Healing at Implants Placed in an Alveolar Ridge with a Sloped Configuration: An Experimental Study in Dogs

Purpose: To study healing around implants placed in an alveolar ridge with a sloped lingual‐buccal configuration. Materials and Methods: Six Labrador dogs were used. Buccal bone defects were prepared in the mandible after extraction of premolars. Three months later, two test implants with a sloped marginal design and two control implants were placed in the chronic defect area with a sloped lingual‐buccal configuration of each premolar region. The test implants were placed in such a way that the buccal margin of the implant coincided with the buccal bone crest. The lingual margin of the control implants was placed to a similar depth as the lingual margin of the test implants. Abutments were connected to the implants in the right mandibular premolar region and flaps were sutured around the neck of the abutments. In the left side of the mandible, cover screws were placed and the flaps were sutured to cover the implants. Biopsies were obtained 4 months later and prepared for histological examination. Results: It was demonstrated that healing around implants placed in an alveolar ridge with a sloped lingual‐buccal configuration resulted in the preservation of a vertical discrepancy between the lingual and buccal marginal bone levels around implants with either a regular cylindrical outline or a modified marginal portion that matched the slope of the alveolar ridge. Conclusion: As the marginal buccal portion of the control implants with a regular design had no bone support, it is suggested that implants with a modified marginal portion may be considered in recipient sites with a sloped lingual‐buccal configuration.     

侧方(牙合)时线性(牙合)种植覆盖全口义齿下颌种植体周围骨组织的应力分布

目的 通过比较侧方(牙合)时线性猞和解剖袷种植覆盖全口义齿下颌种植体周围骨组织的应力分布,为线性牙合种植覆盖全口义齿的临床应用提供依据.方法 选择牙槽嵴重度吸收的无牙颌志愿者1名.采用薄层CT及ANSYS 7.0软件建立志愿者颌骨、黏膜、两枚位于下颌尖牙区由杆卡附着体连接的种植体、线性(牙合)和解剖(牙合)种植覆盖全口义齿的三维有限元模型,模拟咀嚼肌肌力加载下侧方(牙合)时两种模型下颌种植体周围骨组织的应力分布.结果 侧方胎时解剖骀模型下颌种植体周围骨组织的应力主要集中于工作侧种植体的舌侧偏远中;线性(牙合)模型下颌种植体周围骨组织的应力分布于工作侧与非工作侧种植体偏远中,且两侧均有较广泛的应力分布.两种模型种植体周围骨组织的应力峰值均出现于工作侧,垂直方向上应力(σz)显示,解剖(牙合)和线性(牙合)模型的压应力分别为-6.47 MPa、-4.86 MPa,拉应力分别为6.81 MPa、3.04 MPa,最大主应力(σl)显示,解剖(牙合)和线性(牙合)模型的压应力分别为-4.20 MPa、-3.48 MPa,拉应力分别为7.20 MPa、5.33 MPa.结论 对于两枚种植体支持的、杆卡附着体固位的下颌种植覆盖全口义齿,在(牙合)力相同的情况下,侧方(牙合)时线性(牙合)种植覆盖全口义齿下颌两侧种植体负载的(牙合)力比解剖(牙合)更均匀,且种植体所受负荷小.     

Use of alveolar distraction osteogenesis for implant placement: a case report with eight‐year follow‐up

Insufficient alveolar ridge width may impede the success of dental implants. Techniques for resolving this problem include autologous bone grafts, guided bone regeneration, bone splitting and bone spreading techniques. Recently, alveolar distraction osteogenesis has become an alternative method for alveolar augmentation. We propose the use of alveolar bone distraction for insufficient alveolar ridge width. A healthy 33‐year‐old female presented with missing teeth to our clinic. Clinical and radiographic examination revealed the alveolar ridge was too narrow for placement of dental implants. Therefore, horizontal distraction osteogenesis of the posterior mandibular ridge was chosen for augmentation. Two months later, two implants were placed. No significant marginal bone resorption was seen around the implants eight years after placement. Our results indicate that horizontal alveolar distraction is recommended to increase ridge width and allow placement of standard dental implants.     

