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. form www.med66.com

　　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：护士，我刷牙时牙龈出血，不知道是什么原因？

　　护士：这种情况有多长时间了？

　　病人：大约有5个月了。

　　护士：张开嘴，让我看看。… 在您的牙齿上有很多牙垢和牙石。它们可以刺激牙龈的边缘而引起牙龈发炎和出血。

　　病人：什么是牙垢和牙石？

　　护士：牙垢是附在牙齿表面和根缘处的软垢，呈黄色或灰白色，较软，易除去。牙石是附在牙面上的钙化或正在钙化的牙菌班为基质的团块。较硬，不易除去。

　　病人：怎样除去牙垢和牙石呢？

　　护士：大夫可以做到。他们用一种特殊的器具或超声波洁牙器来除去牙垢和牙石。

　　病人：那太好了。您能再变谈超声波洁牙吗？

　　护士：超声波刮治术是一种清扫牙周代软组织壁的有效方法。在刮治后的组织学研究表明：龈沟合，同时牙龈真皮内炎症得到消除。超声波技术清除牙石的作用与常规的手持器械同样有效，但除去色斑的效能较差，当然速度快得多。

　　病人：你们发现它对牙周组织有害吗？

　　护士：没有。

　　病人：牙垢和牙石可以预防吗？

　　护士：最重要的是注意口腔卫生。尤其是学会正确地刷牙。

　　病人：我横着刷牙。

　　护士：那是错误的方法。正确的方法是上下刷。横着刷可能破坏珐琅质。我认为选择一把合适的牙刷也是很重要的。牙刷头不可过长或过短。成年人刷头长度不超过35毫米，宽不超过13毫米。儿童，长度不超过28毫米，宽不超过11毫米。幼儿，长度不超25毫米，宽不超过8毫米。

　　病人：我知道了许多知识。太谢谢您了。

　　护士：不客气。

　　病人：我准备洁齿，您能给我约定个时间吗？

　　护士：好吧。医生明天已经排得相当满了。您可以后天上午10点钟来。

　　病人：好吧，再见。

　　护士：再见。