基牙数目对游离端附着体义齿支持组织应力分布的影响

目的探讨不同基牙数目下,下颌双侧游离缺损冠外附着体义齿支持组织的应力分布情况。方法建立下颌KennedyⅠ类牙列缺损冠外附着体义齿修复的三维有限元模型,分析在垂直载荷作用下采用不同基牙数目时,基牙牙周组织及缺牙区牙槽嵴的von Mises应力分布。结果末端基牙牙周膜应力集中区位于远中的牙颈部,牙槽嵴的高应力区主要位于牙槽嵴顶的近远中两侧。随着基牙数目的增加,基牙牙周组织及缺牙区牙嵴的最大应力值都呈下降趋势,应力分布趋于均匀。当基牙数目从1颗增加到2颗时到再增加到3颗时,牙周膜的最大应力约呈等梯度下降,而基牙牙槽骨和牙槽嵴的下降量则明显减少。结论在下颌游离缺损修复中,冠外附着体义齿支持组织应力的减少与基牙数目的增加不完全成比例,在临床上应根据具体的情况确定联合基牙的数目。     

冠外精密附着体对基牙及牙周组织影响的三维有限元分析

我们建立了包括下颌骨和切牙、尖牙、前磨牙的双侧游离末端牙列缺失的三维有限元模型,在此基础上又建立了配带精密附着体义齿的模型,考虑基托与缺牙处牙槽嵴间的接触,比较修复前后基牙及其牙周组织、牙列缺失部位牙槽嵴的von Mises应力。结果表明:精密附着体修复后,基牙及基牙根周牙槽骨的von Mises应力值较修复前无论舌侧、颊侧都有了明显增加,应力集中范围增大;牙列缺失部位的应力也有所增加。     

下颌56缺失两基牙双端固定桥修复的生物力学分析

目的：研究下颌56缺失两基牙双端固定桥修复的应力分布。方法：采用CT扫描获取健康成人下颌牙及其支持组织的二维图像。通过计算机重建技术建立三维立体图像并获得了下颌56缺失后的两基牙双端固定桥的三维有限元数学模型。在相同垂直载荷和水平载荷下分析了基牙牙槽骨高度对固定桥应力分布的影响。结果：当基牙牙槽骨无吸收时固定桥两基牙应力分布均匀；当基牙牙槽骨有轻度吸收大于10％时。固定桥两基牙即开始出现应力集中。结论：下颌56缺失后选择两基牙双端固定桥修复受基牙牙槽骨吸收程度的影响较大，基牙牙槽骨仅有轻度吸收时就会引起应力分布的变化。     

两种不同附着体固位全口义齿：修复下颌牙列缺失的生物相容性

背景：精密附着体能提供恒定持久的固位力,提高咀嚼效率,防止牙槽骨吸收,近年已在全口义齿修复牙列缺失患者中使用,而磁性附着体和球帽附着体在下颌牙列缺失中应用较多。目的：比较磁性附着体和球帽附着体固位全口义齿修复下颌牙列缺失的临床效果。方法：纳入牙列缺失患者50例,其中男28例,女22例,年龄40-82岁,随机均分为2组,分别行磁性附着体固位的下颌可摘义齿修复和球帽附着体固位的下颌可摘义齿修复。戴入义齿6个月后进行咀嚼功能检查;戴入义齿2年后,进行患者满意度问卷调查及牙周健康检查。结果与结论：戴入义齿6个月后,两组均获得了较高的咀嚼效率,组间比较差异无显著性意义。戴入义齿2年后,磁性附着体组患者对固位情况和舒适性的满意度高于球帽附着体组(P < 0.05);磁性附着体组的牙龈指数、龈沟出血指数、基牙松动度低于球帽附着体组(P < 0.05),牙槽骨高度高于球帽附着体组(P < 0.05)。表明磁性附着体固位全口义齿修复下颌牙列缺失在临床疗效上较球帽附着体具有一定的优越性,能够提供合适的固位力,更好地保护基牙牙周组织健康。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

