Based on morphological data from bones and teeth, Yayoi people in northern Kyushu are thought to have been immigrants or their descendants. They or their ascendants are thought to have introduced agriculture, especially rice growing to Japan. During the middle period of the prehistoric shell midden culture on Okinawa island, equivalent to the latest Jomon and early Yayoi period, the subsistence of Okinawa islander is thought to have been hunting and gathering. In the present study, the dental morbid condition of the hunter-gatherers and the agriculturalists is compared. As reported in previous studies, the carious teeth ratio of the agriculturalists was found to be higher than that of the hunter-gatherers. Moreover, the missing teeth and tooth root caries, those are thought to have been caused by peripheral periodontal disease, abruptly increased in the elder agriculturalists in the samples studied. Therefore, peripheral periodontal disease is thought to have spread to agriculturalists in northern Kyushu during the Yayoi period.