1,720,964 research outputs found
Resonance frequency measurements of implant stability in the dog mandible: experimental comparison with histomorphometric data
No full textThe aim of the present study was to test the hypothesis that measurements of implant stability using resonance frequency analysis (RFA) correlate with histomorphometric data of bone anchorage. Ten adult female foxhounds received a total of 80 implants in their mandibles 3 months after removal of all premolar teeth. At the time of implant placement, torque required for bone tapping was registered as a measure of bone density and immediately after placement implant stability was assessed using RFA. RFA measurements were repeated at the time of implant retrieval after 1 month (5 dogs) and 3 months (5 dogs). Peri-implant bone regeneration was assessed histomorphometrically by measuring bone-implant contact (BIC) and the volume density of the newly formed peri-implant bone (BVD). RFA values at the time of implant placement did not correlate with the torque required to tap the bone for implant placement. After 1 and 3 months, RFA values were significantly increased compared with baseline values. BIC and BVD, however. had increased significantly during this interval. There was no correlation between bone-implant contact and RFA values nor between peri-implant bone density and RFA values. Thus, the hypothesis could not be verified. It is concluded that the validity of the individual measurement of implant stability using RFA should be considered with caution
Effect of modifications of dual acid‐etched implant surfaces on periimplant bone formation. Part II: calcium phosphate coatings
No full textThe aim of the present study was to test the hypothesis that calcium phosphate coatings of dual acid-etched surfaces (DAEs) can improve periimplant bone regeneration. Ten adult female foxhounds received experimental titanium screw implants in the mandible 3 months after removal of all premolar teeth. Five types of surface states were evaluated in each animal: (i) implants with a machined surface (MS) (Control 1); (ii) implants with a DAE (Control 2); (iii) implants with a DAE coated with collagen I (Control 3); (iv) implants with a DAE with mineralized collagen I; and (v) implants with a DAE with a hydroxylapatite (HA) coating. Periimplant bone regeneration was assessed by histomorphometry after 1 and 3 months in five dogs each by measuring bone implant contact (BIC) and the volume density of the newly formed periimplant bone (BVD). After 1 month, mean BIC of experimental implants did not differ significantly from implants with DAE and collagen-coated surfaces, but was significantly higher than the MS implants. BVD was enhanced significantly only in implants with mineralized collagen coating compared with DAE and collagen-coated controls. After 3 months, the mean values of BIC had increased significantly in the group of implants with HA and mineralized collagen coating but were not significantly different from implants with DAE and collagen-coated surfaces. The same held true for the mean BVD values. In conclusion, the present study could not verify the hypothesis that calcium phosphate coatings of DAEs in the present form enhanced periimplant bone formation compared with the DAE surface alone. To cite this article:Schliephake H, Aref A, Scharnweber D, Ro ss ler S, Sewing A. Effect of modifications of dual acid-etched implant surfaces on periimplant bone formation: part II. Calcium phosphate coatings.Clin. Oral Impl. Res. 20, 2009; 38-44.German Federal Ministry of Education and Research BMBF [03N4021
Effect of modifications of dual acid‐etched implant surfaces on peri‐implant bone formation. Part I: organic coatings
No full textThe aim of the present study was to test the hypothesis that peri-implant bone formation can be improved by modifying dual acid-etched (DAE) implant surfaces using organic coatings that enhance cell adhesion and osteogenic differentiation. Ten adult female foxhounds received experimental titanium implants in the mandible 3 months after removal of all premolar teeth. Six types of implants were evaluated in each animal: (i) implants with a machined surface (MS), (ii) implants with a DAE surface topography, (iii) implants with an acid-etched surface coated with RGD peptides, (iv) implants with an acid-etched surface coated with collagen I, (v) implants with an acid-etched surface coated with collagen I and chondroitin sulphate (CS), (vi) implants with an acid-etched surface coated with collagen I and CS and recombinant human bone morphogenetic protein-2. Peri-implant bone regeneration was assessed by histomorphometry after 1 and 3 months in five dogs each by measuring bone implant contact (BIC) and the bone volume density (BVD) of the newly formed peri-implant bone. After 1 month, mean BIC was significantly higher in the coated implants group than in the MS group. There was no significant difference when mean BIC in the DAE group was compared with implants with any of the organic coatings, but the difference was significant when compared with the MS implants. Differences in mean BVD value did not reach significance between any of the surfaces. After 3 months, the same held true for the mean BIC of all the groups except for Coll I. Mean volume density of the newly formed bone was higher in all the surface modifications, albeit without statistical significance. It is concluded that with the exception of Coll I, the tested organic surface coatings on DAE surfaces did not improve peri-implant bone formation when compared with the DAE surfaces but enhanced BIC when compared with the MSs. To cite this article:Schliephake H, Aref A, Scharnweber D, Bierbaum S, Sewing A. Effect of modifications of dual acid-etched implant surfaces on peri-implant bone formation. Part I: Organic coatings.Clin. Oral Impl. Res. 20, 2009; 31-37.BMBF [03N4021
