Comprehensive Study of the Causes of Mandibular Tori

88%的绳纹人和83%的现代日本人有可触及的下颌环。在弥生、古坟、镰仓、室町、江户和现代群体中，只有不到70%的人有明显的tori。21%的日本人患有tori，而在其他群体中，只有不到10%的人患有tori。下颌骨环面受遗传因素的影响。咬合应力、长期持续的咬合应力可能是导致tori发生的环境因素，尽管这些因素在所有因素中所占比例不到30%。

88% of Jomon people and 83% of the present-day Japanese had palpable mandibular tori. In Yayoi, Kofun, Kamakura, Muromachi, Edo and modern groups, less than 70% people had palpable tori. 21% of the preset-day Japanese had developed tori, and in other groups, less than 10% had developed tori. Mandibular tori had proved to be influenced by genetic factor. Occlusal stress, lasting occlusal stress for long years could be environmental factor to develop tori, even though these factors are less than 30% of all factors.