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- Meirelles, Luiz, 1974, et al.
(author)
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Bone reaction to nano hydroxyapatite modified titanium implants placed in a gap-healing model
- 2008
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In: Journal Biomedical MAterials Research - A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87:3, s. 624-631
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Journal article (peer-reviewed)abstract
- Nanohydroxyapatite materials show similar chemistry to the bone apatite and depending on the underlying topography and the method of preparation, the nanohydroxyapatite may simulate the specific arrangement of the crystals in bone. Hydroxyapatite (HA) and other CaP materials have been indicated in cases in which the optimal surgical fit is not achievable during surgery, and the HA surface properties may enhance bone filling of the defect area. In this study, very smooth electropolished titanium implants were used as substrata for nano-HA surface modification and as control. One of each implant (control and nano HA) was placed in the rabbit tibia in a surgical site 0.7 mm wider than the implant diameter, resulting in a gap of 0.35 mm on each implant side. Implant stability was ensured by a fixating plate fastened with two side screws. Topographical evaluation performed with an optical interferometer revealed the absence of microstructures on both implants and higher resolution evaluation with AFM showed similar nanoroughness parameters. Surface pores detected on the AFM measurements had similar diameter, depth, and surface porosity (%). Histological evaluation demonstrated similar bone formation for the nano HA and electropolished implants after 4 weeks of healing. These results do not support that nano-HA chemistry and nanotopography will enhance bone formation when placed in a gap-healing model. The very smooth surface may have prevented optimal activity of the material and future studies may evaluate the synergic effects of the surface chemistry, micro, and nanotopography, establishing the optimal parameters for each of them.
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- Meirelles, Luiz, 1974, et al.
(author)
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Effect of hydroxyapatite and titania nanostructures on early in vivo bone response
- 2008
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In: Clinical Implant Dentistry and Related Research. - : Wiley. - 1708-8208 .- 1523-0899. ; 10:4, s. 245-254
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Journal article (peer-reviewed)abstract
- Objective: Hydroxyapatite or titania nano structures were applied on smooth titanium implant cylinders. The aim was to investigate whether nano HA may result in enhanced osseointegration compared to nano titania structures. Material and Methods: Surface topography evaluation included detailed characterization of nano size structures present at the implant surface combined with surface roughness parameters at the micro- and nano- meter level of resolution. Microstructures were removed from the surface to ensure that bone response observed was dependent only on the nanotopography and/or chemistry of the surface. Early in vivo bone response (4 weeks) evaluation was investigated in a rabbit model. Results: In the present study, nano titania coated implants showed an increased coverage area and feature density, forming a homogenous layer compared to nano HA implants. Bone response observed at 4 weeks could not be explained by the surface chemistry. New formed bone connected to the original cortical bone demonstrated an increase of 24% for the nano titania compared to the nano HA implant, although the difference was not statistically significant. Conclusion: Thus, no evidence of enhanced bone formation to nano hydroxyapatite modified implants was observed compared to nano titania modified implants. The presence of specific nano structures; dependent on the surface modification exhibiting different size and distribution did modulate in vivo bone response.
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- Meirelles, Luiz, 1974, et al.
(author)
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Nano hydroxyapatite structures influence early bone formation
- 2008
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In: Journal Biomedical Materials Research - A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87:2, s. 299-307
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Journal article (peer-reviewed)abstract
- In a study model that aims to evaluate the effect of nanotopography on bone formation, micrometer structures known to alter bone formation, should be removed. Electropolished titanium implants were prepared to obtain a surface topography in the absence of micro structures, thereafter the implants were divided in two groups. The test group was modified with nanosize hydroxyapatite particles; the other group was left uncoated and served as control for the experiment. Topographical evaluation demonstrated increased nanoroughness parameters for the nano-HA implant and higher surface porosity compared to the control implant. The detected features had increased size and diameter equivalent to the nano-HA crystals present in the solution and the relative frequency of the feature size and diameter was very similar. Furthermore, feature density per m2 showed a decrease of 13.5% on the nano-HA implant. Chemical characterization revealed calcium and phosphorous ions on the modified implants, whereas the control implants consisted of pure titanium oxide. Histological evaluation demonstrated significantly increased bone formation to the coated (p < 0.05) compared to uncoated implants after 4 weeks of healing. These findings indicate for the first time that early bone formation is dependent on the nanosize hydroxyapatite features, but we are unaware if we see an isolated effect of the chemistry or of the nanotopography or a combination of both.
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4. |
- Svanborg, Lory Melin, et al.
