| 1. |
- Albrektsson, Tomas, 1945, et al.
(författare)
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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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Ingår i: Clinical Implant Dental Related Research 9. - : Wiley. - 1523-0899. ; 9:2, s. 65-70
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Tidskriftsartikel (refereegranskat)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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| 2. |
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| 3. |
- Fröjd, Victoria, 1986, et al.
(författare)
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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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Ingår i: International Journal of Oral and Maxillofacial Surgery. - : Elsevier BV. - 0901-5027. ; 37:6, s. 561-566
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Fröjd, Victoria, et al.
(författare)
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Increased bone contact to a calcium incorporated oxidized commercially pure titanium implant; an in vivo study in rabbit
- 2008
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Ingår i: International Journal of Oral and Maxillofacial Surgery. - : Elsevier BV. - 0901-5027 .- 1399-0020. ; 37:6, s. 561-566
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Meirelles, Luiz, 1974, et al.
(författare)
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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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Ingår i: Clinical oral implants research. - : Wiley. - 1600-0501 .- 0905-7161. ; 24:4, s. 461-467
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Meirelles, Luiz, 1974, et al.
(författare)
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Bone reaction to nano hydroxyapatite modified titanium implants placed in a gap-healing model
- 2008
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Ingår i: Journal Biomedical MAterials Research - A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87:3, s. 624-631
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Meirelles, Luiz, 1974, et al.
(författare)
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Effect of hydroxyapatite and titania nanostructures on early in vivo bone response
- 2008
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1708-8208 .- 1523-0899. ; 10:4, s. 245-254
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Tidskriftsartikel (refereegranskat)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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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Meirelles, Luiz, 1974, et al.
(författare)
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Increased bone formation to unstable nano rough implants
- 2007
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Ingår i: Clin Oral Implants Res. - : Wiley. - 0905-7161. ; 18:3
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Tidskriftsartikel (refereegranskat)abstract
- Early bone response to cylindrical smooth titanium implants (S(a)=0.1 microm) inserted into the rabbit tibia was compared in a stable and nonstable regime. Surface roughness parameters were calculated from measurements obtained with optical interferometry and atomic force microscopy. Contrary to our hypothesis, the nonstable implant showed higher bone to metal contact and increased bone area in the endosteal region compared with the stable implant after 4 weeks of healing. Bone area measurements in the cortical region revealed similar values. Primitive woven bone was found in close contact with both implants, but significantly more with the nonstable implant. Finding more bone-to-implant contact (BIC) need not necessarily indicate that unstable implants were more strongly integrated. Primitive bone stage development observed indicates less strong implant anchorage than could be expected from BIC percentage alone. Stable implant design used in this study is a reliable model to evaluate submicron and nanostructures in vivo, as implant stability was achieved in the absence of microirregularaties.
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| 12. |
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| 13. |
- Meirelles, Luiz, 1974, et al.
(författare)
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Nano hydroxyapatite structures influence early bone formation
- 2008
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Ingår i: Journal Biomedical Materials Research - A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87:2, s. 299-307
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Tidskriftsartikel (refereegranskat)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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| 14. |
- Meirelles, Luiz, 1974
(författare)
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On nano size structures for enhanced bone formation
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Purpose The general aim of the present thesis was to investigate early bone response to titanium implants modified with nano size structures. Therefore, 1. a model to evaluate titanium implants modified with nano size structures was validated; 2. a suitable detection method of nano size structures was implemented. Materials and Methods A rabbit model was selected and healing time was 4 weeks in all experiments. A smooth cylindrical implant design was selected in order to control the macrothreads and micro-structures. Thus, early bone response could be related to added nano size structures alone. A stabilization plate was utilized to ensure adequate fixation of the attached implant. Smooth implants were obtained through polishing techniques (electrical and mechanical) and were used as control surfaces and, after relevant modifications, as experimental surfaces. Six surface modifications were investigated: 1. mechanically polished, 2. electropolished, 3. nano hydroxyapatite (HA), 4. nano titania, 5. blasted (TiO2) and 6. fluoride-modified. The implant surface topography was measured with an interferometer and an atomic force microscope. Surface roughness parameters were calculated and nano size structures dimension and distribution were characterized. Surface morphology was evaluated by scanning electron microscopy. Surface chemical composition was monitored with X-ray photoelectron spectroscopy. The bone response was measured with removal torque tests and histological and histomorphometrical analyses. Results The model tested to evaluate smooth implants was found adequate. Atomic force measurements combined with image processor analyses software was suitable to characterize nano size structures at the implant surface. Nano HA modified implants enhanced bone formation at 4 weeks of healing compared to electropolished implants. However, placed in a gap healing model the nano HA modified implants showed similar bone formation compared to electropolished implants. If both test and control implants were modified with nano structures, so-called bioactive nano HA and bioinert nano titania, respectively; enhanced bone response of 24% was found to the ?bioinert? nano titania implants, although not statistically significant. The beneficial effect of nano size structures on the experimental model was tested on screw shaped moderately rough implants. The oral implants that exhibited particular nano structures (fluoride and nano HA) showed a tendency of higher removal torque values compared to control (blasted) implants, that lacked such structures. Conclusions Based on in vivo animal experiments, enhanced bone formation was demonstrated to smooth and moderately rough titanium implants modified with nano size structures with different chemical composition.
