A Study on the Tilting of Teeth in Man

Abstract

There is a fair amount of published literature on the positional changes of the residual teeth after substantial loss of the abjacent ones. But the majority of these studies are concerned with macroscopic observations of positional changes on the part of the residual teeth after several years of extraction by use of plaster models. They reflect difficulties in grasping accurately the positional changes of the residual teeth after extraction.Therefore, the author and his associates earlier reported on our measurement. method and measurement apparatus. In the present study, the author was concerned with the positional changes is a selected sample of 10 Japanese dental students by an application of the above measurement method and apparatus. With these subjects, efforts were made to establish chronologically the changes of the residual teeth after extraction of the mandibular first molar on the right side.As a result, the author arrived at the following findings: 1. Throughout the measurement period, all the subjects were found to have suffered from some kind of positional changes in the second premolar and second molar on the extracted side.With the exception of 1 subject, the remaining 9 subjects suffered from the positional change in the first premolar.2. With the residual teeth from the mandibular right canine to left second molar, there were found no positional changes in all the subjects.3. With the right first, second premolars and second molar in which the positional changes were found, the amount of change was the largest in the second molar in common with all the subjects.4. In terms of dental regions where the positional changes were found, there was a statistical difference between the time passage after extraction and the amount of changes except for the first premolar in 1 subject.5. There were observed two different patterns in the positional change of the second molar on the extracted side. One pattern was that the amount of change was noticeably large in the initial stage of extraction, the change becoming smaller in proportion to the passage of time.The other pattern, on the other hand, showed an opposite tendency.6. In terms of the time passage after extraction and the amount of positional change in all the subjects, there was observed a fairly high correlation between the first, second premolars and the second molar in these items.7. Based on the amount of positional changes obtained from all the subjects, the degree of positional change of the second molar was approximately 10 times as large as that of the first premolar, and approximately 7.5 times that of the second premolar.8. Concerning the time-point when positional changes of the adjacent teeth would occur after dental extraction, the change took place comparatively soon in the second molar and anywhere from 15 days to one month in the second premolar. As regards the first premolar, on the other hand, the positional change occurred after that of the second premolar took place.