Abstract: Aim: To evaluate the long-term stability of peri-implant bone formation following implant placement without grafting into resorbed posterior maxillae.
Materials and Methods: Twenty-five implants of 10 mm were placed in 17 patients to rehabilitate atrophic maxillae by means of an osteotome sinus floor elevation (OSFE) procedure without grafting. Mean residual bone height was 5.4±2.3 mm. Bone levels were evaluated at 1, 3 and 5 years using periapical radiographs.
Results: All implants fulfilled survival criteria and gained peri-implant bone (mean increase 3.2±1.3 mm). Implant protrusion into the sinus decreased from 4.9±1.9 mm after surgery to 1.5±0.9 mm after 5 years. Mean crestal bone loss amounting to 0.8±0.8 mm stabilized over the 5-year observation interval. Twenty implants showed additional peri-implant bone gain following the 1-year control.
Conclusions: Implant rehabilitation of atrophic maxillae may be greatly simplified using implants of less than or equal to 10 mm and the OSFE technique without grafting. Grafting material is not needed to gain at least 3 mm of bone in the atrophic maxilla. The procedure appears predictable with favourable long-term results.
Abstract: PURPOSE: Achieving implant primary stability in poor-density bone is difficult when the available bone height is less than 6 mm. This study assesses the 1-year clinical performance of tapered implants in sites of reduced height in combination with osteotome sinus floor elevation without bone grafting material. MATERIALS AND METHODS: An osteotome sinus floor elevation procedure without grafting material was performed in the atrophic posterior maxilla. Tapered implants were placed in maxillary sites with residual bone height of 1 to 6 mm. Implant primary stability was assessed by finger pressure exerted on the implant. Bone gain in the elevated sinus and crestal bone loss were evaluated at 1 year via radiographs. RESULTS: Fifty-four tapered implants were placed in 32 patients and were loaded after a mean of 4.2 +/- 1.6 months. The mean maxillary residual bone height was 3.8 +/- 1.2 mm. All implants achieved primary stability, and all were successfully loaded. At the 1-year radiographic control, the mean bone gain within the sinus was 2.5 +/- 1.7 mm and the mean crestal bone loss was 0.2 +/- 0.8 mm. CONCLUSIONS: In the atrophic posterior maxilla, primary stability can readily be achieved with tapered implants, even when the mean residual bone height is 3.8 mm. Despite limited bone support and lack of grafting material, all loaded implants were clinically stable, and crestal bone loss was limited. A net bone gain of 2.3 +/- 1.8 mm was observed. Survival and success rates were 100% and 94.4%, respectively. Elevation of the sinus membrane without the addition of bone grafting material led to bone formation beyond the original limit of the sinus floor.
Abstract: OBJECTIVE: In a prospective pilot study, short< or =10 mm ITI-SLA implants were placed in the resorbed posterior maxilla by means of an osteotome sinus floor elevation (OSFE) procedure without grafting material. This paper presents 3-year data assessing bone-level changes around implants. MATERIAL AND METHODS: Twenty-five implants were placed in 17 patients to rehabilitate 16 molar and nine premolar sites. The mean residual bone height (RBH) was 5.4 +/- 2.3 mm. A healing period of 3-4 months was allowed before abutment tightening. Most implants (21/25) were 10 mm long, and the others were 8 and 6 mm long. At the 3-year control, endo-sinus bone gain, implant length protruding into the sinus and crestal bone loss (CBL) were measured on periapical radiographs. RESULTS: All implants fulfilled the survival criteria. Despite the absence of grafting material, implants were embedded into newly formed bone tissue. All implants gained endo-sinus bone; the mean gained bone was 3.1 +/- 1.5 mm. The residual protrusion length decreased from 4.9 +/- 2.1 to 1.8 +/- 2.1 mm. CBL was 0.9 +/- 0.8 mm. CONCLUSIONS: This study confirms that the OSFE procedure without grafting material is sufficient to create bone beyond the natural limit of the sinus. On the mid-term of 3 years, the technique was found to be predictable in the posterior maxilla when the RBH is limited. Implants gained endo-sinus bone despite the lack of grafting material. Bone gain was still improving over the first-year control. No shrinkage of the augmented area was observed.
