The esthetic effects of implant platform selection

Implant dentistry has undergone considerable evolution over the history of modern endosseous implant therapy. With the advent of enhanced bone and soft tissue manipulation procedures, improved implant hardware components, and enough experience for the procedures to evolve, an implant restoration today may be indistinguishable from a natural tooth. Guidelines are discussed for implant selection and implant placement dictated by the desired functional and esthetic result. The implant platform should be selected only after the tooth and soft tissue dimensions are decided. In addition, the largest platform diameter that fits within the normal root contours should be selected. Surgically, that platform should be placed 3 mm apically and 1 mm lingually to the buccal emergence point. The buccal cementoenamel junction or free gingival margin thus becomes the key determinant for implant position. Specific implant dimensions are discussed for each tooth to provide appropriate guidelines for the practitioner.     

水平内移距离对种植体及其周围骨组织应力分布影响的有限元研究

目的采用三维有限元分析法,比较平台转移种植体不同水平内移距离对种植体及周围骨组织应力分布的影响。方法以Ankylos C/X4.5 mm×11 mm种植系统为参照,利用Mimics、Solidworks及Patran有限元分析软件,建立平台转移种植体水平内移距离分别为0.0、1.0、1.5、2.0 mm 4组模型,对每个模型分别进行垂直和斜向加载,分析边缘骨组织以及种植体基台的应力分布情况。结果两种载荷下平台转移组(PS)骨组织等效应力峰值均小于平台对接组(PM),随着水平内移距离增加,种植体-骨界面应力峰值减小,但当差异值增加到一定程度时(2.0 mm),种植体周骨组织等效应力峰值有增加趋势。结论平台转移种植体水平内移距离增加对减少边缘骨组织应力有积极影响,但当种植体与基台直径差距过大时,仍有应力集中的趋势。     

下颌第一磨牙平台转移种植体三维有限元模型的建立

目的 构建下颌第一磨牙平台转移种植体的三维有限元模型.方法 选择健康成年男性下颌骨1例进行螺旋CT扫描,将得到的DICOM数据导入Mimics 10.01软件中,建立下颌骨及牙齿的三维几何模型,并用Geomagic studio12软件进行曲面优化;利用UG NX6.0软件建立平台转移种植系统(韩国DIO种植体系统)的三维几何模型;最后将各部分模型导入Hypermesh10.0软件中进行装配组合、网格划分以及材料属性赋值.结果 成功建立了下颌第一磨牙平台转移种植体的三维有限元模型,该模型与实际模型有高度的几何相似性,其网格质量较高、力学性能好.结论 结合CT扫描技术和多种有限元建模软件能够快速、精确地建立下颌第一磨牙平台转移种植体的三维有限元模型,为后续平台转移种植体进行有效的生物力学研究提供基础.     

平台转换连接与对接连接在即刻功能性负重中的对比研究

目的：评价平台转换连接与对接连接种植体即刻功能性负重后短期内的边缘骨丧失及牙龈变化情况。方法：选择上下颌前牙为观察对象,拔除后行即刻种植且功能性负重患者50例,根据种植体?基台连接设计不同随机分为两组,平台转换组25例选用Nobel Active种植体;对接连接组25例,选用Nobel Replace种植体。两组患者种植术后即刻戴入临时冠行使功能性负重,12个月后更换为永久修复体。所有病例进行影像学检测（包括CT、X线全景片、X线根尖片）评估两种连接方式的种植体边缘骨的吸收情况及牙龈位置变化情况。结果：两组种植体均完成骨结合及软组织愈合,随访期内,种植体无松动、脱落,牙龈组织健康,成功率均为100?0％。功能性负载12个月时测得种植体边缘骨吸收,平台转换组为1?09±0?62 mm,对接连接组为1?43±0?62 mm,差异无统计学意义（P＞0?05）。临时冠戴入12个月时平台转换组探诊深度（PD）2?71±0?65 mm,对接连接组探诊深度（PD）2?98±0?86 mm,差异有统计学意义（P＜0?05）。结论：将平台转换技术应用于即刻种植且功能性负重时,短期内种植体颈部边缘骨的吸收与对接连接组比较虽然无明显差异,但牙龈探诊深度优于对接连接组,对临床应用具有参考价值。     

