下颌总义齿不同厚度黏骨膜的能量缓冲作用分析

目的　分析下颌总义齿受力时 ,不同厚度黏骨膜能量缓冲作用的大小 ,运用能量分析方法探讨口腔修复的有关临床问题。方法　应用CT扫描法建立下颌总义齿的三维有限元模型 ,计算黏骨膜厚度不同时义齿及其支持组织受力产生的弹性变形能以及各部分变形能占体系总变形能的百分比。结果　随着黏骨膜厚度的增加 ,黏骨膜弹性变形能占体系总变形能的百分比由 4 4 .5 3%增至5 2 .0 1%和 5 7.91%。结论　黏骨膜的能量缓冲能力随其厚度的增加而增大 ,能量分析方法是探讨口腔生物力学问题的有效方法     

《临床口腔医学杂志》2006年第22卷分类总索引

解剖生理下颌升支截骨手术相关下颌管解剖标志的多层CT测量研究………………华泽权邹明宇李树华(1):3维吾尔族正常牙合青年牙、牙弓、基骨的测量研究………迪丽努尔艾则孜古丽努尔等(1):50无牙下颌不同厚度黏骨膜能量传递率三维有限元分析…………张翔谢伟丽徐晶等(4):214尖牙的生理性与病理性迁徙的临床分析…………何星张静王虎等(4):217松动牙的邻接关系及前牙牙合关系的研究…………李鸿波张文禹姚月玲等(4):243骨性Ⅲ类错牙合的颅底形态研究…………陈红丁寅王燕等(5):281TNSALP在牙胚冠部硬组织发育期的组织学定位………于西佼李…     

外力方向对防护牙托性能影响的有限元分析

目的: 运用有限元分析评估外力方向对牙托缓冲能力的影响。方法: 采集仿真模型锥形束CT（CBCT）影像资料,利用MIMICS软件建立分析模型。运用ABAQUS软件模拟研究在牙托厚度不同的情况下（分别为0、1.5、3、4.5和6 mm）,经不同方向外力（撞击方向与牙长轴交角分别为30°、60°、90°和120°）撞击后,牙体表面的应力变化情况,进而评价牙托的缓冲能力。结果: 在研究实验条件下,当牙托厚度较薄时（1.5 mm和3 mm）,与其他方向相比,牙托缓冲效率在60°交角时最低,在120°交角时最高。而在牙托厚度增加后（4.5 mm和6 mm）,牙托缓冲效率在90°交角时最低,在30°交角时最高。外力方向不同时,牙托的应力缓冲效率随着牙托厚度的增加而提高。结论: 外力方向对防护牙托的缓冲能力有一定影响,但其易受牙托厚度的影响。     

无牙下颌角大小与其皮质骨厚度和剩余牙槽骨高度的关系

目的　分析无牙下颌角角度的变化 ,探讨其角度与性别、年龄、下颌角骨皮质厚度、剩余牙槽骨高度及无牙颌时间的关系。方法　年轻有牙组 131例 ,女性 6 8例 ,男性 6 3例 (平均年龄 2 7岁 ) ,年长有牙组 97例 ,女性 5 9例 ,男性 38例 (平均年龄 6 5岁 ) ,老年无牙颌组 12 8例 (平均年龄 80岁 ,76岁者 5 8例 ,81岁者 39例 ,86岁 31例 )。 3组共拍摄 35 6张曲面断层片。分别测量曲面断层片下颌角角度、无牙下颌角区骨皮质厚度和剩余牙槽骨高度。用调查问卷收集无牙颌患者的病史资料。结果　年轻有牙组和年长有牙组的下颌角大小差异无显著性 ,但两组男性下颌角均小于女性下颌角 (P <0 0 5 ,P <0 0 0 1)。老年无牙颌组下颌角为 12 8 4 °± 6 6 °,大于年长有牙组 ( 12 2 8°± 6 6 °) ,二者间差异有极显著性 (P <0 0 0 1)。 76岁无牙女性组 ,下颌角的大小与下颌角区骨皮质厚度呈负相关 (P <0 0 1) ;无牙颌男性和女性下颌角大小均与剩余牙槽骨平均高度呈负相关 (P <0 0 1)。无牙下颌角角度与无牙颌时间无关。结论　无牙患者较有牙者下颌角增大以及剩余牙槽骨越低下颌角越大的结果说明 ,自然牙列和全口义齿的咀嚼功能可能对下颌角的角度有显著影响。无牙下颌角的大小与其骨皮质厚度的显著关系提示 ,系     

