骨质量对精密附着体天然牙-种植体联合固定桥的应力影响

目的探讨在应用精密附着体天然牙-种植体联合固定桥修复时,骨质量对两种基牙及其周围支持骨组织的应力影响。方法采用三维有限元分析方法,对不同质量骨组织支持的精密附着体天然牙-种植体固定桥的有限元模型进行计算分析。结果固定桥支持骨组织的质量下降后,各基牙和其周围支持骨组织中的应力值明显增大。结论骨质量与精密附着体天然牙-种植体联合固定桥的应力改变具有密切相关性。     

种植体-天然牙半固定桥的制作

种植体-天然牙半固定桥是指桥体一端是以天然牙为基牙，另一端是由种植体支持的联合固定修复体。由于种植体的愈合方式为骨结合，与机体组织之间缺乏牙周膜，没有生理动度，承受负荷能力较差，咬合时易对种植界面造成应力及集中，导致创伤和骨组织吸收，影响种植义齿的远期修复效果。因此，桥体的种植体侧的连接体常设计成附着体装置进行应力缓冲。     

种植体-天然牙半固定桥的制作

种植体-天然牙半固定桥是指桥体一端是以天然牙为基牙,另一端是由种植体支持的联合固定修复体.由于种植体的愈合方式为骨结合,与机体组织之间缺乏牙周膜,没有生理动度,承受负荷能力较差,咬合时易对种植界面造成应力及集中,导致创伤和骨组织吸收,影响种植义齿的远期修复效果.     

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。     

天然牙-种植体共同支持式固定义齿的生物力学研究Ⅰ.垂直集中载荷对种植体、天然牙骨界面应力的影响

目的:通过对天然牙-种植体共同支持式固定义齿受垂直集中载荷时,种植体、天然牙骨界面应力分布情况进行测试,为临床能否使用该方式修复牙列缺损提供生物力学的理论依据。方法:应用电阻应变计电测技术的方法。结果:天然牙-种植体共同支持式固定义齿修复时,在垂直集中载荷下,随着载荷的不断加大,天然牙-种植体与骨组织界面处的应力值不断加大,最大应力出现在种植体、天然牙根颈部区,种植体与稳固的天然牙共同支持式固定修复时,天然牙与骨界面应力分布较均匀。结论:从生物力学的角度来看,在优化临床设计的前提下,天然牙-种植体共同支持式固定义齿是临床可采用的特殊固定义齿,尤其适用于末端游离缺牙的患者。     

天然牙—种植体共同支持式固定义齿的生物力学研究I.垂直集中载荷对种植体、天然牙骨界面应力的影响

目的：通过对天然牙-种植体共同支持式固定义齿受垂直集中载荷时，种植体、天然牙骨界面应力分布情况进行测试，为临床能否使用该方式修复牙列缺损提供生物力学的理论依据。方法：应用电阻应变计电测技术的方法。结果：天然牙-种植体共同支持式固定义齿修复时，在垂直集中载荷下，随着载荷的不断加大，天然牙-种植体与骨组织界面处的应力值不断加大，最大应力出现在种植体、天然牙根颈部区，种植体与稳固的天然牙共同支持式固定修复时，天然牙与骨界面应力分布较均匀。结论：从生物力学的角度来看，在优化临床设计的前提下，天然牙-种植体共同支持式固定义齿是临床可采用的特殊固定义齿，尤其适用于末端游离缺牙的患者。     

天然牙-种植体联合支持式义齿的应力分析

目的:比较以常规固定桥、固定式套筒冠和CEKA冠外精密附着体为上部结构的天然牙-种植体联合支持义齿的应力分布情况,寻求联合支持义齿上部结构的优化设计方案。方法:利用ANSYS三维有限元法,建立下颌右侧第一磨牙缺失、以下颌第二前磨牙和种植体(位于下颌第二磨牙)联合支持局部固定义齿的三维有限元模型,采用分散垂直和分散斜向(45°)两种加载方式(总加载力200N)。结果:2种加载条件下,固定式套筒冠和CEKA附着体都明显降低了种植体和天然牙周围骨组织的应力,垂直加载时,前者应力值低于后者;斜向加载时,后者低于前者,但后者会使天然牙局部应力有所增加。斜向加载时,种植体及其周围骨组织和天然牙及其周围骨组织的应力值均大于垂直加载条件下的应力值。结论:固定式套筒冠和CEKA附着体均能改善联合支持义齿的应力分布,CEKA附着体对侧向力的缓冲作用较优。     

