臼齒

　　The molars are the largest teeth in the mouth and are also very strong — there are four at the top and four at the bottom.

　　臼齒是口腔內較大的牙齒，同樣十分堅韌，分布于左右頰部后端，上下各四顆。

　　PROBLEMS: These are the most likely to need fillings because they are harder to reach when brushing; it’s a -problem for upper molars because salivary ducts in the cheek next to them produce saliva and this causes plaque to harden.

　　問題：位置靠內而難以清潔，所以臼齒是最需“補牙”的牙齒。而上臼齒十分接近臉頰兩側的唾液腺，因為十分容易導致牙菌斑的產生。

來源:可可英語 http://www.ccdyzl.cn/read/201101/123103.shtml