2021 Volume 55 Issue 1 Pages 187-194
Rapid environmental changes and nutritional deficiencies may affect the size of teeth and jaws and lead to dental abnormalities. However, there is no clear evidence yet. The Japanese economy and diet have changed remarkably in the past several decades. We obtained dental casts from Japanese adult men in 1947, 1962, 1977, 1992 and 2007 (Groups I-V) and compared the dimensions of the teeth and dental arches. We found that the maxillary dental arch in Group II was narrower than in Group IV, and that of the mandibular dental arch in Group II was narrower than in Groups I, IV and V. The mesiodistal dimension of the maxillary canine, maxillary first molar, and mandibular canine, first molar and second molar of Group II tended to be smaller than that in other groups. However, the depth index of the maxillary/mandibular dental arch of all groups except for Group I showed increases. In addition, the width index of the maxillary/mandibular dental arch of Group V was greater than in Group III. We found that although the tooth size and the dental arch of subjects born in 1962 were narrower, the size of the mandible steadily decreased over approximately 60 years regardless of differences in the size of teeth and dental arch obtained from subjects born in 1962. Consequently, we think that changes in the size of teeth and dental arch and changes in the maxillomandibular relationship might occur for different reasons. (J Osaka Dent Univ 2021; 55: 187-194)