种植天然牙联合全牙弓即刻固定修复的失败原因分析

目的:通过对一例种植牙和天然牙联合即刻修复的病例进行长达三年追踪观察,从多角度对种植体失败的原因进行分析,为将来的临床治疗提供可供借鉴的经验.方法:两年间,临床共植入8枚种植体,修复方式先后采用了15-25种植牙天然牙联合的即刻修复,15-25种植支持的固定修复+16,17;26,27精密附着体活动修复,覆盖义齿修复.结果:植入的8枚种植体中有5枚种植体失败,与种植体联合即刻修复的2颗天然牙齿被拔除.结论:种植体和天然牙联合的即刻修复风险很高,临床在进行类似设计时,应当认真分析患者的实际条件,方可避免失败.     

口腔种植学

种植体-基台连接形式对种植体周围骨组织应力分布的影响;Ankylos SynCone基台覆盖义齿即刻种植修复的护理配合;圆柱形螺纹种植体螺纹的优化设计和应力分析;天然牙-种植体联合支持式固定义齿的临床观察;牙种植外科骨收集器内骨碎屑成骨活性的研究     

种植体与天然牙联冠修复应力分布的三维有限元分析 Ⅰ.垂直集中载荷对种植体、天然牙骨界面应力的影响

目的 :探讨种植体与天然牙联冠修复在垂直集中载荷作用下 ,种植体、天然牙骨界面应力分布情况及受力的相互影响,为临床优化设计提供生物力学的理论依据。方法 :采用三维有限元法建立模型并计算、分析。结果 :种植体与天然牙联冠修复时 ,种植体、天然牙骨界面颈部和根尖部出现应力集中 ;种植体与稳定的天然牙联合修复时种植体-骨界面应力分布较均匀。结论 :种植体与天然牙可共同承担载荷 ;当天然牙受垂直集中载荷时 ,种植体未过载 ;种植体最好与稳定的天然牙联合修复     

Soft- and hard-tissue augmentation by orthodontic treatment in the esthetic zone

A technique that may effectively create a greater volume of available hard and soft tissue in the vertical plane without surgical intervention is reported and explained. Limitations of the forced eruption are also discussed. Creating an esthetic implant-supported restoration is a challenge in patients who have alveolar resorption and/or attachment loss, especially when they present with a high smile line. Many methods to augment this loss of tissue have been proposed; most involve surgical procedures to add bone or bone substitutes to compensate for the loss of alveolar tissue. This case report presents an alternative to bone augmentation procedures with the use of orthodontic tooth movement in the esthetic zone of a 62-year-old woman. The tooth movement facilitated implant placement by increasing soft-tissue volume and facial bony contours.     

The management of a severely resorbed edentulous maxilla using a bone graft and a CAD/CAM-guided immediately loaded definitive implant prosthesis: a clinical report

Functional reconstruction of an occlusion with severe residual ridge resorption is a clinical challenge. Removable prostheses are unsuccessful in situations with severe bone resorption. A patient with an edentulous maxilla received bone grafts from the anterior iliac crest to augment the maxillary alveolar residual ridges. The maxilla underwent bilateral sinus lift in the posterior area and onlay bone graft on the anterior maxilla using platelet-rich plasma. Eight endosseous implants were placed using a CAD/CAM surgical template approximately 6 months after the bone augmentation procedure. A prefabricated definitive implant-supported fixed complete denture was connected immediately after implant placement using a CAD/CAM-guided surgical implant placement protocol.     

Advantages of the root submergence technique for pontic site development in esthetic implant therapy

A single-tooth implant in the esthetic region has good potential for success, but it is still challenging to restore multiple-tooth defects with implant-supported prostheses that resemble the natural dentition. This article suggests a strategy to provide a more predictable protocol for esthetic implant treatment for multiple-tooth defects using the root submergence technique (RST). By maintaining the natural tooth root with the RST a much greater amount of surrounding tissue may be preserved than with the commonly used socket preservation technique, which almost always leads to crestal bone resorption and thus reduction of the height of the interdental papillae and width of the edentulous ridge. RST instead maintains the natural attachment apparatus of the tooth in the pontic site, which in turn allows for complete preservation of the alveolar bone frame and assists in the creation of an esthetic result in adjacent multiple-tooth-replacement cases. In situations with periodontal bone loss, orthodontic extrusion is required to create the underlying bone support for the papilla that is necessary to guarantee predictability.     

