计算机辅助设计和自制牙支持式导板用于下颌后牙区种植研究

目的 评价计算机辅助设计和自制牙支持式导板应用于下颌后牙区种植的临床疗效。方法 选择2012年4-9月山西医科大学口腔医院口腔外科收治的下颌后牙区单颗缺失患者10例,制取缺牙区牙列模型,选取植入点,制作初导板。采集CT数据,利用Simplant软件对数据分析,使用研磨仪在模型上确定最后植入方向并制作最终导板。口内戴入导板,植入种植体,拍摄CT,测量术前术后角度及深度偏差。结果 种植体在颊舌向与模拟植入体方向存在偏差,但偏差角度在10°以内,可以通过角度基台调整以适应咬合关系。种植深度及近远中向角度术前、术后偏差较小。结论 该系统可指导临床医生在下颌骨高度不足条件下植入种植体,对于提高种植手术质量与精度具有重要意义。     

Technique for transferring the path of insertion of a removable partial denture to a CAD-CAM-generated implant surgical template

A technique is described that uses a surveyor, gutta percha points, and a computer-aided design and computer-aided manufacturing (CAD-CAM)-guided implant surgery system to predetermine and transfer the ideal angulation of the implant to be placed.     

Three-dimensional guidance system for implant insertion: Part II. Dual axes table--problem solving

The three-dimensional guidance system for implant insertion is a technique for placing a radiopaque vertical orientation pin over the crest of the alveolar ridge on the stone cast during fabrication of the radiographic guide. The cross-sectional and panoramic reformatted images were reproduced on a Polaroid or 35-mm print. The true vertical orientation pin facilitates (1) identification and the exact planned location of each implant in the reformatted images of the CT scan, (2) establishment of the internal starting point for the osteotomy on a photographic print, (3) optimum implant orientation, and (4) measurement of the angulation between the true vertical orientation line and optimum implant orientation. With the aid of a newly developed dual-axes base and transfer of the internal starting point of each implant to the stone cast, the buccolingual and mesiodistal implant inclinations for each implant were transferred to a surgical guide in the form of surgical steel drill guide tubes. The resulting pilot osteotomy transfers to the alveolar bone the exact starting point and the buccolingual and mesiodistal inclination for each implant. The technique provides a three-dimensional guidance system for implant insertion that is extremely accurate and yet practical.     

Dental implant imaging: TeraRecon's Dental 3D Cone Beam Computed Tomography System

Early in the development of implant technology, conventional dental imaging techniques were limited for evaluating the patient for implant surgery. During the treatment-planning phase, the recipient bed is routinely assessed by visual examination and palpation, as well as by periapical and panoramic radiology. These two imaging modalities provide a two-dimensional image of the mesiodistal and occlusoapical dimensions of the edentulous regions where the implants might be placed. When adequate occlusoapical bone height is available for endosteal implants, the buccolingual width and angulation of the available bone are the most important criteria for implant selection and success. However, neither buccolingual width nor angulation can be visualized on most traditional radiographs. Although clinical examination and traditional radiographs may be adequate for patients with wide residual ridges that exhibit sufficient bone crestal to the mandibular nerve and maxillary sinus, these methods do not allow for the precise measurement of the buccolingual dimension of the bone or assessment of the location of unanticipated undercuts. Because of these concerns, it is necessary to view the recipient site in a plane through the arch of the maxilla or mandible in the region of the proposed implants. Implant surgeons soon recognized that, for the optimum placement of implants, cross-sectional views of the maxilla and mandible are the ideal means for providing necessary preoperative information. For complex cases where multiple implants are required or where anatomical measurements are crucial, but also increasingly for more routine cases, more and more clinicians are recommending CT scan imaging procedure such as that offered by TeraRecon's Dental CBCT system. Because of its ability to reconstruct a fully three-dimensional model of the maxilla and mandible, CBCT provides a highly sophisticated format for precisely defining the jaw structure and locating critical anatomic structures. CBCT scans, in conjunction with software that renders immediate treatment plans using the most real and accurate information, provide the most precise radiographic modality currently available for the evaluation of patients for oral implants.     

A surgical guide for accurate mesiodistal paralleling of implants in the posterior edentulous mandible

Malaligned implants often complicate the clinical and laboratory procedures employed for the fabrication of superstructures. Due to improper load distribution, an overall increase in stress concentrations on supporting implants may occur; in the long run, this may compromise the maintenance of the bone-implant interface. The utilization of surgical stents is imperative for optimum implant installation. This article describes a modified surgical stent that serves as a guide to proper mesiodistal paralleling of dental implants.     

