Biomedical subjects

A Wennerberg

Publications and source records attributed to A Wennerberg.

At least 19 recordsLinked to original sources

PubMed2007

Inflammatory response to titanium surfaces with fibrinogen and catalase coatings: an in vitro study.

The aim of the present study was to evaluate the possibility to modulate the early inflammatory response in vitro by coating titanium surfaces with candidate proinflammatory (fibrinogen coated turned titanium "Fib") and antiinflammatory proteins (catalase on top of fibrinogen coated turned titanium "Cat"). Additionally, turned titanium surfaces (Ti) were used as controls. The discs were incubated with human mononuclear cells. Adhered cells were investigated with respect to number, viability, differentiation (acute marker 27E10 vs. chronic marker RM3/1), and cytokine production (TNF-alpha and IL-10), after 24 and 72 h. The results indicated that it is possible to modulate the inflammatory response with protein coatings. However, the strongest inflammatory response, indicated by increased number of adhered cells and release of pro and antiinflammatory mediators, was induced by Cat. Furthermore, the cytokine production on this surface was not sensitive to LPS stimulation. Differentiation measured as the expression of the chronic cell surface marker, dominated after 72 h for all surface modifications and Cat displayed an increased number compared to the others. A decrease in the total number of adhered cells and amounts of TNF-alpha were observed on all surfaces over time. The cell viability was, in general, high for all tested surfaces. In conclusion, the study proved it possible to influence the early inflammatory response in vitro by immobilizing protein coatings to titanium surfaces. However, the catalase surface demonstrated the strongest inflammatory response, and the possibility to selectively use the potent antiinflammatory capacity of catalase needs to be further evaluated.

Catalase↗

PubMed2004

Characterisation of structures in salivary secretion film formation. An experimental study with atomic force microscopy.

The purpose of the present study was to characterise the structure dynamics of pure salivary secretions retained on controlled surfaces with different surface energies in the early stage of salivary film formation. Germanium prisms prepared to have either low surface energy or medium surface energy were incubated in fresh secretions of either human parotid saliva (HPS) or human submandibular/sublingual saliva (HSMSLS) for 15, 90, and 180 min. After controlled rinsing with distilled water, the surfaces were air dried and thereafter imaged with atomic force microscopy (AFM). The amount of adsorbed material and the size of the structures detected increased with increased saliva exposure time. The film thicknesses varied from 10 to 150 nm, and both HPS and HSMSLS films contained structures with diameters varying from 40 nm to 2 microm. Some of these were clustered into special formations. The HPS films exhibited a more granular morphology than the HSMSLS films. Furthermore, branched lines were detected on the low surface energy germanium prisms incubated in saliva. The results indicate that exposure time, surface energy, and type of salivary secretion all are factors affecting the adsorption characteristics of salivary films.

Female↗

PubMed2003

Bone formation after 4 weeks around blood-plasma-modified titanium implants with varying surface topographies: an in vivo study.

The aim of the present study was to investigate and compare the stability and bone ingrowth capacity to screw-shaped titanium implants with five different surface treatments. The implants were: (1) standard turned with a thin blood plasma coat (TP), (2) NaOH-etched dito with pore size 0.2-0.3 microm (E), (3) NaOH-etched with pore size 0.2-0.3 microm and a thin blood plasma coat (EP), (4) electrochemically oxidised with pore size 1-2 microm (O), (5) electrochemically oxidised with pore size 1-2 microm and a thin blood plasma coat (OP). A total of 66 implants were divided into the above-described five groups and inserted for 4 weeks into tibia and femur of 11 rabbits. The implants were evaluated by resonance frequency (RF) measurements at the time of insertion and removal, and analysed histomorphometrically at removal. The RF measurements showed that the implant stability was lower in soft bone compared to dense and increased with time. No significant differences were observed between the different surface modifications. The histomorphometric analysis revealed no statistically significant differences between the implants regarding bone-to-metal contact (BMC) and bone area inside the threads (BA). The above results indicate that thin blood plasma-coated and non-coated screw-shaped titanium implants with turned, NaOH-etched and electrochemically etched surface profiles integrate similarly to bone at 1 month of implantation.

Bone Development↗

PubMed2003

Biological behavior of sol-gel coated dental implants.

