侧向加载下套筒冠义齿的三维有限元应力研究

目的：利用有限元法研究牙槽骨有不同程度吸收时基牙和基托下支持组织所受的应力，为缓冲型套筒冠义齿的临床应用提供依据。方法：建立两种套筒冠义齿的三维有限元模型，在侧向加载的情况下对支持组织的生物力学进行分析。结果：在侧向加载的情况下，与非缓冲型套筒冠相比，缓冲型套筒冠义齿可均匀分配基牙及基托下支持组织的应力；随着牙槽骨吸收程度的增加，基牙及基托下支持组织的应力增加，但缓冲型套筒冠义齿可降低其增加幅度。结论：缓冲型套筒冠可有效减小各种侧向力对牙周支持组织的损伤，降低牙齿动度，有利于受损牙周组织的恢复。     

双侧游离端义齿不同固位装置对基牙位移的实验研究

目的：探讨双侧游离端可摘局部义齿的不同因值装置对基牙的影响。方法：分别以联合卡环、延长卡环和套筒冠作为固位装置，制作双侧游离端义齿，在一侧上下习：列间放置食片，当咬合时用高精密度激光位移测量仪测得双侧基牙的位移量，并加以统计分析。结果：3种不同固位体的游离端义齿，在垂直负荷时，双侧基牙54┰45都有不同程度的水平及垂直向移位、扭转及倾斜。套筒冠的垂直向位移量最大，水平扭转位移量最小，且远缺隙侧基牙了4┰4的水平位移量大于近缺隙侧蛀牙了5┰5。结论：各种因值体的基牙动度与固位体和基牙间的连接刚性相一致。刚性度越好，基牙动度越小。套筒冠可使胎力沿基牙牙体长轴传递，降低基牙所受扭转力，多个基牙共同承力，可减轻末端基牙的负胆。     

种植体上部不同结构对下颌游离端义齿应力分布的影响

目的:观察不同上部结构的种植体支持可摘局部义齿修复下颌KennedyⅠ类牙列缺损时的应力和位移。方法:使用软件GeoStar(COSMOSM 2.85,SRAC,USA)建立4个种植体-天然牙联合可摘义齿修复下颌KennedyⅠ类牙列缺损的三维有限元模型,比较不同上部结构时种植体周围骨组织、基牙牙周膜、基托下黏膜的最大等效应力及基托下黏膜组织的位移变化。结果:有种植体支持时,单冠形式的种植体周围骨组织最大等效应力最大;缓冲型套筒冠的基牙牙周膜最大等效应力、基托下黏膜最大等效应力和位移值最大;微型太极扣种植体周围骨组织最大等效应力、基牙牙周膜最大等效应力和黏膜的最大等效应力及位移值均最小。缓冲型套筒冠种植体周围骨组织最大等效应力小于非缓冲型套筒冠,但基牙牙周膜最大等效应力、基托下黏膜最大等效应力和位移则大于非缓冲型。结论:选用种植体-天然牙联合支持修复远中游离端牙列缺损时,种植体上部结构采用微型太极扣作为附着体联接形式是最佳选择。     

联合卡环、延长卡环与套筒冠固位体的基牙位移实验研究

目的　探讨单侧游离端可摘局部义齿的不同固位装置对基牙的影响。方法　在上下牙列间放置食物片 ,应用单侧游离端缺失病例中使用最多的联合卡环、延长卡环和套筒冠作为固位装置。当咬合时 ,用高精度激光位移测量仪测得其基牙各自的位移量 ,进行分析比较。结果　 3种不同固位装置义齿的基牙 45都有牙体移动、倾斜、扭转及垂直向的位移。其位移量在水平扭转时 ,套筒冠为最小 (P <0 0 1 ) ;而垂直向的位移 ,套筒冠则大于联合卡环和延长卡环 (P <0 0 1 )。结论　与联合卡环和延长卡环相比较 ,套筒冠所承受的咬合压力接近牙轴方向并能使基牙力分散 ,受力均匀 ,有利于基牙的健康。     