Abstract: PURPOSE: This case report discusses 2 patients who required implant placement in the atrophic posterior maxilla to support a fixed prosthesis with the least invasive and shortest procedure. MATERIALS AND METHODS: The reference standard of care would be to perform sinus augmentation with an autologous bone graft through the lateral approach with delayed implant placement. However, in these cases, the posterior maxillas were treated with an osteotome sinus floor elevation procedure without grafting material and simultaneous placement of short, 8- and 10-mm-long, tapered implants. RESULTS: All implants achieved primary stability and were successfully loaded after 3.6 months of healing. At the 1- and 2-year follow-up visits, they were clinically stable and the final prostheses were functioning. The mean endosinus bone gain was 5.1 +/- 1.3 mm. In 1 of the patients, the implants were completely embedded in the newly formed bone and the sinus floor had been relocated apical to its previous demarcation. CONCLUSIONS: The findings from these 2 cases suggest that the osteotome sinus floor elevation procedure without grafting material, and immediate placement of tapered implants, might be applied in situations for which previously only the lateral approach was considered (at the condition that implants achieve firm primary stability). More patients and longer follow-up are warranted to investigate how reliable this technique can be when applied to the atrophic maxilla.
Abstract: Diamond-like carbon (DLC) and silicon carbide (SiC) coatings are attractive because of low friction coefficient, high hardness, chemical inertness and smooth finish, which they provide to biomedical devices. Silicon wafers (Si(waf)) and silicone rubber (Si(rub)) plates were coated using plasma-enhanced chemical vapour deposition (PE-CVD) techniques. This article describes: 1- the characterization of modified surfaces using attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FTIR) and contact angle measurements, 2- the results of three in-vitro haemocompatibility assays. Coated surfaces were compared to uncoated materials and various substrates such as polymethylmethacrylate (PMMA), polyethylene (LDPE), polydimethylsiloxane (PDMS) and medical steel (MS). Thrombin generation, blood platelet adhesion and complement convertase activity tests revealed the following classification, from the most to the least heamocompatible surface: Si(rub)/ DLC-Si(rub)/ DLC-Si(waf)/ LDPE/ PDMS/ SiC-Si(waf)/ Si(waf)/ PMMA/ MS. The DLC coating surfaces delayed the clotting time, tended to inhibit the platelet and complement convertase activation, whereas SiC-coated silicon wafer can be considered as thrombogenic. This study has taken into account three events of the blood activation: coagulation, platelet activation and inflammation. The response to those events is an indicator of the in vitro haemocompatibility of the different surfaces and it allows us to select biomaterials for further in vivo blood contacting investigations.
Abstract: BACKGROUND/AIMS: The potential of a new encapsulation system has been evaluated as an artificial housing for liver cells. METHODS: Murine hepatocytes were encapsulated in specially designed multicomponent capsules formed by polyelectrolyte complexation of sodium alginate, cellulose sulphate and poly(methylene-co-guanidine) hydrochloride, the permeability of which has previously been characterised. RESULTS: We demonstrate here the absence of cytotoxicity and the excellent biocompatibility of these capsules towards primary culture of murine hepatocytes. Experimental results demonstrated that the encapsulated hepatocytes retained their specific functions--transaminase activity, urea synthesis and protein secretion--over the first 4 days of culture in minimum medium. The cryopreservation of encapsulated hepatocytes, for periods of up to 4 months, did not alter their functional capacities, as no major differences were observed between unfrozen and frozen encapsulated cells for the functions tested. CONCLUSIONS: Because of the absence of cytotoxicity, and the ease of handling and cryopreservation, while maintaining liver specific functions, the described system appears to be valuable for murine liver cell encapsulation. It is also a promising tool for fundamental research into drug metabolism, intercellular regulation, metabolic pathways, and the establishment of banks for the supply and storage of murine hepatocytes.
