Abstract
From remarkable progress of human culture in the present days, acceleration of reduction of the human occlusion is predicted. It was attempted, therefore, to survey the generational differences of tooth to denture base discrepancy in current population as a basis for further estimation. Subjects of this study were 288 living people sampled from five generations (15-16, 25-26, 35-36, 45-46 and 55-56 years old, respectively), selected from populations of Koromogawa village. As the results, increase of total number of malocclusion was not obvious but decrease of maxillary protrusion and increase of anterior cross-bite was observed. These facts seemed to be an expression of alteration of facial morphology from prognathic to retrognathic pattern. The frequency of the discrepancy has increased from G-I to G-V, though there was irregular fluctuations. From the discussions on size of discrepancy, it seemed to be a fact that the progress of the discrepancy in the current age was induced by two ways, namely by enlargement of tooth size and by diminution of jaw bone.