Evaluation of the effect of the residual bone angulation on implant-supported fixed prostheses in mandibular posterior edentulism. Part I: Spiral computed tomography study

Dental implants are usually angulated buccolingually because of the anatomy of the residual bone in mandibular posterior edentulous cases. Although angulated dental implants compromise the construction of implant-supported prostheses, the effect of buccolingual angulation of the residual bone has not been clearly stated. This study is performed to determine the biomechanical effect of buccolingual angulation. The goal was to reveal the actual buccolingual angulation values of the residual bone in which implants were to be placed. Thirty mandibular Kennedy I and II cases comprised of forty edentulous posterior regions with missing second premolars and first, second, and third molars were included. Buccolingual angulation values along the 28 mm of residual bone were measured on 1-mm spacing cross-sectional images of spiral computed tomography. Paired sample t test was used for the statistical analysis. The minimum angulation values at the second premolar, first molar, and second molar region were 0 degrees, 3 degrees, and 9 degrees, respectively. The average angulation values were 4 degrees, 10 degrees, and 15 degrees, respectively, and the maximum angulation values were 11 degrees, 18 degrees, and 22 degrees, respectively. The ability to measure the buccolingual angulation of mandibular posterior residual bone before dental implantation may help the clinician at the implant treatment-planning phase.     

密质骨厚度影响牙种植体稳定性的有限元固有频率分析

目的：用有限元方法研究密质骨厚度对牙种植体初期稳定性的影响。方法：建立牙种植体、局部下颌骨块三维有限元模型，利用ABAQUS有限元软件，分析不同密质骨厚度对种植体颊舌向、轴向一阶振动固有频率的影响。结果：随着密质骨厚度由缺如逐渐增加至3．0mm，种植体颊舌向、轴向振动的固有频率值均逐渐增加，其中颊舌向固有频率最大增幅达97．61％，而轴向固有频率最大值仅增加了11．06％。结论：种植体周密质骨厚度主要增加了种植体颊舌向稳定性，而对种植体轴向稳定性的增加有限。     

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??Objective    To measure the anatomic buccolingual angulation values of the maxillary alveolar process based on CBCT images in order to form a basis for the implant treatment planning?? including the design of implant position and angulation. Methods    A random sample of 51 CBCT images were selected and analyzed. The NewTom 5G CBCT data sets were reformatted at a 0.5-mm spacing?? with the inferior border of the region of interest parallel to the occlusion plane of maxillary teeth. Twenty-four buccolingual cross-sectional images of the maxillary alveolar process were obtained for buccolingual angulation measurements. Results    Mean or median values of the buccolingual angulation of maxillary alveolar process ranged from about 0 degree to more than 40 degrees. Cross-sections distal to the premolar region showed a statistically higher proportion of vertical process ??angulation equals to 0 degree???? compared to cross-sections corresponding to maxillary premolars and anterior teeth region ??P < 0.05??. There were no statistical differences between the angulation of alveolar process both from the right side and left side and from males and females patients ??P > 0.05??. Conclusion    The buccolingual angulation of maxillary alveolar process decreases from anterior teeth region through the premolars region to the molars region?? with the lateral incisor and canine region being the most inclined bucally and a high proportion of the molars region being nearly vertical. Knowing average values of buccolingual angulation of maxillary alveolar process before dental implantation may help the clinician plan the position and orientation of implants?? especially when an implant surgical template is not available.     