The biocompatibility of dental implants coated with titania/hydroxyapatite (HA) and titania/bioactive glass (BG) composites obtained via sol-gel process was investigated using an in vitro and in vivo model. A device for the in vitro testing of screw-shaped dental implants was developed, in order to well compare the two experimental models studying the behavior of human MG63 osteoblast-like cells seeded onto a particular geometry. The expression of some biochemical parameters of osteoblastic phenotype (alkaline phosphatase specific activity, collagen and osteocalcin production) and some indications on cells morphology obtained by scanning electron microscopy were evaluated. The in vitro and in vivo models were compared after implants insertion in rabbit tibia and femur. The removal torque and histomorphometric parameters (percentage of bone in contact with implant surface and the amount of bone inside the threaded area) were examined. A good agreement was found between the in vitro and in vivo models. These experiments showed better performances of HA and BG sol-gel coated dental implants with respect to uncoated titanium; in particular, it was found that in vitro the HA coating stimulates osteoblastic cells in producing higher level of ALP and collagen, whereas in vivo this surface modification resulted in a higher removal torque and a larger bone-implant contact area. This behavior could be ascribed to the morphology and the chemical composition of the implants with rough and bioactive surfaces.

Journal Article↗

PubMed2002

Interventions for replacing missing teeth: different types of dental implants.

BACKGROUND: Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant surface modifications have been developed for enhancing clinical performances. OBJECTIVES: To test the null hypothesis of no difference in clinical performance between various root-formed osseointegrated implant types. SEARCH STRATEGY: The Cochrane Oral Health Group Specialised Trials Register, The Cochrane Controlled Trials Register, MEDLINE and EMBASE were searched. Hand searching included several dental journals. Bibliographies of relevant clinical trials and review articles were checked for studies outside the handsearched journals. In addition, authors of all identified trials and fifty-five oral implant manufacturers were contacted to find unpublished or ongoing RCTs. Two extensive personal libraries (ME and AJ) were consulted. The last electronic search was conducted 8th May 2002. SELECTION CRITERIA: All randomised controlled trials of oral implants comparing implants with different materials, shapes and surface properties having a follow-up of at least one year. DATA COLLECTION AND ANALYSIS: Data were independently extracted, in duplicate, by two reviewers (ME & HW). Authors were contacted for details of randomisation and withdrawals and a quality assessment was carried out. The Cochrane Oral Health Group's statistical guidelines were followed. MAIN RESULTS: Thirty publications, representing 13 different RCTs, were identified. Five of these RCTs (seven publications), which reported results from a total of 326 patients, were suitable for inclusion in the review. Six implant systems were compared: Astra, Branemark, IMZ, ITI, Steri-Oss and Southern with a follow-up ranging from one to three years. All implants were made in commercially pure titanium and had different shapes and surface preparations. On a patient rather than per implant basis there were no statistically significant differences for failures and marginal bone level changes on intra-oral radiographs between various implant systems. REVIEWER'S CONCLUSIONS: There was no evidence that any of the implant systems evaluated was superior to the other. However, these findings are based on a few RCTs all having short follow-up periods and few participants. More RCTs should be conducted, with follow-up of at least five years and including a sufficient number of patients, to detect a true difference if any exists. Such trials should be reported according to the CONSORT guidelines (http://www.consort-statement.org/).

Dental Implantation, Endosseous↗

PubMed2002

The mucosal attachment to titanium implants with different surface characteristics: an experimental study in dogs.

