氧化锆基台的制作及其与钛基台抗折强度的比较

目的：制作氧化锆基台并将其与钛基台的抗折强度相比较,从而探讨其临床应用的可行性。方法：选用纳米氧化锆粉,采用冷等静压成型和二次烧结工艺制作0sstem USⅡ系统氧化锆基台;选取氧化锆基台和成品钛基台（OSSTEM公司,韩国）各10枚,分别与0sstem USⅡ种植体装配,然后固定于不锈钢夹具中置于万能试验机,将万能试验机压头与种植体长轴成90°角施加压力,记录基台损坏时的加载力值,比较分析两组试件的强度差异。结果：氧化锆基台和钛基台的平均抗折强度分别为（540.5±84.6）N和（753.9±160.8）N,差别有统计学意义（P〈0.05）。氧化锆基台组10枚基台全部颈部折裂;钛基台组2枚种植体损坏,6枚中央固位螺钉损坏,2枚基台颈部折裂。结论：本研究制作的0sstem USⅡ系统的氧化锆基台的抗折强度虽然低于钛基台,但尚能满足临床应用要求。     

Genome analysis and clinical implications of the bacterial communities in early biofilm formation on dental implants restored with titanium or zirconia abutments

This cross-sectional study aimed to identify and quantify up to 42 target species colonizing the early biofilm of dental implants restored with titanium or zirconia abutments. A total of 720 samples from 20 healthy individuals were investigated. Biofilm samples were collected from the peri-implant sulci, inner parts of implants, abutment surfaces and prosthetic crowns over a functioning period of 30 days. Checkerboard DNA–DNA hybridization was used for microbial detection and quantitation. Clinical characteristics (probing depth, bleeding on probing, clinical attachment level and marginal bone loss) were also investigated during the monitoring period. Genome counts were low at the implant loading time point for both the abutment materials, and increased over time. Both the titanium and the zirconia groups presented similar microbial counts and diversity over time, and the microbiota was very similar to that colonizing the remaining teeth. Clinical findings were consistent with a healthy condition with no significant difference regarding marginal bone loss between the two materials.     

Titanium and zirconia particle-induced pro-inflammatory gene expression in cultured macrophages and osteolysis,inflammatory hyperalgesia and edema in vivo

Aims

The biological reaction to wear debris is critical to the osteolysis underlying aseptic loosening of joint prosthetic implants. In an attempt to reduce aseptic loosening, ceramics have been introduced. This study was designed to evaluate, compare and correlate the expression of Toll-like receptors (TLRs), their intracellular adaptors and proinflammatory cytokines in cultured macrophages challenged with titanium or zirconia particles, as well as particle-induced osteolysis in calvaria and hyperalgesia and edema in hind paw.

Main methods

TLRs and their adaptors were evaluated at the mRNA level by RT-PCR, and cytokine expression was evaluated at the mRNA and protein levels. Osteolysis and hyperalgesia and edema were evaluated in vivo, in calvaria and hind paw, respectively.

Key findings

Cultured macrophages challenged with zirconia or titanium particles expressed increased mRNA for TLRs 2, 3, 4 and 9, and their adaptors MyD88, TRIF and NF-κB and cytokines TNF-α, IL-1β and IL-6, which were also increased at protein level. Quantitative differences are evident and, in general, zirconia particle-induced pro-inflammatory gene expression was lower than that induced by titanium particles. In in vivo experiments, exposition to titanium or zirconia particles induced osteolysis in calvaria and hyperalgesia and edema in hind paw; however those induced by zirconia particles were significantly lower. There is a strong and positive correlation between the expressions of mRNA for TLR4, NF-κB, TNF-α, IL-1β and IL-6.

Significance

Collectively, our data suggest that zirconia ceramic particles are less bioactive than titanium particles.     

Present clinical applications of osseointegrated percutaneous implants

Altogether, 389 screws of commercially pure titanium have been inserted at various locations in the facial skeleton of 174 patients. The indications for treatment have been stable anchorage of an external hearing aid or a facial episthesis, in the latter case to restore the facial contours after congenital disorders or status after trauma or cancer surgery. All implants have been inserted in a two-stage procedure, the first being anchorage of the titanium elements in the bone, the second, minimally 3 months later, being establishment of a permanent skin penetration. The outcome of every inserted implant has been analyzed. Only six implants failed to become integrated in bone and had to be removed. Five of these failures occurred in previously irradiated bone, where the success rate was estimated to 85.3 percent. In nonirradiated bone, 354 of 355 inserted implants became osseointegrated, i.e., anchored in bone in a stable manner. The soft tissues were without any adverse reactions in 92 percent of the 951 clinical observations, whereas potentially serious skin complications were observed in only 2.8 percent. Presently, the longest clinical follow-up is 8 years, and 37 implants have been followed for more than 5 years. We believe that this clinical material is the first in which an uneventful bone anchorage and skin penetration have been demonstrated in consecutively operated upon clinical cases. The implants used for anchoring an external hearing aid were also successful in the sense that the patients gained 15 dB (average) in hearing threshold and showed a significantly improved discrimination score. The implants inserted to hold facial epistheses resulted in considerably improved retention and a good cosmetic outcome for the patients.     

