patient： Nurse ， my gums bleed when I brush my teeth . I don't know why .
    nurse： How long has it been like this？
    P： For about 5months.
    N： Open your mouth . Let me have a look There are a lot of dental calculus and odontolith on your teeth . They can stimulate the edge of the gums and cause inflammation and bleding of the gums.
    P： What are dental calculus and odontolith？
    N： The dental calculus is the soft calculs on the surface of teeh or at the edge of gums . It appears yello or grey . It's soft and easy to remove . The odontolith is the hard calcified or calcifying lump which is mainly formed by dental plaque . It's hard and dificult to remove.
    P： How to remove the dental calculus and odontolith？
    N： The doctors can do it . They remove them with a special instrument or an ultrasonic scaler.
    P： That's wonderful . Could you please say something more about ultrasonic curettage？
    N： Ultrasonic curettage is an effective method of debridement of the soft tissue walls of periodontal pockets ， and histological studies of tissue excised after curettage have shown that healing occurs by epithelialization of the sulcuar surface and resolution of inflammation in the gingival corium . The ultrasonic technique is equally as effective as conventional hand instrumentation in calculus removal ， but less effective in stain removal . Of course it is more rapid than hand instrumentation.
    P： Have you found any adverse effects on the tissue of the periodontium？
    N： No.
    P： Can we prevent dental calculus and odontolith？
    N： The most important thing is to pay more attention to dental hygiene . Especially you should learn to brush your teeth correctly.
    P： I brush them horizontally.
    N： That's a wrong way . The correct way is to brush them up and down . To brush them horizontally may rub all the natural enamel off . I think it is also very important to select a suitable toothbrush . The head of the toothbrush should not be too long or too short .For adults ， the length of the head of the brush is not more than 35mm ， the width is not more than 13mm . For children ， the length is not more than 28mm ， the width is not more than 11mm . For infants ， the length is ont more than 25mm ， the width is not more than 8mm.
    P： I have learned a lot . Thank you very much.
    N： Not at all.
    P： I want to have my teeth cleansed . Could you make an appoinment for me ？
    N： All right . The doctor has got rather a full day tomorrow ， You can come here at 10 the day after tomorrow.
    P： All right . Good bye.
    N： Good bye.
    病人：護士，我刷牙時牙齦出血，不知道是什么原因？
    護士：這種情況有多長時間了？
    病人：大約有5個月了。
    護士：張開嘴，讓我看看。… 在您的牙齒上有很多牙垢和牙石。它們可以刺激牙齦的邊緣而引起牙齦發(fā)炎和出血。
    病人：什么是牙垢和牙石？
    護士：牙垢是附在牙齒表面和根緣處的軟垢，呈黃色或灰白色，較軟，易除去。牙石是附在牙面上的鈣化或正在鈣化的牙菌班為基質(zhì)的團塊。較硬，不易除去。
    病人：怎樣除去牙垢和牙石呢？
    護士：大夫可以做到。他們用一種特殊的器具或超聲波潔牙器來除去牙垢和牙石。
    病人：那太好了。您能再變談超聲波潔牙嗎？
    護士：超聲波刮治術是一種清掃牙周代軟組織壁的有效方法。在刮治后的組織學研究表明：齦溝合，同時牙齦真皮內(nèi)炎癥得到消除。超聲波技術清除牙石的作用與常規(guī)的手持器械同樣有效，但除去色斑的效能較差，當然速度快得多。
    病人：你們發(fā)現(xiàn)它對牙周組織有害嗎？
    護士：沒有。
    病人：牙垢和牙石可以預防嗎？
    護士：最重要的是注意口腔衛(wèi)生。尤其是學會正確地刷牙。
    病人：我橫著刷牙。
    護士：那是錯誤的方法。正確的方法是上下刷。橫著刷可能破壞琺瑯質(zhì)。我認為選擇一把合適的牙刷也是很重要的。牙刷頭不可過長或過短。成年人刷頭長度不超過35毫米，寬不超過13毫米。兒童，長度不超過28毫米，寬不超過11毫米。幼兒，長度不超25毫米，寬不超過8毫米。
    病人：我知道了許多知識。太謝謝您了。
    護士：不客氣。
    病人：我準備潔齒，您能給我約定個時間嗎？
    護士：好吧。醫(yī)生明天已經(jīng)排得相當滿了。您可以后天上午10點鐘來。
    病人：好吧，再見。
    護士：再見。