Effect of RGD peptide coating of titanium implants on periimplant bone formation in the alveolar crest - An experimental pilot study in dogs
No full textThe aim of the present study was to analyse the effect of organic coating of titanium implants on periimplant bone formation and bone/implant contact. Three types of implants were used: (i) Ti6Al4V implants with polished surface (control 1) (ii) Ti6Al4V implants with collagen coating (control 2) (iii) Ti6Al4V implants with collagen coating and covalently bound RGD peptides. All implants had square cross-sections with an oblique diameter of 4.6 mm and were inserted press fit into trephine burr holes of 4.6 mm in the mandibles of 10 beagle dogs. The implants of five animals each were evaluated after a healing period of 1 month and 3 months, during which sequential fluorochrome labelling of bone formation was performed. Bone formation was evaluated by morphometric measurement of the newly formed bone around the implant and the percentage of implant bone contact. After 1 month there was only little bone/implant contact, varying between 2.6 and 6.7% in the cortical bone and 4.4 and 5.7% in the cancellous bone, with no significant differences between the three types of implants. After 3 months, implants with polished surfaces exhibited 26.5 and 31.2% contact in the cortical and cancellous bone, respectively, while collagen-coated implants had 19.5 and 28.4% bone contact in these areas. Implants with RGD coating showed the highest values with 42.1% and 49.7%, respectively. Differences between the surface types as such were not significant, but the increase in bone/implant contact from 1 to 3 months postoperatively was significant only in the group of RGD-coated implants (P = 0.008 and P = 0.000). The results of this pilot study thus provide only weak evidence that coating of titanium implants with RGD peptides; in the present form and dosage may increase periimplant bone formation in the alveolar process. The results therefore require further verification in a modified experimental setting
Effect of immobilized bone morphogenic protein 2 coating of titanium implants on peri-implant bone formation
No full textThe aim of the present study was to test the hypothesis that immobilization of bone morphogenic protein (BMP2) on the surface of titanium implants can enhance peri-implant bone formation. Ten adult female foxhounds received experimental titanium screw implants in the mandible 3 months after removal of all premolar teeth. Three types of implant surfaces were evaluated in each animal: (i) implants with machined titanium surface, (ii) implants coated with collagen I, (iii) implants coated with collagen I, chondroitin sulphate (CS) and BMP2. Peri-implant bone regeneration was assessed using histomorphometry after 1 and 3 months in five dogs each by measuring bone-implant contact (BIC) and the volume density of the newly formed peri-implant bone (BVD). After 1 month, there was no significant enhancement in BIC values but volume density of the newly formed peri-implant bone was significantly higher in the two groups of coated implants. No significant difference was found between collagen and BMP2 coating. After 3 months, BIC was significantly higher in both collagen and BMP2-coated implants compared with implants with machined surfaces. Peri-implant BVD was also significantly increased in coated implants in comparison with machined surfaces. It was concluded that collagen coating of dental screw implants can enhance BIC and peri-implant bone formation. Addition of BMP2 does not increase peri-implant bone formation in the present application
Functionalization of dental implant surfaces using adhesion molecules
No full textThe aim of the present study was to test the hypothesis that organic coating of titanium screw implants that provides binding sites for integrin receptors can enhance periimplant bone formation. Ten adult female foxhounds received experimental titanium screw implants in the mandible 3 months after removal of all premolar teeth. Four types of implants were evaluated in each animal: (1) implants with machined titanium surface, (2) implants coated with collagen 1, (3) implants with collagen 1 and cyclic RGD peptide coating (Arg-Gly-Asp) with low RGD concentrations (100 mu mol/mL), and (4) implants with collagen 1 and RGD coating with high RGD concentrations (1000 mu mol/mL). Periimplant bone regeneration was assessed histomorphometrically after 1 and 3 months in five dogs each by measuring bone implant contact (BIC) and the volume density of the newly formed periimplant bone (BVD). After 1 month, BIC was significantly enhanced only in the group of implants coated with the higher concentration of RGD peptides (p = 0.026). Volume density of the newly formed periimplant bone was significantly higher in all implants with organic coating. No significant difference was found between collagen coating and RGD coatings. After 3 months, BIC was significantly higher in all implants with organic coating than in implants with machined surfaces. Periimplant BVD was significantly increased in all coated implants in comparison to machined surfaces also. It was concluded that organic coating of machined screw implant surfaces providing binding sites for integrin receptors can enhance bone implant contact and periimplant bone formation. (c) 2004 Wiley Periodicals, Inc