两种牙体预备方法制作玻璃纤维夹板固定松动前牙5年临床观察

背景：研究发现采用舌侧凹槽加邻面流体树脂牙体预备方法制作玻璃纤维夹板,用其固定松动前牙可达到较为理想的临床固定修复效果。 目的：观察两种牙体预备方法制作玻璃纤维夹板固定松动前牙5年基牙与夹板脱黏率及固定修复效果。 方法：根据慢性牙周病诊断标准,并严格按照牙周夹板固定适应证选取经过牙周基础治疗后需纤维夹板固定的94例Ⅱ-Ⅲ度前牙松动患者,根据松动患牙间是否进行邻面固定分为2组,邻面未固定组采用舌侧凹槽牙体预备方法,邻面固定组采用舌侧凹槽加邻面流体树脂牙体预备方法进行纤维夹板固定。随后5年中定期临床复诊或电话随访,对固定修复效果进行评价。 结果与结论：5年中定期临床复诊或电话随访显示,邻面固定组76例基牙与夹板脱黏7例,邻面未固定组18例基牙与夹板脱黏12例,均已经进行再固定。与邻面未固定组相比,邻面固定组5年后两组患牙的探诊深度、附着丧失明显改善(P  < 0.05),牙槽骨高度占根长的百分比增加(P < 0.05),患者自觉舒适无异物感。结果证实,采用舌侧凹槽加邻面流体树脂牙体预备方法制作玻璃纤维夹板固定松动前牙的5年观察固定效果较好。     

三维有限元分析前牙区单端固定桥及骨组织的应力与应变

背景：单端固定桥在临床修复牙列缺损时,对于种植体和桥体的数量、位置以及受力情况方面还存在一些争议。 目的：通过三维有限元方法分析前牙区单端固定桥的受力情况。 方法：应用计算机模拟三维有限元的方法,对种植体支持的固定义齿进行有限元分析,不同数量种植体以及种植体位于固定桥不同位置时,种植体及其周围骨组织的应力应变情况,为临床提供指导意义。 结果与结论：①当加载力量及角度相同的情况下,随种植体数量减少或桥体长度增加,种植体及周围骨质的最大等效应力值逐渐增大,最小安全系数逐渐减小。当加载角度为22.5°时,种植体及周围骨质的最大应力值最小,最小安全系数为所有加载角度的最大,随着角度的继续增大,种植体及周围骨质的最大应力逐渐增大,最小安全系数又逐渐减小。②单端桥修复前后应力分布不均,基牙骨支持组织的应力均集中于其颈部。③3个单位缺牙区域,基牙数越多,修复成功率越高。合理选择单端固定桥和双端固定桥的修复设计是治疗成功的关键。     

正畸牙移动过程中尼古丁摄入对牙周组织影响

背景：吸烟是严重影响牙周组织和牙根健康的危险因素之一,烟草中的尼古丁会加速牙周病患者牙周组织的破坏。 目的：分析正畸牙移动过程中不同剂量尼古丁作用下牙周组织内环氧化酶2及mRNA表达的变化规律。 方法：将110只SD大鼠随机分为5组,空白对照组10只,生理盐水组和尼古丁0.5,0.75,1 mg/kg组各25只。除空白组外所有大鼠使用50 g力牵拉一侧上颌第1磨牙向近中移动。生理盐水组每日腹腔注射0.1 mL生理盐水;尼古丁组每日腹腔注射0.5,0.75,1 mg/kg尼古丁酒石酸溶液。各组大鼠分别在加力1,3,5,7,14 d时处死取上颌组织,苏木精-伊红染色观察牙周组织变化,免疫组织化学染色计数破牙骨质细胞阳性细胞,原位杂交染色法检测环氧化酶2在牙周组织中表达的平均吸光度值。 结果与结论：尼古丁各剂量组在各加力时间点破牙骨质细胞数目均高于未注射尼古丁组,且环氧化酶2阳性细胞表达强度也均高于未注射尼古丁组。随尼古丁注射剂量增大,破牙骨质细胞数目也逐渐增加(P < 0.05),加力7 d时各组破牙骨质细胞数目均达到峰值;环氧化酶2阳性细胞表达强度也随尼古丁注射剂量增大而增强(P < 0.05),加力5 d时表达强度达到峰值。结果表明,在相同加力时间点,破牙骨质细胞数目随剂量增大而增多,且环氧化酶2阳性细胞表达强度也随剂量增加而增强。正畸牙移动过程中的尼古丁摄入会造成牙周组织的破环,且尼古丁摄入剂量的高低直接影响牙周组织的破坏程度。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