上颌牙槽突颊舌向生理倾斜角的锥形束CT研究

目的    采用锥形束CT（CBCT）影像测量上颌牙槽突颊舌向生理倾斜角,为种植体植入位置和方向的确定提供参考。方法    按照事先制定的纳入与排除标准,从中国人民解放军总医院口腔医学中心影像数据库中随机抽取2014年11月至2015年11月初次就诊患者拍摄的CBCT影像51份（均由NewTom 5G设备拍摄）。采用NewTom 5G自带软件进行重建,重建区域上下边界与上颌牙牙合平面平行,采用0.5 mm层厚、5 mm层间距,在牙列弧形线上对牙槽突进行垂直切割,获得上颌牙槽突的24个等间距的颊舌向断面。使用NNT 5.6软件测量每个颊舌向切面的牙槽突倾角。结果    按从右上颌最后一个层面（第2层）到左上颌最后一个层面（第23层）的顺序,上颌各层面牙槽突倾角平均值或中位值分别为：0°、0°、0°、0°、10.2°、17.4°、23.9°、31.9°、40.7°、42.3°、31.8°、32.6°、41.7°、40.7°、31.8°、22.9°、16.1°、8.2°、0°、0°、0°、0°。左右对称层面牙槽突倾角差异无统计学意义（P > 0.05）。男女之间的牙槽突倾角差异无统计学意义（P > 0.05）。第2～5层和第20～23层（对应于磨牙区）中,牙槽突倾角为0°的牙槽突比例高于颊侧倾斜牙槽突（P < 0.05）。结论    前牙区牙槽突倾角最大,前磨牙区倾角次之,磨牙区倾角逐渐递减为0。前牙区和前磨牙区牙槽突向唇、颊侧倾斜,磨牙区牙槽突在多数情况下呈垂直向,其次为向颊侧倾斜。了解牙槽突倾角有助于种植体植入位置和方向的确定,在不具备种植手术导板的情况下,其参考作用尤其明显。     

双皮层骨种植影响牙种植体稳定性的有限元固有频率分析

目的:用有限元方法研究双皮层骨种植对牙种植体初期稳定性的影响。方法:建立牙种植体、局部下颌骨块三维有限元模型,利用ABAQUS有限元软件,分析双皮层骨种植对种植体颊舌向、轴向一阶振动固有频率的影响。结果:在模拟的3种不同骨质类型中,双皮层骨种植均可提高种植体颊舌向、轴向振动的固有频率值,但颊舌向频率的增加有限,最高增加了13. 77%,而轴向频率值最大增加了一倍以上。结论:双皮层骨种植主要增加种植体轴向稳定性,对种植体水平向稳定性的增加有限。     

Changes in lower third molar position in the young adult.

Changes in position of unerupted lower third molars between 18 and 21 years were examined in a group of 17 men and 24 women with intact lower arches. Mesiodistal third molar angulation, molar space, molar space condition, and buccolingual third molar angulation and the changes in these dimensions were measured on 60 degree cephalograms taken at 18 and 21 years. At 18 years molar space was inadequate by an average of 5.0 mm. Average changes in dimensions were statistically nonsignificant except for an increase in molar space of 0.7 mm. Changes in third molar position ranged from 39 degrees to -46 degrees in the mesiodistal and from 24 degrees to -24 degrees in the buccolingual dimension. Only 10 third molars did not change their mesiodistal angulation. Four third molars erupted fully during the observation period.     

A comparison of implant stability quotients measured using magnetic resonance frequency analysis from two directions: a prospective clinical study during the initial healing period

Objectives: Given that the orientation of the transducer (mesiodistal or buccolingual) affects the data obtained from a piezoelectric resonance frequency analysis (RFA), this study evaluated whether it is necessary to use measurements taken in two different directions (mesiodistal and buccolingual) when using magnetic RFA to assess changes in the stiffness of dental implants. Materials and methods: A prospective clinical trial was completed, in a total of 53 patients, on 71 non‐submerged dental implants that were inserted to replace the unilateral loss of mandibular molars. All of the implants were of the same diameter (4.1 mm), length (10 mm), and collar height (2.8 mm). The implant stability quotient (ISQ) was measured during the surgical procedure, and at 4 and 10 weeks after surgery. Measurements were taken twice in each direction: in the buccolingual direction from the buccal side and in the mesiodistal direction from the mesial side. The average of two measurements in each direction was regarded as the representative ISQ of that direction. The higher and lower values of the two ISQs (buccolingual and mesiodistal) were also classified separately. In addition, the variation in ISQ was quantified by subtracting the lower value from the higher value, and the implants were classified into two groups according to this variation: one with ISQ variation of 3 or more and the other with a variation of <3. Results: There were no differences between the two ISQs when measured from different directions, but there were significant differences between the higher and lower values of the ISQs at each measurement point. A significant difference was also observed between the two ISQ variation groups in the pattern of change of the lower value for the period from immediately after surgery to 10 weeks after surgery. Conclusion: Acquisition of two directional measurements and classification of the higher and lower values of the two directional ISQs may allow clinicians to detect patterns of change in ISQ that would not be identified if only one directional measurement were made. To cite this article:
Park J‐C, Kim H‐D, Kim S‐M, Kim M‐J, Lee J‐H. A comparison of implant stability quotients measured using magnetic resonance frequency analysis from two directions: a prospective clinical study during the initial healing period.
Clin. Oral Impl. Res. 21 , 2010; 591–597.
doi: 10.1111/j.1600‐0501.2009.01868.x     

