| 71. |
- Jimbo, Ryo, et al.
(författare)
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The biological response to three different nanostructures applied on smooth implant surfaces
- 2012
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Ingår i: Clinical Oral Implants Research. - Hoboken, USA : Wiley-Blackwell. - 0905-7161 .- 1600-0501. ; 23:6, s. 706-712
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate the biological effects of three calcium phosphate (CaP) coatings with nanostructures on relatively smooth implant surfaces.Material and methods: Stable CaP nanoparticle suspensions of different particle sizes and structures were coated onto implants by immersion and subsequent heat treatment. An uncoated implant was used as the control. After topographical and chemical characterizations, implants were randomly inserted into rabbit tibiae for removal torque (RTQ) testing. To confirm the biological reaction, implants were placed in the bilateral femurs of three rabbits.Results: The topographical characterization showed that each surface had different nanostructural characteristics and X-ray photon spectroscopy showed various CaP compositions. The control and test groups had different nanotopographies; however, the differences among the test groups were only significant for Surfaces B and C and the rest were insignificant. The RTQ tests showed significantly higher values in two test groups (Surface A and Surface C). Histologically, no adverse effects were seen in any group. Histomorphometrical evaluation showed comparable or better osseointegration along the implant threads in the test groups.Conclusion: The three different CaP coatings with nanostructures on the implant surfaces had enhancing effects on osseointegration. Along with the surface nanotopography, the CaP chemistry might have influenced the biological outcomes.
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| 72. |
- Johansson, Pär, et al.
(författare)
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Biomechanical, histological, and computed X-ray tomographic analyses of hydroxyapatite coated PEEK implants in an extended healing model in rabbit
- 2018
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 106:5, s. 1440-1447
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Tidskriftsartikel (refereegranskat)abstract
- A nanosized hydroxyapatite (HA) modification on polyetheretherketone (PEEK) using a novel spin coating technique was investigated in a rabbit model. Spin coating technique creates a 20-40 nm thick layer of nanosized HA particles with similar shape, size, and crystallinity as human bone. Some implants were designed with a perforating hole in the apical region to mimic a fusion chamber of a spinal implant. The coating nano-structures were assessed using a scanning electron microscope. The in vivo response to HA-PEEK was compared to untreated PEEK with respect to removal torque, histomorphometry, and computed microtomography. The HA-coated and pure PEEK implants were inserted in the tibia and femur bone according to simple randomization. The rabbits were sacrificed 20 weeks after implantation. Removal torque analysis showed significantly higher values for HA-PEEK. Qualitative histological evaluation revealed an intimate contact between PEEK and the bone at the threads and perforated hole. Histomorphometric assessment showed higher bone-implant and bone area values for HA-PEEK but without statistical significance. The effect of the HA coating showed most prominent effect in the removal torque which may be correlated to an alteration in the bone quality around the HA-PEEK implants. (c) 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1440-1447, 2018.
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| 73. |
- Juodzbalys, Gintaras, et al.
(författare)
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Titanium dental implant surface micromorphology optimization.