CAD/CAM氧化锆全瓷冠修复对牙周组织的影响

背景：全冠修复体远期疗效的维持很大程度上取决于牙周组织的健康状况。 目的：探讨CAD/CAM氧化锆全瓷冠修复体对牙周组织健康状况的影响。 方法：随机选择需行全冠修复的55例患者64颗基牙作为研究对象,实验组为CAD/CAM氧化锆全瓷冠修复的29例患者32颗基牙,对照组为进行镍铬合金烤瓷冠修复的26例患者32颗基牙。检测两组修复前和修复后12个月的龈沟液含量、肿瘤坏死因子α和白细胞介素6水平,以及牙龈出血指数、牙周探诊深度、菌斑指数及附着丧失。 结果与结论：实验组修复前后各指标比较差异均无显著性意义(P > 0.05)。对照组修复12个月后的龈沟液含量、肿瘤坏死因子α、白细胞介素6、牙龈出血指数、牙周探诊深度及菌斑指数均高于修复前(P > 0.05)。修复12个月后,实验组龈沟液含量、肿瘤坏死因子α、白细胞介素6、牙龈出血指数、牙周探诊深度及菌斑指数均低于对照组(P < 0.05)。表明CAD/CAM氧化锆全瓷冠修复后对牙周组织健康基本无不良影响。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

磁性附着体在老年患者全口覆盖义齿中的应用

背景：磁性附着体能提供持久恒定的固位力,可显著提高全口义齿的固位和稳定,有效减少牙槽嵴的吸收,提高咀嚼效率,改善修复效果。 目的：观察Magfit磁性附着体在全口覆盖义齿中的临床应用效果及对基牙健康的影响。 方法：选择36例牙齿缺失患者,单颌选择1~3个基牙,以Magfit EX磁性附着体作为固位装置,制作覆盖义齿57件,其中上颌覆盖义齿27件,下颌覆盖义齿30件,共96副磁性附着体。 结果与结论：36例随访6~36个月,34例感觉义齿舒适,2例不适者经调改和适应后使用良好;33例咀嚼功能恢复良好,3例咀嚼功能恢复较好,但固位力下降,经调节后改善;1例基牙疼痛,经调颌后缓解;5例基牙松动度有好转;2例牙龈红肿充血经缓冲基托及对症治疗有所好转;1例活动义齿部分折断。说明磁性附着体可为覆盖义齿提供长期稳定的固位力,并有助于基牙健康。 关键词：磁性附着体;覆盖义齿;义齿固位;满意度;口腔生物材料 doi:10.3969/j.issn.1673-8225.2012.12.043     

不同材料充填修复下颌第一前磨牙楔状缺损的应力分析

目的 研究三种材料对两种角度下颌第一前磨牙楔状缺损的修复效果.方法 在下颌第一前磨牙颊颈部深度为1 mm,夹角分别为30°、90°的楔状缺损有限元模型上用银汞合金、复合树脂和玻璃离子粘固粉三种材料进行缺损修复,以未修复的楔模型为对照,加载100N轴向力后,利用三维有限元方法进行牙颈部应力分析.结果 三种材料修复均改善了缺损牙体的应力集中.银汞合金修复体较其他两种材料承受了更大的应力,使缺损局部牙体应力集中状况得以更多缓解,在角度增加时作用更明显.复合树脂最有效降低牙体内部区域的应力集中.结论 楔状缺损充填修复可缓解缺损区牙体硬组织的应力集中,复合树脂相对理想.     