密质骨厚度影响牙种植体稳定性的有限元固有频率分析

目的：用有限元方法研究密质骨厚度对牙种植体初期稳定性的影响。方法：建立牙种植体、局部下颌骨块三维有限元模型,利用ABAQUS有限元软件,分析不同密质骨厚度对种植体颊舌向、轴向一阶振动固有频率的影响。结果：随着密质骨厚度由缺如逐渐增加至3．0mm,种植体颊舌向、轴向振动的固有频率值均逐渐增加,其中颊舌向固有频率最大增幅达97．61％,而轴向固有频率最大值仅增加了11．06％。结论：种植体周密质骨厚度主要增加了种植体颊舌向稳定性,而对种植体轴向稳定性的增加有限。     

二矽酸锂陶瓷高嵌体修复不同垫底厚度的下颌第一磨牙等效应力分析

目的　探讨应用二矽酸锂陶瓷高嵌体修复不同垫底厚度的下颌第一磨牙修复体、剩余牙体组织、牙釉质、牙本质、粘接剂的等效应力大小及分布情况。方法　收集一颗完整的离体下颌第一磨牙,通过锥形束CT（CBCT）扫描技术,Mimics19.0、Hypermesh、ANSYS Workbench15.0等逆向工程软件,建立下颌第一磨牙近中面不同垫底厚度的三维有限元模型,以垫底厚度（h）0 mm、1 mm、3 mm、5 mm为变量,分别记为h0、h1、h3、h5,观察静态垂直向加载300 N或斜向加载180 N时修复体、剩余牙体组织、牙釉质、牙本质、粘接剂的等效应力大小及分布情况。结果　（1）垂直向加载时各结构不同垫底厚度等效应力大小比较,修复体：h5 > h3 > h1 > h0,剩余牙体组织：h5 > h3 > h0 > h1,牙釉质：h3 > h5 > h1 > h0,牙本质：h0 > h1 > h3 > h5,粘接剂：h5 > h0 > h3 > h1;斜向加载时各结构不同垫底厚度等效应力大小比较,修复体：h5 > h3 > h1 > h0,剩余牙体组织：h1 > h3 > h5 > h0,牙釉质：h3 > h5 > h1 > h0,牙本质：h0 > h1 > h3 > h5,粘接剂：h5 > h3 > h0 > h1。（2）同一垫底厚度时,各部结构等效应力分布范围不同;不同垫底厚度时,同一结构等效应力分布基本相同。结论　垫底厚度是影响修复体及牙体各结构等效应力大小及分布的重要因素;根据等效应力的大小和分布,当采用二矽酸锂陶瓷材料作为高嵌体修复下颌第一磨牙时,1 mm的垫底厚度有利于修复体及牙体各结构稳定,但需注意调牙合时应减小侧向力。     

