Surface treatments of titanium dental implants for rapid osseointegration.

The osseointegration rate of titanium dental implants is related to their composition and surface roughness. Rough-surfaced implants favor both bone anchoring and biomechanical stability. Osteoconductive calcium phosphate coatings promote bone healing and apposition, leading to the rapid biological fixation of implants. The different methods used for increasing surface roughness or applying osteoconductive coatings to titanium dental implants are reviewed. Surface treatments, such as titanium plasma-spraying, grit-blasting, acid-etching, anodization or calcium phosphate coatings, and their corresponding surface morphologies and properties are described. Most of these surfaces are commercially available and have proven clinical efficacy (>95% over 5 years). The precise role of surface chemistry and topography on the early events in dental implant osseointegration remain poorly understood. In addition, comparative clinical studies with different implant surfaces are rarely performed. The future of dental implantology should aim to develop surfaces with controlled and standardized topography or chemistry. This approach will be the only way to understand the interactions between proteins, cells and tissues, and implant surfaces. The local release of bone stimulating or resorptive drugs in the peri-implant region may also respond to difficult clinical situations with poor bone quality and quantity. These therapeutic strategies should ultimately enhance the osseointegration process of dental implants for their immediate loading and long-term success.     

Implant rehabilitation in Erdheim-Chester disease: a clinical report.

Successful osseointegration of endosseous titanium implants is thought to be dependent upon close apposition of bone to the implant surface. The integration of implants in this patient was achieved despite the lipid-laden histiocytic infiltration of the bone marrow. Presumably, enough unaffected stromal cells were present to allow sufficient bone formation for osseointegration of the implant fixtures. This result invites speculation regarding both the mechanism of osseointegration and the minimum surface area of bone-implant interface necessary for achieving and maintaining osseointegration of titanium implants. This patient is periodically examined to determine if the loaded fixtures will remain clinically immobile for a prolonged period.     

Characterization of the surface properties of commercially available dental implants using scanning electron microscopy, focused ion beam, and high-resolution transmission electron microscopy

Background: Since osseointegration of the respective implant is claimed by all manufacturing companies, it is obvious that not just one specific surface profile including the chemistry controls bone apposition. Purpose: The purpose was to identify and separate out a particular set of surface features of the implant surfaces that can contribute as factors in the osseointegration process. Material and Methods: The surface properties of several commercially available dental implants were extensively studied using profilometry, scanning electron microscopy, and transmission electron microscopy. Ultrathin sections prepared with focused ion beam microscopy (FIB) provided microstructural and chemical data which have not previously been communicated. The implants were the Nobel Biocare TiUnite® (Nobel Biocare AB, Göteborg, Sweden), Nobel Biocare Steri‐Oss HA‐coated (Nobel Biocare AB, Yorba Linda, CA, USA), Astra‐Tech OsseoSpeed? (Astra Tech AB, Mölndal, Sweden), Straumann SLA® (Straumann AG, Waldenburg, Switzerland), and the Brånemark Integration Original Fixture implant (Brånemark Integration, Göteborg, Sweden). Results: It was found that their surface properties had differences. The surfaces were covered with crystalline TiO₂ (both anatase and rutile), amorphous titanium oxide, phosphorus doped amorphous titanium oxide, fluorine, titanium hydride, and hydroxyapatite, respectively. Conclusion: This indicates that the provision of osseointegration is not exclusively linked to a particular set of surface features if the implant surface character is a major factor in that process. The studied methodology provides an effective tool to also analyze the interface between implant and surrounding bone. This would be a natural next step in understanding the ultrastructure of the interface between bone and implants.     

Analysis of failed commercially pure titanium dental implants: a scanning electron microscopy and energy-dispersive spectrometer x-ray study