Loading conditions of endosseous implants in an edentulous human mandible: a three-dimensional, finite-element study

The design of dental superstructures influences the loading on dental implants and the deformation of the anterior interforaminal bone in an edentulous mandible. This deformation causes stress in the bone around the implants and may lead to bone resorption and loss of the implant. The stress distribution around dental implants in an edentulous mandible was calculated by means of a three-dimensional, finite-element model of the anterior part of the jaw. This model was built from data obtained from slices of a single human mandible and was provided with four endosseous implants in the interforaminal region. The implants were either connected with a bar or remained solitary. The solitary implants or the bars were loaded either uniformly or non-uniformly. In case of a non-uniform distribution, either the central bar or the central implants were loaded or the lateral bars or the lateral implants were loaded. The most extreme stresses in the bone were always located around the neck of the implant. In the case of the uniform distribution of the loading there were more or less equal extreme principal stresses around the central and lateral implants. If the load was not uniformly distributed on the superstructure then the implant that was nearest to the place of loading showed the highest stress concentration; with connected implants there was a reduction in the magnitude of the extreme principal stresses compared to solitary implants.     

不同附着体下颌种植覆盖义齿咬合运动与应力分布的有限元研究

目的：采用有限元分析法,研究不同附着体类型对种植覆盖义齿咬合运动方式、载荷分配及牙槽骨内应力分布的影响。方法：采集下颌骨及其所佩戴义齿的CT数据,利用逆向工程技术构建包含下颌骨、附着体（杆卡附着体B;ERA附着体E;球帽附着体R;磁性附着体M）和义齿的完整下颌2植体种植覆盖义齿三维有限元模型,通过对上述不同部件接触关系的定义,模拟正中咬合力作用下,种植覆盖义齿运动方式、载荷分配及颌骨内应力分布情况。结果：正中咬合时,ERA组和球帽组义齿整体均匀沉降,植体所受载荷较小;磁性组和杆卡组垂直向无缓冲,义齿前端无沉降,后端旋转下沉,植体所受载荷增大。植体周围应力分布：杆卡组最高,磁性组其次,ERA组较低,球帽组最低;后方牙槽嵴应力分布：杆卡组最高,球帽组其次,ERA和磁性组最低。结论：不同附着体类型对义齿的运动方式、载荷分配及应力分布有显著影响;附着体缓冲间隙可以延缓植体所受垂直向载荷,降低植体周围颌骨吸收的风险。     

Stress distribution around dental implants: influence of superstructure, length of implants, and height of mandible.

The stress distribution around dental implants was investigated by use of a two-dimensional model of the mandible with two implants. A vertical load of 100 N was imposed on abutments or the bar connection. The stress was calculated for a number of superstructures under different loading conditions with the help of the finite element method. The length of the implants and the height of the mandible were also varied. A model with solitary abutments showed a more uniform distribution of the stress when compared with a model with connected abutments. The largest compressive stress was also less in the model without the bar. Using shorter implants did not have a large influence on the stress around the implants. When the height of the mandible was reduced, a substantially larger stress was found in the bone around the implants because of a larger overall deformation of the lower jaw.     

Ten years of experience with the anterior maxillary and mandibular osteoplasty (class IV ridges): a retrospective analysis of implant survival rates

The anterior maxillary osteoplasty restores adequate bone to the edentulous Class IV ridge prior to placement of endosseous implants. The aim of this retrospective study was to compare the long-term survival of implants placed into the particulate bone of an anterior alveolar osteoplasty to those placed into a 'block' onlay bone graft. Of 85 patients with Class IV 'knife-edge' alveolar ridges, 50 received interpositional particulate bone via an alveolar osteoplasty and 35 received an onlay cortico-cancellous graft. A total of 386 implants were placed as a secondary procedure and followed postoperatively (mean 6 years; 39 failures). There was improved cumulative survival of implants placed into the particulate bone of an osteoplasty compared to the block bone of an onlay graft. Implants supporting a fixed superstructure had a longer cumulative survival than those supporting a removable appliance. There was no statistical difference between implants placed into male and female bone, or between those in edentulous and partially dentate jaws. Within a partially dentate jaw there was a statistically significant increase in cumulative survival for implants within osteoplasty inlay bone compared to onlay bone grafts. Anterior osteoplasty is the surgical treatment of choice for augmentation of the resorbed Class IV alveolar ridge prior to placement of osseo-integrated implants.     