Biomimetic calcium phosphate composite coating of dental implants
No full textPurpose: The aim of the present study was to test the hypothesis that calcium phosphate coating of titanium screw-type implants enhances peri-implant bone formation in the jaw. Materials and Methods: Ten adult female foxhounds received experimental titanium screw-type implants in the mandible 3 months after removal of all premolar teeth. Four types of implants were evaluated in each animal: implants with machined titanium surface (the control group), implants coated with collagen I (the collagen-only group), implants with a composite coating of calcium phosphate and mineralized collagen I (the composite g roup), and implants with calcium phosphate (hydroxyapatite [HAD coating (the HA-only group). Peri-implant bone regeneration was assessed histomorphometrically after 1 and 3 months in 5 dogs each by measuring bone-implant contact (BIC) and the volume density of the newly formed peri-implant bone (BVD). Results: After 1 month, BIC was significantly enhanced only in the group of implants with composite coating of calcium phosphate and mineralized collagen (P =.038). Volume density of the newly formed peri-implant bone was significantly higher in all coated implants after 1 month. No significant difference from baseline was found in BIC for the collagen-only and HA-only groups, but BVD was significantly higher in implants with composite coating (P =.041). After 3 months, BIC and BVD were significantly higher in all coated implants than in the controls with machined surfaces. Conclusion: It was concluded that composite coating of dental screw-type implant surfaces using calcium phosphate and collagen can enhance BIC and peri-implant bone formation
Use of a mineralized collagen membrane to enhance repair of calvarial defects in rats
No full textThe aim of the present study was to evaluate mineralized collagen membranes for enhancement of bone regeneration in calvarial defects. Forty adult female Sprague-Dawley rats received calvarial full thickness defects with a diameter of 8 mm. In 20 animals, the defects were covered with a mineralized collagen membrane, and 20 animals served as controls. After 6, 13, 26 and 52 weeks, bone regeneration was evaluated using undecalcified thick-section histometry. There was no clear enhancement of bone regeneration during the first 26 weeks after the operation. Bone regeneration underneath the membrane produced consistently thicker bone, albeit without statistical significance. Accumulation of membrane material occurred in the center of the defects surrounded by multinuclear giant cells during early stages of healing. After complete resorption of the membrane, significantly increased bone formation was seen after 52 weeks in the defects that had received membrane coverage. It was concluded that mineralization in the present form did not increase mechnical strength of the membrane to prevent interference of the membrane with bone regeneration in the defect. The reason for the increase in bone formation after resorption of the membrane after 26 weeks remains to be clarified
Biological performance of biomimetic calcium phosphate coating of titanium implants in the dog mandible
No full textThe aim of the present study was to analyze the in vivo effect of biomimetic calcium phosphate coating of titanium implants on periimplant bone formation and bone-/implant contact. Five types of implants were used: 1) Ti6Al4V implants with a polished surface; 2) Ti6Al4V implants with collagen coating; 3) Ti6Al4V implants with a mineralized collagen layer; 4) Ti6Al4V implants with sequential coating of hydroxyapatite (HA) and collagen; and 5) Ti6Al4V implants with HA coating only. All implants had square cross sections with an oblique diameter of 4.6 mm and were inserted press fit into trephine burr holes of 4.6 mm in the mandibles of ten beagle dogs. The implants of five animals each were evaluated after a healing period of 1 month and 3 months, respectively, during which time sequential fluorochrome labeling of bone formation had been performed. Bone formation was evaluated by morphometric measurement of the newly formed bone around the implants and the percentage of implant bone contact. After 1 month, there was a significantly higher percentage of mean bone/implant contact in the HA-coated implants compared to those with polished surface and those with the collagen-coated surface. After 3 months, these differences were not present anymore. Bone apposition was significantly higher next to implants with sequential HA/collagen coating compared to polished surfaces and mineralized collagen layer. It is concluded that biomimetic coating of titanium implants with HA has shown the clearest trend to increase bone-implant contact in the early ingrowth period. The addition of collagen to an HA coating layer may hold some promise when used as sequential HA/collagen coating with mineralized collagen as the surface layer. (C) 2002 Wiley Periodicals, Inc
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