Implant Contact Area Research Articles

Effects of the application of low-temperature atmospheric plasma on titanium implants on wound healing in peri-implant connective tissue in rats

PurposeThis study aimed to clarify the effects of surface modification of titanium (Ti) implants by low-temperature atmospheric pressure plasma treatment on wound healing and cell attachment for biological sealing in peri-implant soft tissue.MethodsHydrophilization to a Ti disk using a handheld low-temperature atmospheric pressure plasma device was evaluated by a contact angle test and compared with an untreated group. In in vivo experiments, plasma-treated pure Ti implants using a handheld plasma device (experimental group: PL) and untreated implants (control group: Cont) were placed into the rat upper molar socket, and samples were harvested at 3, 7 and 14 days after surgery. Histological evaluation was performed to assess biological sealing, collagen- and cell adhesion-related gene expression by reverse transcription quantitative polymerase chain reaction, collagen fiber detection by Picrosirius Red staining, and immunohistochemistry for integrins.ResultsIn in vivo experiments, increased width of the peri-implant connective tissue (PICT) and suppression of epithelial down growth was observed in PL compared with Cont. In addition, high gene expression of types I and XII collagen at 7 days and acceleration of collagen maturation was recognized in PL. Strong immunoreaction of integrin α2, α5, and β1 was observed at the implant contact area of PICT in PL.ConclusionsThe handheld low-temperature atmospheric pressure plasma device provided hydrophilicity on the Ti surface and maintained the width of the contact area of PICT to the implant surface as a result of accelerated collagen maturation and fibroblast adhesion, compared to no plasma application.

Effect of Bovine Milk on Implant Osseointegration: an in vivo Study.

The safety and success of an implant after surgery depend on many factors, some related to the implant's biocompatibility, properties, surface modification, design, and other factors related to surgical procedures, implant bed preparation, and drilling techniques. It is recognized that the success of implant dentistry depends on several factors that may be related to biochemical properties and modification in mechanical properties. The present study aimed to assess the effect of using bovine milk as an irrigant solution on implant osseointegration. The implant socket was prepared by drilling bone holes in 20 femurs of the rabbits at steady rotation speeds with different irrigate solutions (normal saline / commercial pasteurized bovine milk). Mechanical tests and histological investigation were performed to estimate the removal torque record and implant contact area, BIC. Findings illustrate that implant contact area (BIC) and removal torque mean values are higher in experimental compared to control with more bone apposition and maturation at 4&8 week measured periods. Osseointegration is accelerated by using bovine milk in irrigation and rinsing of implant socket.

Human umbilical cord mesenchymal stem cells accelerate and increase implant osseointegration in diabetic rats.

This study was conducted to assess the effect of hUCMSCs injection on the osseointegration of dental implant in diabetic rats via Runt-related Transcription Factor 2 (Runx2), Osterix (Osx), osteoblasts, and Bone Implant Contact (BIC). The research design was a true experimental design using Rattus norvegicus Wistar strain. Rattus norvegicus were injected with streptozotocin to induce experimental diabetes mellitus. The right femur was drilled and loaded with titanium implant. Approximately 1 mm from proximal and distal implant site were injected with hUCMSCs. The control group was given only gelatin solvent injection. After 2 and 4 weeks of observation, the rats were sacrificed for further examination around implant site using immunohistochemistry staining (RUNX2 and Osterix expression), hematoxylin eosin staining, and bone implant contact area. Data analysis was done using ANOVA test. Data indicated a significant difference in Runx2 expression (p<0.001), osteoblasts (p<0.009), BIC value (p<0.000), and Osterix expression (p<0.002). In vivo injection of hUCMSCs successfully increased Runx2, osteoblasts, and BIC value significantly, while decreased Osterix expression, indicating an acceleration of the bone maturation process. The results proved hUCMSCs to accelerate and enhance implant osseointegration in diabetic rat models.