钛及钛合金种植体表面处理的研究进展

钛的优良特性早已被公认为首选牙用种植材料,其表面氧化膜是形成骨结合的关建。为了进一步增加其耐腐蚀性和生物相容性,人们采取了多种方式进行表面处理,最终达到在植入体的不同部位产生不同的粗糙表面,以利于不同细胞在不同地方的附着,增加其生物活性。同时,达到避免各种污染物对纯钛种植体影响的目的。近年来钛种植体材料表面处理已经成为研究热点,本文就表面处理的方法进行综述。     

The role of fluoride on the process of titanium corrosion in oral cavity

Titanium is known to possess excellent biocompatibility as a result of corrosion resistance, lack of allergenicity when compared with many other metals. Fluoride is well known as a specific and effective caries prophylactic agent and its systemic application has been recommended widely over recent decades. Nevertheless, high fluoride concentrations impair the corrosion resistance of titanium. The purpose of this article is to summarize the current data regarding the influence of fluoride on titanium corrosion process in the last 5?years. These data demonstrate noxious effects induced by high fluoride concentration as well as low pH in the oral cavity. Therefore, such conditions should be considered when prophylactic actions are administrated in patients containing titanium implants or other dental devices.     

Electrochemical disinfection of dental implants--a proof of concept

Background

Peri-implantitis has gained significant clinical attention in recent years. This disease is an inflammatory reaction to microorganisms around dental implants. Due to the limited accessibility, non-invasive antimicrobial strategies are of high interest. An unexpected approach to implant disinfection may evolve from electrolysis. Given the electrical conductivity of titanium implants, alkalinity or active oxidants can be generated in body fluids. We investigated the use of dental titanium implants as electrodes for the local generation of disinfectants. Our hypothesis was that electrolysis can reduce viable counts of adhering bacteria, and that this reduction should be greater if active oxidative species are generated.

Methodology/Principal Findings

As model systems, dental implants, covered with a mono-species biofilm of Escherichia coli C43, were placed in photographic gelatin prepared with physiological saline. Implants were treated by a continuous current of 0 - 10 mA for 15 minutes. The reduction of viable counts was investigated on cathodes and anodes. In separate experiments, the local change in pH was visualized using color indicators embedded in the gelatin. Oxidative species were qualitatively detected by potassium iodide-starch paper. The in situ generated alkaline environment around cathodic implants caused a reduction of up to 2 orders of magnitude in viable E. coli counts. On anodic implants, in contrast to cathodic counterparts, oxidative species were detected. Here, a current of merely 7.5 mA caused complete kill of the bacteria.

Conclusions/Significance

This laboratory study shows that electrochemical treatment may provide access to a new way to decontaminate dental implants in situ.     

Predicting bone remodeling around tissue- and bone-level dental implants used in reduced bone width

The objective of this study was to predict time-dependent bone remodeling around tissue- and bone-level dental implants used in patients with reduced bone width. The remodeling of bone around titanium tissue-level, and titanium and titanium–zirconium alloy bone-level implants was studied under 100 N oblique load for one month by implementing the Stanford theory into three-dimensional finite element models. Maximum principal stress, minimum principal stress, and strain energy density in peri-implant bone and displacement in x- and y- axes of the implant were evaluated. Maximum and minimum principal stresses around tissue-level implant were higher than bone-level implants and both bone-level implants experienced comparable stresses. Total strain energy density in bone around titanium implants slightly decreased during the first two weeks of loading followed by a recovery, and the titanium–zirconium implant showed minor changes in the axial plane. Total strain energy density changes in the loading and contralateral sides were higher in tissue-level implant than other implants in the cortical bone at the horizontal plane. The displacement values of the implants were almost constant over time. Tissue-level implants were associated with higher stresses than bone-level implants. The time-dependent biomechanical outcome of titanium–zirconium alloy bone-level implant was comparable to the titanium implant.     

