A higher number of deepened periodontal pockets (infection of the gum around the base of the tooth) had a 53 percent increased risk of heart attack compared to those with the fewest pockets.

牙周袋（牙根周围牙龈感染）多的比牙周袋最少的心脏病风险高53%；

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On the base of principle of involute gear and its property, the formation of tooth surface are introduced.

根据渐开线齿轮的原理和渐开线的基本性质，介绍渐开线齿轮齿廓的形成。

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The tooth deformation includes the contact deformation, deflection, base deformation and the influence of the body deformation, and the contact stress and the stress distribution are computed too.

轮齿变形包括轮齿接触、挠曲、基础变形和齿轮本体变形的对它影响，还有接触应力和分布。

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