四种材料套筒冠义齿加载时无牙区牙槽嵴的三维有限元分析

目的探讨套筒冠义齿固位部分材料不同、受载相同时,缺牙区牙槽嵴黏膜应力和位移的分布。方法螺旋CT对被测者行横断超薄扫描,对所得图像用自编程序、AutoCAD和ANSYS软件建立精确的下颌骨三维有限元模型。分析比较相同载荷下,套筒冠义齿金属内冠为镍铬合金、钴铬合金、金合金、钛合金4种材料时,无牙区牙槽嵴黏膜所受应力和位移。结果受载相同、套筒冠义齿金属内冠为4种材料时,无牙区牙槽嵴黏膜最大压应力的差异无统计学意义（F=0.927,P=0.437）,位移的差异无统计学意义（F=0.558,P=0.626）。结论从生物力学的角度分析,使用镍铬合金、钴铬合金、金合金、钛合金4种材料制作套筒冠的固位部分均是可行的,非贵金属可以替代贵金属进行套筒冠的制作。     

缓冲圆锥型套筒冠可摘义齿的支持组织应力研究

为探明缓冲型圆锥型套筒冠可摘义齿对多数牙缺失，少数牙残存牙列缺损修复效果的生物力学原理，作者采用有限元法对义齿受力后牙牙周支持组织与基托下支持组织的应力分布与非缓冲型套筒冠可摘义齿作对比分析，结果提示：采用缓冲型圆锥套筒冠固位体，Ｈｅ力通过义齿得到重新分配，减轻基牙所承受的Ｈｅ力而增中基托下支持组织承受Ｈｅ力，使基牙避免创伤同时有一定的生理性刺激；通过扩大基托范围，又可减轻基托下支持组织承受力，减     

冠外固位体义齿基牙牙周组织应力分布的三维有限元分析

目的研究下颌第一磨牙缺失、第二磨牙近中倾斜30°或45°时,用栓道附着体义齿或套筒冠义齿2种冠外固位体(extra-coronal retainer,ECR)义齿修复的基牙牙周组织应力分布。方法采用CT扫描技术和Mimics、Freeform、ANSYS软件,建立下颌第一磨牙缺失、第二磨牙近中倾斜30°或45°及ECR义齿修复后的三维有限元模型,模拟加载并计算分析基牙牙周组织应力的分布情况。结果下颌第二磨牙近中倾斜30°、45°模型,修复前第二前磨牙Von Mises应力分别是2.80 MPa、3.47 MPa,栓道附着体义齿修复后分别是19.26 MPa、25.18 MPa,套筒冠义齿修复后分别是19.47 MPa、24.48 MPa,ECR义齿修复后下颌第二前磨牙牙周组织应力明显增大;修复前第二磨牙Von Mises应力分别是20.45 MPa、20.50 MPa,栓道附着体义齿修复后分别是15.02 MPa、11.84 MPa,套筒冠义齿修复后分别是18.04 MPa、12.18 MPa,ECR义齿修复后下颌第二磨牙牙周组织应力明显减小。结论栓道附着体义齿和套筒冠义齿均能改善倾斜基牙牙周组织的应力分布,当下颌第二磨牙近中倾斜角度过大或下颌第二前磨牙牙周状况欠佳时,应该考虑增加近中端基牙数目。     

垂直载荷下分割式可摘局部义齿与套筒冠义齿的有限元分析

目的研究并比较分割式可摘局部义齿与缓冲圆锥型套筒冠义齿在垂直载荷下的应力情况。方法选择上颌双侧第二前磨牙、第一磨牙缺失并伴有基牙有Ⅰ度松动的患者1名,通过螺旋CT扫描,利用Materialise Mimics、Pro/Engineer WF 2.0软件和ANSYS Workbench软件建立精确的上颌三维有限元模型,并在其上进行垂直方向加载,分析比较分割式可摘局部义齿与缓冲圆锥型套筒冠义齿缺牙区黏膜及基牙牙周膜应力情况。结果垂直载荷下,分割式可摘局部义齿缺牙区黏膜所受von Mises力值大于缓冲圆锥型套筒冠义齿缺牙区黏膜所受力值;分割式可摘局部义齿基牙牙周膜von Mises力值接近或小于缓冲圆锥型套筒冠义齿基牙牙周膜所受力值。结论在垂直载荷下,通过与缓冲圆锥型套筒冠义齿相比,分割式可摘局部义齿具有减少基牙受力,保护基牙的功能。     