口腔种植体颈部骨吸收和平台转换设计的研究进展

两段式种植体修复1年后种植体-基桩界面即种植体颈部骨吸收约1.5～2mm已被作为种植成功标准之一,但骨吸收的具体机制尚未明确。平台转换设计应用于种植体修复后可显著减少种植体颈部骨吸收。本文就该领域的研究进展进行综述。     

非潜入式植入法对平台转换连接种植体颈部牙槽骨吸收的影响

目的：评价非潜入式植入法对平台转换连接种植体颈部牙槽骨吸收有无影响。方法：23例共33颗后牙缺失患者按要求植入ankylos种植体,取出覆盖螺丝并上愈合基台。植入当天和二期修复时拍牙片并进行前后对比。结果：1枚种植体植入一周时出现异常予以拔除,其余种植体均能形成良好的骨结合。经牙片对比,植入当天与二期修复时种植体颈部牙槽骨无明显变化。结论：非潜入式植入法对平台转换连接种植体颈部牙槽骨吸收无明显影响。     

Influence of various implant platform configurations on peri-implant tissue dimensions: an experimental study in dog

Aim: To evaluate the influence (i) of various implant platform configurations and (ii) of implant surface characteristics on peri‐implant tissue dimensions in a dog model. Material and methods: Mandibular premolars and first molars were extracted bilaterally in six Labrador dogs. After 3 months of healing, two implants, one with a turned and a second with a moderately rough surface, were installed on each side of the mandible in the premolar region. On the right side of the mandible, implants with a tapered and enlarged platform were used, while standard cylindrical implants were installed in the left side of the mandible. Abutments with the diameter of the cylindrical implants were used resulting in a mismatch of 0.25 mm at the tapered implant sites. The flaps were sutured to allow a non‐submerged healing. After 4 months, the animals were sacrificed and ground sections were obtained for histometric assessment. Results: All implants were completely osseointegrated. A minimal buccal bone resorption was observed for both implant configurations and surface topographies. Considering the animals as the statistical unit, no significant differences were found at the buccal aspect in relation to bone levels and soft tissue dimensions. The surface topographies did not influence the outcomes either. Conclusions: The present study failed to show differences in peri‐implant tissue dimensions when a mismatch of 0.25 mm from a tapered platform to an abutment was applied. The surface topographies influence a neither marginal bone resorption or peri‐implant soft tissue dimension. To cite this article:
Baffone GM, Botticelli D, Pantani F, Cardoso LC, Schweikert MT, Lang NP. Influence of various implant platform configurations on peri‐implant tissue dimensions: an experimental study in dog.
Clin. Oral Impl. Res. 22 , 2011; 438–444.     

Benefits of an implant platform modification technique to reduce crestal bone resorption

PURPOSE: The alveolar bone resorption that occurs around a 2-piece implant following abutment attachment is a well-documented observation. Several investigators propose that crestal bone loss is a response to the invasion of the biologic width by secondary bacterial colonization and micromovements at the implant-abutment interface. This study proposes the creation of a difference between the diameter of the implant platform and diameter of the abutment (implant platform modification), shifting the implant-abutment interface medially to minimize invasion of the biologic width. MATERIAL AND METHODS: We present a series of 30 control cases and 30 study cases using the platform-modification technique. Interproximal bone resorption on the medial and distal of each implant was assessed using digital radiography at 1, 4, and 6 months after abutment attachment. RESULTS: The mean value of bone resorption observed in the mesial measurement for the control group was 2.53 mm, whereas for those patients included in the study group, it was 0.76 mm. The mean value of bone resorption observed in the distal measurement for patients in the control group was 2.56 mm, whereas for those included in the study group, it was 0.77 mm. CONCLUSIONS: All patients in the study group had a significant reduction of bone loss in comparison to the control group (P < 0.0005).     