A novel strategy for fabricating zirconia implants with a trabecular biomimetic porous surface

AbstractFor successful osseointegration of load‐bearing implants, an improved bone–implant contact area through a trabecular porous surface resulting in minimized stress shielding effect is highly desirable. We propose a novel strategy of green net shaping a ceramic dough, combined with a reticular foam replica method and gradient coating, to fabricate biomimetic porosity in a customizable ceramic dental implant for the first time. About 85 vol% porosity and 300–600‐μm pore size were evident in microCT and electron microscopy of the sintered samples, suitable for bone ingrowth. Excellent integrity at the interface along with homogeneous distribution of secondary alumina phase in zirconia matrix was achieved, despite the difference in the green state powder loading between the dough and the slurry.

Scientific Rationale of Implant Design: A Review Article

There is no one implant system present that is ideal for every condition. Implant design research has been based on increasing the bone implant contact area or functional surface area in order to increase the implant stability and implant survival in poor density bone. Designing of an implant include both Macroscopic and Microscopic features. Macroscopic features include crest module, implant thread geometry and apical design of implant whereas Microscopic features include surface modificationS. This article reviews elements of various dental implant designs currently in use.

Improved in vivo osseointegration and degradation behavior of PEO surface-modified WE43 magnesium plates and screws after 6 and 12 months

Magnesium is a highly promising candidate with respect to its future use as a material for resorbable implants. When magnesium degrades, hydrogen gas is released. High doses of gas emergence are reported to impair osseointegration and may therefore lead to fixation failure. The successful delay and reduction of the degradation rate by applying plasma electrolytic oxidation (PEO) as a post processing surface modification method for magnesium alloy has recently been demonstrated. The aim of this study was thus to compare the degradation behavior of a WE43-based plate system with and without respective PEO surface modification and to further investigate osseointegration, as well as the resulting effects on the surrounding bony tissue of both variants in a miniature pig model.WE43 magnesium screws and plates without (WE43) and with PEO surface modification (WE43-PEO) were implanted in long bones of Göttingen Miniature Pigs. At six and twelve months after surgery, micro-CT and histomorphometric analysis was performed.Residual screw volume (SV/TV; WE43: 28.8 ± 21.1%; WE43-PEO: 62.9 ± 31.0%; p = 0.027) and bone implant contact area (BIC; WE43: 18.1 ± 21.7%; WE43-PEO: 51.6 ± 27.7%; p = 0.015) were increased after six months among the PEO-modified implants. Also, surrounding bone density within the cortical bone was not affected by surface modification (BVTV; WE43: 76.7 ± 13.1%; WE43-PEO: 73.1 ± 16.2%; p = 0.732). Intramedullar (BV/TV; WE43: 33.2 ± 16.7%; WE43-PEO 18.4 ± 9.0%; p = 0.047) and subperiosteal (bone area; WE43: 2.6 ± 3.4 mm2; WE43-PEO: 6,9 ± 5.2 mm2; p = 0.049) new bone formation was found for both, surface-modified and non-surface-modified groups. After twelve months, no significant differences of SV/TV and BV/TV were found between the two groups.PEO surface modification of WE43 plate systems improved osseointegration and significantly reduced the degradation rate within the first six months in vivo. Osteoconductive and osteogenic stimulation by WE43 magnesium implants led to overall increased bone growth, when prior PEO surface modification was conducted.

P3. Total implant contact area versus contact surface topology: Which one has a greater role on subsidence resistance of an interbody device, comparison of two 3D-printed titanium anterior lumbar spine fixation devices