Factorial analysis of variables influencing mechanical characteristics of a single tooth implant placed in the maxilla using finite element analysis and the statistics-based Taguchi method

The aim of this study was to determine the relative contribution of changes (design factors) in implant system, position, bone classification, and loading condition on the biomechanical response of a single-unit implant-supported restoration. Non-linear finite-element analysis was used to simulate the mechanical responses in an implant placed in the maxillary posterior region. The Taguchi method was employed to identify the significance of each design factor in controlling the strain/stress. Increased strain values were noted in the cortical bone with lateral force and an implant with a retaining-screw connection. Cancellous bone strain was affected primarily by bone type and increased with decreasing bone density. Implant stress was influenced mainly by implant type and position. The combined use of finite-element analysis and the Taguchi method facilitated effective evaluation of the mechanical characteristics of a single-unit implant-supported restoration. Implants placed along the axis of loading exhibit improved stress/strain distribution. The reduction of lateral stress through implant placement and selective occlusal adjustment is recommended. An implant with a tapered interference fit connection performed better as a force-transmission mechanism than other configurations.     

Implant-retained dentures for full-arch rehabilitation: a case report comparing fixed and removable restorations

Dental implants as abutments for full-arch restorations are a well-documented treatment modality. This report presents a case in which the patient was treated initially with fixed restorations supported by either implants or natural teeth and subsequently treated with a removable implant/telescopic crown-supported overdenture. Advantages and disadvantages of each approach are described and discussed. While the fixed restoration resulted in a functionally satisfactory treatment outcome, the patient was displeased with the esthetic appearance. The main concern was the unnaturally long tooth shape necessary to compensate for the insufficient alveolar ridge height. Replacement of the existing restoration with an implant-supported removable overdenture led to a functionally and esthetically acceptable result. When deciding whether to use a fixed or removable implant-supported full-arch restoration, a multitude of factors must be considered. Due to the possible need for additional surgical steps to enhance the esthetic appearance surrounding fixed restorations, removable implant-supported partial dentures often are the better choice.     

Mechanical interactions of an implant/tooth-supported system under different periodontal supports and number of splinted teeth with rigid and non-rigid connections

OBJECTIVES: This study investigated the mechanical interactions of implant-teeth splinting systems under different periodontal supports and number of splinted teeth with rigid and non-rigid connectors using non-linear finite element (FE) approach. METHODS: Two FE models with normal and compromised periodontal supports containing a Frialit-2 implant splinted to the first and second premolars were constructed. Non-linear contact elements were used to simulate a realistic interface fixation within the implant system and the sliding function of the non-rigid connector. ANOVA was used to test for relative importance of the investigated factors and main effects for each level of the three investigated factors (periodontal supports, teeth splinting and connector designs) in terms of the stress values were performed. RESULTS: The simulated results indicated that the cross-interaction of the periodontal support and the splinting situation was a major factor affecting the stress value in alveolar bone. An additional splinting decreased the stress values of bone significantly for a compromised periodontal support. The individual factor of periodontal support also influenced the stress found in the alveolar bone (28%) and implant (72%), and the stress values increased when the periodontal support was reduced. Using different connectors affected the stresses found in bone (15%), implant (21%) and prosthesis (99%). The stress values of the implant and prosthesis increased, but were decreased in bone when the splinting system used non-rigid connectors. The mobility of natural teeth and the implant system between non-rigid and rigid connections showed only small differences. CONCLUSIONS: A non-rigid connector should be used with caution since it breaks the stress transfer and increases the unfavorable stress values in the implant system and prosthesis. The tooth/implant-supported system with an additional splinting is more efficient in compromised periodontal supports.     

Photoelastic stress analysis of load transfer to implants and natural teeth comparing rigid and semirigid connectors

STATEMENT OF PROBLEM: Controversy exists regarding the connection of implants to natural teeth. PURPOSE: This simulation study measured photoelastically the biologic behavior of implants. Stress transfer patterns with variable implant support and simulated natural teeth through rigid and nonrigid connection were examined under simulated functional loads. MATERIAL AND METHODS: A photoelastic model of a human left mandible edentulous distal to first premolar was fabricated having 2 screw type implants (3.75x13 mm) embedded within the edentulous area. Two fixed prosthetic restorations were fabricated with either a nonsplinted proximal contact or a soldered proximal contact, and cast precision dowel attachment between implant areas and simulated tooth. Simulated vertical occlusal loads were applied at fixed locations on the restorations. Stresses, which developed in the supporting structure, were monitored photoelastically and recorded photographically. RESULTS: The rigid connector in the 1 implant situation caused only slightly higher stresses in the supporting structure than the nonrigid connector. The distally loaded 1 and 2 implant-supported restoration produced the highest apical stresses, which occurred at the distal implant. The rigid connector demonstrated the greatest stress transfer in the 2 implant-supported restoration. CONCLUSIONS: Lower stresses apical to the tooth or implant occurred with forces applied further from the supporting abutment. Although the least stress was observed when using a nonrigid connector, the rigid connector in particular situations caused only slightly higher stresses in the supporting structure. The rigid connector demonstrated more widespread stress transfer in the 2 implant-supported restoration. Recommendations for selection of connector design should be based on sound clinical periodontal health of a tooth and the support provided by implants.     

