patient： Nurse ， would you like to tell me something about caries？

　　Nurse： Of course . What do you want to know？

　　P： What causes dental caries？

　　N： It's mainly caused by certain organisms of the oral flora . It is an irreversible ， slowly progressive decay of the hard tissues . It leads to a disintegration of tooth structures and cavitation.

　　P： I wonder if the lesions occus predominantly in particular regions of the tooth（teeth）？

　　N： That's right . It's also connected with the defect of the structure of the tooth（teeth）。

　　P： What is the defect of the structure of the tooth（teeth）？

　　N： It means the dyspasia of the dentine or the uneven squeezingly positioned teeth and the physically defect with sulci and fossae on the teeth.

　　P： How can we prevent this disease？

　　N： The first . it's very important that you pay more attention to the dental hygiene . You should brush your teeth twice a day . once in the morning ， and once in the evening . The upper row of the teeth should be brushed first ， then the lower row . All the crevices must be cleared of remnant food . Besides that . you should rinse your mouth after meals . The second ， take less sweet food ， especially for children . Don't take fermented food before you go to bed or wake up at night ， such as candy or biscuit . The third ， come here for periodical checkups once or twice a year . Caries may progress microscopically a considerable period of time before the lesion can be observed clinically in the tooth strucure . Generally if the cavity is not deep ， you'll have no symptom， so you should have the permanent filling in case that the cavity may get bigger . The fourth ， the methods in using immunization ， laser and coating material to prevent caries are still being carried out in tests . The fifth ， to build up your health is very important.

　　P： It's very kind of you to answer my questions.

　　病人：護(hù)士，您能給我講講齲齒嗎？

　　護(hù)士：當(dāng)然可以，您想了解什么？

　　齲齒是由什么引起的？

　　護(hù)士：齲齒是由口腔菌叢中的某些細(xì)菌所引起的。它是在牙齒硬組織中發(fā)生的一種不可逆的緩慢進(jìn)行腐蝕過程，導(dǎo)致牙齒組織崩解及腔洞形成。

　　病人：該病變是否主要發(fā)生在牙齒的一些特殊部位？

　　護(hù)士：晃的，它知牙齒的結(jié)構(gòu)有缺陷有關(guān)。

　　病人：什么是牙齒結(jié)構(gòu)上的缺陷呢？

　　護(hù)士：那是指牙齒的硬組織發(fā)育不良或牙位擁擠，排列不齊，以及牙齒站的溝窩等生理缺陷。

　　病人：如何預(yù)防齲齒病呢？

　　護(hù)士：第一，注意口腔衛(wèi)生非常重要。每日應(yīng)刷牙兩次，早晚各一次。先刷上牙，后刷下牙。要把牙縫里的殘余食物都刷干凈。除此之外，飯后要漱口。第二，少吃甜食，特別是兒童。不要在睡前或半夜醒來時(shí)吃可發(fā)酵的食物，如糖果、餅干等。第三，定期來這里檢查，一年1-2次。在臨床上能夠觀察到牙齒結(jié)構(gòu)病變之前，顯微鏡下齲齒病的進(jìn)展可能已持續(xù)了相當(dāng)長的時(shí)期。一般齲洞不深時(shí)，無任何癥狀，所以應(yīng)該早期填充以免齲洞擴(kuò)大。第四，關(guān)于免疫防齲，激光防齲，使用防齲涂料等，現(xiàn)仍在試驗(yàn)階段。第五，重要的是增進(jìn)身體健康。

　　病人：非常感謝您給我解答了這么多問題。