BACKGROUND: Findings from in vitro studies have indicated that the orientation and proliferation of cells on titanium surfaces may be influenced by the topography of the surface on which they are grown. It may be argued, therefore, that differences may occur in the mucosal attachment to titanium implants with different surface roughness. AIM: The present experiment was performed to study the composition of the soft tissue barrier that formed to implants prepared with well-defined smooth or rough surfaces. MATERIAL AND METHODS: Five beagle dogs were used. Four implants made of c.p. titanium were placed in the right edentulous mandibular premolar region. After 3 months, two different types of abutments were connected: one experimental (OA) with a dual, thermal acid-etched surface ('Osseotite'), and one regular (RA) abutment with a 'turned' surface. At the end of a 6-month period during which proper plaque control had been maintained, biopsies including the implant and the surrounding soft and hard tissues were obtained, decalcified and processed for light and electron microscopy. A confocal He-Ne laser profilometer was used to study the surface topography of the abutments. RESULTS: The attachment between the peri-implant mucosa and titanium abutments with either a turned (RA; 'smooth') or acid-etched (OA; 'rough') surface was similar from both a quantitative and a qualitative aspect. The attachment comprised a barrier epithelium and a zone of connective tissue attachment of similar dimension at RA and OA. It was further observed that the 'inner' zone of the connective tissue attachment at both types of abutment was composed of about 30-33% fibroblasts and 63-66% collagen. CONCLUSION: It was demonstrated that the soft tissue attachment that formed to implants made of c.p. titanium was not influenced by the roughness of the titanium surface.

Acid Etching, Dental↗

PubMed2001

The importance of surface texture for bone integration of screw shaped implants: an in vivo study of implants patterned by photolithography.

The aim of the present study was to investigate the influence of different properties inherent in surface topography on the integration of an implant in bone. Using a photolithography technique, a specific surface pattern was produced on the screw flanks of threaded titanium oral implants. Surface topography was qualitatively assessed by scanning electron microscopy (SEM) and a confocal laser scanning profilometer. Quantitative analysis with the confocal laser profilometer derived parameters for surface roughness and surface roughness together with waviness. The chemical composition of the implant surfaces was analyzed by Auger electron spectroscopy. The patterned and control (turned) implants were inserted in New Zealand White rabbits with a healing period of 3 months. Bone fixation was evaluated with resonance frequency analysis (RFA), peak removal torque analysis (RTQ), and by histomorphometry. No statistically significant differences were seen in the fixation, with respect to bone-to-implant contact, between the patterned and control implants.

Animals↗

PubMed2001

Surface characteristics and in vitro biofilm formation on glass ionomer and composite resin.

In the initial stages of dental plaque formation, early colonizing bacteria bind to receptor structures in the pellicle, a proteinaceous film formed instantly after cleaning of the tooth surface. Dental restorative materials with surface characteristics different from the tooth might affect pellicle formation and the ability of bacteria to colonize the oral cavity. In this study (i) roughness and chemical composition of glass ionomer and composite resin surfaces before and after polishing, and (ii) the adsorption of salivary proteins and bacterial adherence to the pellicle-coated surfaces were examined. Compared with unpolished composite resin, unpolished glass ionomer had higher surface roughness, contained more inorganic, positively charged components, collected more proteins, and promoted better bacterial adherence. Polishing had the most pronounced effect on the composite resin, giving an enlarged and a rougher surface with a more inorganic character. Polishing the composite resin also led to increased biofilm formation.

Actinomyces↗

PubMed2001

Cellular reactions and bone apposition to titanium surfaces with different surface roughness and oxide thickness cleaned by oxidation.

Titanium surfaces with three different surface characteristics were exposed to an intraperitoneal milieu in mouse or rat, or inserted into rabbit bone. The cleaning regimen of the TiO2 surfaces in this study included oxidation by heat or acid and a final rinsing and storage in water. Intraperitoneal exposure ranged from 1 to 64 min and the healing period in bone was 6 weeks. Cell recruitment to the surfaces was quantified by acridine orange staining and specific antibodies directed against cell membrane antigens. Removal torque, bone-to-metal contact, total bone area and histological evaluations were used to evaluate fixture stability and the healing-in of the implants. After the healing period of 6 weeks only a transient significant difference was seen in the total number of cells adherent on the surfaces. No significant differences were observed between any of the surfaces for removal torque, bone-to-metal contact, or bone area. The areas lacking bone-to-metal contact were filled with normal vascularised connective tissue with no signs of fibrous capsule formation or giant cells. These findings differ from findings published earlier of Ti implants that underwent a cleaning regimen with alcohol as the final rinsing step. The tissues around the implants were richly vascularised and there was continued bone growth toward the surfaces. The bone-to-metal contact in this study was lower than that seen with alcohol-cleaned TiO2.

Animals↗

PubMed2001

Protein characterisation of salivary and plasma biofilms formed in vitro on non-corroded and corroded dental ceramic materials.