(author)
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Evaluation of bone healing on sandblasted and Acid etched implants coated with nanocrystalline hydroxyapatite: an in vivo study in rabbit femur
- 2014
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In: International Journal of Dentistry. - : Hindawi Limited. - 1687-8728 .- 1687-8736. ; 2014
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Journal article (peer-reviewed)abstract
- This study aimed at investigating if a coating of hydroxyapatite nanocrystals would enhance bone healing over time in trabecular bone. Sandblasted and acid etched titanium implants with and without a submicron thick coat of hydroxyapatite nanocrystals (nano-HA) were implanted in rabbit femur with healing times of 2, 4, and 9 weeks. Removal torque analyses and histological evaluations were performed. The torque analysis did not show any significant differences between the implants at any healing time. The control implant showed a tendency of more newly formed bone after 4 weeks of healing and significantly higher bone area values after 9 weeks of healing. According to the results from this present study, both control and nano-HA surfaces were biocompatible and osteoconductive. A submicron thick coating of hydroxyapatite nanocrystals deposited onto blasted and acid etched screw shaped titanium implants did not enhance bone healing, as compared to blasted and etched control implants when placed in trabecular bone.
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5. |
- Albrektsson, Tomas, 1945, et al.
(author)
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Survival of NobelDirect Implants: An Analysis of 550 Consecutively Placed Implants at 18 Different Clinical Centers
- 2007
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In: Clinical Implant Dental Related Research 9. - : Wiley. - 1523-0899. ; 9:2, s. 65-70
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Journal article (peer-reviewed)abstract
- BACKGROUND: A recently introduced implant, the NobelDirect (Nobel Biocare AB, Göteborg, Sweden), has previously been documented with substantial bone resorption in a large number of operated cases. PURPOSE: The aim of this study was to evaluate the failure rate of NobelDirect implants in a retrospective multicenter survey. MATERIALS AND METHODS: A total of 550 NobelDirect implants consecutively placed in over 269 patients at 18 centers were evaluated with regard to failure rate after an average follow-up of about 1 year. RESULTS: The overall failure percentage was 10.9% (59 failures). The 58 implants not loaded directly showed only one failure (1.7%) versus 58 failures (11.8%) of those implants that were loaded directly. A chemical x-ray photoelectron spectroscopy analysis of an implant from the original batch showed up to 3.5% silicon at parts of the implants. A retrieval analysis of one implant removed at 2 years after placement demonstrated bone resorption down to the level of the fifth thread. CONCLUSIONS: It is concluded that the NobelDirect implant, if placed with a punch procedure, ground down in situ, and loaded directly, shows an unusually high failure rate at 1 year.
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7. |
- Fröjd, Victoria, 1986, et al.
(author)
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Increased bone contact to a calcium incorporated oxidized c.p. titanium implant: an in vivo study in rabbit.
- 2008
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In: International Journal of Oral and Maxillofacial Surgery. - : Elsevier BV. - 0901-5027. ; 37:6, s. 561-566
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Journal article (peer-reviewed)abstract
- The aim of this study was to evaluate the bone response to an oxidized titanium implant (Ox) and a calcium-incorporated oxidized titanium implant (Ca). A blasted titanium implant (Bl) was used as control. The implants were topographically characterized using an optical interferometer and placed: one in each distal femoral metaphysis and two in each proximal tibial metaphysis in rabbits. The rabbits were killed 12 weeks after implant insertion, and the implants and their surrounding tissues were removed en bloc for histomorphometrical evaluations. Topographical evaluation revealed three different surfaces: average height deviation (S(a), microm) values for Ca:Ox:Bl implants were 0.3:0.6:0.9, developed surface area ratios (%) 17:44:31, number of summits per microm(2) 208:136:118, and core fluid retention index values 1.33:1.33:1.38. The mean percentages of bone contact to the implants placed in the tibia (Ca:Ox:Bl) were 47:30:34 and to the implants placed in the femur (Ca:Ox) 32:20. The mean percentages of surrounding bone area for the implants placed in the tibia were 40:47:37 and for the implants placed in the femur 43:46. A significant increase in bone contact was found for smooth (S(a) <0.5 microm) but more densely peaked calcium-incorporated oxidized implants when compared to slightly rougher (S(a)=0.5-1.0 microm) oxidized or blasted implants.
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8. |
- Meirelles, Luiz, 1974, et al.
(author)
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A novel technique for tailored surface modification of dental implants - a step wise approach based on plasma immersion ion implantation.
- 2013
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In: Clinical oral implants research. - : Wiley. - 1600-0501 .- 0905-7161. ; 24:4, s. 461-467
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Journal article (peer-reviewed)abstract
- OBJECTIVES: A novel technique based on plasma immersion ion implantation (PIII) is presented to modify titanium implant surfaces. MATERIALS AND METHODS: Initially, the implants are cleaned with argon to remove contaminants and the nanostructures are created by the bombardment of the surface with a mix of noble gases. Desired crystal structure of the titanium is obtained by the implantation of oxygen on the contaminant-free surface with particular nanostructures. RESULTS: In this study, turned implants modified by PIII revealed a high density of rutile-TiO(2) nanostructures. Turned implants used as control revealed mainly microstructures and amorphous crystal structure. Surface roughness values were similar at the microscale for both turned and turned+PIII implants. Bone response was evaluated by removal torque tests of implants placed in the rabbit tibia and femur. After 4weeks of healing, turned+PIII demonstrated higher removal torque values (P=0.001) compared to turned implants. CONCLUSIONS: The presence of rutile-TiO(2) nanostructures may explain the improved bone formation to turned+PIII implants.
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