The influence of the alveolar ridge shape on the stress distribution in a free-end saddle removable partial denture supported by implant

The alveolar ridge shape plays an important role in predicting the demand on the support tooth and alveolar bone in the removable partial denture (RPD) treatment. However, these data are unclear when the RPD is associated with implants. This study evaluated the influence of the alveolar ridge shape on the stress distribution of a free-end saddle RPD partially supported by implant using 2-dimensioanl finite element analysis (FEA). Four mathematical models (M) of a mandibular hemiarch simulating various alveolar ridge shapes (1-distal desceding, 2-concave, 3-horizontal and 4-distal ascending) were built. Tooth 33 was placed as the abutment. Two RPDs, one supported by tooth and fibromucosa (MB) and other one supported by tooth and implant (MC) were simulated. MA was the control (no RPD). The load (50N) were applied simultaneously on each cusp. Appropriate boundary conditions were assigned on the border of alveolar bone. Ansys 10.0 software was used to calculate the stress fields and the von Mises equivalent stress criteria (sigmavM) was applied to analyze the results. The distal ascending shape showed the highest sigmavM for cortical and medullar bone. The alveolar ridge shape had little effect on changing the sigmavM based on the same prosthesis, mainly around the abutment tooth.     

Effect of alveolar bone support on zygomatic implants: a finite element analysis study

The objective of this study was to investigate the influence of maxillary alveolar bone on the stress distribution of zygomatic implants. A three-dimensional finite element model was created of half of a skull. Two zygomatic implants were modelled, placed in the skull supported by the zygomatic bone and the maxillary alveolar bone and connected by a fixed bridge. This model was duplicated, and the area of the maxillary alveolar bone supporting the implants was removed. Occlusal and lateral forces were applied to both models and the maximum von Mises stresses were recorded. Higher maximum stresses were noted in the model with no alveolar support. Occlusal stresses were higher than lateral stresses in the model with no alveolar support. Low stresses were noted in the zygomatic bone in both models. In conclusion, maxillary alveolar bone support is beneficial in the distribution of forces for zygomatic implants.     

拔牙后牙槽嵴位点保存在口腔种植学中的应用

拔牙后牙槽嵴的高度、宽度以及周围软组织的保存对于缺牙部位进行种植修复有着非常重要的意义。牙齿拔除后,拔牙窝内新生骨一般无法达到原牙槽嵴的水平,唇颊侧骨板受到的损害尤其严重,造成种植体植入时骨量不足。牙槽嵴位点保存的目的是在拔牙后能有效地保存剩余牙槽嵴的高度、宽度以及相应软组织量,为随后的种植手术和修复提供足够的骨量和美学基础。本文对牙槽嵴位点保存技术及相关的移植材料在骨内种植体领域的研究进展作一综述。     

Vertical alveolar ridge augmentation prior to inferior alveolar nerve repositioning: a patient report

This report describes treatment of a patient using vertical alveolar ridge augmentation performed prior to transposition of the inferior alveolar nerve (IAN). A preoperative computerized tomographic (CT) scan revealed 2 to 3 mm of bone above the canal in the left mandibular molar region. An autogenous bone graft harvested from the chin area was utilized along with a titanium mesh for vertical alveolar ridge augmentation in this area. CT scan after bone grafting revealed 5 mm of vertical ridge augmentation. Bone height above the IAN was 7 to 8 mm after bone grafting procedure. For IAN transposition, an osteotomy was performed to obtain a lateral access window located 4 mm below the crestal bone along the lateral side of the mandible. Two cylindric hydroxyapatite-coated implants were placed. Autogenous bone from the lateral access window that had been removed en bloc was particulated and placed around the implants. Because vertical alveolar ridge augmentation had been performed, the coronal portion of the implant was not exposed after transposition of the IAN. It is suggested that vertical ridge augmentation may be considered prior to transposition of the IAN in situations where minimal bone height exists above the IAN canal. However, long-term clinical investigations are recommended.     

Endosseous implants in horizontal alveolar ridge distraction osteogenesis

PURPOSE: This study evaluated horizontal distraction of the narrow alveolar ridge in dogs and the possibility of achieving osseointegration of implants placed into the distracted site during a consolidation period. MATERIALS AND METHODS: Six beagle dogs weighing approximately 9 to 10 kg were used in this experiment. Twelve weeks after extraction of the mandibular premolars, horizontal alveolar ridge distraction was performed using an originally designed lengthening apparatus. Twelve days after the completion of distraction, screw-type implants were placed into the distracted site. RESULTS: Twelve weeks after the placement of implants, thin lamellar bone rose horizontally from the transport segment toward the surface of the implant. Twenty-four weeks after their placement, the implants were fully embedded in mature lamellar bone, and direct bone contact with the implant surface could be seen. DISCUSSION: Horizontal alveolar ridge distraction was performed successfully by using a lengthening apparatus in the narrow alveolar models. Osseointegration was achieved even though the implants were placed into the distracted site during the consolidation period. CONCLUSION: Horizontal alveolar ridge distraction can be a beneficial technique in the placement of implants In the narrow alveolar ridge in the dog population.     