BACKGROUND: The failure of osseointegration in oral rehabilitation has gained importance in current literature and in clinical practice. The integration of titanium dental implants in alveolar bone has been partly ascribed to the biocompatibility of the implant surface oxide layer. The aim of this investigation was to analyze the surface topography and composition of failed titanium dental implants in order to determine possible causes of failure. METHODS: Twenty-one commercially pure titanium (cpTi) implants were retrieved from 16 patients (mean age of 50.33 +/- 11.81 years). Fourteen implants were retrieved before loading (early failures), six after loading (late failures), and one because of mandibular canal damage. The failure criterion was lack of osseointegration characterized as dental implant mobility. Two unused implants were used as a control group. All implant surfaces were examined by scanning electron microscopy (SEM) and energy-dispersive spectrometer x-ray (EDS) to element analysis. Evaluations were performed on several locations of the same implant. RESULTS: SEM showed that the surface of all retrieved implants consisted of different degrees of organic residues, appearing mainly as dark stains. The surface topography presented as grooves and ridges along the machined surface similar to control group. Overall, foreign elements such as carbon, oxygen, sodium, calcium, silicon, and aluminum were detected in failed implants. The implants from control group presented no macroscopic contamination and clear signs of titanium. CONCLUSION: These preliminary results do not suggest any material-related cause for implant failures, although different element composition was assessed between failed implants and control implants.     

Osseointegration assessment of dental implants using a synchrotron radiation imaging technique: a preliminary study

PURPOSE: This study tests the possibility of using synchrotron radiation (SR) x-ray micro-imaging as a new method to evaluate osseointegration. MATERIALS AND METHODS: A simple imaging setup with primarily unmonochromatic SR was used to study the interface of a dental implant in contact with bone. The samples were prepared by sectioning the undecalcified specimen of a titanium screw implanted in the tibia of a New Zealand white rabbit. Radiographs of the interface between surrounding tissues and dental titanium implant were imaged using the SR imaging system at PLS (Pohang Light Source) 5C1 beamline, a micro-computed tomography (microCT) system (SkyScan-1072), and a conventional dental x-ray system (Siemens Heliodent MD). RESULTS: The image quality of the osseointegrated titanium implant was compared among the 3 imaging systems. The SR imaging technique showed greater details than other radiographic modalities for evaluation of the healing stage of bone-implant contact. DISCUSSION: The evaluation was especially focused on the image quality of the osseous contact at the bone-to-implant interfaces. CONCLUSIONS: This SR imaging technique provides finer details and can be expected to make an impact in the clinical study of osseointegration.     

Histomorphometric analyses of bone interface with titanium-aluminum-vanadium and hydroxyapatite-coated implants by biomimetic process

PURPOSE: The surface properties of dental implants have been considered directly related to the success of the osseointegrated interface. Hydroxyapatite (HA)-coated implants promote a bioactive surface because they facilitate cellular migration and bone growth, resulting in a faster osseointegration. MATERIALS AND METHODS: This study analyzed and compared 2 different implant surfaces: a group composed of titanium implants and another group coated with HA. The HA coating was produced by the biomimetic process to reduce costs. RESULTS AND CONCLUSIONS: After histomorphometric analyses it was possible to demonstrate that there were no statistically significant differences between the groups.     

改良喷砂表面处理对钛牙种植体骨结合的组织学作用

研究改良喷砂表面处理对钛牙种植体骨结合的影响。方法柱状纯钛种色植分两组（光滑表面和改良喷砂表面组）进行表面处理,植于狗后肢股骨内侧髁,分别于2、4、12周取材、固定、脱钙后常规HE染色,光镜观察。结果：改良喷砂表面组与光滑表面组的骨愈合过程,均为膜内成骨,并形成完全的骨结合。二者的差别主要表现在愈合的早期（割周）,改良喷砂表面组界面成骨较快,愈合中晚期差别不明显。结论：改良喷砂表面处理可以加快钛牙种植体的骨结合速度。     

钛种植体表面改性方法

钛种植体具有美观舒适、不损伤邻牙、临床效果显著等优点,广泛应用于口腔种植修复领域;但应用中存在骨结合失败、种植体周围骨吸收、种植体周围炎等问题,使其应用受到一定的限制。对钛种植体进行表面改性,在其表面制备不同的理化涂层和生物活性涂层,可以提高种植体的种植成功率,满足临床应用需求。本文从物理、化学、生物三方面对各种钛种植体表面改性方法的特点进行总结,为牙种植材料的研究和临床应用提供参考。     

A comparison of femoral and mandibular animal models for the evaluation of HA-coated implants.

The application of hydroxylapatite coatings promises marked improvement in the rapidity and durability of osseointegration for both dental and orthopedic metallic implants. Standard methods for the in vivo assessment of the performance of experimental implants include canine mandibular and femoral transcortical implantations. This study compared the results of the two procedures by use of similar HA-coated titanium implants. The results indicate that the rapidity of osseointegration and the maximum attachment strength for mandibular dental implants approximate those of the femoral transcortical implants, especially at longer post-operative intervals. We conclude that the two models are comparable for the purpose of evaluating the performance of this type of implant and can be used interchangeably by dental and orthopedic implant designers. HA-coating of titanium implants provides extensive osseointegration in both mandibular and long-bone models, with similar mechanical attachment strengths and histologic appearance.     