Dental ceramics are generally regarded as low-adhesive materials. Different ceramics may, however, differ in composition and physico-chemical surface properties, which may be changed after corrosion. The aim of this study was to examine the adsorption of proteins onto specimens of different ceramic materials after the incubation in saliva and plasma before and after in vitro corrosion. In addition, the topography of the biofilm was examined by AFM. Surface-bound proteins were desorbed and analysed by polyacrylamide gel electrophoresis (PAGE) and immunoblotting using antibodies to saliva and plasma proteins. Silver-stained gels indicated differences in the adsorption of proteins. Differences in surface roughness at the nanometer level did not, however, seem to be correlated to the protein adsorption. After corrosion, unchanged or increased protein staining was generally seen in the gels and Western blots. The reactions for salivary amylase and proline-rich proteins varied between the different materials. Albumin and fibrinogen were identified in samples from all materials tested. Fibronectin and in specific IgA were more sparsely seen. No saliva but all plasma proteins were identified in the alumina and yttria-stabilised zirconia samples and reduced protein reactions were obtained after corrosion.

Adsorption↗

PubMed2001

A new microtomographic technique for non-invasive evaluation of the bone structure around implants.

A new X-ray microtomographic technique for non-invasive assessment of the structure of bone surrounding implants was tested. Three titanium microimplants retrieved directly (n = 2) or 6 months (n = 1) after insertion in 3 patients were used as test samples. Two samples were used dry and one was embedded in plastic resin prior to microtomography. The technique provided high-resolution consecutive cross-sectional X-ray images of the specimens with a slice-to-slice distance of 4.4 to 11.0 microns. The pictures could be imported into an image analysing software with which semiautomatic quantitative measurement of the bone area and three-dimensional images of the specimens could be made. It is suggested that the technique may be used for non-invasive assessment of the bone structure around implants. Further studies are needed to evaluate the accuracy of the technique, for instance by comparing tomographic sections with histologic ones.

Dental Implantation, Endosseous↗

PubMed2001

Histologic evaluation of the bone integration of TiO(2) blasted and turned titanium microimplants in humans.

Twenty-seven patients received 2 microimplants each during implant surgery. One microimplant was blasted with 25 microm sized particles of TiO(2); the other was left as machined i.e. a turned surface. Before insertion the surface topography was characterized with an optical confocal laser profilometer. The surface roughness was greater than standard implants, and was similar for both surface modifications averaging over all parts of the implant i.e. tops, valley and flanks. The mean surface roughness from flank measurements only replicated previously reported findings: i.e. significantly rougher surfaces on blasted implants. After a mean healing period of 6.3 months in the maxillae and 3.9 months in the mandible, the microimplants and surrounding tissue were removed with a trephine burr. The histomorphometrical evaluation demonstrated significantly higher bone-to-implant contact for the blasted implants, inserted in the maxilla or in the mandible. Significantly more bone was found inside the threaded area for the blasted implants in the mandible, but there was no difference for implants positioned in maxillae.

Aged↗

PubMed2001

Determining optimal surface roughness of TiO(2) blasted titanium implant material for attachment, proliferation and differentiation of cells derived from human mandibular alveolar bone.

