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Various attempts have been made to investigate what effects the constitutional elements of a partial denture have on the abutment teeth and how the difference in its design, retention and supporting method affects the abutment teeth. However, no analysis seems to have been reported as to the difference in the capacity of load that the abutment teeth have and the force on the periodontal tissues, which have different dental root shapes.Therefore, the strain in the periodontal membrane of the straight root and curving root shapes were investigated by using the 3-dimensional strain gauge system. The results were as follows:1. In both root shapes, the greater the load, the greater the strain on the periodontal membrane.2. There was a difference in the value and direction of strain between straight root and curving root shapes. Furthermore, the strain on the curving root shape was greater than that on the straight one.

抄録顎口腔系は咀嚼筋を始めとする頭頸部諸筋群, 歯, 顎関節および周辺組織ならびにこれらを支配している神経系などにより成り立っておりこれらが調和することにより, 顎口腔系の機能が営まれる.顎関節症は主に咬合に起因する様々な原因により, これらの調和が崩れることにより起こるとされている.このような顎関節症患者の中には顎口腔系のみでなく全身症状を含む種々の不定愁訴を持つ者も多くみられることから顎口腔系の不調和がそれのみにとどまらず, 全身状態にまで影響が及んでいるのではないかと推測され, 近年この顎口腔系と全身状態との関連についての報告も多くみられるようになってきた.著者らも, これらの関連を探求することを目的とした一連の報告の中で顎口腔系の変化が, 全身状態に与える影響について重心動揺分析システム, 聴性脳幹反応, 眼振図および指尖容積脈波などを用い, 検討を行ってきた.これらの研究の一つとして, これまでに水平的下顎位保持装置を用い, 健: 常者における水平的下顎位の変化が重心動揺および抗重力筋筋活動量に影響を与えることを報告した.そこで今回は水平的下顎位の変化が, 顎関節症患者の直立姿勢にどのような影響を及ぼすかについて検討を行ったところ, 重心動揺, 抗重力筋筋活動量のいずれについてもアペックスに比べ, いずれの水平的下顎位においても, その値は日間変動範囲を越え増加傾向にあるとともに左右側差の大きい者が多く見られる傾向であった.よって, 水平的下顎位の変化は, 重心動揺および筋活動量に影響を与えることから, 顎口腔系の変化は全身状態に影響を及ぼすこと, また, 顎関節症患者においてはすでに全身状態に影響が及んでいるだけでなく, 負荷を加えることによりその影響がより著明に現れる可能性が示唆された.

Purpose: To date, the minimum thickness required for a mouthguard has been assumed to be around 2 mm to 4 mm. However, this figure is based mostly on experience and is yet to be standardized. The purpose of this study is to determine the minimum thickness required to obtain sufficient energy absorption.Methods: The thicknesses of the tested ethylene vinyl acetate) samples were 1, 2, 3, 4, 5, and 6 mm. The pendulum-type testing equipment used in the present study was also used in a series of earlier studies. Three types of sensors (strain gauge, accelerator, and load cell) and two different impact objects (a steel ball and baseball) were used.Results: The results showed that all the abovementioned mouthguard thicknesses reduced shocks for all the three types of sensors and both types of impact objects; little difference was observed between sensors and clear results were obtained for the steel ball. An improvement in the energy absorption was observed with an initial increase in the thickness. However, a further increase in the thickness from 4 mm to 5 mm and 6 mm tended to yield a smaller improvement in energy absorption.Conclusion: Within the limitations of this study, from the viewp int of energy absorption ability, the minimum thickness required for a mouthguard is 4 mm, which is generally too large from the viewpoint of player comfort. This finding indicates the necessity of improving the impact absorption ability of mouthguards by considering new designs and developing new materials.

Silicon consumption in a selective tungsten chemical vapor deposition (SWCVD) process using SiH 4 reduction of WF 6 was investigated. In the SWCVD process, the Si surface was consumed through the reduction of the WF 6 until a continuous W cladding layer was formed. The dependence of Si consumption on growth temperature and impurity concentration was investigated by measuring the decrease in silicon on insulator (SOI) thickness using an ellipsometer. The consumption decreased with a decrease of the growth temperature dependent on an activation energy of 0.104 eV; the consumption increased in proportion to the phosphorus concentration, in the region where the concentration was above about 9 × 10 19 cm -3 . It was demonstrated that SWCVD could he applied to fabricate a W cladding layer on the gate/source/drain regions of the fully depleted 20 nm SOI complementary metal oxide semiconductor field effect transistors (CMOSFETs). Moreover, optimizing the fabrication process to avoid excess impurity concentration in the n + -S/D regions of the n-MOSFETs will make this technology suitable for use with thinner SOI devices.