补骨合剂促进口腔种植体骨整合的免疫组织化学研究

目的：通过观察补骨合剂对口腔骨内种植体骨整合免疫组织化学指标的影响,探讨补骨合剂促进骨整合的作用机理。方法：成年杂种犬20只,拔除左侧下颌第二、三、四前磨牙,3个月后各植入CDIC种植体3枚,随机分为实验组和对照组,实验组每日予补骨合剂1ml/kg灌胃,分别于术后1、2、4、8、12周取出标本进行免疫组织化学分析,观察种植体一骨界面骨整合情况。结果：实验组第1周种植体－－骨形成蛋白（BMP）平均灰度显著增高（P＜0.01）,较对照组提前约1周。结论：补骨合剂可以促进口腔骨内种植体骨整合。该药物可促进BMP的早期释放和聚集,提高种植体－－骨界面的BMP浓度,促进其成骨。     

Research on implants and osseointegration

Osseointegration was originally defined as a direct structural and functional connection between ordered living bone and the surface of a load‐carrying implant. It is now said that an implant is regarded as osseointegrated when there is no progressive relative movement between the implant and the bone with which it is in direct contact. Although the term osseointegration was initially used with reference to titanium metallic implants, the concept is currently applied to all biomaterials that have the ability to osseointegrate. Biomaterials are closely related to the mechanism of osseointegration; these materials are designed to be implanted or incorporated into the living system with the aims to substitute for, or regenerate, tissues and tissue functions. Objective evaluation of the properties of the different biomaterials and of the factors that influence bone repair in general, and at the bone tissue–implant interface, is essential to the clinical success of an implant. The Biomaterials Laboratory of the Oral Pathology Department of the School of Dentistry at the University of Buenos Aires is devoted to the study and research of the properties and biological effects of biomaterials for dental implants and bone substitutes. This paper summarizes the research work resulting from over 25 years’ experience in this field. It includes studies conducted at our laboratory on the local and systemic factors affecting the peri‐implant bone healing process, using experimental models developed by our research team. The results of our research on corrosion, focusing on dental implants, as well as our experience in the evaluation of failed dental implants and bone biopsies obtained following maxillary sinus floor augmentation with bone substitutes, are also reported. Research on biomaterials and their interaction with the biological system is a continuing challenge in biomedicine, which aims to achieve optimal biocompatibility and thus contribute to patient health.     

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.     

Advances in surfaces and osseointegration in implantology. Biomimetic surfaces

The present work is a revision of the processes occurring in osseointegration of titanium dental implants according to different types of surfaces -namely, polished surfaces, rough surfaces obtained from subtraction methods, as well as the new hydroxyapatite biomimetic surfaces obtained from thermochemical processes. Hydroxyapatite’s high plasma-projection temperatures have proven to prevent the formation of crystalline apatite on the titanium dental implant, but lead to the formation of amorphous calcium phosphate (i.e., with no crystal structure) instead. This layer produce some osseointegration yet the calcium phosphate layer will eventually dissolve and leave a gap between the bone and the dental implant, thus leading to osseointegration failure due to bacterial colonization. A new surface -recently obtained by thermochemical processes- produces, by crystallization, a layer of apatite with the same mineral content as human bone that is chemically bonded to the titanium surface. Osseointegration speed was tested by means of minipigs, showing bone formation after 3 to 4 weeks, with the security that a dental implant can be loaded. This surface can be an excellent candidate for immediate or early loading procedures. Key words:Dental implants, implants surfaces, osseointegration, biomimetics surfaces.     

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提要：钛和钛合金因具有良好的机械力学性能和生物相容性被广泛用作牙科种植体。种植体植入机体后,与骨的骨性结合是关系到种植体在体内维持时间长短的关键。种植体进入机体后,首先是其表面与组织接触,因此对种植体表面改性是提高种植体与骨的骨性结合的有效方法。本文对目前钛和钛合金表面改性的方法进行简要概述。     

Clinical and radiographic experience with a hydroxyapatite-coated titanium plasma-sprayed porous implant.