<h3>BACKGROUND CONTEXT</h3> Anatomical loads in combination with poor bone quality may lead to interbody fixation device subsidence. Severe subsidence can often cause nerve compression and pain that may require revision surgery. It is often believed that the total contact area or footprint size of the implant has a direct impact on subsidence resistance of the interbody device. Traditionally, it was believed that cages with larger contact area have low incidence and severity of subsidence versus cages with smaller total contact area at bone-implant interface. With the advancement in additive manufacturing, we are able to create implants with advanced structural designs and surface topology that can improve subsidence resistance of the interbody device. These new designs focus on architecture and load distribution at the bone implant interface rather than overall dimensional design specifications. <h3>PURPOSE</h3> This study is aimed to evaluate subsidence resistance of two 3D-printed titanium ALIF interbody devices of the same size, but with different contact surface topology. <h3>STUDY DESIGN/SETTING</h3> Mechanical testing using foam blocks. <h3>OUTCOME MEASURES</h3> Subsidence rate of different interbody constructs. <h3>METHODS</h3> Two ALIF 3D-printed titanium interbody fixation devices were used. The first device had a truss design that spans throughout the entire construct and contains a snowshoe style bone interface and the other had two cylindrical holes through the center with micro lattice truss structure filling the rest of the volume. Both interbody devices were the same dimensions (36mm x 25mm, width x depth and 18mm tall). The truss device had the total graft volume of 7cc whereas the predicate device had the overall graft volume of 1cc. The total metal-to-bone contact area at the endplate was 401mm2 for the truss device versus 620mm2 for the predicate device. To mimic mechanical properties similar to human bone density (osteoporotic through normal), 5, 10, 15 and 20 PCF SawBone® foam blocks were utilized for testing. To mimic clinical subsidence, the interbody device was placed over the foam block and compressive displacement was applied to push the device into the foam substrate at the rate of 5mm/min. The test was repeated 6 times for each block/implant combination. The subsidence load at 1 and 2mm displacement was collected for each test combination. To calculate the modulus/stiffness, the ratio of load (normalized to contact area) to axial compression rate of the cage-only construct was calculated. Two-way ANOVA with Sidak-Bonferroni Posthoc was used for multiple comparisons and analysis of statistical significance. <h3>RESULTS</h3> The truss interbody device had subsidence resistance significantly greater than the generic titanium device at both 1mm and 2mm subsidence rates (p<0.05) across all density blocks. In foam representing osteoporotic bone (5pcf), the truss cage had subsidence resistance load of 238.3N±25.6N vs 172.2N ±13N in the predicate cage at 1mm displacement respectively. The corresponding numbers at in rigid bone (20PCF) were 1774N±174N vs 1428N ±66N. <h3>CONCLUSIONS</h3> The truss device with snowshoe design had metal-to-bone contact area of 60% of the predicate device and had total graft volume of 7 times of the predicate device; nevertheless, the truss device demonstrated significantly better resistance to subsidence for all foam densities including those that mimic osteoporotic bone compared to the same size predicate titanium device. The subsidence resistance of the truss cage, despite its smaller contact area for the same footprint size, may be due to the a more efficient distribution of load across the bone/implant interface where the load is uniformly distributed across more of the interbody footprint. The data suggests that the implant's surface contact topology at the endplate plays a greater role than the overall contact area for resisting subsidence. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

A Clue to the Existence of Bonding between Bone and Implant Surface: An In Vivo Study.

We evaluated the shear bond strength of bone–implant contact, or osseointegration, in the rabbit tibia model, and compared the strength between grades 2 and 4 of commercially pure titanium (cp-Ti). A total of 13 grades 2 and 4 cp-Ti implants were used, which had an identical cylinder shape and surface topography. Field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and confocal laser microscopy were used for surface analysis. Four grades 2 and 4 cp-Ti implants were inserted into the rabbit tibiae with complete randomization. After six weeks of healing, the experimental animals were sacrificed and the implants were removed en bloc with the surrounding bone. The bone–implant interfaces were three-dimensionally imaged with micro-computed tomography. Using these images, the bone–implant contact area was measured. Counterclockwise rotation force was applied to the implants for the measurement of removal torque values. Shear bond strength was calculated from the measured bone–implant contact and removal torque data. The t-tests were used to compare the outcome measures between the groups, and statistical significance was evaluated at the 0.05 level. Surface analysis showed that grades 2 and 4 cp-Ti implants have similar topographic features. We found no significant difference in the three-dimensional bone–implant contact area between these two implants. However, grade 2 cp-Ti implants had a higher shear bond strength than grade 4 cp-Ti implants (p = 0.032). The surfaces of the grade 2 cp-Ti implants were similar to those of the grade 4 implants in terms of physical characteristics and the quantitative amount of attachment to the bone, whereas the grade 2 surfaces were stronger than the grade 4 surfaces in the bone–surface interaction, indicating osseointegration quality.

In vivo electrical application on titanium implants stimulating bone formation.