Three-dimensional finite elemental analysis of zygomatic implants in craniofacial structures

The objective of this study was to analyse stress distribution in craniofacial structures around zygomatic osseointegrated implants. An integrated system for Digital Imaging and Communications in Medicine (DICOM) data were utilized to create a three-dimensional model of craniofacial structures. The amount and distribution of the main stresses were compared using three-dimensional finite elemental analysis. The system allowed visual confirmation and analysis of stress distribution as well as the convenient and simple construction of a digital biomechanical model that provided details of anatomical structures in the regions of interest. Zygomatic implants with or without connected implants supporting the superstructure were compared. Stresses in severely resorbed maxillae with connected implants were not concentrated around the alveolar bone supporting the zygomatic implants. Stresses where there were no connected implants tended to be generated in the zygomatic bone, at the middle part of the zygomatic implant and at the joint of the fixture-abutment. Stress due to occlusal forces is mainly supported by the zygomatic bone, is transferred predominantly through the infrazygomatic crest, and is divided between the frontal and temporal processes of the zygomatic bone in different directions.     

Localized vertical maxillary ridge augmentation using symphyseal bone cores: a technique and case report

Vertical augmentation of the alveolar ridge is intended to restore resorbed alveolar ridges. This procedure is important for the placement of dental implants in a favorable position and also to enhance restoration esthetics. This article presents an approach for vertical ridge augmentation in the anterior maxilla utilizing symphyseal bone cores. A patient presented with 2 localized bony defects around the maxillary lateral incisors. Following extraction of these teeth, vertical bone defects of 7 mm on the right and 6 mm on the left were observed in relation to the cementoenamel junction of the adjacent teeth. Two bone cores were harvested from the mandibular symphysis using a trephine. These bone cores were tapped into 2 predrilled osteotomy sites with corresponding diameters until stabilization was achieved. The 2 sites were grafted with demineralized freeze-dried bone allograft and a titanium-reinforced expanded polytetrafluoroethylene membrane. After 5 months, the membranes were removed and vertical ridge augmentation of 5 mm on the right and 4 mm on the left was observed. The width of the ridge was increased as well. Two implants were placed in favorable positions, restored after 6 months, and followed successfully for 1 year after loading. This technique represents a viable approach for augmentation of deficient alveolar ridges prior to the placement of dental implants.     

Residual alveolar ridge maintenance with a new endosseous implant material

In an effort to maintain the height of the residual alveolar ridge, Bioglass cones were placed in fresh sockets after tooth extraction. Today the emphasis is on maintaining the residual alveolar ridge instead of letting it resorb and subsequently resorting to heroic efforts for augmentation. To date, 242 cone implants have been placed in 29 patients. Implant follow-up observation time ranged from 12 to 32 months with an average of 19.9 months. Twenty-seven patients have been fitted with dentures. To date seven implants (2.9%) have been lost. The Bioglass implants appear to be highly biocompatible as evidenced by absence of infection, normal mucosal healing, and radiographic evidence of bone healing around the implants. Evaluation of several implants reexposed surgically revealed new bone in direct contact with the immobile implants circumferentially. The problem of implant dehiscence that started to occur after approximately 10 months in other investigations had not manifested itself in the Bioglass implant patients who have been wearing their dentures for at least 12 months.     

二单位式与四单位式种植牙周骨界面应力分布规律差异的三维有限元分析

为了探讨人工种植牙的数目、上部结构对种植牙周骨界面应力分布的影响，本实验应用三维有限元分析方法，对二单位和四单位式杆式覆盖种植义齿种植牙周骨界面的应力分布规律进行了探讨。结果表明：最大压应力、最大拉应力二单位式与四单位式均位于颈周密质骨，二单位式大于四单位式，两者有显著差异性，（Ｐ＜０．００１）。四单位式最大拉、压应力，远中种植牙要大于近中种植牙。最大位移运动二单位式小于四单位式，四单位式近中种植牙大于远中种植牙。二单位式与四单位式位、压应力主要集中于颈部，其它部位与颈部相比有非常显著的差异性，（Ｐ＜０．０００１）。结论：种植牙数目的增加，可以减小种植牙周颈部密质骨内的最大应力值。四单位式种植义齿颈周骨内应力要小于二单位式种植牙，从这点上看，四单位式种植义齿要优于二单位式种植义齿。多个种植牙种植时，杆的连接，改变了种植牙周骨内的应力分布规律，其应力主要由种植牙颈周密质骨来承担     