Recent efforts to improve the interface between implant and bone have involved the use of bioactive materials, specifically hydroxyapatite (HA). HA coatings applied to implants have shown excellent clinical results at 2 years. There have been no radiolucent lines around the HA-coated implants. The long-term strength of the HA coating-substrate bone interface remains a concern as osseointegration of the HA appears to be a consistent phenomenon. This can lead potentially to an interruption between the substrate itself and the osseointegrated coating.     

Osseointegration of titanium,titanium alloy and zirconia dental implants: current knowledge and open questions

Bone healing around dental implants follows the pattern and sequence of intramembraneous osteogenesis with formation of woven bone first of all followed later by formation of parallel‐fibered and lamellar bone. Bone apposition onto the implant surface starts earlier in trabecular bone than in compact bone. While the first new bone may be found on the implant surface around 1 week after installation, bone remodeling starts at between 6 and 12 weeks and continues throughout life. Bone remodeling also involves the bone–implant interface, thus transiently exposing portions of the implant surface. Surface modifications creating micro‐rough implant surfaces accelerate the osseointegration process of titanium implants, as demonstrated in numerous animal experiments. Sandblasting followed by acid‐etching may currently be regarded as the gold standard technique to create micro‐rough surfaces. Chemical surface modifications, resulting in higher hydrophilicity, further increase the speed of osseointegration of titanium and titanium‐zirconium implants in both animals and humans. Surface modifications of zirconia and alumina‐toughened zirconia implants also have an influence on the speed of osseointegration, and some implant types reach high bone‐to‐implant contact values in animals. Although often discussed independently of each other, surface characteristics, such as topography and chemistry, are virtually inseparable. Contemporary, well‐documented implant systems with micro‐rough implant surfaces, placed by properly trained and experienced clinicians, demonstrate high long‐term survival rates. Nevertheless, implant failures do occur. A low percentage of implants are diagnosed with peri‐implantitis after 10 years in function. In addition, a low number of implants seem to be lost for primarily reasons other than biofilm‐induced infection. Patient factors, such as medications interfering with the immune system and bone cells, may be an element contributing to continuous bone loss and should therefore be monitored and studied in greater detail.     

Oxidized, bioactive implants are rapidly and strongly integrated in bone. Part 1--experimental implants

OBJECTIVES: The study presented was designed to investigate the speed and the strength of osseointegration of oxidized implants at early healing times in comparison which machined, turned implants. MATERIAL AND METHODS: Screw-shaped titanium implants were prepared and divided into two groups: magnesium ion incorporated, oxidized implants (Mg implants, n=10) and machined, turned implants (controls, n=10). Mg implants were prepared using micro-arc oxidation methods. Surface oxide properties of implants such as surface chemistry, oxide thickness, morphology/pore characteristics, crystal structures and roughness were characterized with various surface analytic techniques. Implants were inserted into the tibiae of ten New Zealand white rabbits. After a follow-up period of 3 and 6 weeks, removal torque (RTQ), osseointegration speed (DeltaRTQ/Deltahealing time) and integration strength of implants were measured. Bonding failure analysis of the bone-to-implant interface was performed. RESULTS: The speed the and strength of osseointegration of Mg implants were significantly more rapid and stronger than for turned implants at follow-up periods of 3 and 6 weeks. Bonding failure for Mg implants dominantly occurred within the bone tissue, whereas bonding failure for turned implants mainly occurred at the interface between implant and bone. CONCLUSIONS: Oxidized, bioactive implants are rapidly and strongly integrated in bone. The present results indicate that the rapid and strong integration of oxidized, bioactive Mg implants to bone may encompass immediate/early loading of clinical implants.     

低强度脉冲超声促进钛种植体骨结合的实验研究

目的 建立种植体植入动物模型,研究低强度脉冲超声(low intensity pulsed ultrasound,LIPUS)对种植体骨结合的促进作用.方法 选用雌性SD大鼠24只,每只大鼠双侧胫骨干骺端内侧植入螺纹状钛种植体.植入术后第2天对右侧胫骨种植体周围进行LIPUS刺激作为实验侧,每日20 min,左侧胫骨种植体植入部位不刺激作为自身对照侧.超声刺激后第4、8、12 周分批处死动物,每批8只,获取双侧胫骨标本.采用X线片、显微CT、组织切片等观察LIPUS对种植体骨结合的作用.结果 3个时间点种植体与骨组织之间均形成了不同程度的骨结合.显微CT组织形态计量学分析结果显示,种植体周骨结合率在实验侧第4、8、12周分别为(45.708±3.316)%、(46.231±1.954)%、(46.807±1.451)%,在对照侧分别为(43.021±3.558)%、(44.272±3.023)%、(44.894±4.215)%,第4周时差异具有统计学意义(P<0.05).种植体周骨体积分数在第4、8周,种植体周骨小梁厚度及第8周、第12周各向异性程度,实验侧均高于自身对照侧,差异有统计学意义(P<0.05).组织学切片可见实验侧种植体周新生骨组织厚度明显大于自身对照侧,骨结合量更多.结论 LIPUS可以促进种植体周围骨组织的愈合,加快种植体骨结合,并能促进骨小梁早期呈一定方向改建.