平台转换技术用于上颌前牙种植修复的临床研究

目的 评估应用平台转换技术种植修复上颌前牙区牙列缺损的临床效果,探讨该技术的临床应用特点.方法 2001年1至12月就诊于北京大学口腔医学院·口腔医院口腔种植中心上颌前牙区牙列缺损患者17例,共植入Frialit-2系统种植体26枚,Ⅱ期手术后应用平台转换技术修复.随访时间24～74个月,平均56.3个月,观察方法为临床检查和x线检查,评价种植体周骨高度丧失,进行红色美学评分.结果 全部患者至最后一次随访,均未见严重并发症,应用平台转换技术的种植体修复临床效果满意.种植修复完成1年和5年后边缘骨吸收分别为0.13(-0.12～0.55)mm和0.27(-0.04～0.77)mm;相邻种植体间牙槽骨高度丧失分别为0.14(0～0.30)mm和0.21(0.09～0.31)mm.按Jemt牙间乳头分类本组36个位点中达Ⅰ度3个位点,Ⅱ度23个位点,Ⅲ度10个位点.单牙种植修复Fürhauser红色美学评分为10～14,平均11.8分.结论 上领前牙区应用平台转换技术操作简单可靠,短期临床效果满意,可减少种植体边缘骨吸收、增进种植修复美学效果.     

Regular and platform switching: bone stress analysis varying implant type

Purpose: This study aimed to evaluate stress distribution on peri‐implant bone simulating the influence of platform switching in external and internal hexagon implants using three‐dimensional finite element analysis. Materials and Methods: Four mathematical models of a central incisor supported by an implant were created: External Regular model (ER) with 5.0 mm × 11.5 mm external hexagon implant and 5.0 mm abutment (0% abutment shifting), Internal Regular model (IR) with 4.5 mm × 11.5 mm internal hexagon implant and 4.5 mm abutment (0% abutment shifting), External Switching model (ES) with 5.0 mm × 11.5 mm external hexagon implant and 4.1 mm abutment (18% abutment shifting), and Internal Switching model (IS) with 4.5 mm × 11.5 mm internal hexagon implant and 3.8 mm abutment (15% abutment shifting). The models were created by SolidWorks software. The numerical analysis was performed using ANSYS Workbench. Oblique forces (100 N) were applied to the palatal surface of the central incisor. The maximum (σ_max) and minimum (σ_min) principal stress, equivalent von Mises stress (σ_vM), and maximum principal elastic strain (ε_max) values were evaluated for the cortical and trabecular bone. Results: For cortical bone, the highest stress values (σ_max and σ_vm) (MPa) were observed in IR (87.4 and 82.3), followed by IS (83.3 and 72.4), ER (82 and 65.1), and ES (56.7 and 51.6). For ε_max, IR showed the highest stress (5.46e‐003), followed by IS (5.23e‐003), ER (5.22e‐003), and ES (3.67e‐003). For the trabecular bone, the highest stress values (σ_max) (MPa) were observed in ER (12.5), followed by IS (12), ES (11.9), and IR (4.95). For σ_vM, the highest stress values (MPa) were observed in IS (9.65), followed by ER (9.3), ES (8.61), and IR (5.62). For ε_max, ER showed the highest stress (5.5e‐003), followed by ES (5.43e‐003), IS (3.75e‐003), and IR (3.15e‐003). Conclusion: The influence of platform switching was more evident for cortical bone than for trabecular bone, mainly for the external hexagon implants. In addition, the external hexagon implants showed less stress concentration in the regular and switching platforms in comparison to the internal hexagon implants.     

平台转换技术对种植体-骨界面影响的组织学观察

目的 观察种植牙即刻负重时平台转换技术对种植体-骨界面的影响.方法 比格犬5只,拔除下颌双侧第四前磨牙,3个月后植入10枚种植体并即刻接入基台形成即刻负重.采用自身对照,实验侧5枚种植体采用平台转换设计基台,对照侧5枚种植体采用传统基台.种植体植入3个月后处死实验动物,制作不脱钙种植体-骨组织磨片后组织学观察.结果 除1只动物(2枚种植体)即刻负重失败,余4只动物(8枚种植体)的种植体-骨界面骨结合良好,可见大量成骨细胞与矿化程度不等的骨组织.实验侧种植体颈部骨质与种植体颈部基本平齐,对照侧种植体颈部出现明显骨吸收.结论 即刻负重种植修复时,不同的上部结构对种植体颈部骨结合有明显影响,平台转换技术有利于种植体颈部的骨组织保存.     