In the complex process of bone formation at the implant-tissue interface, implant surface roughness is an important factor modulating osteoblastic function. In this study, primary cultures of osteoblast-like cells, derived from human mandibular bone, were used. The aim was to examine the effect of varying surface roughness of titanium implant material on cellular attachment, proliferation and differentiation. A recognized method of increasing surface roughness and enlarging the surface area of titanium implants is by blasting with titanium dioxide particles: the four specimen types in the study comprised surfaces which were machine-turned only, or blasted after turning, with 63-90 microm, 106-180 microm, or 180-300 microm TiO(2) particles, respectively. The specimens were analyzed by scanning electron microscopy and confocal laser scanning. The turned samples had the smoothest surfaces: average height deviation (S(a)) of 0.20 microm. The roughest were those blasted with 180-300 microm particles, S(a) value 1.38 microm. Blasting with intermediate particle sizes yielded S(a) values of 0.72 microm and 1.30 microm, respectively. Cell profile areas were measured using a semiautomatic interactive image analyzer. Figures were expressed as percentage of attachment. DNA synthesis was estimated by measuring the amount of [(3)H]-thymidine incorporation into trichloroacetic acid (TCA) insoluble cell precipitates. The specific activity of alkaline phosphatase was assayed using p-nitrophenylphosphate as a substrate. The ability of the cells to synthesize osteocalcin was investigated in serum-free culture medium using the ELSA-OST-NAT immunoradiometric kit. After 3 h of culture, the percentage of cellular attachment did not differ significantly between specimens blasted with 180-300 micromparticles and the turned specimens. All blasted surfaces showed significantly higher [(3)H]-thymidine incorporation than the turned surfaces (P<0.05), with the highest on the surfaces blasted with 180-300 microm particles. Osteocalcin synthesis by the cells in response to stimulation by 1,25(OH)2D3, was also significantly greater (P<0.05) on the surfaces blasted with TiO(2) particles. However, analysis of alkaline phosphatase activity disclosed no significant differences among the four surface modifications. It is concluded that in this cellular model, the proliferation and differentiation of cells derived from human mandibular bone is enhanced by surface roughness of the titanium implant. However, increasing the size of the blasting particles to 300 microm does not further increase the initial attachment of the cells compared to turned surfaces and those blasted with 63-90 microm particles.

Adolescent↗

PubMed2001

Histomorphometric and mechanical evaluation of the bone-tissue response to implants prepared with different orientation of surface topography.

BACKGROUND: Several studies have shown that in soft tissue, the orientation of surface topography affects cell response. However, the response of hard tissue to the orientation is not fully understood. PURPOSE: This study was undertaken to determine how orientation of the microstructure of implant surfaces influences bone healing. MATERIALS AND METHODS: Forty cylindrical implants were prepared with a dominant orientation of the microstructure (20 with a horizontal orientation and 20 with a vertical orientation) and investigated in vivo. Three methods for surface topographic characterization were used to investigate the topography in different resolution levels. RESULTS: Topographic analysis showed that a clear orientation was achieved at the implant surface, and a rougher surface structure was found on the vertically oriented grooves than on the horizontal ones. The implants were inserted in the tibia of 10 New Zealand White rabbits. Pull-out tests and histomorphometric analyses of ground-sections were made after 12 weeks of healing. The pull-out test showed a higher mean value for the vertically grooved implants, but the difference was not significant. Histomorphometric analyses showed no statistically significant differences between the horizontally and the vertically grooved implants when measuring bone-to-implant contact or amount of bone area around the implant. CONCLUSIONS: No advantages could be found for either the horizontal or vertical orientation compared with each other, but further studies are needed in which implant roughness should be similar between the different topographies.

Animals↗

PubMed2001

Application of oxygen ion implantation to titanium surfaces: effects on surface characteristics, corrosion resistance, and bone response.

BACKGROUND: The surface oxide layer of titanium plays a decisive role in determining biocompatibility. However, there are some reports demonstrating that the natural oxide film may not be sufficiently protective in the aggressive biologic environment. PURPOSE: The goal of this study was to examine the effectiveness of a thick oxide layer on corrosion resistance in vitro and the bone formation around titanium implants in vivo. MATERIALS AND METHODS: A plasma source ion implantation (PSII) method was used to increase the thickness of the surface oxide layer. Several instruments were employed to confirm the surface properties before and after the surface modification. Potentiodynamic polarization measurements in a phosphate-buffered saline (PBS) solution were carried out to investigate corrosion resistance in vitro. Bone formation around this surface-modified specimen was examined in a rabbit model and assessed in histomorphometry. RESULTS: Improved corrosion resistance was demonstrated by the potentiodynamic polarization measurements. Light microscopic histomorphometry showed that all implants were in contact with bone and had some proportion of bone within the threads at 4 weeks; however, there were no significant differences compared with as-machined controls. CONCLUSIONS: The results indicate that in spite of improved corrosion resistance in vitro, a thick oxide layer fabricated with the PSII method does not influence early bone formation around titanium implants in vivo.

Animals↗

PubMed2001

Reactions in the oral mucous membrane after exposure to Carisolv--combined results from a clinical screening test in humans and an experimental study in rats.