Interruption of Electrical Conductivity of Titanium Dental Implants Suggests a Path Towards Elimination Of Corrosion

Peri-implantitis is an inflammatory disease that results in the destruction of soft tissue and bone around the implant. Titanium implant corrosion has been attributed to the implant failure and cytotoxic effects to the alveolar bone. We have documented the extent of titanium release into surrounding plaque in patients with and without peri-implantitis. An in vitro model was designed to represent the actual environment of an implant in a patient’s mouth. The model uses actual oral microbiota from a volunteer, allows monitoring electrochemical processes generated by biofilms growing on implants and permits control of biocorrosion electrical current. As determined by next generation DNA sequencing, microbial compositions in experiments with the in vitro model were comparable with the compositions found in patients with implants. It was determined that the electrical conductivity of titanium implants was the key factor responsible for the biocorrosion process. The interruption of the biocorrosion current resulted in a 4–5 fold reduction of corrosion. We propose a new design of dental implant that combines titanium in zero oxidation state for osseointegration and strength, interlaid with a nonconductive ceramic. In addition, we propose electrotherapy for manipulation of microbial biofilms and to induce bone healing in peri-implantitis patients.     

Influence of Different Abutment Designs on the Biomechanical Behavior of One-Piece Zirconia Dental Implants and Their Surrounding Bone: A 3D-FEA

BackgroundIn a dental implant/bone system, the design factors affect the value and distributions of stress and deformations that plays a pivotal role on the stability, durability and lifespan of the implant/bone system.ObjectiveThe aim of this study was to compare the influence of different abutment designs on the biomechanical behavior of one-piece zirconia dental implants and their surrounding bone tissues using three-dimensional finite element analysis.MethodsA three-dimensional geometrical model of a zirconia dental implant and its surrounding bone tissue were created. The occlusal loading force applied to the prosthetic abutments was a combination of 114.6 N in the axial direction, 17.1 N in the lingual direction and 23.4 N toward the mesial direction where these components represent masticatory force of 118.2 N in the angle of approximately 75° to the occlusal plane.ResultsThe system included implant abutment Model 01 showed a decrease of 9.58%, 9.92% and 3.62% at least in the average value of maximum von Mises stress compared to Model 02, Model 03 and Model 04 respectively. The results also showed that the system included implant abutment Model 01 decreases the average value of maximum deformation of 16.96%, 7.17% and 9.47% at least compared to Model 02, Model 03 and Model 04 respectively.ConclusionThe one-piece zirconia dental implant abutment Model 01 presents a better biomechanical behavior in the peri-implant bone than others. It can efficiently distribute the applied load and present more homogeneous behavior of stress distribution and has less deformation than others, which will enhance the stability of implant/bone system and prolong its lifespan.     

Water-insoluble papain conjugates of titanium (IV)-activated supports

Glass fibre paper, treated with titanium (IV) chloride and subsequently water-washed, has a significant quantity (27.7 μg/cm²) of surface-bound titanium (IV) which may be removed by exposure to acidic hydrogen peroxide solution. This observation supports the view that materials that have been treated with titanium (IV) chloride by the method of Emery et al.¹possess a surface layer of hydrous titanium (IV) oxide which is able to bind protein in a manner analogous to that of free hydrous titanium (IV) oxide. Titanium (IV)-activated derivatives of polypropylene netting, zirconia fibre sheet and glass fibre paper have each been found able to bind papain. The papain conjugate of each titanium (IV)-activated support exhibited a high ratio of specific proteolytic activity to specific esterolytic activity. These ratios ranged from 29 to 64% of the ratio for the soluble papain employed; the highest ratio obtained was for the papain conjugate of the titanium (IV)-activated glass fibre support. This conjugate was also very satisfactory with regard to its protein content, specific activities, catalytic stability, pH range of activity, mechanical stability and ease of separation from substrate solution. The papain conjugate of titanium (IV)-activated polypropylene was more active and more stable than a papain conjugate of non-activated polypropylene. However, both preparations lost their activity during prolonged storage in substrate solutions, even though the activity of the papain conjugate of titanium (IV)-activated polypropylene was initially maintained for about 20 days. In each case the loss of activity is attributed to protein desorption during storage. The papain conjugate of titanium (IV)-activated zirconia was catalytically stable to storage in substrate solutions but suffered from poor wet strength.     

Isolation of primary osteoblast cell lines from adult rat and rat embryos and their use as models for in vitro biocompatibility tests of nanostructured titanium-based implants

Methods for obtaining osteoblast cultures from the calvaria of adult Wistar rats and 12-day-old embryos of these rats have been adapted for studying the biocompatibility and ossointegration of titanium-based implants. The osteoblast morphology and their differentiation into osteocytes on a titanium matrix with specially treated surface have been studied. It has been confirmed that two cultures of diploid rat cells obtained in the study can serve as efficient models for preclinical in vitro testing of nanostructured titanium implants for biocompatibility and osseointegration.     