附着体义齿修复近中倾斜30°基牙的牙周组织应力分析

目的研究两种附着体义齿（栓道附着体义齿和套筒冠固定义齿）修复下颌第一磨牙缺失伴下颌第二磨牙近中倾斜30&#176;的基牙的牙周组织应力分布。方法在已经建立的下颌第一磨牙缺失伴下颌第二磨牙近中倾斜30&#176;修复前及两种附着体义齿修复后的三维有限元模型上,将200N垂直负荷和斜向负荷分别模拟加载于下颌第二磨牙,计算分析基牙牙周组织的应力情况。结果在下颌第二磨牙近中倾斜30&#176;时,两种附着体义齿修复后倾斜基牙应力主要集中在其颈部牙槽骨或根分叉区。斜向加载下,栓道附着体义齿修复后倾斜基牙牙周组织应力小于套筒冠义齿修复。斜向加载下,下颌第二前磨牙和第二磨牙牙周组织应力远远大于垂直加载。结论在下颌第二磨牙近中倾斜30&#176;时,栓道附着体义齿修复在改善倾斜基牙牙周组织应力方面更优于套筒冠义齿修复。斜向加载时,下颌第二前磨牙和第二磨牙牙周组织中产生较大的应力集中。     

下颌固定义齿基牙齿槽骨降低时不同受载的三维有限元分析

目的 研究下颌后牙固定义齿在齿槽骨降低后受载的三维有限元应力分布情况。方法在建立的下颌固定义齿三维有限元模型的基础上，选取桥体、两侧基牙的咬合面施加不同方向的载荷，利用MARC有限元分析软件计算并绘制各种载荷下的应力分布图像。结果 固定义齿受垂直载荷时基牙的牙周支持组织的应力分布集中在根尖部位，以压应力为主。斜向载荷使基牙支持组织的应力增加且分布不均匀，颈部的应力增加较多。齿槽骨的降低使固定义齿基牙支持组织的应力增加，但分布规律不变。结论 齿槽骨的降低使固定义齿基牙支持组织的应力增加，此类修复体的设计应特别注意基牙牙周组织的健康。     

A three-dimensional finite element analysis of a passive and friction fit implant abutment interface and the influence of occlusal table dimension on the stress distribution pattern on the implant and surrounding bone

Aims:

The aim of the study was to evaluate the stress distribution pattern in the implant and the surrounding bone for a passive and a friction fit implant abutment interface and to analyze the influence of occlusal table dimension on the stress generated.

Materials and Methods:

CAD models of two different types of implant abutment connections, the passive fit or the slip-fit represented by the Nobel Replace Tri-lobe connection and the friction fit or active fit represented by the Nobel active conical connection were made. The stress distribution pattern was studied at different occlusal dimension. Six models were constructed in PRO-ENGINEER 05 of the two implant abutment connection for three different occlusal dimensions each. The implant and abutment complex was placed in cortical and cancellous bone modeled using a computed tomography scan. This complex was subjected to a force of 100 N in the axial and oblique direction. The amount of stress and the pattern of stress generated were recorded on a color scale using ANSYS 13 software.

Results:

The results showed that overall maximum Von Misses stress on the bone is significantly less for friction fit than the passive fit in any loading conditions stresses on the implant were significantly higher for the friction fit than the passive fit. The narrow occlusal table models generated the least amount of stress on the implant abutment interface.

Conclusion:

It can thus be concluded that the conical connection distributes more stress to the implant body and dissipates less stress to the surrounding bone. A narrow occlusal table considerably reduces the occlusal overload.Key Words: Conical connection, friction fit interface, implant abutment interface, occlusal table dimension, passive fit interface, Tri-lobe connection     

下颌游离端义齿(牙合)支托设计的有限元分析

用三维有限元的方法,对设计了三种(牙合)支托的下颌单侧游离端义齿,分别在人工牙上采用九种不同的加载方法,对近基牙支持组织的应力和位移进行了研究分析,并进行统计学处理.结果远中(牙合)支托引起基牙支持组织的应力和位移值均最大;而近中(牙合)支托和双支托在近远中方向上,基牙牙周组织应力和位移的差异无统计学意义;无论是何种(牙合)支托应力和位移值均随加载点向远中移动过程中而逐渐减小.     

