With a total of 120 complete dentures installed on the male and female patients, ranging from 27 to 82 in age, the measurement was made of their respective bite forces by a joint use of biting force measuring apparatus with four strain gauges attached and multiple monitoring recorder.
These biting forces were carefully examined in terms of age, sex, height of occlusion, denture base area, alveolar ridge form, sagittal horizontal co-transposition of upper and lower ridges, compression of jaw mucous membrane, co-transposition of upper and lower alveolar, arches and chief masticating side.These data were further studied in conjunction with the arrangement of artificial teeth and construction of occlusion so that the above conditions might be adequately complied with.
As a result of these efforts, the author obtained the following conclusions.
1.In nearly 60%of the complete denture cases under survey, the maximum biting force was registered around 6 to 8 mm distance between the upper and lower teeth arrangements.
2.In an age group of 27 to 69 years old, the biting force in the centric occlusion of males is about 12 kg while that of female is 9 kg.As regards the anteriors, the biting force of male is about 6 kg and that of females is 5 kg.On the other hand, the biting force of male molar masti. cating side in lateral occlusion is about 14 kg and that of females is 10 kg. As for an age group of 70 to 82 years old, the biting force in the centric occlusion of males is about 9 kg and that of females is 6 kg, and in the anteriors the biting forces are respectively about 5 kg for males and 4 kg for females. In the case of lateral occlusion, the biting force of male molar msticating side is about 11 kg and that of females is 8 kg.
3.In nearly half the number of complete denture cases examined, the right side registered a higher biting force than the left with a margin of 10 % in favor of the former. On the other hand, cases in which the identical biting force was measured on both sideds of jaws were as small as about 12%.
4.The general tendency was that the biting force reduced in proportion to the progress of age. Although the reduction in force was relatively small till the age of 60's, remarkable decline in force took place beyond the age of 70's.
5.As compared with the males, the female patients gave smaller biting force measurements. The difference was about 12%for the anteriors and about 30%for the molars.
6.The biting force was correspondingly small according as the upper and lower denture base area were small or the denture base area of either jaw happended to be small.In a pair of maxillar large tipe and mandibular large type, the maximum biting force was measured, where anteriors gave about 6 kg and molars about 12 kg in the case of centric occlusion while the masticating side of the jaw registered about 14 kg in lateral occlusion.When compared with this maximum biting force, the following reduction were measured.
Maxillar middle type Mandibular middle type-10%
Maxillar middle type Mandibular large type-15%
Maxillar small type Mandibular middle type-17%
Maxillar large type Mandibular middle type-20%
Maxillar middle type Mandibular small type-24%
Maxillar small type Mandibular small type-30%
7.The biting pressure (mean value) on the upper denture base area was less than that of the lower denture base area, the difference being 1.2 to 1.5 times.That is, the lower jaw tissues under denture base receive this much more burden of biting pressure than the upper jaw tissues.

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In the present study, measurements were undertaken on a total of 5, 728 healthy deciduous teeth and those which had the first class amalgam restorations in a mixed group of boys and girls ranging in age from 36 to 72 postnatal months. For measurement purposes, use was made of the biting force measuring apparatus with the strain gauges attached in association with a multiple monitoring recorder. The measurement data were then analyzed in terms of postnatal months, sex distinctions, stability and resorption of the dental root, etc. As a result of these efforts, the following conclusions were obtained.
1. Concerning individual biting forces of the deciduous teeth under study, there were not observed any significant differences between the sexes, upper and lower jaws and right and left sides of the body.
2. The maximum biting force and the postnatal months in which each deciduous tobth registered the maximum value were as follows. As regards deciduous central incisors, the maximum biting forces that took place in the 48th postnatal month were respectively 6.34kg for the upper and 6.52kg for the lower jaws, and deciduous lateral incisors in the 60th postnatal month registered 7.04kg for the upper and 7.16kg for the lower jaws. Deciduous cuspids gave the maximum biting forces in the 72nd postnatal month respectively 13.70kg and 14.03kg for the upper and lowet jaws. The maximum biting forces of deciduous first molars in the 72nd postnatal month were 21.66kg for the upper and 22.02kg for the lower jaws and those of deciduous second molars in the 72nd postnatal month were 22.68kg for the upper and 23.27kg for the lower jaws.
3. When the maximum biting forces of these deciduous teeth were compared with those of corresponding permanent successors (an age group of 20's males used by TAKAMIZAWA), the deciduous central incisors, lateral incisors, cuspids, first molars and second molars were respectively 0.4, 0.5, 0.5, 0.5 and 0.5 times in the case of upper jaw. On the other hand, in the case of lower jaw they were 0.3 for deciduous central incisors, 0.4 for lateral incisors, 0.5 for deciduous cuspids and first molars alike and 0.4 times for deciduous second molars.
4. When chronological changes were investigated in the individual biting forces, a slight increase was observed between the 36th postnatal month to the 48th postnatal month with reference to the deciduous central incisors, and a decrease in the 60th postnatal month. As regards the deciduous lateral incisors, . on the other hand, there was observed a slighti ncrease between the 48th postnatal month and the 60th postnatal month and a decrease in the 72nd postnatal month. With reference to individual biting forces of deciduous cuspids and molars their individual biting forces increased in a period from the 48th postnatal month to the 72nd postnatal month.
5. The root of deciduous central incisors had been already formed by the 36th postnatal month and the root resportation was observed occasionally. The root resorption progressed to a fair degree in the 48th postnatal month, in which the cases of good root stability and root resorption were observed more or less to the same extent. The majority had their roots resorbed by 1/2 and the cases where the root resorption was more than 1/2 were only few. However, the root resorption became much advanced in the 60th postnatal month. Here the root resorption was either by 1/2 or more than 1/2.
6. As regards the deciduous lateral incisors, on the other hand, the root resorption had not yet begun in the 48th postnatal month with a few exceptions but after the 60th postnatal month it became quite apparent, in which the cases of root stability, apical resorption and 1/2 root resorption were mixedly found. In the 72nd postnatal month, the root resorption was further advanced and here all the cases were the root resorption by 1/2 or more than 1/2.

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