牙尖斜度对套筒冠义齿基牙位移的影响

目的:探讨人工牙牙尖斜度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,制作不同牙尖斜度的套筒冠义齿,在食片介在的咬合状态下垂直加载29.4、49、68.6N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:解剖式人工牙与25°半解剖式人工牙相比,两基牙在颊舌向及垂直向位移差异有统计意义(P<0.05);解剖式人工牙与12°半解剖式人工牙相比,基牙在各方向的位移、倾斜、扭转差异均有统计意义(P<0.05);无尖人工牙与25°半解剖人工牙相比,除近远中向外,基牙的位移、倾斜、扭转差异均有统计意义(P<0.05);无尖人工牙与12°半解剖人工牙相比,基牙水平扭转程度差异无统计意义(P>0.05)。随负荷力增加,基牙位移量、倾斜角度、水平扭转角度也随之增加,各组之间差异有统计意义(P<0.05)。结论:套筒冠义齿修复下颌牙列单侧游离端缺损时,减小人工牙牙尖斜度,基牙在各轴向的位移、倾斜、扭转程度随之减小;基牙的位移量与负荷力大小有关。     

可摘局部义齿

磁性附着体静磁场对人牙龈成纤维细胞形态的影响；人工牙颊舌径对单侧游离端套筒冠义齿基牙位移的影响；门诊986例老年人牙齿缺失及修复情况调查分析     

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。     

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。     

基牙数目对附着体式义齿基牙位移的影响

目的：探讨基牙数目对下颌单侧游离端MK-1附着体式义齿基牙位移的影响。方法：选用单基牙、双基牙和三基牙支持的MK-1附着体制作下颌单侧游离端MK-1附着体式义齿,在义齿侧上下牙列间放置食物片,咬合时用LB-72型高精度半导体激光位移测量仪,测量并计算出基牙在不同方向的位移量,并用随机方差分析法进行统计学分析。结果：单基牙组的近远中向、颊舌向、垂直向的位移、倾斜、扭转均大于双基牙组,差别有统计学意义（P〈0.05）。双基牙组的近远中向的位移大于三基牙组,差别有统计学意义（P〈0.05）,其余差别没有统计学意义（P〉0.05）。结论：单侧游离端MK-1附着体式义齿不宜设计单基牙,宜设计双基牙,如双基牙条件不理想时,可增加第三基牙。     

下颌KennedyⅡ类牙列缺损冠外附着体义齿的三维有限元分析——基牙数目对支持组织应力分布的影响

目的：探讨不同基牙数目下,下颌单侧游离端缺损冠外附着体义齿修复支持组织的应力分布情况。方法：建立下颌KennedyⅡ类牙列缺损冠外附着体义齿修复的三维有限元模型,分析在垂直向和侧向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：不同载荷方向,末端基牙均受到较大的非轴向应力,应力主要集中在牙颈部,缺牙区牙槽嵴的应力较大。单侧基牙数由1个增加到2个时,远中基牙牙周的应力略有减小,但当基牙数目从2个增加至3个时,垂直向和颊舌向加载时末端基牙牙周膜和牙槽骨的应力均有明显下降,但在舌颊向加载时,第二前磨牙各部位的应力没有明显下降,部分牙颈部的应力反而有所增加。结论：在下颌单侧游离端缺损修复中,冠外附着体义齿支持组织应力的减小与基牙数目的增加不完全成比例,在临床上应根据具体情况确定联合基牙的数目。     

基牙及义齿支持形式对套筒冠义齿修复效果影响

目的：了解基牙条件、数目及义齿支持形式对套筒冠义齿修复效果的影响。方法：对38例戴用圆锥形套筒冠义齿病例的基牙状况、数目、基牙牙冠、牙周情况、义齿支持形式及修复体等情况进行临床调查,并对结果进行统计分析。结果：基牙牙折多发生在1-2颗基牙或多基牙的末端游离侧,3个以上基牙折断明显减少。牙折多见于前牙和双尖牙,以双尖牙多见,且折断均发生在末端游离侧基牙邻近缺隙区。末端游离缺损病例基牙牙折和基托折裂发生率高于非末端游离者。残根残冠修复基牙牙折发生率高于牙周炎和少数余留牙基牙（P〈0.05）。混合固位体组牙折发生率高于套筒冠固位体组（P〈0.05）。结论：套筒冠义齿基牙尽量选择两颗或以上,且分布于牙弓两侧。对于前牙和双尖牙基牙,需减小基牙的受力。     