Mosasaurs and snakes have a periodontal ligament: timing and extent of calcification,not tissue complexity,determines tooth attachment mode in reptiles

Squamates present a unique challenge to our understanding of dental evolution in amniotes because they are the only extant tooth‐bearing group for which a ligamentous tooth attachment is considered to be absent. This has led to the assumption that mammals and crocodilians have convergently evolved a ligamentous tooth attachment, composed of root cementum, periodontal ligament, and alveolar bone, whereas squamates are thought to possess a single bone of attachment tissue that fuses teeth to the jaws. The identity and homology of tooth attachment tissues between squamates, crocodilians, and mammals have thus been a focal point of debate for decades. We provide a novel interpretation of the mineralized attachment tissues in two focal taxa in this debate, mosasaurids and snakes, and compare dental tissue histology with that of the extant crocodilian Caiman sclerops. We identify a periodontal ligament in these squamates that usually exists temporarily as a soft connective tissue anchoring each tooth to the alveolar bone. We also identify two instances where complete calcification of the periodontal ligament does not occur: in a durophagous mosasaur, and in the hinged teeth of fossil and modern snakes. We propose that the periodontal ligament rapidly calcifies in the majority of mosasaurids and snakes, ankylosing the tooth to the jaw. This gives the appearance of a single, bone‐like tissue fusing the tooth to the jaw in ankylosed teeth, but is simply the end stage of dental tissue ontogeny in most snakes and mosasaurids.     

磨牙根分叉病变对固定义齿应力分布的影响

目的：研究磨牙根分叉病变对固定桥应力大小分布的影响。方法：采取CT平描的方法获得健康年轻人下颌牙及其周围组织的二维数据．通过计算机三维重建技术生成下颌第二前磨牙缺失的双端三单位固定义齿的有限元数学模型,在同等水平向载荷和垂直向载荷下分析了磨牙根分叉病变对固定桥应力大小分布的影响。结果：当磨牙根分叉区牙槽骨无吸收时,固定桥双侧两基牙应力大小分布均匀;当磨牙端根分叉区牙槽骨吸收达30％,前磨牙端牙槽骨无病变时,磨牙端根分叉区表现为应力集中;当前磨牙端和磨牙端根分叉区牙槽骨同时吸收达10％时,固定桥两侧基牙均表现为应力集中。结论：磨牙根分叉病变对固定义齿应力分布的影响较为明显,尤其是与前磨牙端基牙牙槽骨同时吸收时对基牙应力分布的影响最大。     

Nonlinear finite element analysis of the vibration characteristics of the maxillary central incisor related to periodontal attachment

The vibration characteristics of a maxillary central incisor were investigated by using the finite element method (FEM) according to nonlinear behavior of the human periodontal ligament (PDL). The effect of alveolar bone loss was also studied to obtain the relationship between the vibration property of the tooth in the periodontal system and the level of periodontal attachment for assessing the condition of periodontium. Three-dimensional (3D) finite element model of the tooth was constructed using CT image-reconstruction, and the elastic face foundation constraint was applied to the surface of the tooth root where the PDL was attached to. Modal analysis was performed by using FEM. The nonlinear behavior of the PDL was assigned and approached by the piecewise linearized method. The results indicated that the vibration of the maxillary central incisor in the periodontal system could be described by several modal frequencies and modes. The first four modes were dominant, which varied with the deformation of the PDL or the force applied on the tooth. The vibration frequency of the maxillary central incisor decreased with the losing of the alveolar bone, but the ratio of decrease had no significant correlation with the nonlinear behavior of the human PDL. The vibration frequency of the maxillary central incisor can be used to describe the loss of the alveolar bone and the level of periodontal attachment, under physiological short-term loading.     

