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°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°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°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°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。     

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。     

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。     

改良3/4冠应用于基牙倾斜的固定桥修复

目的 研究改良3/4冠应用于基牙倾斜的固定桥修复的效果.方法 对18例需将倾斜磨牙用作基牙的牙缺失患者,采用改良3/4冠修复,观察修复效果.结果 18例固定桥修复后固位、舒适性及咬合关系良好,半年～1年后复查,无1例患者出现基牙松动、固定桥松动、牙龈炎症等情况.结论 改良3/4冠用于基牙倾斜的固定桥修复效果肯定.     

套筒冠在下颌义齿修复中的应用研究

目的：探讨套筒冠在下颌义齿修复中的应用效果。方法：382例保留部分残根残冠的下颌牙体进行套筒冠修复,1年后观察基牙松动度、桩核松动度、牙龈萎缩度及牙周情况,介绍套筒冠的制作工艺。结果：382例中基牙松动占4.71%,其中以前牙发生率较高。桩核松动占6.02%,也以前牙桩核松动发生率较高;继发性根尖周炎以磨牙居多。结论：套筒冠可摘下颌总义齿修复时应根据不同个体选择适应症,套筒冠义齿是牙齿缺失保留患牙的一种较理想的修复方式。     

栓体栓道式附着体在下颌倾斜基牙固定修复中的应用

目的研究栓体栓道式附着体在下颌倾斜基牙固定修复中的临床应用效果。方法对20例下颌第二前磨牙或第一磨牙缺失,两端基牙牙体牙髓牙周组织正常,且向缺牙区倾斜,通过常规的牙体预备两基牙不能获得共同就位道的病例,利用栓体栓道式附着体进行固定修复。结果经过3年的随访观察,有2例患者固定桥栓体栓道连接部位出现松动,但修复体的咀嚼功能良好,无一例患者出现固位体的松动,基牙无松动,无牙髓牙周以及根尖周炎症。结论栓体栓道式附着体在下颌倾斜基牙固定修复中的应用效果较好。     

固定修复后倾斜基牙角度对牙周受力影响的有限元分析

目的:分析第一磨牙缺失,采用双端固定桥修复,作为基牙的下颌第二磨牙倾斜不同角度时,基牙牙周膜等支持组织的应力分布情况,为临床修复提供理论依据。方法:采用三维激光扫描与Marc软件结合的方式,分别建立下颌第一磨牙缺失、下颌第二磨牙向近中倾斜时,行双端固定桥修复后的三维有限元模型,施加载荷计算并分析牙周膜支持组织中的应力分布状况。结果:当下颌第二磨牙近中倾斜24°时,其近中牙颈部牙周膜的应力值达到0°时的2倍,同时下颌第二前磨牙牙周膜受力也呈现上升趋势。结论:固定修复时,当牙齿倾斜达到或超过24°时,应慎重作为双端固定桥的基牙。     

口腔生物力学

穿下颌种植体周围骨界面应力分析;双根管牙及其桩核烤瓷冠三维有限元模型的建立;残冠牙体余量对核桩冠桩根联合体水平承载力学性能的影响;上颌第一磨牙核桩冠的三维有限元模型建立;下颌磨牙游离缺失套筒冠修复的基牙受载分析     

下颌第二磨牙缺失单端固定义齿修复的临床观察

目的：观察下颌第二磨牙缺失单端固定义齿修复的临床效果。方法：对以下颌第二前磨牙和第一磨牙为基牙，以单端固定义齿修复下颌第二磨牙缺失的25例患者进行临床和放射检查。结果：所修复的25例病例中有2例失败于固位力不足，1例失败于基牙折裂。其它均使用良好。结论：只要桥体设计合理，基牙牙体及牙周状况好，可以单端固定义齿的形式修复缺失的下颌第二磨牙。     

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。     

第三磨牙倾斜不同角度对下颌双端固定桥应力的影响

目的:下颌第一二磨牙缺失三基牙双端固定桥修复的条件下,分析近中倾斜不同角度的第三磨牙作为基牙后受力时修复体、牙体组织及牙周膜的应力分布情况,为临床修复提供理论依据.方法:在已建好的第一二磨牙缺失三基牙双端固定桥修复的三维有限元模型基础上,将第三磨牙近中倾斜0°、10°、20°、30°和40°,通过Ansys软件分析修复...     