The aim of the present in vivo study was to measure the bone implant contact area after electrical stimulation of dental implants. Ninety titanium dental implants (6 mm × 11.5 mm) with a smooth surface were placed in six male Beagle dogs and then the implant-bone interfaces was assessed by histological analyses after 7 and 15 d. The 12-mo-old dogs, with a weight of 15 kg, were randomly divided into two groups based on the duration of bone healing: 7 and 15 d. Also, implants were divided into three groups based on electrical stimulation: group A, 10 μA; group B, 20 μA; and group C, control group. The electrical current was applied by an electrical device coupled to the implant connection. After 7 d of electrical stimulation, no statistical differences in bone-implant interface contact area were observed. However, a significantly higher bone-implant interface contact area was recorded for group B than for groups A and C (p < 0.01) after 15 d. No statistical difference was observed between groups A and C (p > 0.05). The electrical stimulation of dental implants can generate a larger area of bone-implant interface contact as a result of bone formation. Factors such as different electrical current intensity and duration should be studied in further work to clarify the potential of this method.

Studying the coating of Alumina and Hydroxy Apatite on Tapered Dental Implant (In Vivo and In Vitro Study)

Background : In clinical trial studies, the success of dental implant depends on excellent biocompatibility, mechanical strength and characteristic of material such as surface properties of material. The Objective of this study was to evaluate the effects of coating implants with two materials (Al2O3 &amp;HA) .And this was in mixture form or in two layers form. Then their effect on the bond strength at the bone/implant interface with cell compatibility was evaluated. Materials and methods: Electrophoretic deposition technique (EPD) was used to obtain a uniform coating for each one of two types of coated layers on the screws (mixture of 50%HA and 50% Alumina and two layers). For examination of the changes occurred on the surface, structural ,elemental analysis and morphological investigations were carried out on the modified surfaces of the Ti-6Al-7Nb alloy using different techniques, namely X-ray diffraction (XRD), and Energy Dispersive X-ray Fluorescence (EDXRF). The in vivo study was done by the implantation of tapered screw–shaped uncoated and coated implants of 3mm diameter, 8 mm length (the threaded part is 5 mm and the smooth part is 3 mm) and 0.5mm pitch height.The tibia of white New Zealand rabbits were chosen as implantation sites. The right tibia of rabbit received two screws, (one uncoated and coated) while the left tibia of a rabbit received coated screws of two layers. To understand the bone-implant interface, biomechanical test was performed after 2, 6 and 18 weeks healing periods. 15 rabbits were sacrificed for each period. A removal torque was done for ten animals in each group, whereas the other five ones were used for histological testing with optical microscope. Results: The results indicates that there was a rapid reaction of bone towards coated Ti-6Al-7Nb alloy implants as compared with the uncoated one and more mature bone was observed after 6 weeks of implantation in screws coated with a mixture of Alumina and HA. The biomechanical test revealed that there was an increase in the torque mean value at bone-implant interface with time, with the highest mean values of bond strength in implants coated with a mixture of 50% HA and 50%Alumina. Also the bond strength of two layers coating was more than that of uncoated. The results of histological examination revealed a well tissue response with the formation of a lamellate and haversian type of osteon tissue after 18 weeks. Conclusion : this study concludes that coating by electrophoresis proved to be a valuable process to coat metallic implants with an osteoconductive material, and to form a uniform biocomposite and multiple layer coating. The biomechanical and biological properties of the bone-implant interface associated with the coated implants were improved comparing to the uncoated ones they have better mechanical properties and excellent biocompatibility through the improved performance of bone at the site of a bone implant contact area than the uncoated implants.