Abstract：

Objective To establish an animal model of titanium implant and to investigate the effects of low intensity pulsed ultrasound(LIPUS)on the implant osseointegration. Methods Twenty-four female Sprague Dawley(SD)rats were used. Titanium implants were inserted into tibia metaphysis bilaterally in each SD rat. Since the second day following implant surgery, LIPUS stimulation were carried out around the implant on the right side for 20 minutes per day, and implants on the left side remain untouched as self-control. Eight rats were sacrificed and tibiae specimens were harvested on the end of the 4th, 8th, and 12th week respectively. X-ray picture,micro-CT analysis and histological sections were performed to evaluate the effects of LIPUS on the implant osseointegration. Results Osseointegration at the interface between the implant and bone tissue was observed bilaterally. In the micro-CT histomorphometry analysis, the percentage of osseointegration(%OI)of experiment side were (45.708±3.316)%, (46.231±1.954)%, and (46.807±1.451)% on the end of the 4th, 8th, and 12th week. Meanwhile, the %OI of control side were (43.021±3.558)%, (44.272±3.023)%, and (44.894±4.215)% respectively. The %OI on the 4th weekend, bone volume ratio(BV/TV)on the 4th and 8th weekend,trabecular thickness(Tb. Th)and degree of anisotropy(DA)on the 8th and 12th weekend of the experiment side tibia were significantly greater than those on the control side(P<0.05). The histological examination showed that the thickness of new bone around the implant and the bone-implant contact area was obviously greater in the LIPUS treated side compared to the control side.Conclusions The LIPUS therapy may accelerate the bone healing and osseointegration at the interface between titanium implant and bone, and promote remodeling of bone trabecula on the early stage.     

四种骨内人工牙种植体X线片分析

对一期手术后4个月以上的4种不同类型骨内人工牙种植体X线片进行分析，从种植体边缘垂直骨吸收程度及种植体与骨界面结合情况两个方面进行评价，结果表明叶扶种植体垂直骨吸收程度明显大于其他3种螺旋种植体，2种国产螺旋状种植体与瑞典Branemark种植体骨吸收程度相近，同为纯钛金属的4种种植体与骨界面结合能力并无显著性差异。     

Needs and current research directions of biological regenerative medicine in prosthodontic practice--to attain reliable and sophisticated dental implant therapy

Appropriate dental implants are known to improve the quality of life in totally and partially edentulous patients, as well as to prevent future tooth loss, and so prosthetic treatment modalities have drastically changed recently with reconstruction therapy. However, dental implant therapy did not win the confidence of the dental community in the early developmental stage, until osseointegration between titanium and surrounding bone tissue was discovered and the modality utilizing osseointegration became reliable and produced durable treatment outcomes for long-term function. On the other hand, the biological mechanism of osseointegration has not been clarified yet and the time required for osseointegration is still long, e.g. three to four months. As well, when the implant is applied in the upper posterior region, the acquisition of osseointegration and the long-term survival of the implant are still not clinically adequate. Therefore, to reduce the time required for osseointegration and to regenerate enough alveolar bone mass in the target implantation site, the oral implant modality must be made more useful and potent as one of the treatment options for partial and total edentulism. With this background, we have studied biological strategies for reducing the time required for osseointegration and for regenerating enough alveolar bone mass, e.g., investigation of the specific genes for osseointegration between titanium and bone, nano-level surface modification of the titanium, biodegradable apatite foam for alveolar bone regeneration, application of bone formation-related growth factors with biological scaffold, and autologous cell transplantation of bone marrow derived mesenchymal stem cells. In this article, we review the current status of regenerative medicine being applied in prosthodontics and discuss our future research direction.