in normal and abnormal occlusions. In addition, the angular relationships of the molar and key ridge to the palatal and occlusal planes do not differ between the two groups. This suggests that perhaps the key ridge should be investigatedas a possible diagnostic aid in order to determine, cephalometrically, the proper position of the maxillary first molar.
Description
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Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry. Dept. of Orthodontics.
Charts, bibliography included.
Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry. Dept. of Orthodontics.
Charts, bibliography included.
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This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.