Stress distribution and abutment tooth mobility of distal-extension removable partial dentures with different retainers: an in vivo study

Three types of retainers (wrought wire clasp, Aker's cast clasp, and conical crown telescopic retainer) designed for distal-extension removable partial dentures (RPDs) were assessed in two Kennedy class I patients' mouths. The assessment, included the ratio of denture base shearing load and mobility of the terminal abutments when loaded on a free-end RPD occlusal surface. The mean values of denture base shearing ratios of wrought wire clasp, Aker's clasp and conical crown telescope were 60, 42 and 20%, respectively. The abutment mobility of the three types of retainers were all within the 'mobile ability area' except the wrought wire clasp for patient A's right side. The greatest tooth mobility was observed with the wrought wire clasps, followed by Aker's clasp and the conical crown telescopic retainer. From the analysis the following was concluded: (i) different retainers do influence the occlusal load distribution; (ii) the occlusal load distributed to the free-end saddle is closely related to the connecting rigidity of the retainer; (iii) mucosal support has an indispensable role in sharing the occlusal load with various retainers, even the rigid telescopic retainer.     

The effect of pontic occlusal form on abutment tooth displacement]

The three-dimensional displacements of abutment teeth in fixed partial dentures (FPDs) during mastication were measured while changing the pontic occlusal design, for comparison against those of natural teeth. The purpose of this study was to clarify the influence of pontic occlusal form on the displacements of the abutment teeth, and to decide the optimum pontic occlusal design. Three subjects, who each had a single missing tooth (upper first molar or second premolar), were chosen. After 3-unit FPDs were cemented, abutment tooth displacement during mastication was measured using a three-dimensional tooth displacement transducer Type M-3. The functional or non-functional cusp inclination of the pontic was changed gradually. The flatter the inclination of the functional cusp of pontic became, the more the abutment teeth displaced in the buccal direction. The flatter the inclination of pontic non-functional cusp became, the less the abutment teeth displaced in the buccal direction, and the more the abutment teeth mostly displaced in the palatal direction. If the inclination of the functional cusp of pontic becomes excessively flatter, or the inclination of pontic non-functional cusps becomes as steep as the natural teeth, non-physiological distortion may occur in periodontal tissues of the abutment teeth.     

不同临床设计的ERA附着体义齿修复下颌牙列游离端缺损的三维有限元分析

目的:研究3种不同临床设计ERA附着体义齿修复下颌远中游离端缺损的应力及位移分布.方法:建立ERA附着体义齿修复下颌远中游离端缺损的三维有限元模型,根据临床设计分为基本组、支托组和跨弓组.应用有限元法研究在垂直及45°斜向2种载荷方向100 N的作用下,基牙及基托下黏膜的应力和位移以及基托的位移情况.结果:2种载荷下3组模型均在远中基牙远中邻面肩台出现应力集中,远中基牙预备体咬合面位移最大,支托组基牙位移最大,分别为14.91 μm和63.09μm,其次为基本组(9.38 μm和50.56μm),跨弓组最小(8.85 μm和47.31μnn).结论:在本研究条件下,为远中游离端牙列缺损设计基本的ERA附着体义齿更趋于合理.     

Prosthetic aspects in endosseous implantation]

Since 1975, 12 intra-osseous titanium blade implants have been applied to patients with unilateral or bilateral edentulousness of the terminal region of the mandible or with combined mandibular edentulousness. After taking impressions by means of individually fabricated transmitting copings and medium-flow silicone impression compounds, the temporary plastics bridges and the definite telescope bridge prostheses were made of precious metal alloys, using the "Biokop-Orthomat". Essential prerequisites for optimal functional performance of the implant bridge constructions are: creation of optimal occlusal conditions, tangential blocking of the remaining teeth by splinting one implant abutment with at least two natural teeth, and gingiva-free modelling of the telescope and crown margins at the implant abutment.     