小直径种植体在无牙颌覆盖义齿修复中的应用

目的：探讨Sterngold太极扣种植体覆盖义齿在下颌无牙颌修复中的临床运用。方法：13例牙槽骨严重吸收的无牙颌患者的下颌植入26枚Sterngold太极扣种植体,太极扣附着体覆盖义齿修复,术前术后评估种植体周围的骨质及牙龈的健康状况,检查修复体的戴用状况,评价患者的满意度。结果：26枚种植体全部成活,未发生种植体周围炎,X线片检查显示种植体周围的骨质未见吸收,全部患者对修复体满意。结论：太极扣种植体覆盖义齿修复严重吸收的牙槽嵴病例临床效果满意。     

Coronal ridge augmentation in the absence of bilateral bony plates around a pathologically denuded implant surface

Guided bone regeneration via an osteopromotive barrier is indicated in different alveolar bone deficiencies and in periimplant bone destruction around pathologically denuded exposed implants. Regeneration of the osseous volume is determined by understanding the biologic behavior response of hard and soft tissues in guided tissue regeneration procedures. Consequently, a meticulous surgical approach is mandatory to preserve wound healing cascades and tissue stability. However, hard tissue augmentation in the nonsupported coronal direction has been unpredictable. A case report is presented in which a severely defected ridge around a pathologically exposed functional implant combined with a destructive extraction site was restored and regenerated. Bovine bone mineral particles (Bio-Oss) served as the graft material and were followed by an expanded polytetrafluoroethylene (e-PTFE) occlusive membrane as a bilateral regenerative tissue guide. Subsequently, 2 additional implants were placed in the augmented hard tissue ridge.     

牙种植术钻孔骨碎作植骨的临床研究

目的:评价在牙种植术中,钻备种植窝时收集到的自体骨颗粒单独或与Bio-Oss人工骨混合作为骨移植材料应用的临床效果。方法:34例52枚牙种植术的病例分成四组。第一组(对照组)22枚植体,单纯植入种植体,种植区无植入自体骨或人工骨。第二组6枚植体,植入螺纹种植体后,在部分暴露的植体处植入Bio-Oss人工骨。第三组8枚植体,收集种植术中准备植体窝时,在各种钻针上的自体骨颗粒,植入种植体周骨量不足区域。第四组16枚植体,自各种钻针上收集到的自体骨颗粒与Bio-Oss人工骨混合,植入种植体周骨缺损区。记录I、II期手术种植体周围骨组织高度。结果:植入术后3-12个月,II期手术时,实验组有新生骨形成,第四组(即Bio-Oss人工骨与自体骨颗粒混合物植入组),新生骨形成的量较其余组别多。结论:研究表明牙种植术中钻备种植窝时收集到的自体骨颗粒可作为有效的植骨材料,这种简单的方法避免从他处手术获得自体骨,对扩大牙种植适应症有重要意义。RRRR     

Reconstruction of the alveolar ridge by osteodistraction for implant placement

Alveolar Distraction is a method for reconstructing a deficient or atrophic alveolar bone. Alveolar ridge reconstruction may be indicated for the atrophic alveolar process resulting from maxillofacial trauma, periodontal disease, or post aggressive large cyst or tumor resection. The aim of this paper is to demonstrate the method of reconstruction of the alveolar ridge by Distraction Osteogenesis. A total of 32 patients were treated. An alveolar segmental osteotomy was carried out and the distraction device was mounted. In patients with an extensive alveolar defect two distraction devices were placed in order to better control the vector of elongation in both bone edges. The distraction was started on the fourth post-operative day at a rate of 0.5 mm/day as necessary and according to the length of the distraction device, followed by a consolidation period of 90 days. Subsequently, the devices were removed, and dental implants were placed for osteointegration. The amount of elevation was 8-15mm. All the patients had panoramic x ray before the distraction, during the lengthening, at the end of distraction and after removal of the device. Early mineralization in the distracted area was seen radiographically during the consolidation period that increased after device removal. As a result of alveolar distraction, a segment of mature bone was transported vertically in order to lengthen the crest for better implant anchorage, either for esthetic purposes or for functional prosthetic requirements. A total of 68 implants were introduced. In follow-up at 24 months, failure of only one implant was noted, due to inadequate transported bone stability. In conclusion, distraction osteogenesis is an alternative treatment in moderate to severe alveolar deficiencies for an ideal three-dimensional reconstruction with no need for bone harvesting. This method offers the possibility to place dental implants in a correct position to obtain proper prosthetic results.