Abstract
In recent years, the increasing number of senile dementia patients has become a serious problem in Japan. To deal with the problem, we should find the best and easiest way to treat these patients. In recent studies, the significant relationship between the masticatory function and general health has been shown, suggesting that mastication with normal occlusion might have various roles in keeping individual general health. Untreated missing teeth might cause not only an abnormal occlusion but also other ail ments such as temporomandibular joint disorder, headache and dementia. The purpose of this study is to evaluate whether improvement of the occlusion restores the damaged frontal lobe function whichhas been observed even at an early stage of dementia.
We examined 29 subjects (male, 16; female, 13) who showed dysfuncional mastication apparently due to missing teeth or unfitted dentures. All subjects showed no sign of disorders of vision, hearing or body movement. We employed the Kana-pick up test which has been widely used to estimate the frontallobe functions such as creativity, volition and emotion. The test was performed before (1st test) and after (2nd test) improvement of their occlusion by well-fitted dentures or other treatment. Subjects wereclassified as normal and dementia depending on their test scores. Those with below normal scores were taken as dementia subjects. The normal score appears to depend on subject age (Kaneko, 1991): the younger the subject were, the higher the score were. The difference of scores of 1st and 2nd tests were compared for each age group and the significance of the difference was calculated.
Four subjects with uncomfortable mastication were diagnosed by the first test as having dementia. One of them became normal by improvement of the occlusion. Though the other 3 scored higher on the second test than on the first test, they remained in a dementia state. Among all the subjects tested only one scored lower on the second test. The mean±SD of the first test score of all subjects was 24.2±11.8 and the mean±SD of the second test score was 28.1±13.2, showing that most of the subjects scored higher on the second test than on the first test (p<0.0001). We also examined among age groups the mean difference of the first and second test scores. The difference was 10.5 for subjects in forties and younger (n=4), 8.0 for those in fifties (n=5), 2.5 for those in sixties (n=8), 3.7 for those in seventies (n=7), and 1.8 for those ineighties and above (n=5).
Those figures show that the difference is greater among the younger than the older generation.This indicates that an improved occlusion markedly improves the frontal lobe function in younger subjects and elevate volition, activity and concentrating power. It is possible that malocclusion may lead to marked functional impairment of the frontal lobe particularly of younger generation. Furthermore, if left untreated, the degree of dementia would proceed into a severe dementia state. Therefore, the maintenance of a normal occlusion is very important in the prevention of the deterioration of the frontal lobe function and the worsening of dementia. The present study suggests that leaving missing teeth untreated particularly in the younger generation may lead to mental disorders and affect their future lives.