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| 15. |
- Meirelles, Luiz, 1974, et al.
(författare)
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The effect of chemical and nano topographical modifications on early stage of osseointegration
- 2008
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Ingår i: The International Journal of Oral & Maxillofacial Implants. - 0882-2786. ; 23:4, s. 641-7
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate the effect of chemically modified implants with similar micro but different nano topography on early stage of osseointegration. Materials and Methods: Screw shaped implants were placed in the flat proximal medial tibial methaphyses of 10 New Zealand white rabbits. Blasted (control); blasted-fluoride and blasted-nano HA implants were investigated. Surface evaluation included chemical analyses with x-ray photoelectron spectroscopy, morphological analyses with scanning electron microscopy and topographical analyses with interferometry. Bone response was investigated with removal torque measurements and histological analyses after a healing period of 4 weeks. Results: Chemical analyses revealed the presence of Ti, O, C and N in all implant groups. The blasted-F group revealed F and the blasted nano HA group Ca and P with simultaneous decrease of Ti and O. Surface roughness parameters showed a slight decrease of the average height deviation for the blasted nano-HA and blasted-F compared to the blasted control implants. SEM images at high magnification indicated the presence of nano structures on the chemically modified implants. Removal torque (RTQ) mean values revealed an increase of 17% to 25% for the chemically modified implants compared to the control implants and the histological analyses demonstrated a similar enhanced bone formation to the chemically modified implants with nanostructures. Conclusion: Chemical modifications used in the present study were capable of producing a unique nano topography and together with the ions present at the implant surface may explain the increased RTQ and histomorphometric values after a healing period of 4 weeks.
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| 16. |
- Meirelles, Luiz, et al.
(författare)
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The effect of chemical and nanotopographical modifications on the early stages of osseointegration
- 2008
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Ingår i: International Journal of Oral & Maxillofacial Implants. - 0882-2786 .- 1942-4434. ; 23:4, s. 641-647
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the effect of chemically modified implants with similar microtopographies but different nanotopographies on early stages of osseointegration. MATERIALS AND METHODS: Forty screw-shaped implants were placed in 10 New Zealand white rabbits. The implant surface modifications investigated in the present study were (1) blasting with TiO2 and further (2) fluoride treatment or (3) modification with nano-hydroxyapatite. Surface evaluation included topographical analyses with interferometry, morphologic analyses with scanning electron microscopy, and chemical analyses with x-ray photoelectron spectroscopy. Bone response was investigated with the removal torque test, and histologic analyses were carried out after a healing period of 4 weeks. RESULTS: Surface roughness parameters showed a slight decrease of the average height deviation for the fluoride-treated compared to the blasted (control) and nano-hydroxyapatite implants. Scanning electron microscopic images at high magnification indicated the presence of nanostructures on the chemically modified implants. Chemical analyses revealed the presence of titanium, oxygen, carbon, and nitrogen in all implant groups. The blasted-fluoride group revealed fluoride, and the blasted-nano HA group calcium and phosphorus with simultaneous decrease of titanium and oxygen. Removal torque values revealed an increased retention for the chemically modified implants that exhibit specific nanotopography. The histologic analyses demonstrated immature bone formation in contact with the implant surface in all groups, according to the healing period of the experiment. CONCLUSION: Chemical modifications used in the present study were capable of producing a particular nanotopography, and together with the ions present at the implant surface, may explain the increased removal torque values after a healing period of 4 weeks.
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| 17. |
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| 18. |
- Svanborg, Lory Melin, et al.
(författare)
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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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Ingår i: International Journal of Dentistry. - : Hindawi Limited. - 1687-8728 .- 1687-8736. ; 2014
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Tidskriftsartikel (refereegranskat)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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