- 2007
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Ingår i: The Journal of oral implantology. - 0160-6972. ; 33:4, s. 177-85
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this investigation was to create an acid-etched implant surface that is similar to that created by sandblasting combined with acid etching and to compare it with the surfaces of various commercially available screw-type implants. Titanium grade 5 disks were machined in preparation for acid etching. Tests were carried out using different acids and combinations of them with varying time exposures. All etched surfaces were scanned with an electron microscope, and digital images were created for visual evaluation and description of the surfaces. The etched surfaces were evaluated for surface morphology (combination of microroughness and waviness); the surface most like the sandblasted/acid-etched surface was best obtained with a combination of sulfuric and hydrochloric acids. The etched titanium disks were fixed in acrylic resin (2 were cut and polished and 2 were scored and fractured) and the surface profile was examined. In the second part of the investigation, 28 screw-shaped implants that were manufactured from commercially available titanium grade 5 were selected and divided into 2 groups: 3 implants were used as controls (machined surface), and 25 implants were processed using the preferred etching method determined in the first part of the investigation. Magnifications of 27, 200, and 2000 were used to analyze the first 2 consecutive crests of threads, flanks, and root of threads of each implant with the treated surface. A 3-dimensional optical interferometer was used to characterize the surface roughness of both control and test groups. Three screws were selected from each group and measured at 9 sites: 3 measurements each on the crest, root, and flank of the threads. To describe the surface roughness in numbers, the following parameters were used: the average height deviation (Sa), the developed interfacial area ratio (Sdr), the fastest decay autocorrelation length (Sal), and the density of summits (Sds). In addition, in a third experiment, the surfaces of 5 commercially available screw-type implants and the experimental ones were analyzed and compared. It was concluded that the new experimental acid-etched titanium surface had the features of a roughened titanium surface, with glossily microroughness and large waviness. In general, the experimental surface was significantly rougher than the selected commercially available implants and similar to a sandblasted/acid-etched surface (top Sa: 2.08 +/- 0.36 microm, Sdr: 1.34 +/- 0.3 microm, valleys: 1.16 +/- 0.1 microm and 0.68 +/- 0.1 microm, flanks: 2.24 +/- 0.8 microm and 1.27 +/- 0.1 microm, respectively).
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| 74. |
- Kanno, T., et al.
(författare)
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Topography, microhardness, and precision of fit on ready-made zirconia abutment before/after sintering process
- 2007
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Ingår i: Clin Implant Dent Relat Res. ; 9:3, s. 156-65
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Tidskriftsartikel (refereegranskat)abstract
- Background Sintering porcelain on a ceramic abutment may change the microstructure and result in aging processes that influence the mechanical properties, internal strain, and the three-dimensional form of the abutment, thus causing a possible misfit between the abutment and the fixture. Purpose The aim was to investigate topography, microhardness, and precision of fit on yttrium-stabilized zirconia (Y-TZP) abutments before/after the sintering process. Materials and Methods Ten Y-TZP abutment samples were ground to a shape used in the clinical situation and divided at random into two groups: before/after sintering. After the surface roughness was measured on all abutments, the abutments were connected to fixture replicas, embedded in resin, and cut in the longitudinal axis. Both sides of the cut samples were measured with respect to microhardness and minimum distance between fixture and abutment surface. t-Test, one-way analysis of variance, and Bonferroni multiple comparisons were used to investigate statistical significant differences. Results The surface roughness (S(a) and S(dr)) after sintering was significantly higher than before sintering. The total average values of microhardness after sintering were statistically lower than before sintering with a difference of 2%. The total distance between abutment/fixture before/after sintering demonstrated no statistically significant difference. Contact between abutment/fixture was most common at the top area of the fixture. Conclusion A slight decrease of microhardness and contamination of porcelain particles immediately below the veneered part were found on the Y-TZP abutment after sintering. The sintering process did not affect the precision of fit.
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| 75. |
- Kjellin, P., et al.
(författare)
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A nanosized zirconium phosphate coating for PEEK implants and its effect in vivo
- 2020
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Ingår i: Materialia. - : Elsevier BV. - 2589-1529. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Surface treatments and coatings can be applied to polyether ether ketone (PEEK) implants to improve their ability to osseointegrate. A new coating, consisting of amorphous nanosized zirconium phosphate (ZrP) was applied to PEEK and titanium substrates. The coating was applied by using a microemulsion as a carrier for the nanoparticles. It was found that the coating formed a thin continuous porous layer on top of the substrate, with pore diameters of 10–50 nm. The thickness of the coating was estimated to <100 nm. The resistance to acidic (pH = 4) conditions and exposure to ultrasonication was investigated with XPS, which showed no loss of coating. The adherence of the coating was investigated by insertion of implants in simulated bone material, which showed a minor loss in coating. In vitro (SBF) testing showed that the coating promoted crystallization of calcium phosphates, for uncoated PEEK, no crystallization was detected. The in vivo performance of the ZrP coating was examined by coating screw shaped PEEK implants which were implanted in rabbit tibia for 6 weeks. The anchoring strength of the implants was evaluated with removal torque (RTQ) measurements. The average RTQ for the ZrP coated implants was significantly higher compared to the non-coated implants. The results show that a nanosized ZrP coating on PEEK implants can transform the surface from having a low ability to osseointegrate to a surface which stimulates bone tissue growth. This makes the ZrP coating an interesting alternative for coating PEEK implants, such as spinal fusion cages and tendon fixation screws. © 2020
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| 76. |
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| 77. |
- Kruger, D., et al.
