レントゲン写真でみた歯槽骨頂部の骨変化に関する疫学的特徴

抄録

As a preliminary study for evaluating bony changes of the alveolar crest, 1, 115 sheets of intra-oral roentgenograms obtained from 130 dental patients with the bisecting-angle technique were observed.
In the age group lower than 30 years, the bone loss on the interalveolar and the interradicular septa were found in 72% and 16% of the samples. These values became higher with age. The former attained to a plateau level of 99% in the age group of the thirties and the latter the level of 51% in the age group the fifties.
It was suggested that the progressive bony loss with age was characterized by homologous change in the age group less than forty, while heteromorphous change was predominant in the age group higher than forty, resulting from an increase in the case of transformation H-type bony loss into V-type one.
Bony loss in the upper molars and the lower incisors might highly progressed than in others.
In the portions of the molars and the second premolar, V-type of bone loss was more frequently recognized than H-type on the mesial site of the tooth of the interalveolar septa, but inverted on the distal site of the tooth of the interalveolar septa.
In the portions of the incisors and the cuspid, frequency of bone loss with H-type was higher than that with V-type and wasnearly equal on both of the sites.