Abstract: In the whole animal, metabolic regulations are set by reciprocal interactions between various organs, via the blood circulation. At present, analyses of such interactions require numerous and uneasily controlled in vivo experiments. In a search for an alternative to in vivo experiments, our work aims at developing a coculture system in which different cell types are isolated in polymer capsules and grown in a common environment. The signals exchanged between cells from various origins are, thus, reproducing the in vivo intertissular communications. With this perspective, we evaluated a new encapsulation system as an artificial housing for liver cells on the one hand and adipocytes on the other hand. Murine hepatocytes were encapsulated with specially designed multicomponent capsules formed by polyelectrolyte complexation between sodium alginate, cellulose sulphate and poly(methylene-coguanidine) hydrochloride, of which the permeability has been characterized. We demonstrated the absence of cytotoxicity and the excellent biocompatibility of these capsules towards primary culture of murine hepatocytes. Encapsulated hepatocytes retain their specific functions--transaminase activity, urea synthesis, and protein secretion--during the first four days of culture in minimum medium. Mature adipocytes, isolated from mouse epidydimal fat, were embedded in alginate beads. Measurement of protein secretion shows an identical profile between free and embedded adipocytes. We finally assessed the properties of encapsulated hepatocytes, cryopreserved over a periods of up to four months. The perspective of using encapsulated cells in coculture are discussed, since this system may represent a promising tool for fundamental research, such as analyses of drug metabolism, intercellular regulations, and metabolic pathways, as well as for the establishment of a tissue bank for storage and supply of murine hepatocytes.
Abstract: A new generation of microcapsules based on the use of oligomers which participate in polyelectrolyte complexation reactions has been developed. These freeze-thaw stable capsules have been applied as a bioartificial pancreas and have resulted in normoglycemia for periods of six months in concordant xenotransplantations. The new chemistry permits the control of permeability and mechanical properties over a wide range and can be adapted both to microcapsule and hollow fiber geometries rendering it a robust tool for encapsulation in general. Methods, and metrics, for the characterization of the mechanical properties and permeability of microcapsules are presented.
Abstract: Silica-based packing materials induce non-specific interactions with proteins in aqueous media because of the nature of their surface, mainly silanol groups. Therefore, the silica surface has to be modified in order to be used as stationary phase for the High Performance Size-Exclusion Chromatography (HPSEC) of proteins. For this purpose, porous silica beads were coated with hydrophilic polymer gels (dextrans of different molecular weights) carrying a calculated amount of diethyl-aminoethyl groups (DEAE). Actually, as shown by HPSEC, these dextran modified supports minimize non-specific adsorption for proteins and pullulans in aqueous solution. Then, in order to change the pore size in response to temperature, temperature responsive polymer of poly(N-isopropylacrylamide) (PIPAAm) was introduced into the surface of dextran-DEAE on porous silica beads. The structure of these supports before and after modification was alternately studied by Scanning Electronic Microscopy (SEM) and Scanning Force Microscopy (SFM). An adsorption of radiolabelled albumin was performed to complete our study. Silica modifications by dextran-DEAE and PIPAAm improve the neutrality of the support and minimize the non-specific interactions between the solid support and proteins in solution. At low temperature, the support having PIPAAm exhibits a high resolution domain in HPSEC and finally permits a better resolution of proteins and pullulans. At higher temperature, hydrophobic properties of PIPAAm produce interactions with some proteins and trigger off a slight delay of their elution time.
Abstract: Central venous catheters are widely used in clinical practice; however, complications such as venous thrombosis or infection are frequent. The physical and biological effects of a coating procedure designed to improve the blood-contacting properties of polyurethane central venous catheters (CVCs) were studied. The surface atomic composition of poly(vinyl pyrrolidone) (PVP)-coated or uncoated Pellethane single lumen CVCs was characterized by electron spectroscopy for chemical analysis (ESCA), which confirmed the presence of an oxygen-rich PVP layer on the former material. Topological analysis of both single and triple lumen CVCs by scanning force microscopy (SFM) revealed a very smooth surface in PVP-coated catheters compared to the more frequent surface irregularities found either in uncoated Pellethane or in four additional randomly selected, commercially available triple lumen polyurethane CVCs. The PVP-coated Pellethane showed a strong reduction in either fibrinogen or fibronectin adsorption compared to all other PVP-free polyurethane CVCs. This decreased protein adsorption led to a proportional reduction in protein-mediated adhesion of either Staphylococcus aureus or Staphylococcus epidermidis and in the binding of a monoclonal antibody directed against the cell-binding domain of fibronectin. Increased surface smoothness and hydrophilic properties of polyurethane CVCs might decrease the risk of bacterial colonization and infection.