(författare)
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High-resolution ex vivo analysis of the degradation and osseointegration of Mg-xGd implant screws in 3D
- 2022
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Ingår i: Bioactive Materials. - : Elsevier BV. - 2452-199X. ; 13, s. 37-52
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Tidskriftsartikel (refereegranskat)abstract
- Biodegradable magnesium (Mg) alloys can revolutionize osteosynthesis, because they have mechanical properties similar to those of the bone, and degrade over time, avoiding the need of removal surgery. However, they are not yet routinely applied because their degradation behavior is not fully understood. In this study we have investigated and quantified the degradation and osseointegration behavior of two biodegradable Mg alloys based on gadolinium (Gd) at high resolution. Mg-5Gd and Mg-10Gd screws were inserted in rat tibia for 4, 8 and 12 weeks. Afterward, the degradation rate and degradation homogeneity, as well as bone-to-implant interface, were studied with synchrotron radiation micro computed tomography and histology. Titanium (Ti) and polyether ether ketone (PEEK) were used as controls material to evaluate osseointegration. Our results showed that Mg-5Gd degraded faster and less homogeneously than Mg-10Gd. Both alloys gradually form a stable degradation layer at the interface and were surrounded by new bone tissue. The results were correlated to in vitro data obtained from the same material and shape. The average bone-to-implant contact of the Mg-xGd implants was comparable to that of Ti and higher than for PEEK. The results suggest that both Mg-xGd alloys are suitable as materials for bone implants.
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| 78. |
- Larsen, Olav Inge, et al.
(författare)
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Antimicrobial effects of three different treatment modalities on dental implant surfaces.
- 2017
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Ingår i: The Journal of oral implantology. - 1548-1336. ; 43:6, s. 429-436
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Tidskriftsartikel (refereegranskat)abstract
- Resolution of peri-implant inflammation and re-osseointegration of peri-implantitis affected dental implants seem to be dependent on bacterial decontamination. The aims of the this study were to evaluate the antimicrobial effects of three different instrumentations on a micro-textured dental implant surface contaminated with an avirulent or a virulent Porphyromonas gingivalis strain and to determine alterations to the implant surface following instrumentation. Forty-five dental implants (Straumann SLA) were allocated to three treatment groups: Er:YAG laser, chitosan brush, and titanium curette (10 implants each), a positive (10 implants) and a negative (five implants) control. Each treatment group and the positive control were split into subgroups of five implants subsequently contaminated with either the avirulent or virulent P. gingivalis strain. The antimicrobial effect of instrumentation was evaluated using checkerboard DNA-DNA hybridization. Implant surface alterations were determined using a light interferometer. Instrumentation significantly reduced the number of attached P. gingivalis (p<0.001) with no significant differences among groups (p=0.310). A significant overall higher median score was found for virulent compared with avirulent P. gingivalis strains (p=0.007); the Er:YAG laser uniquely effective removing both bacterial strains. The titanium curette significantly altered the implant surface micro-texture. Neither the Er:YAG laser nor the chitosan brush significantly altered the implant surface. The three instrumentations appear to have a similar potential to remove P. gingivalis. The titanium curette significantly altered the microstructure of the implant surface.