Errors in radiographic assessment of marginal bone height around osseointegrated implants

Abstract – Radiographic assessment of marginal bone height is included in longitudinal control of osseointegrated implants. Previous studies have revealed a mean annual loss of less than 0.1 mm. The purpose of the present study was by means of an experimental model to analyze the influence upon alveolar bone height measures around osseointegrated implants of buccolingual bone dimensions as well as angulations of fixture axis to central X-ray beam. Brånemark titanium implants were inserted into acrylic test blocks simulating alveolar ridges of various widths. 0.2 mm steel wires visualized buccal and lingual bone margins. Standardized radiographs were obtained by stepwise variation of projection angles. Separation of the wire images varied from 0.1 mm (buccolingual width 5 mm and 1° angulation) to 4.8 mm (width 13 mm and angulation 20°). In clinical cases distortion of buccal and lingual bone margins may result in overestimation of bone heights. The degree of overestimation is influenced by the buccolingual position of the fixture. Strict parallelism between fixture axes and film plane is essential to obtain valid results using single films.     

Socket grafting: a predictable technique for site preservation

The demand for dental implants continues to rise worldwide, requiring clinicians to consider the incorporation of bone preservation procedures into their dental practice. Socket grafting offers a predictable, simple way to conserve the buccolingual and mesiodistal dimensions of the future implant site. Careful bone management and the use of various bone-grafting materials must be part of the practice of every implantologist. In this case report, the authors present a fundamental technique for socket grafting and 3 cases of site preservation with subsequent implant placement and restoration. Emphasis is placed on the evidence-based rationale for this procedure, the clinical technique, and the various grafting materials that can be employed by the clinician.     

种植牙即刻负载与延期负载的生物力学三维有限元分析

目的比较即刻负载和延期负载对种植体骨界面生物力学分布的影响。方法采用CT扫描和自主开发的USIS软件建模,用有限元法计算分析即刻负载和延期负载时种植体骨界面的应力、应变及种植体的位移。结果即刻负载时种植体骨界面的VonMises应力稍小于延期负载,均集中于种植体颈部骨皮质,底部骨松质次之;但VonMises应变有较明显的增加,均集中于种植体底部骨松质和螺纹部位;种植体的位移较延期负载略有增大。即刻负载种植体和延期负载种植体在受到颊舌向力时,VonMises应力、应变及位移均有不同程度的增加。结论即刻负载时种植体骨界面的生物力学分布规律与延期负载时相似,受到侧向力时应力、应变增大。种植牙即刻负载技术是可行的。     

Surgical factors influencing mesiodistal implant angulation

OBJECTIVES: The aim of this experimental study was to identify relevant surgical parameters influencing the mesiodistal angular deviation of dental implants. MATERIAL AND METHODS: Pilot drillings of 2 mm diameter were performed in bovine ribs with a parallelometer. The subsequent preparation of the implant socket was performed freehand. Utilizing six different implant systems, at least 80 drillings per system of different diameters were performed. The pilot drillings were marked with 2 mm steel pins and cephalometric radiographs were taken. The mesiodistal angle between the longitudinal implant axis and the marked pilot drillings was measured and evaluated by a blinded investigator. To evaluate the influence of the surgeons' experience, their drillings were compared with those of a group of unexperienced surgeons. Additionally, the influence of drilling speed and size of bur steps on drilling accuracy were evaluated. RESULTS: The difference between the lowest value of 0.91 degrees of mesiodistal angular deviation found for 3i implants and the highest of 1.36 degrees for Ankylos implants was of low statistical significance (P=0.065). Drillings of experienced surgeons showed less deviation compared with those of a beginners group (P<0.0001). Higher deviations were measured when a bur size was skipped. Drillings performed at high speed showed significantly higher deviations than those with fewer rewinds per minute. CONCLUSION: In order to achieve precise implant angulation, all bur diameters available should be used. Utilizing low drilling speeds results in less mesiodistal deviation. The surgeon's experience seems to be the most relevant factor in precise implant placement.     