Prosthetic platforms in implant dentistry

The use of implant-supported prosthesis to replace missing teeth became a predictable treatment. Although high success rate has been reported, implant treatment is suitable to complications, failures, and limitations such as peri-implant bone loss after implant loading. Stress evaluation on the bone-abutment-implant interface has been carried out to develop new designs of prosthetic platform and to understand the stress distribution in this interface. Several types of prosthetic platforms are available such as external and internal hexagon, Morse cone connection, and the concept of platform switching. Therefore, this study aimed to critically describe the different options of prosthetic platforms in implant dentistry, by discussing their biomechanical concepts, clinical use, and advantages and disadvantages. It was observed that all types of prosthetic platforms provided high success rate of the implant treatment by following a strict criteria of indication and limitation. In conclusion, a reverse planning of implant treatment is strongly indicated to reduce implant overload, and the use of advanced surgical-prosthetic techniques is required to obtain a long-term success of oral rehabilitations.     

Immediately loaded titanium implant with a tissue-stabilizing/maintaining design ('beyond platform switch') retrieved from man after 4 weeks: a histological and histomorphometrical evaluation. A case report

BACKGROUND: After implant insertion and loading, crestal bone usually undergoes remodeling and resorption. If the horizontal relationship between the outer edge of the implant and a smaller-diameter component ('platform switching') is altered, there seems to be reduced crestal bone loss. Immediate loading allows immediate restoration of esthetics and function, reduces morbidity, and facilitates functional rehabilitation. MATERIALS AND METHODS: Three Morse cone connection implants were inserted in the right posterior mandible in a 29-year-old partially edentulous patient. The platform of the implant was inserted 2 mm below the level of the alveolar crest. After a 1-month loading period, the most distal mandibular implant was retrieved with a trephine bur for psychological reasons. RESULTS: At low-power magnification, it was possible to see that bone was present 2 mm above the level of the implant shoulder. No resorption of the coronal bone was present. No infrabony pockets were present. At the level of the shoulder of the implant, it was possible to observe the presence of dense connective tissue with only a few scattered inflammatory cells. Newly formed bone was found in direct contact with the implant surface. The bone-implant contact percentage was 65.3+/-4.8%. CONCLUSIONS: Abutments smaller than the diameter of the implant body (platform switching) in combination with an absence of micromovement and microgap may protect the peri-implant soft and mineralized tissues, explaining the observed absence of bone resorption. Immediate loading did not interfere with bone formation and did not have adverse effects on osseointegration.     