3种游离端附着体义齿基牙位移的实验研究

目的:探讨3种附着体类型作为下颌单侧游离端义齿固位体对基牙的影响。方法:选用Snap附着体、Ceka附着体和Mini-SG附着体,制作单侧附着体义齿,在义齿侧上下牙列间放置食物片,咬合时用LB-72型高精度半导体激光位移测量仪,测量并计算出基牙在不同方向的位移量,并用随机方差分析法进行统计学分析。结果:3种附着体义齿基牙的近远中向、颊舌向、垂直向的位移、倾斜、扭转均有统计学差异(P<0.05)。Mini-SG附着体导致基牙近远中向的倾斜角度最大,Ceka附着体对基牙近远中向和根尖位移的影响最大,Snap附着体基牙的牙合方移动和逆时针旋转角度最小。结论:Snap附着体的弹性固位装置使应力在基牙和剩余牙槽嵴之间得到了最为均匀的分布,Ceka附着体的应力主要由基牙承担,Mini-SG附着体不能有效减少施于基牙上的有害的扭力。     

下颌磨牙游离缺失套筒冠修复的基牙受载分析

目的研究下颌磨牙游离缺失采用第一，第二前磨牙为基牙的套筒冠修复，义齿受载时不同基牙的位移与应力分布特点。方法采用螺旋CT扫描，自编程序和ANSYS软件建立起精确的套筒冠三维有限元模型，在其上进行不同载荷的加载，分析不同基牙的位移与应力分布趋势。结果 套筒冠义齿在受情况下不同基牙的位移差别占其总位移的9%以下，应力均匀分布于不同基牙。结论套筒冠义齿中不同位置的基牙受载时共同下沉，承担着（牙合）力。     

改良套筒内冠对于倾斜基牙在固定桥修复中的临床应用

目的：改进套筒内冠用于倾斜基牙的固定桥修复，扩大固定桥的适用范围。方法：将改良套筒冠用于有倾斜基牙且髓角高，咬合紧，颊肌肥厚，无法采用或者无法耐受正畸治疗又不接受根管治疗，同时又无法制备出套筒冠内外冠所需的狳龈空间的病例进行固定桥修复。结果：修复后经2-3年的随访观察患者固定义齿修复的临床效果较好。结论：改良套筒内冠的应用扩大了固定桥修复的适用范围，是倾斜基牙固定修复中较为实用的方法。     

Retainer design for unilateral extension base partial removable dental prosthesis by three-dimensional finite element analysis

PurposeThe purpose of this study was to evaluate the effect of differences in the retainer design on load on abutment teeth and displacement of the denture base in mandibular unilateral extension base partial removable dental prosthesis to determine the optimum design for a mechanically appropriate retainer.MethodsThree models were used. Each incorporating a removable denture with different designs of retainer positioned. In design A, Akers clasps were positioned over the first and second premolars. In design B, embrasure clasp was positioned over the first and second premolars. In design C, rest and back-action clasps were positioned over the first and second premolars, respectively. Loading on the occlusal surface of the dentures was performed in the vertical, oblique lingual and buccal directions. Load on the abutment teeth and displacement of the denture base were determined by the three-dimensional finite element method analysis.ResultsVertical and buccolingual load on the abutment teeth by lingual and buccal direction loading on the denture were smaller in designs B and C than in design A. However, the superioinferior and buccolingual displacement of the denture base by buccal direction loading on the denture were largest in design A. Superioinferior and buccolingual displacement of the denture base by the lingual direction loading on the denture were largest in design C.ConclusionsUnder the conditions set in this study, the stability of design A was greater than that of design B or C, but load on the abutment teeth was larger.     

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.     

