恒牙

AIM:To determine the efficiency of surgical o perating microscopein locating the se- cond mesiobuccal canal of perm anent upper first molar.

上颌第一恒磨牙在口腔内萌出较早，其龋病和尖周病的发病率较高，然而有资料统计其根管治疗的成功率较低。

Methods A modified Bramante muffle was used and 22 chinese mandibular second molars with Cshaped root or seperated roots were sectioned into four pieces perpendicularly distance from apex to 3,3.5,8 mm,respectively.The crosssectional anatomical morphology was observed and the minimum root canal wall thickness of each section was measured.

使用改良Branmante体外模型，将具有C形牙根或两个独立牙根中国人下颌第二恒磨牙各22颗，在距根尖3，5.5，8 mm处将样本锯为四段，观察C形根管横断面形态，测量断面最小根管壁厚度。

Objective This study was designed to examine the relationship of children抯 eating habit and initial demineralization of the first permanent molar.

目的 研究儿童饮食习惯与第一恒磨牙早期脱矿的关系。

Methods Enamel surface specimens were randomly allocated into 3 groups: 1 450 mg/L sodium fluoride dentifrice group, 1 450 mg/L sodium monofluorophosphate dentifrice group and non-fluoride dentifrice control group. Sound enamel surfaces were dematerialized in bacteria model in vitro. QLF was used to analyze the area of lesionsArea, the loss of fluorescenceΔF and ΔQArea×ΔF on enamel surfaces after demineralization.

将30个牙釉质块开窗后分为3组，分别使用氟含量1 450 mg/L的氟化钠牙膏、单氟磷酸钠牙膏和无氟牙膏的处理液处理，并在体外恒化器龋病模型中进行脱矿循环，定量光导荧光技术QLF分析病损脱矿后的面积、荧光损失和总荧光损失量，激光扫描共聚焦显微镜CLSM分析脱矿后矿物质含量变化。

Methods Enamel surface specimens were randomly allocated into 3 groups: 1 450 mg/L sodium fluoride dentifrice group, 1 450 mg/L sodium monofluorophosphate dentifrice group and non-fluoride dentifrice control group. Sound enamel surfaces were dematerialized in bacteria model in vitro. QLF was used to analyze the area of lesions, the loss of fluorescence and ΔQ on enamel surfaces after demineralization.

将30个牙釉质块开窗后分为3组，分别使用氟含量1 450 mg/L的氟化钠牙膏、单氟磷酸钠牙膏和无氟牙膏的处理液处理，并在体外恒化器龋病模型中进行脱矿循环，定量光导荧光技术分析病损脱矿后的面积、荧光损失和总荧光损失量，激光扫描共聚焦显微镜分析脱矿后矿物质含量变化。

Enamel surface ecime were randomly allocated into 3 grou : 1 450 mg/L sodium fluoride dentifrice group, 1 450 mg/L sodium monofluoropho hate dentifrice group and non-fluoride dentifrice control group. Sound enamel surfaces were dematerialized in bacteria model in vitro. QLF was used to analyze the area of lesio, the lo of fluorescence and ΔQ on enamel surfaces after demineralization.

将30个牙釉质块开窗后分为3组，分别使用氟含量1 450 mg/L的氟化钠牙膏、单氟磷酸钠牙膏和无氟牙膏的处理液处理，并在体外恒化器龋病模型中进行脱矿循环，定量光导荧光技术分析病损脱矿后的面积、荧光损失和总荧光损失量，激光扫描共聚焦显微镜分析脱矿后矿物质含量变化。

Methods 1000 children first permanent molar normal eruptively were surveyed the extent of initial demineralization on the caries saitivity position by laser-fluorescence system KaVo DIAGNOdent,and chosen 60 no- demineralized children and 60 initial-demineralized or caries-susceptible children,Data were collected by questionnaire from their parents and analyzed by logistic regression and x2 test on computer.

采用激光荧光测定仪对1000名第一恒磨牙均已正常萌出的儿童进行龋敏感点位脱矿程度检查，随机抽取釉质无脱矿组和釉质脱矿组或龋病损组，60份有效配对问卷，进行x2检验及Logistic回归分析。

Objective To investigate the clinical effect of one-time root canal therapy and reattachment of permanent incisors with crown fracture.

目的：观察恒切牙外伤冠折后行一次性根管治疗与断冠再接术的临床效果。

Majority of the four root canals of first maxillary molars showed curvatures at varing degrees in mesiodistal and buccolingual directions, and the second curvatures of them were different too.

上颌第一恒磨牙四个根管在近远中方向、颊舌方向均有不同程度的弯曲，其第二弯曲出现的情况也各不相同。

Radiograph of teeth in buccolingual and mesiodistal directions with 15#~20# reamers in root canals calculated and recorded for both views using Photoshop6.0 by computer.

收集南京地区80例上颌第一恒磨牙，在根管中分别插入15#~20#扩大针，拍摄近远中向和颊舌向X线片，用Photoshop 6.0软件测量分析根管弯曲位置、弯曲方向和弯曲角度。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。