We made an oral survey of the Tibetans in three quite different areas and got interesting results. The comparative study was made in Karakoram (1974), North-west Nepal (1983), and Yunnan province, China (1989).
1) In Karakoram, North-west Nepal, the number of cases of decidous tooth caries was extremely small. On the other hand, it was very great in Yunnan province.
2) The eruption age of permanent teeth was quite similar in the three Tibetan areas. Japanese teeth change from deciduous teeth to permanent teeth at a younger age.
3) In Yunnan province, the inhabitants had many decayed teeth in the upper front jaw, and few at lower front jaw. The number of decayed deciduous molars was large as in the Japanese.
4) Caries surfaces: In Yunnan province, the number of cases of proximal and distal surface caries was great compared with that on occlusal and labiolingual surfaces. Caries in Yunnan province may be closely related to the manner of carbohydrate intake.