In vivo forces on dental implants: hard-wiring and telemetry methods

Methods are presented for measuring vertical force components on bridged titanium dental implants in dog mandibles. These methods have included custom-made strain-gauge transducers, plus hard-wiring and telemetric schemes for data collection. The essential components of the measurement system are described, and typical bite force data are illustrated.     

Preliminary fabrication and characterization of electron beam melted Ti–6Al–4V customized dental implant

The current study was aimed to fabricate customized root form dental implant using additive manufacturing technique for the replacement of missing teeth. The root form dental implant was designed using Geomagic™ and Magics™, the designed implant was directly manufactured by layering technique using ARCAM A2™ electron beam melting system by employing medical grade Ti–6Al–4V alloy powder. Furthermore, the fabricated implant was characterized in terms of certain clinically important parameters such as surface microstructure, surface topography, chemical purity and internal porosity. Results confirmed that, fabrication of customized dental implants using additive rapid manufacturing technology offers an attractive method to produce extremely pure form of customized titanium dental implants, the rough and porous surface texture obtained is expected to provide better initial implant stabilization and superior osseointegration.     

A random fatigue of mechanize titanium abutment studied with Markoff chain and stochastic finite element formulation

To measure fatigue in dental implants and in its components, it is necessary to use a probabilistic analysis since the randomness in the output depends on a number of parameters (such as fatigue properties of titanium and applied loads, unknown beforehand as they depend on mastication habits). The purpose is to apply a probabilistic approximation in order to predict fatigue life, taking into account the randomness of variables. More accuracy on the results has been obtained by taking into account different load blocks with different amplitudes, as happens with bite forces during the day and allowing us to know how effects have different type of bruxism on the piece analysed.     

Different titanium surfaces modulate the bone phenotype of SaOS-2 osteoblast-like cells

Commercially pure titanium implants presenting a relatively smooth, machined surface or a roughened endosseous surface show a large percentage of clinical success. Surface properties of dental implants seem to affect bone cells response. Implant topography appears to modulate cell growth and differentiation of osteoblasts affecting the bone healing around the titanium implant. The aim of the present study was to examine the effects of 1cm diameter and 1mm thick titanium disks on cellular morphology, adhesion and bone phenotypic expression of human osteoblast-like cells, SaOS-2. SaOS-2 cells were cultured on commercially 1 cm pure titanium disks with three different surface roughness: smooth (S), sandblasted (SB) and titanium plasma sprayed (TPS). Differences in the cellular morphology were found when they were grown on the three different surfaces. An uniform monolayer of cells recovered the S surface, while clusters of multilayered irregularly shaped cells were distributed on the rough SB and TPS surfaces. The adhesion of SaOS-2 cells, as measured after 3h of culture, was not affected by surface roughness. ECM components such as Collagen I (CoI), Fibronectin (FN), Vitronectin (VN) and Tenascin (TN) were secreted and organized only on the SB and TPS surfaces while they remained into the cytoplasm on the S surfaces. Osteopontin and BSP-II were largely detected on the SB and TPS surfaces, while only minimal production was observed on the S ones. These data show that titanium surface roughness affects bone differentiation of osteoblast like-cells, SaOS-2, indicating that surface properties may be able to modulate the osteoblast phenotype. These observations also suggest that the bone healing response around dental implants can be affected by surface topography.     

Greater osteoblast proliferation on anodized nanotubular titanium upon electrical stimulation

Currently used orthopedic implants composed of titanium have a limited functional lifetime of only 10–15 years. One of the reasons for this persistent problem is the poor prolonged ability of titanium to remain bonded to juxtaposed bone. It has been proposed to modify titanium through anodization to create a novel nanotubular topography in order to improve cytocompatibility properties necessary for the prolonged attachment of orthopedic implants to surrounding bone. Additionally, electrical stimulation has been used in orthopedics to heal bone non-unions and fractures in anatomically difficult to operate sites (such as the spine). In this study, these two approaches were combined as the efficacy of electrical stimulation to promote osteoblast (bone forming cell) density on anodized titanium was investigated. To do this, osteoblast proliferation experiments lasting up to 5 days were conducted as cells were stimulated with constant bipolar pulses at a frequency of 20 Hz and a pulse duration of 0.4 ms each day for 1 hour. The stimulation voltages were 1 V, 5 V, 10 V, and 15 V. Results showed for the first time that under electrical stimulation, osteoblast proliferation on anodized titanium was enhanced at lower voltages compared to what was observed on conventional (nonanodized) titanium. In addition, compared to nonstimulated conventional titanium, osteoblast proliferation was enhanced 72% after 5 days of culture on anodized nanotubular titanium at 15 V of electrical stimulation. Thus, results of this study suggest that coupling the positive influences of electrical stimulation and nanotubular features on anodized titanium may improve osteoblast responses necessary for enhanced orthopedic implant efficacy.     