An Investigation of Tooth/Implant-Supported Fixed Prosthesis Designs with Two Different Stress Analysis Methods: An in vitro Study

PURPOSE: Tooth/implant-supported fixed prostheses (TIFPs) present biomechanical design problems, because the implant is rigidly anchored within the alveolus, and the tooth is attached by the periodontal ligament that allows movement. While TIFP designs with rigid connectors (RCs) are preferred by many clinicians, the designs containing non-rigid connectors (NRCs) are suggested as a method to compensate for these mobility differences. However, studies have failed to show the advantage of one design over the other. This study examined stresses formed around the implant and natural tooth abutments under occlusal forces, using two dimensional finite element (2D-FEM) and photoelastic stress analysis methods (PSAM). MATERIALS AND METHODS: Connection of TIFP designs were investigated in distal extension situations using stress analysis interpreted with the 2D-FEM and PSAM. Three TIFP (screw type implant, 3.75 mm x 13 mm) models with various connection designs (i.e., rigidly connected to an abutment tooth, connected to an abutment tooth with an NRC, connected to an abutment implant with an NRC) were studied. The stress values of the three models loaded with vertical forces (250 N) were analyzed. RESULTS: The highest level of stresses around the implant abutment was noted on the TIFPs with the RC. On the other hand, NRCs incorporated into prostheses at the site of the implant abutment reduced the level of stresses in bone. CONCLUSION: It could be suggested that if tooth and implant abutments are to be used together as fixed prostheses supports, NRCs should be placed on the implant abutment-supported site.     

Rationale for socket preservation after extraction of a single-rooted tooth when planning for future implant placement

After tooth extraction, the alveolar ridge will commonly decrease in volume and change morphologically. These changes are usually clinically significant and can make placement of a conventional bridge or an implant-supported crown difficult. If bone resorption is significant enough, then placement of an implant may become extremely challenging. Postextraction maintenance of the alveolar ridge minimizes residual ridge resorption and, thus, allows placement of an implant that satisfies esthetic and functional criteria. Recent advances in bone grafting materials and techniques allow the dentist to place implants in sites that were considered compromised in the past. This article focuses on the healing pattern of sockets, with and without the use of regenerative materials, and the rationale for preserving the dimensions of the extraction socket. Histologic and clinical evidence is reviewed to provide an in-depth understanding of the logic behind and value of socket preservation.     

单纯种植体与天然牙联合种植体的临床修复效果及影响因素分析

目的 ：分析单纯种植体与天然牙联合种植体的临床修复效果及影响因素。方法 ：选择2016年5月—2017年6月上饶市人民医院收治的采用天然牙联合种植体修复的牙列缺损患者34例（联合组）,单纯种植体修复的牙列缺损患者33例（单纯组）,随访3年,评价2组患者修复与骨吸收情况,收集患者一般资料,分析种植体失败影响因素。采用SPSS 20.0软件包对数据进行统计学分析。结果：联合组种植体修复成功率为93.65%,与单纯组的95.08%相比无显著差异（P>0.05）。联合组术后1年半,牙槽嵴吸收水平均高于单纯组（P<0.05）。种植体失败组,女性、上颌后牙区、牙体牙髓病、缺失骨密度Ⅳ级、糖尿病、吸烟、种植体直径>4.5 mm、长度>12 mm、牙周探针深度>3 mm、龈沟出血指数≥2均显著高于成功组（P<0.05）。缺牙骨密度、糖尿病、吸烟及天然牙龈沟出血指数≥2、探针深度>3 mm是种植体失败的危险因素（P<0.05）。结论：单纯种植体与天然牙联合种植体均具有较好的临床修复效果,短期随访结果显示,天然牙联合种植体修复是可行的。缺牙骨密度、糖尿病、吸...