当代牙种植体设计进步与临床意义

牙种植体本身的研发设计进展深刻的影响了临床技术的进步,也深刻的影响了临床治疗效果,甚至给临床治疗理念或流程带来里程碑式的变革。当代牙种植体的设计与临床进步主要表现为：1）种植体根方设计影响了即刻种植的初期稳定性,即刻种植时植入超出牙槽窝上方约3~5 mm的种植体部分的外形结构决定了该种植体的初期稳定性,其外形结构主要体现在种植体根方轮廓设计、螺纹设计及自攻性方面。2）种植体的外形结构设计影响了即刻修复的可能性,即刻修复的基础在尚无骨结合时种植体通过其机械设计可以获得大于35 Ncm的初期稳定性。 微锥度种植体外形,密集型深螺纹,含有良好的自攻刃设计均有利于机械锚定,即初期稳定性,这是即刻修复的物理学基础与机械可能性。3）种植体颈部设计影响美学效果,为了避免拔牙窝唇颊侧骨板吸收显露种植体颈部的金属暗影,均应避免使用颈部膨大设计的种植体,而应采用小直径种植体以利于美学修复美学区域进行种植修复,最好具有平台转移的设计,以获得良好的美学效果。4）种植体与基台的连接设计是骨内种植体设计的关键环节,功能上除了连接种植体与修复体,抗旋转外还需要抵抗或传导各个方向的咀嚼力,连接方式的稳定性会直接影响种植体颈部骨组织的长期稳定性,锥度连接和管套管连接方式都是有良好记录的种植体连接方式。5）平台转移设计影响到种植体颈部骨组织的稳定性,国际上大量临床研究结果及笔者所在科室应用均认为,具有平台转移设计的种植体有利于保存种植体颈部骨组织,无论是在单牙修复还是在多牙或无牙颌种植修复中都表现出良好的种植体颈部骨组织稳定性。6）数字化技术为种植临床技术提供了更为精确,更为高效的高科技方式。应用数字化印模技术结合计算机辅助设计/计算机辅助制作软件及专用设备进行修复体的设计、制作将成为未来种植修复的发展趋势。种植体及其配件的持续研发为临床数字化技术提供了可能性,新一代椅旁数字化系统口内扫描前无需喷粉,免除了即刻种植后伤口由喷粉致感染的潜在风险,解决了即刻种植术后即刻扫描的技术难题。7）种植体基台的特殊设计以满足临床新技术创新发展的需求,推进了临床流程的显著变革。All-on-four即刻修复技术和Weldone口内焊接即刻修复技术的问世都是新型特殊修复基台研发突破进而推动了临床新技术的创新。     

Biological space adaptation to implant dimensions

PURPOSE: Implant osseointegration has been well described, but coronal osseous healing continues to be investigated because of its impact on esthetic results and long-term maintenance. Although numerous implant diameters and designs exist, little is known about the role of these parameters on surrounding bone. Therefore, this study aimed at elucidating the influence of implant dimensions on crestal bone morphology. MATERIALS AND METHODS: Sixty Biomet/3i implants (20 standard, 20 wide, and 20 expanded platform [XP]) were randomly placed in posterior quadrants of 5 mongrel dogs. After healing, exposure of the implants to the oral cavity, and euthanasia of the animals, samples were harvested. Histomorphometric measurements were performed to determine the bone cuff height, width, and angle, and analysis of variance was applied to compare groups. RESULTS: Formation of a periimplant cuff was noticed in all implant sites. Mean cuff height was 0.8 mm, 1 mm, and 1.4 mm for standard, wide, and XP implants, respectively. Mean cuff width was 1.9 mm, 2.1 mm, and 2.8 mm for standard, wide, and XP implants, respectively. These differences were statistically significant between wide and XP implants (P = .035), as well as between standard and XP implants (P = .001). Angle did not differ significantly between implants of different platform widths. CONCLUSIONS: Craterization after placement of healing abutments and a healing period was observed around all implants. Width and height of the cuff varied significantly with implant diameter and platform design, but the angle formed with the implant did not vary significantly.     

Cast-based guided implant placement: a novel technique

One of the most challenging aspects of implant placement is the correct spatial positioning of the dental implant in the bone. Surgical guides of various configurations have been proposed to aid implant placement. If a fully limiting surgical guide is used, the encoded information should be reliable, as deviations are not possible during surgery. This article describes a combination of analog techniques, including bone sounding and periapical radiographs used to study the available bone volume. A simplified casting protocol is proposed, and the implant platform position of the implant analog is transferred to a surgical guide composed of a stiff vinyl polysiloxane material. This surgical guide is used in a conventional flapless guided implant surgery protocol. This combination of techniques allows precise placement of a dental implant, abutment, and provisional restoration in a minimally invasive manner.     