人工(牙合)干扰部位对下颌前伸运动轨迹的影响

目的：观察[牙合]干扰部位对下颌前伸运动中下颌切点运动轨迹的影响,并探讨其意义。方法：应用Arcus DigMa三维下颌运动轨迹描记仪,检查下颌切点的运动轨迹随拾干扰部位变化而发生的改变。通过SAS9．0统计软件包分析[牙合]干扰部位与下颌切点在矢状轴、垂直轴、水平轴上的运动轨迹的相关性．建立直线回归方程。结果：随着[牙合]干扰部位的后移,下颌切点在矢状轴的运动距离有增大趋势;在垂直轴的运动距离无显著规律,与[牙合]干扰部位无明显相关性;在水平轴有向非干扰侧偏斜的趋势。并且在矢状轴上得到[牙合]干扰部位与下颌切点运动距离直线回归的混合效应模型：y^=4．9429＋0．1336x1,δ=0．3144,P〈0．001。结论：随[牙合]干扰部位的后移,下颌前伸运动轨迹更向前、向[牙合]干扰对侧偏斜,且在矢状轴方向的改变随着[牙合]干扰部位的后移呈现一定的线性规律。     

防护牙托的性能评价

目的 研究标准型定制类牙托对于外力打击的缓冲能力。方法 利用一个特殊的工作模型。将外力打击时,单个中切牙所受的力通过舌侧金属导杆传递到压力传感器上,记录数据。比较戴防护牙托和无防护时的相对值。结果 获得了不同厚度牙托的缓冲率,各组间差异有显著性。结论 牙托的缓冲效果与材料厚度呈正相关。建议在高对抗性、高风险性的体育活动中,参加者应使用适宜的防护牙托以防止牙外伤的发生。     

影响不锈钢种植钉稳定性的相关因素研究

目的探讨不锈钢种植钉稳定性与性别、年龄、植入部位之间的关系。方法237例患者植入691枚自攻型Bio．Ray不锈钢种植钉，比较不同性别组和年龄组在上颌颧牙槽嵴区及下颌颊棚区植人自攻型Bio—Ray不锈钢种植钉后松动率的差异。结果237例患者共植入自攻型不锈钢种植钉691枚，71枚出现松动，总松动率10．3％；上颌颧牙槽嵴区松动率15．4％，下颌颊棚区松动率4．4％，两者间差异有统计学意义（P〈0．001）；男女间在不同植入部位的松动率均无明显差异；10—14岁组上颌松动率为30．4％，下颌松动率为9．6％，与15～18岁组、19岁及以上组相比差异均有统计学意义（P〈0．05）；15～18岁组与19岁及以上组在上颌和下颌的松动率差异无统计学意义。结论10～14岁组在上颌颧牙槽嵴区及下颌颊棚区的松动率明显较高，不适宜在此部位做种植钉支抗。下颌颊棚区种植钉稳定性好于上颌颧牙槽嵴区。性别对种植钉稳定性无明显影响。     

PLA/PGA组织膜应用于牙槽嵴黏骨膜扩张初探

目的：了解可降解性材料PLA／PGA组织膜应用于牙槽嵴黏骨膜扩张的生物学性能。方法：40只新西兰大耳白兔建立萎缩性牙槽嵴模型和卵巢切除后模型,按照扩张类型随机分成4组,对PLA／PGA组织膜扩张牙槽嵴黏骨膜后,对各观察时段内PLA／PGA组织膜的生物学性能进行定量和定性观察。结果：PLA／PGA组织膜的降解于4周时开始,24周降解基本完成;12周时组织膜使用组新骨生成率为28％,非使用组为7％;24周时使用组骨改建基本完成,非使用组新骨生成率为13％;48周时使用组骨改建完全,非使用组新骨生成率为39％。结论：PLA／PGA组织膜良好的生物学性能对于促进牙槽嵴增高具有较好的应用前景。     

Measurement in vivo of masticatory mucosal thickness with 20 MHz B-mode ultrasonic diagnostic equipment

Analysis of the movement of the denture foundation under function is very important for construction of a denture. For this analysis, the thickness of the masticatory mucosa gives the required quantitative information. The thickness measurements were taken from 21 oral sites in 100 edentulous patients, by means of 20 MHz B-mode ultrasonic equipment. The average thickness of the masticatory mucosa ranged from 1.92 mm to 2.38 mm at the upper edentulous ridge and from 1.45 mm to 1.58 mm at the lower edentulous ridge. The center of the palate had the thinnest mucosa and the lateral area of the palate had the thickest among all the measuring points. Contrary to what is often believed, a decrease in mucosal thickness with age was not observed by one-way analysis of variance. Furthermore, as the degree of ridge reduction increased, a decrease in the mucosal thickness was found by one-way analysis of variance at only two of the 14 measuring sites on the ridges. At four of the 21 measuring sites, male patients had significantly thicker mucosa than did females, and the correlation coefficients of the thickness of mucosa between right and left sides in the palate were higher than those in residual ridges.     