Accuracy of a chairside fused deposition modeling 3D-printed single-tooth surgical template for implant placement: An in vitro comparison with a light cured template

PurposeTo compare the accuracy of a chairside fused deposition modeling (FDM) 3D-printed surgical template with that of a light-cured template for implant placement.Materials and methodsTwenty standard mandibular resin models with missing teeth 36 and 46 were selected. Surgical templates were fabricated using a chairside FDM 3D-printer (test group) or a light-curing 3D printer (control group) (n = 20/group). Forty implants were placed by a clinician blinded to group allocation. The angular, 3D, mesiodistal, buccolingual, and apicocoronal deviations at the implant base and tip between preoperative design and postoperative implant position were recorded.ResultsThe mean angular (test vs control groups: 3.22° ± 1.55° vs 2.74° ± 1.24°, p = 0.343) and 3D deviations at the implant base (test vs control groups: 0.41 ± 0.13 mm vs 0.35 ± 0.11 mm, p = 0.127) and tip (test vs control groups: 0.91 ± 0.34 mm vs 0.75 ± 0.28 mm, p = 0.150) were similar. The mesiodistal, buccolingual, and apicocoronal deviations at the implant base and tip also did not differ significantly between groups (p > 0.05).ConclusionsFor single tooth gap indications, implant placement with an FDM 3D-printed surgical template was as accurate as that with a light-cured template, and more efficient.     

Implant angulation: a measurement technique,implant overdenture maintenance,and the influence of surgical experience

PURPOSE: The purposes of this study were to develop a technique to measure the angulation between two implants and between each implant and reference planes, to analyze the relationship between the maintenance (adjustments and repairs) of ball-attachment mandibular implant overdentures and implant angulation, and to see if there is any correlation between surgeon experience and implant orientation. MATERIALS AND METHODS: Final casts of 41 patients who had received two-implant ball-attachment mandibular overdentures were used to measure implant angulations using digital photographs and plane geometry. The measured angles were compared with the number of adjustments and repairs of the prostheses and analyzed by surgeon experience for any trends. RESULTS: No significant relationships were found between number of adjustments and repairs and the interimplant angles. However, there was a significantly higher number of repairs when the lingual inclination of an implant was > or = 6.0 degrees (P = .033) or if the facial inclination was < 6.5 degrees (P = .036). Less experienced surgeons had a significantly greater tendency to place implants that diverged from each other in the frontal plane (P = .045) and with a facial or lingual inclination in the sagittal plane (P = .035). CONCLUSION: While interimplant angulation did not appear to affect prosthesis maintenance, individual implants with a lingual inclination > or = 6 degrees and a facial inclination < 6.5 degrees were associated with significantly more prosthesis repairs. There was a tendency for implants placed by less experienced surgeons to demonstrate greater inclination.     

The relationship between biologic concepts and fabrication of surgical guides for dental implant placement

This article reviews guidelines for construction of surgical guides to direct dental implant placement. Biologic principles are discussed with regard to the mesiodistal, buccolingual, and apicocoronal insertion of implants. The application of these data to develop surgical guides is discussed. Also, with respect to specific prosthetic reconstructions, a variety of guides are described that can be fabricated for partially and fully edentulous arches.     

Multidimensional osteodistraction for correction of implant malposition in edentulous segments

This study examined multidimensional osteodistraction as a treatment method for correction of implant malposition and as an alternative to augmentation procedures. The prosthetically unfavourable implant positions were due to growth-related implant malposition (in the context of treatment of young patients with oligodontia) or primary bone-driven implant insertions. The radiographical and clinical findings obtained with this osteodistraction technique are presented and discussed. A tooth-supported osteodistractor for multidimensional distraction with custom-fabricated distraction abutments was used for treatment of 8 patients with a total of 9 maxillary and mandibular edentulous segments including single-tooth gaps. All patients underwent an osteotomy at a minimum distance of 1 mm from the implant surface. Following primary wound healing, distraction was carried out by 1 mm in vertical direction and 0.5 mm in the demanded transverse direction daily until the prosthetically optimized position was achieved. During and after the 12-week retention phase, the patients were evaluated clinically and radiographically. Multidimensional osteodistraction was carried out successfully in all 8 patients. The distraction distances were 3 to 11 mm in vertical direction and a maximum of 5 mm in buccolingual/buccopalatal direction. The malpositioned implants were brought into a prosthetically optimized position in all cases. The results of this study show that this multidimensional osteodistraction technique allows both augmentation of edentulous segments with a clearly compromised implant host site and correction of unfavourable implant positions.