过盈植入对种植体-骨界面应力分布影响的三维有限元分析（英文）

目的：应用三维有限元分析法研究牙种植体过盈植入对种植体-骨界面接触压力的影响。方法：选择直径为3.3 mm的ITI种植体和成人离体下颌骨,模拟种植体植入下颌骨内,过盈量为0.5 mm,建立三维有限元模型,应用ANSYS软件分析种植体-骨界面的应力分布情况。结果：种植体周围骨最大应力为48.796 MPa,应力分布均匀。种植体所受应力主要集中于颈部,最大应力值为87.832 MPa。结论：过盈量为0.5 mm时,种植体-骨界面所产生的应力值在骨组织所能承受的最大应力值范围内,种植体所受到的应力值远远小于钛的屈服强度,从生物力学角度,周围骨所受应力在骨组织能够承受范围,种植体也不会断裂,过盈联结在临床种植时有其可行性。     

Blood and plasma titanium levels associated with well-functioning hip implants

BackgroundHip implants are usually manufactured from cobalt-chromium and titanium alloys. As the implants wear and corrode, metal debris is released into the surrounding tissue and blood, providing a potential biomarker for their function. Whilst there are laboratory reference levels for blood cobalt and chromium in patients with well and poorly functioning hip implants, there are no such guidelines for titanium. This is despite the increasing use of titanium implants worldwide.Patients and methodsWe recruited a consecutive series of 95 patients (mean age 71 years, mean time after surgery 8.5 years) with one hip implant type, inserted by the same surgeon. We assessed clinical and radiological outcome, and measured blood and plasma titanium using high resolution inductively-coupled plasma mass spectrometry.ResultsThe upper normal reference limit for blood and plasma titanium was 2.20 and 2.56 μg L⁻¹, respectively, and did not differ significantly between males and females.ConclusionWe are the first to propose a laboratory reference level for blood and plasma titanium in patients with well-functioning titanium hip implants. This is an essential starting point for further studies to explore the clinical usefulness of blood titanium as a biomarker of orthopaedic implant performance, and comes at a time of considerable controversy regarding the use of certain titanium alloys in hip arthroplasty.     

Ectopic bone formation in titanium mesh loaded with bone morphogenetic protein and coated with calcium phosphate

The osteoinductive properties of porous titanium fiber mesh, with or without a calcium phosphate coating and loaded with recombinant human bone morphogenic protein-2 (rhBMP-2) or rhBMP-2 and native bovine BMP (S-300) were investigated in a rat ectopic assay model. A total of 112 calcium phosphate-coated and 112 noncoated porous titanium implants, either loaded with rhBMP-2 and S-300 or loaded with rhBMP-2 alone, were subcutaneously placed in 56 Wistar-King rats. The rats were killed 5, 10, 20, and 40 days postoperatively, and the implants were retrieved.Histologic analysis demonstrated that all growth factor and carrier combinations induced ectopic cartilage and bone formation at 5 and 10 days, respectively. At 20 days, bone formation increased and was characterized by trabecular bone and bone marrow-like tissue. At 40 days, more lamellar bone and hemopoietic bone marrow-like tissue were present. At both times, more bone had been formed in calcium phosphate-coated implants than in noncoated samples. Further, in rhBMP-2 and S-300-loaded specimens, bone formation was higher than in rhBMP-2 only-loaded specimens. In rhBMP-2 only-loaded specimens, bone formation was mainly localized inside the mesh material, whereas in specimens loaded with both rhBMP-2 and S-300, the bone was localized inside and surrounding the titanium mesh. The histological findings were confirmed by calcium content and alkaline phosphatase activity measurements. In addition, all specimens showed osteocalcin expression as early as 5 days postoperatively.Our results show that the combination of titanium mesh with BMPs can induce ectopic bone formation and that this bone formation seems to be similar to "enchondral" ossification. In addition, a thin calcium phosphate coating can have a beneficial effect on the bone-inducing properties of a scaffold material. Finally, rhBMP-2 and native BMP act synergistically in ectopic bone induction.