A new development of an apparatus for measuring the degree of tooth mobility (author's transl)

Abstract

Although there have been published many methods for the measurement of the degree of tooth mobility, the majority of them are far from practical. In the present study, the author developed a new measuring apparatus for the same purpose, where two cylinders having different internal diameters were applied.The results of the study, in which various degrees of the tooth mobility were measured by this new apparatus, were as follows.1. A high accuracy of the new apparatus was confirmed. That is, when the measuring part A was used, the measurement precision was about 5 times as high as that of the Periodontometer and, when the measuring part B was used, it was about twice as high.2. As for the record of the new apparatus for the subjects in possession of normal periodontal tissues, coefficient of variation was 0.20 with the measuring part A, and it was 0.79 with B. This fact showed that the variation is extremely small.3. When the new apparatus was applied to the subjects in possession of normal periodontal tissues, respective degrees of tooth mobility were 106 by the former and 114 by Periodontometer. A high statistical difference was observed between the degrees of the tooth mobility subjected to various loads.4. When the new apparatus and the Periodontometer were used at the same time for the measurement of the same teeth to which different loads of 50g, 100g, 200g and 300g were exerted, it was seen that a pronounced difference took place between the two when a load of 50g was applied, with the measurement value by the new apparatus being larger.With loads of 200g and 300g, however, there were no appreciables defference between the sets of values by the new apparatus and the Periodontometer.5. A high degree of correlation was establisheb between the degrees of alveolar bone resorptionobtainedby Bjorn's method and the degree of tooth mobility as measured by the present apparatus.6. When the present appartus was used to measure the degree of tooth mobility under a load of 500g, the following values were obtained. That is, with the subjects in possession of normal periodontal tissues the degree of tooth mobility was below 150 those teeth which were diagnosed as P1 were from 150 to 250, those of P2 were from 250 to 400, and those of P3 were from 400 to 1500.As were confirmed by the results given above, it is to be concluded that the present apparatus, which is simple in its structure and is capable of making precise measurements, may be readily adopted for clinical purposes.