Estimation of the acetabular cup implant stability using impact analysis

Event Abstract Back to Event Estimation of the acetabular cup implant stability using impact analysis Adrien Michel1, Romain Bosc1 and Guillaume Haiat1 1 CNRS, Laboratoire MSME UMR 8208, France Introduction: Press-fit procedures for the insertion of cementless hip prostheses aim at obtaining an optimal implant stability. Primary stability of the acetabular cup (AC) implant is an important factor for long term surgical success. The aim of this study is to determine the feasibility of the application of an acoustical method to retrieve the AC implant stability based on the analysis of the signal corresponding to the time variation of the force applied between the hammer and the ancillary. Materials and Methods: 1) In vitro Study: The first objective of this work was to investigate whether the AC implant primary stability can be evaluated using the signals obtained with an impact hammer in vitro. The experimental configuration is shown in Fig. 1. A hammer equipped with a force sensor was used to impact the AC implant in 20 bovine bone samples. For each sample, different stability conditions were obtained by changing the cavity diameter. For each configuration, the inserted AC implant was impacted four times with a maximum force comprised between 2500 and 4500 N. An indicator I was determined based on the partial impulse estimation and the pull-out force F was measured. 2) In silico study: The second aim of this study was to investigate the dynamic interaction occurring between the hammer, the ancillary and bone tissue during the impact and to assess the potential of impact analysis to retrieve AC implant insertion conditions. A dynamic two-dimensionnal axisymmetric finite element model was developed to simulate the impaction of the AC implant into bone tissue assuming friction at the bone-implant interface and large deformations. Different values of interference fit (from 0.5 to 2 mm) and impact velocities (from 1 to 2 m.s-1) were considered. For each configuration, the variation of the force applied between the hammer and the ancillary was analyzed and an indicator I was determined based on the impact momentum of the signal. 3) Cadaveric study: The third objective was to assess the potential of the method to retrieve the primary stability of acetabular cup (AC) implants inserted in cadaveric specimens. AC implants were implanted in 12 cadaveric hips. A hammer instrumented with a piezoelectric force sensor was used to measure the impacts signals between the hammer and the ancillary. The tangential pull-out force F was measured. Results: The implant stability and the value of the indicator I reached a maximum value for an interference fit equal to 1 mm for 18 out of 20 samples. When pooling all samples and all configurations, the implant stability and I were significantly correlated (R2=0.83, see Fig. 2)[1]-[4]. The value of the polar gap decreases as a function of the impact velocity and increases as a function of the interference fit. The bone implant contact area was significantly correlated with the resonance frequency (R²=0.94) and the indicator (R²=0.95). Concerning the cadaveric experiments, a significant correlation (R2 = 0.69) was found between the indicator I and the pull-out force F. Discussion and Conclusion: The AC implant primary stability can be assessed through the analysis of the impact force signals obtained using an impact hammer. This study opens new paths for the development of a medical device which could be used as a decision support system to assist the surgeon during the insertion of the AC implant.

In vivo degradation of magnesium plate/screw osteosynthesis implant systems: Soft and hard tissue response in a calvarial model in miniature pigs

Biodegradable magnesium plate/screw osteosynthesis systems were implanted on the frontal bone of adult miniature pigs. The chosen implant geometries were based on existing titanium systems used for the treatment of facial fractures. The aim of this study was to evaluate the invivo degradation and tissue response of the magnesium alloy WE43 with and without a plasma electrolytic surface coating. Of 14 animals, 6 received magnesium implants with surface modification (coated), 6 without surface modification (uncoated), and 2 titanium implants. Radiological examination of the skull was performed at 1, 4, and 8 weeks post-implantation. After euthanasia at 12 and 24 weeks, X-ray, computed tomography, and microfocus computed tomography analyses and histological and histomorphological examinations of the bone/implant blocks were performed. The results showed a good tolerance of the plate/screw system without wound healing disturbance. In the radiological examination, gas pocket formation was found mainly around the uncoated plates 4 weeks after surgery. The micro-CT and histological analyses showed significantly lower corrosion rates and increased bone density and bone implant contact area around the coated screws compared to the uncoated screws at both endpoints. This study shows promising results for the further development of coated magnesium implants for the osteosynthesis of the facial skeleton.

Biomechanics and strain mapping in bone as related to immediately-loaded dental implants

The effects of alveolar bone socket geometry and bone–implant contact on implant biomechanics, and resulting strain distributions in bone were investigated. Following extraction of lateral incisors on a cadaver mandible, implants were placed immediately and bone–implant contact area, stability implant biomechanics and bone strain were measured. In situ biomechanical testing coupled with micro X-ray microscopy (µ-XRM) illustrated less stiff bone–implant complexes (701–822N/mm) compared with bone–periodontal ligament (PDL)–tooth complexes (791–913N/mm). X-ray tomograms illustrated that the cause of reduced stiffness was due to limited bone–implant contact. Heterogeneous elemental composition of bone was identified by using energy dispersive X-ray spectroscopy (EDS). The novel aspect of this study was the application of a new experimental mechanics method, that is, digital volume correlation, which allowed mapping of strains in volumes of alveolar bone in contact with a loaded implant. The identified surface and subsurface strain concentrations were a manifestation of load transferred to bone through bone–implant contact based on bone–implant geometry, quality of bone, implant placement, and implant design. 3D strain mapping indicated that strain concentrations are not exclusive to the bone–implant contact regions, but also extend into bone not directly in contact with the implant. The implications of the observed strain concentrations are discussed in the context of mechanobiology. Although a plausible explanation of surgical complications for immediate implant treatment is provided, extrapolation of results is only warranted by future systematic studies on more cadaver specimens and/or in vivo models.