单侧游离端义齿三种腭部连接形式的光弹应力分析

用光弹模型“冻结”法对三种不同位置腭杆的单侧游离端义齿进行侧向加载，研究缺牙区牙槽嵴、缺牙区同侧基牙和缺牙区对侧基牙的应力情况，分析连接杆传递和分散侧向力的作用。结果表明：腭连接杆的位置与侧向力的传递和分散有一定关系。前金属基托型单侧游离端义齿向缺牙区对侧基牙传递的侧向力比后腭杆型义齿传递的力小。单侧游离端义齿受侧向力时连接杆传递力的作用不明显，缺牙区牙槽嵴和同侧基牙承担主要载荷     

Finite element analysis of deflections in major connectors for maxillary RPDs

PURPOSE: The effect of major connector design on deflection in maxillary removable partial denture (RPD) frameworks under simulated occlusal loading was analyzed by means of three-dimensional finite element models. MATERIALS AND METHODS: Thirteen maxillary major connectors were produced for a Kennedy Class II case. Eleven frameworks consisted of posterior palatal straps with different anteroposterior widths at the midline. Anteroposterior and horseshoe bars were also constructed for comparison. In each framework, the occlusal rest on the abutment adjacent to the edentulous ridge was fixed in a vertical direction, and the rest on the contralateral side was fixed in all directions. A biting force of 20 N was vertically distributed simultaneously on each of the three missing posterior teeth locations. RESULTS: For the posterior palatal straps, the maximum vertical displacement at the saddle and the buccal displacement at both the saddle and the rest adjacent to the saddle decreased as their connector width increased from 6 to 29 mm, whereas maximum distal displacements were insensitive to the connector width. The posterior straps with anteroposterior widths of more than 18 mm revealed comparable rigidity to the anteroposterior bar. The horseshoe bar and the posterior straps with smaller widths demonstrated greater displacements than the other frameworks. CONCLUSION: The rigid connectors proved to be the most effective in transmitting applied occlusal forces to the contralateral side of the framework.     

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.     

Influence of the buccolingual position of artificial posterior teeth on the pressure distribution on the supporting tissue under a complete denture

SUMMARY The buccolingual position of artificial teeth is one of the important factors affecting denture stability, chewing efficiency, and pressure distribution on the supporting tissue under a denture. This study compared the pressure values on the supporting tissue under a denture during chewing in denture wearers, each of whom tried three different setting positions of artificial posterior teeth. The pressure on supporting tissue was greater on the working side that on the non-working side during chewing. The difference in mean pressure was found among the buccolingual positions of artificial posterior teeth. When the posterior teeth were set on the crest, the total pressure was the smallest. This strongly suggests that the setting position of artificial teeth should be considered not only for denture stability but also for the avoidance of high pressure on the supporting structures.     

An investigation of the effectiveness of indirect retainers.

A mandibular bilateral distal-extension base removable partial denture was lifted from a model under standardized conditions. The amount of denture base displacement under various loads and the forces of removal were measured electronically. The framework was constructed to allow repeated changes in the type of clasp, location of indirect retainer, and position of the rest seat on the terminal abutment tooth. The usefulness of an indirect retainer in preventing occlusal displacement of the denture base appears to be limited. The type of clasp had the greatest influence on the amount of denture base movement. Proximal surface guiding planes were also found to be important in preventing lifting of the denture base. Use of mesial instead of distal rests on the terminal abutment teeth did not decrease indirect retention.     

Follow-up study of periodontal tissues around the abutment teeth in Konus telescope denture

The purpose of this study was to evaluate the periodontal tissues around the 47 abutment teeth in patients with advanced periodontitis for 5 years maintenance periods. The periodontal and prosthetic treatment were carried out and 16 Konus telescope dentures were applied for 11 patients. During 5 years maintenance therapy, periodontal conditions were observed once a year assessing probing depth, attachment level, tooth mobility index, gingival index, marginal alveolar bone height, width of periodontal ligament and loss of lamina dura. The results showed that increase of probing depth in 0.61 mm and attachment loss in 0.78 mm were observed for 5 years. A slight gingival inflammation occurred and tooth mobility increased in some extent. Enlargement of periodontal ligament space and loss of lamina dura in 40% of abutment teeth were observed for 5 years. There were six decayed teeth, six teeth, from which a intracoronal crown was removed, and two extracted teeth in 47 abutment teeth. In conclusion, the periodontal tissues around abutment teeth in Konus telescope denture changed slightly at one year after denture placement, after which, the periodontal tissues were well maintained.