Finite element analysis of stress relaxation in soft denture liner

To gather knowledge related to establishing criteria for selecting soft denture liners for individual patients, the effects of certain properties of soft denture liners on stress distribution were evaluated by two-dimensional finite element analysis. A partial mandibular edentulous ridge crest was modelled. Six combinations of thickness (mucosa: 1 or 2 mm; soft denture liner: 1, 2, or 3 mm) and 18 combinations of Young's modulus (mucosa: three kinds; soft denture liner: six kinds) were analysed. The ratio of maximum to minimum stress in the mucosa (stress ratio) was calculated to estimate stress concentration. In the case of thin mucosa (1 mm thickness), the lower the Young's modulus of the soft denture liner, the lower the stress ratio. However, if the soft denture liner had a lower Young's modulus than the mucosa, stress concentrated adversely. These results suggest that the elasticity of the soft denture liner should match the elasticity of the mucosa to obtain the optimum cushioning effect.     

全口义齿咬合力与下颌承托区粘膜变形度的相关性研究

采用咬合力计和光电式位移传感器对１０例无芽颌患者进行了咬合力、咬全程后时间与承托区粘膜压缩度及承托区粘膜回复度间关系的研究。结果表明：适合承托区粘膜生理点的咬合力阈值，前芽区和蘑芽区分别为１．３ｋｇ和２．５ｋｇ。     

无牙颌固有条件的定量测定及对总义齿固位力的影响

目的：研究无牙颌固有条件对总义齿固位力的影响。方法：本研究对31名无牙颌患者进行口腔混合唾液量及黏度测定，黏膜厚度测量，承托面积、牙槽嵴高度及总义齿固位力测定，并对影响下颌总义齿固位力的相关因素作多元逐步回归分析。结果：上颌总义齿的固位力约为下颌的5．7倍以上。在多元逐步回归分析中，自变量黏膜厚度被收入回归方程，在未收入回归方程的自变量中，唾液黏度与固位力相关性最大。结论：上颌总义齿固位力远大于下颌总义齿。黏膜厚度、唾液黏度是影响下颌总义齿固位力的主要因素。     

Studies on the thinning of the upper acrylic resin complete denture with the reinforced palate. (Part 1). Thinning of the resin denture base with the standard shape (author's transl)]

The acrylic denture bases are most commonly used as compared with metallic denture bases at present. For this reason, it is due to many excellent properties, for example, simple processing, easy repair, cheapness and so on. But an inherent disadvantage is liability of an acrylic denture base to make thick so as to maintain stiffness and strength and it makes patients uncomfortable. Therefore, the purpose of this paper is to make the palatal region of the upper complete denture thin with about 0.7 mm in thickness, and to keep the same mechanical properties as the normal resin dentures using the composites materials with carbon cloth. Tensils test of the plate test-piece and uniform bending test of the upper complete denture with steel wings were respectively performed. The results obtained in this investigation are as follows: 1) The acrylic composites reinforced with carbon cloth have shown the superior mechanical properties to be compared with the acrylic resin to be generally used. 2) The thickness of the reinforced thin denture is decreased to 0.7 mm (its thickness is 60% of the normal thickness of the one), nevertheless, the stiffness and strength are increased with the using of the composite materials. 3) The region of highest surface tensile stress in the denture was on the polished surface of the palatal aspect of the denture in the area immediately behind the anteriors, but at this region, the strain of the reinforced thin denture base decreased its strain 10% in comparison with the non-reinforced normal thick one.     