磨牙冠延长术在固定义齿修复中的应用

目的：观察磨牙冠延长术后作为固定义齿基牙的修复效果及相关问题。方法：临床牙冠殆龈距过小且被选为固定义齿基牙的末端磨牙21例,施以冠延长术,即翻瓣术或翻瓣术联合牙槽骨修整术,然后于2—8w后以固定义齿修复。6个月、1年后复查,检查修复体固位情况、固位体边缘、牙龈健康状况、龈沟出血指数等。结果：6-12个月后义齿固位良好,边缘密合,患者无不适,牙龈无明显红肿,龈沟出血指数与对称牙出血指数差异均无统计学意义（P〉0．05）。结论：对于临床牙冠短的磨牙,冠延长术是改善其固定修复效果的一种有效方法。     

Treatment of molar furcation involvement using root separation and a crown and sleeve-coping telescopic denture. A longitudinal study.

Because of the inconsistent results of periodontal and prosthetic therapy, periodontists may choose to treat maxillary molar furcation involvements (FI) with poor root morphology utilizing a root resection technique (RRT). In addition, poor root morphology of the remaining root following RRT is usually considered a high risk factor for long-term periodontal and prosthetic success. The purpose of this retrospective study was to investigate the differences in the clinical periodontal parameters between molar abutments with and without molar root separation and/or resection (RSR) before and after periodontal and prosthetic therapy, using a crown and sleeve-coping telescopic denture (CSCTD). A total of 85 molars (47 maxillary and 38 mandibular) were treated in 25 subjects. There were 33 abutments without root separation/resection and 52 abutments with RSR. Forty-three CSCTD were placed, 23 in the maxillary arch and 20 in the mandibular arch. The mean observation period was 6.7+/-1.9 years (range, 5 to 13 years). The plaque index, gingival index, probing depth, clinical attachment level, and alveolar bone change were recorded. The differences in these parameters before and after periodontal and prosthetic therapy between the advanced furcation-involved molars with and without RSR were evaluated. The results revealed a remarkable improvement in the periodontal parameters in advanced Class II and Class III FI in molars with RSR as compared to those without RSR. It was, therefore, concluded that molar abutments with RSR in conjunction with a specifically designed telescopic device provide a modified approach for treating molars with advanced Class II and III FI.     

固定义齿倾斜基牙牙周应力分布的三维有限元研究

目的 :用三维有限元方法对近中倾斜的下颌第二磨牙单独受力及作为固定桥基牙后受力时牙周支持组织中的应力分布进行比较分析。方法 :采用薄层CT扫描技术和Ansys有限元分析软件建立下颌第一磨牙缺失、下颌第二磨牙近中倾斜 3 0°、行双端三单位固定桥修复前后的三维有限元模型 ,施加载荷计算并分析牙周支持组织中的应力分布状况。结果 :修复前 ,第二磨牙近中牙槽嵴顶、根尖处应力值较大 ,修复后 ,第二磨牙根周应力值减小 ,第二前磨牙颈部及根尖应力值增大 ,应力分布得到改善。结论 :在一定的倾斜角度内 ,从生物力学角度来评价固定修复有利于倾斜基牙的牙周健康。     

利用阻生智齿预备钛金属冠改善下颌义齿固位的应用观察

目的:利用阻生智齿增加下颌单颌总义齿固位力。方法:通过手术暴露下颌阻生智齿,在智齿冠上预备牙体,制作钛金属套冠将阻生齿牙冠形态转移至口腔中,从而把固位力不足的下颌单颌总义齿修复,转变成有正常基牙固位的可摘局部义齿修复。结果:通过3例利用埋伏阻生智齿接钛金属套冠,对下颌牙槽嵴严重吸患者的可摘局部义齿修复,经2～3年的临床观察,钛套冠固定良好,无松动,牙龈正常。可摘局部义齿固位良好。结论:利用埋伏阻生智齿接钛金属套冠,加强下颌牙槽嵴严重吸收可摘局部义齿固位力的效果明显。     

Removable partial denture with molar uprighting spring: An innovative hybrid appliance

