有上颌的

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。

There are 20 primary or baby teeth that every child has during their lifetime, with ten in the upper jaw and ten in the lower.

有20个小学或婴儿的牙齿说，每个儿童在其一生中，与10 ，在上颌骨和10在较低的。

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。

Based the above research, we chosen 48 cephalometric radiographs of skeletal classⅢocclusion (18-39 years old, ANB4°) and measured with computer assistant Delaire cephalometric analysis. The data were deal with ANOVA analysis through SAS9.0 statistical software. The research divided the cranio-maxillo-facial hard tissue structure feature of skeletal classⅢinto four classifications through Delaire cephalometric analysis including hypo-divergent, hyper-divergent, maxilla normal and glenoid fossa retrocession, nine parameters of four groups have significantly variability through ANOVA analysis(P.05),for example, anterior cranial base angle, sphenoidal angle, percentage of craniospinal area to cranial depth ,percentage of craniofacial area to cranial depth and so on.

在上述研究的基础上，首先选取48例骨性Ⅲ类错牙合畸形患者(18-39岁，ANB角4°)应用Delaire头影测量分析法进行测量，经SAS9.0行ANOVA分析，将骨性Ⅲ类错牙合畸形区分为低角型、高角型、上颌正常型和关节窝后移型四组，四组均数ANOVA分析发现九项分析指标的均数差异均有统计学意义(P.05)，如蝶鞍角、前颅基底角、颅面区比和颅颈区比。

Besides, the occurrence of simple imperforation was confirmed during operation in 26 cases of the 88 patients (30%) without positive finding of preoperative CT examination.

在术前CT显示无上颌窦腔密度增高及骨质增厚的88例病例中，有26例(30%)术中发现有单纯性下鼻道开窗闭锁。

Besides, the occurrence of simple imperforation was confirmed during operation in 26 cases of the 88 patients (30%) without positive finding of pre operative ct examination.

在术前ct显示无上颌窦腔密度增高及骨质增厚的88例病例中，有26例(30%)术中发现有单纯性下鼻道开窗闭锁。

Large amounts of scar tissues were found in maxillary sinus cavities during the operation in the 48 cases, and 22 cases of which (46%) developed imperforation of inferior meatal openig.

在术前CT显示无上颌窦腔密度增高及骨质增厚的88例病例中，有26例(30%)术中发现有单纯性下鼻道开窗闭锁。

MB1 root canals of the mesiobuccal root canals in maxillary molars were found obvious curve out by the rate of 82.5% in mesiodistal direction,77.5% in buccoling

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。

METHODS:Fifty two permanent maxillary first molars,which were diagnosed as pulpitis and periapical periodontitis clini cally,were selected.The pulp chamber floors were examined and detected to locate the mesiolingual canals(MB2) by naked eyes and SOM respectively.

由于其近颊根通常有近中颊和近中舌(MB2 ) 2个根管，而其近中舌根管细小且根管口常较为隐蔽，因此，Weine认为上颌第一恒磨牙根管治疗失败的一个主要原因是治疗中遗漏了MB2根管。

Each of them had 3 anterior maxillary teeth restored by porcelain-fused-to-nichrome crowns, without other metal fillings or protheses.

对象：选择2006-01/12在河北北方学院附属第一医院口腔修复科就诊的60例上颌前牙有3颗行镍铬合金烤瓷冠修复的患者为实验组，男28例，女32例，平均40岁，均无其他金属充填物和修复体者。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