腭穹隆形态对上颌全口义齿基托位移的影响

目的：研究腭穹隆形态对上颌全口义齿基托位移的影响。方法：模拟5种咬合状态,对尖、平、凹3种腭穹隆形态的上颌全口义齿的三维有限元模型进行加载。结果：3种腭穹隆形态上颌全口义齿基托在5种加载方式下,凹型腭穹隆形态基托的上腭前部及后缘区向黏膜组织的下压位移最大,基托边缘封闭区背离黏膜组织的位移最小。基托的位移方式因加载方式不同而不同。结论：上颌全口义齿基托位移方式及大小与加载方式有关;腭穹隆形态对上颌全口义齿基托位移方式无明显影响,对位移值大小有影响。     

厚度对塑料基托材料颜色的影响

目的：了解塑料基托材料在临床常用厚度下的颜色变化规律。方法：采用分光光度计(PR-650)测量Dentsply199#，169#．301#及Heraeus 29#，43#，65#常用颜色热凝基托塑料在黑白背景下及在1．5mm、2mm、2．5mm、3mm、3．5mm不同厚度时的颜色参数。结果：Dentsply169#的透光性最强，199#的最弱；随厚度增加，各材料的a^*值都不断增大；厚度与L^*值的相关性取决于材料的透光性。结论：厚度会影响塑料基托材料的颜色再现。     

Finite element model based on a mandibular cast and a waxed complete denture: Evaluation of the accuracy and the reproducibility of analysis

PurposeThe purpose of this study was to evaluate a newly developed method to construct customized finite element models from the viewpoints of the accuracy of measurement and the reproducibility of calculated denture movement under loads.MethodsA cast of an edentulous mandibular alveolar ridge and a waxed complete denture were used. Measurement of the surface was done using a 3D-digitizer. After superposing, they were rotated so that the occlusal plane became level. The border of the alveolar ridge on the cast was decided in each buccolingual section. From a series of cross sections, the surface of the alveolar ridge was made. Based on the surfaces of the mucosa and denture, a finite element model consisting of the denture and underlying mucosa, which was given a uniform thickness, was constructed. This procedure and analysis under bilateral or unilateral loads on an artificial molar region were done repeatedly to evaluate its reproducibility and the error of the measurement of the surface.ResultsThe standard error of the measured shapes of spheres was estimated to be within 0.1 mm. The error caused by superposing was estimated to be within 0.38 mm. The results of analysis showed that the coefficient of variation of the displacement of the denture at selected nodes was approximately 14.1% at most.ConclusionsWe conclude that this method has sufficient measurement accuracy and reproducibility for the calculated movement of dentures.     

Variation in blood flow of supporting tissue during use of mandibular complete dentures with hard acrylic resin base and soft relining: a preliminary study

PURPOSE: This study investigated the influence of hard and resilient polymerized acrylic resin base materials on the blood flow of the supporting underlying mucosa of mandibular denture wearers during different denture-wearing periods. MATERIALS AND METHODS: Measurements were carried out on 20 complete denture wearers, 10 with hard bases and 10 with soft ones. The mucosal blood flow underlying the dentures was measured bilaterally in the canine and molar regions using a laser Doppler flowmeter. Baseline measurements were performed before denture wearing and after the dentures were worn for 1 week, 1 month, 3 months, and 6 months. RESULTS: Mean blood flow to the mucosa after 1 week was significantly lower in the measured regions than that obtained before the dentures were worn. Blood flow in the canine region returned to almost normal levels 6 months after beginning to wear complete dentures. However, blood flow in the molar region of the denture wearers in the hard base group increased after 6 months, whereas blood flow values did not return to the levels recorded before denture insertion in the soft lining group. CONCLUSION: It appears that wearing dentures hinders blood flow to denture-supporting tissues, even when soft liners are used.