人工牙颊舌径对单侧游离端套筒冠义齿基牙位移的影响

目的：探讨不同的人工牙颊舌径对单侧游离端套筒冠义齿基牙位移的影响。方法：建立肯氏Ⅱ类塑料模型，制作套筒冠义齿，改变人工牙颊舌径，垂直加载29．4N、49N、68．6N力时，测量基牙位移值，通过计算求出各方向的位移、扭转量，最后进行统计分析。结果：与未减径时相比，人工牙颊舌向减径1／4后，2基牙水平扭转程度显著减小，差异有统计意义（P〈0．05）；减径1／3后，2基牙在各方向的位移、倾斜、扭转均显著减小，差异有统计意义伊〈0．05）。结论：单侧游离端套简冠义齿人工牙颊舌向减径1／3后，基牙的位移、倾斜，扭转程度明显减小，可增加义齿稳定性，有利于基牙牙周支持组织的健康。     

Stress distribution of abutments and base displacement with precision attachment- and telescopic crown-retained removable partial dentures

Five types of removable partial dentures (two attachment dentures, two telescopic dentures and one clasp denture) were designed. The two attachment dentures were retained by the rigid-precision attachments with or without a stabilizing arm, and the two telescope dentures were retained with cone telescope crowns with or without cross-arch stabilization. The stresses acting on abutment teeth and denture bases and the movements of denture bases were investigated, and the influences of denture design were clarified. The stress acting on a terminal abutment tooth retained by a rigid-precision attachment or cone telescopic crown was larger than that acting on a terminal abutment tooth retained by a clasp. The attachment dentures tended to concentrate more stress at the terminal abutment tooth than did the telescopic dentures. The stress of denture base of an attachment denture and a telescopic denture was less than that of a clasp denture. There was no difference between the stresses of attachment and telescopic dentures. The displacement of the denture base tended to be less when the denture was designed with a rigid connection for the retainer and with cross-arch stabilization.     

The effect of occlusal contacts on adjacent tooth

PURPOSE: The purpose of this study was to clarify the influence of changes of occlusal contacts on adjacent tooth displacement during articulation. MATERIALS AND METHODS: The amount and direction of displacement of the maxillary left first molar and adjacent teeth were measured using a displacement transducer, Type M-3. Seven subjects were included in this study. On the maxillary left first molar, 8 experimental occlusal contact points were established using platinum foil and these were divided into 2 groups, the buccal and lingual groups, which corresponded to the buccal and lingual cusps, respectively. RESULTS: During clenching, the buccal group showed differences in the direction of the tooth displacement paths among the 3 teeth (second premolar, first and second molar), but there was no difference in the lingual group and the direction of displacement of these 3 teeth was similar to the natural teeth. CONCLUSION: It is necessary to make at least one lingual occlusal contact point to obtain displacement of not only the abutment tooth but also the adjacent teeth.     

改良杆卡式附着体与不同可摘局部义齿对支持组织应力分布的研究

目的探讨改良杆卡式附着体义齿与RPI卡环组、联合卡环组可摘局部义齿修复单侧游离缺失对支持组织的应力分布。方法在下颌47、46单侧游离缺失的环氧树脂模型上分别以改良杆卡式附着体、RPI卡环组、联合卡环组3种固位形式的可摘义齿修复,用三维光弹应力冻结切片技术测试义齿加载后对基牙和缺牙区牙槽骨应力分布。结果对基牙牙槽骨的应力：改良杆卡式附着体义齿〉RPI卡环组〉联合卡环组（P〈0．05）;附着体义齿对基牙的近、远中应力无显著性：差异（P〉0．05）;RPI卡环组义齿有猞支托处的应力大于无拾支托处的应力（P〈0．05）;联合卡环组对远中的应力大于近中（P〈0．05）。对缺牙区牙槽骨应力：改良杆卡式附着体与RPI卡环组均小于联合卡环组（P〈0．05）;附着体义齿、RPI对缺牙区牙从近中到远中的4个切片应力无显著性差异（P〉0．05）,联合卡环组远中大于近中（P〈0．05）。结论改良杆卡式附着体义齿有应力中断作用,各点应力分布较均匀。RPI固位的活动义齿应力主要分布在基牙上,缺牙区应力稍小。联合卡环组义齿对失牙区的应力最大,基牙上应力较小。