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| 79. |
- Macdonald, Warren, 1954, et al.
(författare)
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Variation in surface texture measurements.
- 2004
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Ingår i: Journal of biomedical materials research. Part B, Applied biomaterials. - : Wiley. - 1552-4973. ; 70:2, s. 262-9
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Tidskriftsartikel (refereegranskat)abstract
- Surface texture influences cellular response to implants, implant wear, and fixation, yet measurement and reporting of surface texture can be confusing and ambiguous. Seven specimens of widely different surface textures were submitted to three internationally renowned laboratories for surface texture characterization. The specimens were from dental implants, orthopedic implants, and femoral heads. Areas to be measured were clearly marked; simplified instructions were supplied but specific measurement parameters were not requested. Techniques used included contact profilometry, two- and three-dimensional laser profilometry, and atomic force microscopy. Four to thirteen parameters were reported, 2D or 3D, including R(a) or S(a); only three were common to all centers. The results varied by as much as +/-300-1000%, depending on technique and surface type. Some surfaces were not measurable by some techniques. One dental implant surface was reported with R(a) of 0.17, 0.85, 1.9, and 4.4 microm. The CoCr femoral head ranged from an R(a) of 0.011 to 0.10 microm; the zirconia head from 0.006 to 0.05 microm. Similar variability was reported for the other parameters. Useful surface texture characterization requires reporting of all measurement parameters. Comparisons between studies may be compromised if differences in technique are not considered.
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| 80. |
- Mahmood, Deyar Jallal Hadi, et al.
(författare)
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Production tolerance of conventional and digital workflow in the manufacturing of glass ceramic crowns
- 2019
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Ingår i: Dental Materials. - : Elsevier BV. - 0109-5641 .- 1879-0097. ; 35:3, s. 486-494
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. To measure and compare the size of the cement gap of wax and polymer copings and final glass-ceramic crowns, produced from conventional and digital workflows, one additive and one subtractive. Methods. Thirty wax copings were made by conventional manual layering technique and modeling wax on stone models with spacer varnish simulating a cement spacer. The wax copings were embedded and press-cast in lithium disilicate glass ceramic. Thirty wax copings were produced by milling from a wax blank, i.e. subtractive manufacturing, and thirty polymer burn-out copings were produced by stereolithography, i.e. additive manufacturing. These copings were embedded and press-cast in lithium disilicate glass ceramic in the same manner as the conventional group. The fit of the wax/polymer copings and subsequent crowns was checked using an impression replica method. Mean values for cement gap for marginal, axial, and occlusal areas were calculated and differences were analyzed using Student's t-test. Results. There were significant differences in mean values for accuracy/production tolerance among different manufacturing techniques for both production stages: wax and polymer copings and final pressed glass-ceramic crowns. In general, crowns produced from a digital additive workflow showed smaller mean cement gaps than crowns produced from a conventional workflow or a digital subtractive workflow. Additive polymer copings showed significantly smaller cement gaps than milled wax copings (p <=.001) and conventional wax copings (p <=.001) in the axial area. In the occlusal area, both additive polymer copings and conventional wax copings showed significantly smaller cement gaps than milled wax copings (p = .002 and p <=.001 respectively). Crowns produced from conventional manual build-up wax copings showed significantly larger mean cement gaps than crowns produced from milled wax and additively manufactured polymer copings in the marginal and axial areas (p <=.001). Among the crowns with smaller cement gaps, crowns produced from additively manufactured polymer copings showed significantly smaller mean cement gaps than crowns produced from milled wax in the marginal and axial areas (p <=.001). In the occlusal areas, the differences in mean cement gaps were only statistically significant between crowns produced from conventional manual build-up wax copings and crowns produced from milled wax where the latter ones showed smaller mean cement gaps (p = .025). Significance. The present study suggests that an additive manufacturing technique produces smaller mean cement gaps in glass-ceramic crowns than a conventional or subtractive manufacturing technique. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.
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