微种植体复合力作用下竖直倾斜磨牙牙周膜的应力分析

背景：微螺钉种植体虽然能提供强支抗,但控制牙齿的三维移动存在不足。Tomas微种植钉的顶部设计成十字形,可固定方形弓丝,从而利用方丝控制牙齿的三维移动,目前对于研究Tomas微种植钉此方面的研究尚未见报道。 目的：观察Tomas微种植体复合矫治力系统对竖直倾斜磨牙的影响。 方法：对上颌第二恒磨牙向近中、颊侧倾斜的干燥头颅骨进行多层螺旋CT扫描,利用有限元软件建立上颌第二恒磨牙及其牙周支持组织的三维有限元模型,观察计算机模拟微种植体位于不同位置、施加不同的远中向力值和根颊向力偶矩值作用下磨牙牙周膜Von Mises应力。 结果与结论：牙周膜的最大应力均出现在上颌第二恒磨牙颈部,沿着根尖的方向应力逐渐减小,在2个牙根的根尖处未出现应力集中。提示实验所建立的有限元模型达到了几何相似性和生物力学相似性,可用于精确的生物力学分析;Tomas微种植体可控制牙齿的移动方式。     

固定桥基牙牙槽骨三侧吸收对基牙应力分布的影响

目的:研究双端固定桥基牙牙槽骨三侧吸收对基牙应力分布的影响。方法:采用螺旋CT扫描获取健康人下颌骨、牙齿及牙周支持组织的二维图像,通过图像合成软件建立三维数字模型,并应用三维有限元分析软件生成下颌后牙三单位固定桥的三维有限元分析模型。在相同垂直和水平载荷情况下,分析基牙牙槽骨三侧吸收时固定桥各基牙的应力分布。结果:当前磨牙端基牙牙槽骨三侧吸收达15%、磨牙端基牙牙槽骨无吸收时,前磨牙端基牙开始出现应力集中;当磨牙端基牙牙槽骨三侧吸收达25%、前磨牙端基牙牙槽骨无吸收时,磨牙端基牙开始出现应力集中。结论:下颌后牙固定桥基牙牙槽骨吸收形式的不同直接影响着其应力分布,基牙牙槽骨三侧吸收的程度对基牙应力分布的影响强于单侧和多侧吸收时。     

微型种植体支抗压低犬切牙移动过程中牙周牙根骨性组织的变化

背景：牙齿压低移动更容易造成牙根吸收,以往针对矫正引起牙根吸收的研究或基于X射线片的回顾性临床研究,或因无法精确控制压低力量,结果误差较大。 目的：建立应用微型种植体支抗压低犬切牙的实验动物模型,观察牙齿压低移动过程中牙周、牙根骨组织学的变化,以评价该治疗方法的可行性及安全性。 方法：将9只犬分为5组：对照组1只,未加力;1周、2周、4周、12周组每组2只,在上颌两侧第二、三切牙牙根之间唇侧的牙槽间隔处植入微型种植体作为支抗,每侧施加100 g的牵引力压低上颌两侧第一、二切牙,分别于加力后1,2,4,12 周（主动加力4周,撤力后保持8周)时处死动物,将第一、二切牙连同牙龈、牙槽骨完整切取,制作组织学标本,苏木精-伊红染色,观察牙周、牙根的组织学变化。 结果与结论：与对照组相比,1周组组织改建主要在根尖部和牙槽嵴顶,牙槽骨及牙骨质可见吸收,牙周膜局部出现玻璃样变性;2周组骨质吸收程度及范围明显扩大,吸收有从根尖部向根中及颈部扩展的现象;4周组骨质吸收仍然活跃,牙周膜玻璃样变性消失;12周组牙槽骨及牙骨质表面显著修复,骨陷窝新骨沉积,牙周膜排列有序。提示应用微型种植体支抗压低牙齿,早期组织变化主要在根尖部和牙槽嵴顶,表现为牙槽骨及牙骨质吸收、牙周膜玻璃样变性。随着压低力的持续,吸收程度及范围扩展。停止加力后,牙根及牙周组织逐渐修复。     

The remodeling of alveolar bone supporting the mandibular first molar with different levels of periodontal attachment