The removal of Al 2O 3 particles from grit-blasted titanium implant surfaces: Effects on biocompatibility, osseointegration and interface strength in vivo

For the improvement of surface roughness and mechanical interlocking with bone, titanium prostheses are grit-blasted with Al 2O 3 particles during manufacturing. Dislocated Al 2O 3 particles are a leading cause of third-body abrasive wear in the articulation of endoprosthetic implants, resulting in inflammation, pain and ultimately aseptic loosening and implant failure. In the present study, a new treatment for the removal of residual Al 2O 3 particles from grit-blasted, cementless titanium endoprosthetic devices was investigated in a rabbit model. The cleansing process reduces residual Al 2O 3 particles on titanium surfaces by up to 96%. The biocompatibility of the implants secondary to treatment was examined histologically, the bone–implant contact area was quantified histomorphometrically, and interface strength was evaluated with a biomechanical push-out test. Conventional grit-blasted implants served as control. In histological and SEM analysis, the Al 2O 3-free implant surfaces demonstrated uncompromised biocompatibility. Histomorphometrically, Al 2O 3-free implants exhibited a significantly increased bone–implant contact area ( p = 0.016) over conventional implants between both evaluation points. In push-out testing, treated Al 2O 3-free implants yielded less shear resistance than conventional implants at both evaluation points ( p = 0.018). In conclusion, the new surface treatment effectively removes Al 2O 3 from implant surfaces. The treated implants demonstrated uncompromised biocompatibility and bone apposition in vivo. Clinically, Al 2O 3-free titanium prostheses could lead to less mechanical wear of the articulating surfaces and ultimately result in less aseptic loosening and longer implant life.

Machining and Accuracy Studies for a Tibial Knee Implant Using a Force-Controlled Robot

Total knee arthroplasty requires accurate preparation of the bone surfaces to maximize bone implant contact area in cementless surgery and to obtain proper joint kinematics and ligament balancing. Robots can make the cuts with the necessary high precision. The purpose of this article is threefold: to propose an alternative method for intraoperative registration using an in-tramedullary rod and an alternative method for force control using the hybrid force-velocity control scheme; to demonstrate that the accuracy and the surface flatness of the cuts machined by a robot are better than in a conventional operation; and to monitor the machining process and to try to derive some information about the local bone quality from it. The results of the laboratory study are promising: the surface flatness of the tibial plateau, calculated using a least squares method, is 0.1–0.2 mm, which is significantly better than in conventional surgery; and the high angular accuracy of the robot allows the bone cuts to be located precisely. Further, an exponential relation between milling forces and local bone density was established, so measurements of the milling forces can provide the surgeon with on -line information about the local bone quality.

Machining and accuracy studies for a tibial knee implant using a force-controlled robot

Total knee arthroplasty requires accurate preparation of the bone surfaces to maximize bone implant contact area in cementless surgery and to obtain proper joint kinematics and ligament balancing. Robots can make the cuts with the necessary high precision. The purpose of this article is threefold: to propose an alternative method for intraoperative registration using an intramedullary rod and an alternative method for force control using the hybrid force-velocity control scheme; to demonstrate that the accuracy and the surface flatness of the cuts machined by a robot are better than in a conventional operation; and to monitor the machining process and to try to derive some information about the local bone quality from it. The results of the laboratory study are promising: the surface flatness of the tibial plateau, calculated using a least squares method, is 0.1-0.2 mm, which is significantly better than in conventional surgery; and the high angular accuracy of the robot allows the bone cuts to be located precisely. Further, an exponential relation between milling forces and local bone density was established, so measurements of the milling forces can provide the surgeon with on-line information about the local bone quality.