牙根

This paper reports the case of a maxillary first molar that presented two root canals in the Mesiobuccal root.

本论文为在职专班研究生以案例报告，叙述上腭第一恒磨牙近中颊侧牙根，发现两个根管的案例。

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。

Through designing of composition and structure of the bioactive graded coating,innerstress and its distribution in the coating were analyzed and calculated, the resultsshowed that when composition distribution coefficient n was 1.5, a reasonable stressdistribution could be got, that was at the beginning of deposition the suspension containingrichly BG granules was used so that a rich BG granules layer, a good transitional layerbetween BG layer at the bottom and the coating could be obtained at the titanium alloy side,the bottom of the coating; the stress value near the interface and surface and its character,pressure stress or tensile stress, were decided by the character of its composition itself.Changing composition distribution coefficient n could only change the variation tendency ofstress in the coating, but did not change the stress distribution rule in the coating. Thethinner the coating is, the sharper stress variation in the coating is, which does not mean thatthicker coating is better because the thicker the coating is, the little the permitteddeformation of coating is, so the coating thickness should be thinner, for example, about50μm for bending applications, but for applications only bearing pure shear stress, such asroot of tooth implant, the coating can be thicker little, for instance, about 80～100μm. The study on electrification characteristic and electrophoresis deposition of HAand BG granules in aqueous and non-aqueous solution system found that EPD almost didn'toccur in aqueous solution system. However, because HA granules take position charges inabsolute alcohol, a homogeneous EPD be carried out on the cathode titanium alloy slice, but taking negative charge in absolute alcohol the BG granules not be deposited on the cathode. A guided HA crystallizing, 100～300nm, on surface of the BG granules be realized by metathetical reaction, which cover BG granules with HA microcrystals and make the covered BG granules taking position charges in absolute alcohol, sequentially realize the EPCD of the BG and HA granules on the cathode, so it is feasible to make a titanium alloy/BG/HA bioactive graded coating by making use of EPCD technology. The corrosion experiment of rich boron bioglass coating and plasma spray coating showed that split phase, rich boron and rich silicon phase, occurred during its preparation. In basic medium the corrosion behavior of 〓 BG coating showed uniformity corrosion, the corrosion mostly occurred at rich boron phase area, therefore batch formula design of BGshould avoid the occurring of split phase. The corrosion appearance of plasma spray coatingappeared a non-uniform corrosion, mostly occurred at the edge of the laminated HA moltendrops, and emerged an accelerated corrosion tendency, which will easyly lead to corrosioncrackles extending to the interface and the happening of osmotic interfacial corrosion, thatmay be one of the major reasons leading to the coating cracking-off in the later period. Thetesting results of thermal expansion coefficient of 〓 and 〓BG showed the thermalexpansion coefficient of 〓 BG matched with that of titanium alloy better, and 〓 BG couldsinter with titanium alloy into densification enamel layer at low temperature (720℃).

将Ti6Al4V合金在1000℃下进行真空热处理会降低其力学性能，且合金内的V元素会向表面富集，因此，钛合金真空热处理和表面涂层的烧结温度不能过高，即应低于其相转变点；通过对生物活性梯度涂层的组成和结构的设计，分析和计算了梯度涂层内的应力大小和分布，结果表明：对于本研究，当成分分布系数n=1.5时，可以获得较合理的涂层力学性能，即在沉积开始时，采用富含BG颗粒的悬浮液，以便在钛合金侧获得同底层BG有良好过渡的富BG涂层；梯度涂层界面和表面的应力大小、性质由材料组成本身的性质决定，改变成分分布系数，只能改变涂层内应力变化的趋势；涂层的厚薄不影响涂层内的应力分布规律，但涂层越薄，涂层内的应力变化越快，但这并不意味着涂层越厚越好，因为涂层越厚，涂层允许的变形越小，对于应用于弯曲受力部位的涂层而言，涂层应薄一点为好(50μm)；而对于仅纯受剪切应力的部位，如牙根种植体，涂层可适当加厚(80～100μm)；通过对HA和BG颗粒在水溶液体系和非水溶液体系中的带电特性和电泳沉积的研究发现，它们在水溶液体系中很难发生电沉积；在无水乙醇溶液中，HA颗粒带正电，可在阴极钛合金片上发生均匀的电泳沉积，而BG颗粒则带负电荷；利用复分解反应法，可以制得100～300nm的HA，通过诱导HA在BG颗粒表面结晶，可对BG颗粒进行表面包覆，获得了被HA包覆的BG颗粒，改变了BG颗粒表面的带电特性，使BG和HA颗粒在无水乙醇中均带上正电荷，从而实现了HA和BG颗粒在阴极上的共沉积。