Stress analysis and factor of safety in three dental implant systems by finite element analysis

ObjectiveThe purpose of this study was to compare the stress distribution and the factor of safety of three dental implant systems using the finite element method.Materials and methodsThree commercial dental implant systems were designed using Solid Works 2020 software: Model A with an internal octagonal connection and matching platform, Model B with an internal hexagon connection and switching platform, and Model C with an internal 15° conical-cylindrical connection and switching platform. A 200 N load was applied to each design in both axial and 30° oblique directions using the finite element method.ResultsIn the three dental implant systems, the maximum von Mises stress was concentrated at the cervical level of the bone-implant interface in all models. Model C showed lower maximum stress values in both axial and 30° oblique loads. The highest maximum stress value was observed with the application of the oblique load in all the study models, and the factor of safety was less than one in Model A when subjected to a 200 N oblique load.ConclusionThe switching platform models generated lower maximum stress values and a factor of safety higher than one which is considered an acceptable value.Clinical relevance: A dental implant system with an internal hexagon or conical connection and a switching platform generates lower maximum von Mises stress values both on the implant components and on the peri-implant tissues.     

Pilot clinical and histologic evaluations of a two-piece zirconia implant

An investigation was conducted to evaluate the clinical and histologic results of bone and soft tissue healing around a two-piece zirconia dental implant in a human model. A healthy female patient requiring tooth replacement with dental implants received a two-piece zirconia implant together with conventional titanium implants to be implemented in a prosthesis. Clinical and radiographic evaluations at 6 months revealed stable osseointegrated zirconia and titanium dental implants. Light microscopy and backscatter scanning electron microscopic analyses confirmed the biocompatibility and achievement of osseointegration, in addition to maintenance of the crestal bone level. The findings suggest that the bone-to-implant contact with a zirconia implant surface is sufficient to provide clinical and histologic evidence of osseointegration. The biopsied two-piece zirconia dental implant with platform switching demonstrated osseointegration occlusal to the implant-abutment junction, eliminating the significance of the microgap.     

Immediate provisionalization on a new implant design for esthetic restoration and preserving crestal bone

PURPOSE: This article describes how the concept of platform switching has been incorporated into a new implant design as a method of reducing crestal bone loss and maintaining the gingival papillae. A 6-month study of the effects of this implant on bone loss is described. MATERIALS: Ten new platform switched implants were placed into fresh anterior maxillary extraction sites in 3 men and 7 women, ranging in age between 29 and 45 years old, and immediately provisionalized. The adjoining bone height was evaluated with digital radiography on the day after implant placement, and at 15 days, 1, 2, 3, and 6 months later. RESULTS: After 6 months, the mean bone loss on the mesial of the central-incisor implants was 0.05 mm. The mean bone loss was 0.07 mm on the distal of the central incisor implants, 0.07 mm on the mesial of the lateral-incisor implants, and 0.06 mm on the distal of the lateral-incisor implants. CONCLUSIONS: An implant design that incorporates the concept of platform switching is a simple and effective way to control circumferential bone loss around dental implants, helping to ensure a predictable esthetic result.     

Esthetic outcomes of immediate implant placements

BACKGROUND: Single-rooted teeth deemed not restorable via conventional means may be candidates for implant placement at the time of tooth extraction. Immediate implant placements are believed to preserve soft and hard tissue form and contours, reduce the need for augmentation procedures, minimize surgical exposure of the patient, reduce treatment time and improve esthetic outcomes. METHOD: This retrospective review analyzed the esthetic outcomes of 42 non-adjacent single-unit implant restorations completed using an immediate implant surgical placement protocol. RESULTS: The mean time in function was 18.9 months (range 6-50 months) and the majority of implants placed had a restorative platform diameter of 4.1 and 4.8 mm. A highly significant change in crown height due to marginal tissue recession of 0.9 +/- 0.78 mm (P=0.000) was recorded for all sites, with no difference seen between implant systems (P=0.837). Thin tissue biotype showed slightly greater recession than thick tissue biotype (1 +/- 0.9 vs. 0.7 +/- 0.57 mm, respectively); however, this difference was not statistically significant (P=0.187). Implants with a buccal shoulder position showed three times more recession than implants with a lingual shoulder position (1.8 +/- 0.83 vs. 0.6 +/- 0.55 mm, respectively) with the difference being highly statistically significant (P=0.000). CONCLUSIONS: Immediate implant placement requires very careful case selection and high surgical skill levels if esthetic outcomes are to be achieved. Long-term prospective studies on tissue stability and esthetic outcomes are needed.