OBJECTIVE: To evaluate reactions in the oral mucosa after direct contact with Carisolv. SETTING: The Faculty of Odontology in Göteborg, Sweden. SUBJECTS: 34 healthy persons for a clinical screening test and 35 Sprague Dawley rats for a histological study. DESIGN: Mixed Carisolv or 0.5 % NaOCl were soaked in paper and applied to either side of the medial frenula of the lower lip of 34 persons. The solutions were left on the oral mucosa for three minutes. Inspection was made and photographs were taken immediately after exposure and also after 1 hour, 24 hours, and 72 hours. Mixed Carisolv was applied in a similar manner as described above to 35 adult Sprague Dawley rats. The animals were killed and biopsies were taken immediately after Carisolv exposure and also after 1 hour, 24 hours, and 48 hours. The biopsies were sectioned and prepared for histomorphometrical evaluation in light microscopy where cells were counted on regions from the epithelium layer deeper into the mucous membrane. RESULTS: Some adverse reactions were detected on the oral mucosa of humans up to 24 hours after Carisolv exposure for 3 minutes. The detected inflammatory reactions were slight and no patient felt any discomfort. The results of the histological study on rat did not show any statistically significant increase of the number of cells at any time after Carisolv exposure. CONCLUSIONS: If the oral mucosa gets in direct contact with Carisolv for 3 minutes no or only a weak inflammatory response may be expected.

Adult↗

PubMed2000

Quantifying the adherence of fibroblasts to titanium and its enhancement by substrate-attached material.

Normal human skin fibroblasts were cultured on tissue culture polystyrene and on commercially pure titanium. In addition, substrate-attached material that remained on the surfaces after detachment of fibroblasts with a chelating agent was examined. The force required to detach 50% of the fibroblasts from each substrate was assessed by centrifugation. The results showed a time-dependent decrease in the force required to detach fibroblasts from titanium not seen on tissue culture polystyrene. Nearly all cells detached from the titanium surfaces at 7.85 x 10(x3) dynes/cell after 3 or 5 days in culture, whereas few cells detached from tissue culture polystyrene. Cells freshly seeded onto titanium substrates that had been coated with substrate-attached material by prior culture of fibroblasts for 3 or 5 days showed an approximately sixfold increased adherence. The results of immunofluorescence staining for fibronectin and its receptor suggest that the nature of the interaction between this extracellular matrix ligand and the substrate may be important in determining cellular stiffness at the cell-extracellular matrix interface.

Biocompatible Materials↗

PubMed2000

Chemical and topographical surface analysis of five different implant abutments.

The surface characteristics of the dental implant abutment which penetrates through the gingival mucosa and is exposed to the oral cavity play an important role not only for the biocompatibility but also for the bacterial adhesion and stagnation. The purpose of this study was to investigate the surface characteristics of 5 commercially available implant abutments which were Brånemark (Nobel Biocare, Gothenburg, Sweden), Astra (AstraTech, Mölndal, Sweden), IMZ (Friatec, Mannheim, Germany), STERI-OSS (Denar, CA, USA) and POI (Kyocera, Kyoto, Japan). The three dimensional imaging and analysis of the surface topography were carried out using a confocal laser scanning profilometer (TopScan 3D). The chemical composition of abutment surfaces was analyzed by Auger Electron Spectroscopy (AES). The results indicated that quite different surface features were shown in three dimensional images. These features reflected roughness parameters. Sa and Scx values of these abutments in micron were Brånemark (0.23 +/- 0.09, 7.76 +/- 0.64), Astra (0.23 +/- 0.05, 7.92 +/- 0.25), IMZ (0.18 +/- 0.03, 7.76 +/- 0.80), STERI-OSS (0.15 +/- 0.01, 10.22 +/- 0.90) and POI (0.24 +/- 0.01, 8.08 +/- 0.77), respectively. The chemical elemental analysis showed all specimens to have thin titanium oxide layers (approximately 4 to 7 nm) except POI which is anodized titanium alloy, hence it has rather a thick oxide layer (95 to 110 nm). Some minor elemental traces (S, Si and P) were also seen on the outermost layer. The specimens which were investigated in this study varied in their topography and elemental composition. These variations were strongly due to the manufacturing processes which were milling, polishing, cleaning and sometimes oxidation methods.

Carbon↗