According to the site condition and biological characteristics, Bermudagrass, Bahiagrass and weeping lovegrass were chosen to hydroseed 8 different type turf in south slopes of red soil in Shenzhen. The turfgrass seeds were sowed singly or mixedly according to different species and ratios. The ecological, social and economical effectiveness of the turf was studied systematically, and AHP structure model was used to assess different turfs.

根据立地条件和生物学特性，选择狗牙根、百喜草和弯叶画眉草在探圳市赤红壤阳坡上单独或按不同比例混合喷建了8种不同类型草坪，系统地研究了它们的生态、社会和经济效益。

This report presents 2 cases of inadvertent injection of sodium hypochlorite into the periradicular tissue because of apical constriction destruction and canal perforation. Acute severe pain, gingival swelling, cellulites, and even parathesis over the circumscribed region of the upper lip were noted.

本病例报告是两例有关根管治疗过程中，因治疗过程不愼使根尖孔破坏与穿孔，并将根管冲洗溶液次氯酸钠挤压至牙根周围组织中，造成急性疼痛、牙龈肿胀、蜂窝组织炎，甚至有局部性的嘴唇麻痹现象等剧烈组织反应。

Absctrct: Objective This study was designed to investigate the stress distribution in the surface of tooth and peridental tissues and the initial displacements of tooth in the maxillary under two orthodental simulating force rectangular archwire with T loop and II class elastic used clinically by the 3-D finite element method so as to clarify the biomechanism of orthodontic tooth movement and component of optimal orthodontic force system.

目的：通过有限元分析法比较两种工况下上颌各牙齿的位移趋势和牙根及牙周支持组织内的应力分布规律，为临床治疗中合理选用矫治力系统以便有效的控制牙齿移动类型提供可靠的理论依据。

In order to analyze the association of the periodontitis severity with changes of the human dental pulp, one hundred caries-free and restoration-free periodontally involved teeth with different periodontic destruction were studied histologically.

为了分析牙周炎的病变程度与牙髓组织改变的关系，对100个牙体完好的具有不同牙周破坏程度的牙周炎患牙进行了组织学观察，分析牙根暴露量、牙周袋深度和牙齿松动度与牙髓病变的关系。

MTA was used to manage clinical problems. These included pulpless permanent teeth with incomplete root formation and perforation in roots or furcations.

本研究收集了2000—2001年期间在临床上治疗的牙根或根分叉穿孔的病例和根尖未发育完成并牙髓坏死的病例，用MTA修补穿孔和行根尖屏障术，共治疗10例，12颗患牙。

The follow-up periods were various from 6m to 21m. The apical MTA barrier technique was used to manage pulpless permanent teeth with incomplete root formation. The postoperative radiographs showed complete repair of periradicular tissue in 5 of 7 teeth and improvement obviously in other 2 teeth. Only one case (1 tooth) had a 3mm periodontal pocket in four perforation repair cases. The lesion at the perforation sites was improved obviously.

追踪观察时间为6-21月。4例穿孔修补的病例，均为延迟修补，除一例为根尖1／3处的病理性吸收外，其余患牙的穿孔部位位于牙根的冠1／3或根分叉处，一例6m复查时有3mm的牙周袋形成，其余患牙骨吸收暗影均明显缩小。7例根尖发育不全并无髓牙的病例均为成人，5例根尖暗影完全消失，2例明显缩小。

The use of subepithelial connective tissue graft for root coverage procedure had been carried out for over twenty years.

皮下结缔组织移植(subepithelial connective tissue graft)於牙根覆盖手术已有二十余年之历史。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。