PatientA 45-year-old female patient with need of fixed replacement of her missing teeth which were lost long time before. Posterior teeth were severally tipped bilaterally in the edentulous space. Hybrid removable partial denture with molar uprighting spring was fabricated for molar uprighting on both side tilted molars. After 3 month and 15 days of treatment with hybrid appliance the molar abutment were uprighted for fabrication of fixed partial dentures.DiscussionThe objective in molar uprighting is ideal positioning of the molar which will eventually become an abutment tooth for a fixed prosthesis. The ideal position will provide an optimal periodontal environment for the molar. The prosthodontic advantages of molar uprighting via distal tipping include an improved line-of-draw if a FPD is being constructed. Concept of designing of appliances was based on our basic knowledge of forces for uprighting the tooth along with maintaining the function during the treatment period. Another advantage of this appliance was that it prevented supra eruption of opposing teeth during the period when the molar was being uprighted.ConclusionUprighting of tilted molar is extremely beneficial for long term success of fixed denture prosthesis by using hybrid appliances in very short period of treatment without hampering the function of the patient during the treatment period which is very economical as well.     

The tilted posterior tooth. Part III: Abutment for a fixed partial denture

The problem of achieving a common path of insertion for a fixed partial denture when a tilted posterior abutment is involved can usually be solved by well planned tooth preparation in conjunction at times with intentional endodontic therapy. When tooth preparation alone cannot solve the problem, the mechanical solutions of the locked attachment and the telescopic retainer are available and must be considered. Other problems involved with the tilted abutment, adjacent tilted teeth, space reduction, supraversion of the antagonist, and the problem of a long-span fixed partial denture were discussed.     

Analysis of stress on a fixed partial denture with a blade-vent implant abutment.

Using a two-dimensional finite element method, a study was made that compared the behavior of a model mandibular posterior fixed partial denture constructed on the second premolar abutment and a blade-vent implant imbedded at the site of the second molar with the behavior of a fixed partial denture constructed on the second premolar and second molar abutments. The following were the results: 1. Deflections of the implant fixed partial denture were less than those of the natural tooth fixed partial denture in vertical and inclined loads. 2. Stress concentration was markedly found in the pontic and the mesial and distal parts of the premolar retainer in both restorations and the implant neck in the implant fixed partial denture. 3. In the implant fixed partial denture, stresses induced in the surrounding bone became higher around the posterior abutment and became lower around the premolar retainer than the stresses produced with the natural tooth fixed partial denture. 4. Therefore it was suggested that, to relieve stress to the surrounding bone around the implant abutment, occlusal forces loaded to the implant fixed partial denture have to be more concentrated on the premolar abutment than do forces loaded to the natural tooth fixed partial denture.     

用三维有限元方法对单端固定桥进行应力分析

目的分析磨牙游离缺失单端固定桥修复的受力情况。方法运用三维有限元应力分析法,对一侧磨牙游离缺失通过改变牙槽骨支持高度,采用不同基牙数目,不同桥体长度建立不同的单端固定桥有限元模型进行应力和位移的计算和分析。结果较高的应力集中在游离端近中的基牙上,牙槽骨高度降低会增加基牙的移位及应力集中;单纯增加基牙的数目不会导致牙周组织中应力明显相应减少;基牙数目增加会减少修复体移位及应力集中;增加桥体长度会引起义齿应力明显增加和向远中移位。结论游离缺失端行单端固定桥修复最好选择桥体为一个磨牙长度,且基牙数至少两个,以提高单端固定桥修复的成功率。     

Effect of abutment mobility, site, and angle of impact on retention of fixed partial dentures

Fixed partial dentures cemented to dies of adjustable mobility were subjected to repeated impacts at three different sites. Immobile abutments retained their prostheses longer than mobile abutments. Impacts that fell between the centers of rotation of the abutments were withstood longer than impacts that fell nearer the ends of the prostheses. This study failed to show a significant difference between the effect of impacts perpendicular to the occlusal plane and impacts angled 45 degrees toward the lingual plane. The results of this study suggest that (1) crowns that anchor rigid prostheses to mobile teeth require greater retentive ability than crowns on relatively immobile abutments and (2) occlusal impacts are best withstood when they fall on the areas of the fixed partial denture over and between the centers of rotation of the abutment teeth. If a fixed partial denture must withstand loading outside these areas, as is the case with cantilevered pontics and some tilted abutments, the retainer furthermost from the anticipated eccentric load must have exceptionally good retention.