The objective of this study was to investigate alveolar bone remodeling of the mandibular first molar with differing levels of periodontal attachment under mastication loading. Three-dimensional finite element models of the mandibular first molar with differing levels of periodontal attachment were established. The stress distributions and bone density changes were analyzed under mastication loading to simulate the remodeling process of mandibular bone based on the theory of strain energy density. The results showed that the alveolar buccal, lingual ridges and root apex areas experienced higher stresses. The stresses and densities of the alveolar bone increased proportionally to increased mastication loading. Decrease in alveolar bone density under extreme loading indicated bone resorption. The remodeling rate was continual with gradual loading. Periodontal ligament support marginally decreased with an increased remodeling rate under extreme loading. Changes in alveolar bone density can reflect the remodeling process of periodontal tissue under mastication loading. The relationship between the change in density and mastication loading during remodeling can provide useful indicators into clinical treatment and diagnosis of the periodontal disease.     

可注射性磷酸钙骨水泥修复下颌阻生第三磨牙微创拔除后牙槽骨缺损

目的:研究一种可注射性磷酸钙骨水泥(ICPCS)修复下颌阻生第三磨牙微创拔除后牙槽骨缺损的临床效果。方法:将下颌阻生第三磨牙需拔除,同时X线片显示其近中第二磨牙远中牙槽骨已丧失1/3以上的33例患者分为2组。试验组17例,17颗下颌阻生第三磨牙微创拔除后应用ICPCS注入第二磨牙远中牙槽骨缺损。对照组16例,16颗下颌阻生第三磨牙微创拔除后采取血凝块机化愈合。分别于拔牙术后1周及术后1、3个月复查,比较两组患者术后伤口愈合情况、牙周临床指标及X线片。结果:全部33例患者伤口均顺利愈合,牙周评估指标显示术后1、3个月的ICPCS组下颌第二磨牙牙周状况明显改善。X线片示术后1、3个月下颌第二磨牙远中骨缺损区的骨密度明显增高,远中牙槽嵴高度有明显增高,均位于远中牙根1/3以上。结论:ICPCS具有良好的可注射性、操作方便、组织相容性好、降解时间适当和骨引导骨诱导能力,能修复下颌阻生第三磨牙微创拔除后下颌第二磨牙远中缺损骨壁,明显改善其牙周状况及牙松动。     

圆锥型套筒冠义齿和传统可摘义齿修复孤立基牙的三维有限元分析

BACKGROUND: The conical telescopic crown denture has a better long-term effect on dentition defects of few remaining teeth than the traditional removable denture. However, there are few studies to analyze the application of these two kinds of repair methods using the finite element method. OBJECTIVE: To compare the stress distribution of the isolated abutment tooth repaired using the conical telescopic crown denture and traditional removable denture. METHODS: Two-dimensional images of the mandible and dentition in healthy adults were scanned by CT. Three-dimensional finite element models of conical telescopic crown denture and traditional removable denture were established in the mandible only with the bilateral canines. Under the same vertical and oblique loadings, the maximum equivalent stress of the abutment, periodontal membrane or edentulous alveolar ridge was compared between two repair methods. RESULTS AND CONCLUSION: Under the vertical and oblique loadings, the total stress of abutment and periodontal membrane in the traditional removable denture was higher than that in the conical telescopic crown denture and the stress in the corresponding ring was concentrated obviously; the total stress of edentulous alveolar ridge in the conical telescopic crown denture was slightly larger than that in the traditional removable denture, but the stress was well-distributed and concentrated in a small area. Under the oblique loading, the total stress of abutment, periodontal membrane and edentulous alveolar ridge was higher than that under the vertical loading in these two dentures, and the stress was concentrated in the periodontal membrane of lingual neck, but the total stress in the traditional removable denture was larger, with a wider concentration range. These findings indicate that the stress on the supporting tissue of conical telescopic crown denture is more evenly distributed within a smaller range than that of traditional removable denture, and the former is more fit for the health of abutment, periodontal tissues and edentulous alveolar ridge.