Abstract: Biomer is a poly(ether-urethane-urea) block copolymer widely used as biomedical devices. Extraction process of this polymer has purified its surface of low molecular weight polyurethane chains and Santowhite Powder additive. ESCA and ATR/FTIR have suggested a homogenization of the polymer by enrichment of the first layers with poly(aminomethacrylate) additive after extraction. Therefore, the surface of the extracted Biomer exhibits a different wettability and biological response. The treatment causes a significant decrease in fibronectin adsorption and induces a reduction in Staphylococcus aureus adhesion.
Abstract: The surface characterization of Biomer and extracted Biomer has been investigated using atomic force microscopy (AFM) in order to show the influence of extraction process on the morphology and local interactions which monitor surface properties at a molecular scale. The high viscoelasticity of these polymers provided by the soft segments makes AFM imaging in contact mode quite difficult, the scanning of the tip inducing artifacts on the surface. The rate, direction, and number of scans strongly influence this friction effect. The recording of force curves has shown that the extraction and conditions of drying can modify the interaction forces present at the polymer surface. Imaging of the extracted Biomer obtained with AFM in non-contact mode has revealed inclusion nodules embedded in an amorphous phase. This may be attributed to the migration at the surface of the non-eliminated poly(aminomethacrylate) additive.
Abstract: Imaging Techniques in Biomaterials: Digital Image Processing Applied to Orthopaedic & Dental Implants
This volume presents the available knowledge on imaging techniques applied to biomaterials, especially in the orthopaedics field. It includes basic and practical aspects of recent techniques, with particular emphasis on the study of materials, biological tissues (including bone) and tissue/implant interfaces.Chapter 1 addresses fundamental aspects of image processing and chapter 2 the question of 3-D visualisation. In chapters 3 to 6 techniques used for the study of materials surfaces are dealt with, including digital analysis of SEM images, Auger spectroscopy, X-ray mapping, Scanning Tunnelling Microscopy, Scanning Force Microscopy. The application of imaging techniques to the study of cells, tissues and bone is covered in chapters 7 to 12, including the use of confocal scanning optical microscopy and acoustic microscopy. Chapters 13 to 22 cover the use of computer graphics in the study of joints, computer aided densitometric analysis of X-rays, computed tomography, image reconstruction for preoperative planning, prediction of bone properties by non-evasive techniques, quantitative analysis of the tissue/implant interfaces, thermoelasticity, optical pedobarography and the application to scoliotic deformities. Finally in chapter 23 the technological aspects of fabrication are dealt with including the subject of crown reconstruction by CAD/CAM.
Author: Edited by M. A. Barbosa and A. Campilho.
ISBN: 0444897747
Publisher: Elsevier Science
Binding: Hardcover
Year Published: 1994
Contents:
Preface. Fundamentals of image processing and analysis (A.J.C. Campilho). Visualization techniques for 3-D medical images (D. Vandermeulen, P. Suetens, G. Marchal). Digital analysis of SEM images for materials characterization and interface/surface studies of biological materials (C.P.M. de Sa). Scanning imaging techniques (SEM, Auger, X-ray mapping) applied to biomaterials surfaces (D. Muster, A. Mosser, M. Romeo). Surface characterisation of biomaterials and imaging of adsorbed molecules using scanning tunneling microscopy (STM) and ,Scanning force microscopy (SFM) (P. Descouts et al.). Advances in biomaterials related to progress in imaging techniques (G.W. Hastings). Processing interference microscopy images in the analysis of cell translocation and intracellular motility (G.A. Dunn). Image processing techniques for the study of muscular biopsies (C. Gabbi, A. Merolli, P. Tranquilli Leah). Microscopic methods of special relevance to the examination of bone and the implant interface (A. Boyde, L.A. Wolfe, S.J. Jones). Image processing techniques for the study of bone (A. Merolli, P. Tranquilli Leah. 0. Palmacci). Three-dimensional quantification of cancellous bone structure (A. Odgaard). Application of acoustic microscopy to bone and biomaterials evaluation (A. Meunier. J.L. Katz). Image processing techniques in orthopaedic clinical practice (P. Tranquilli Leali, A. Merolli, F. Cortese). Computer aided densitometric image analysis (CADIA) of X-ray films related to bone remodeling with total hip arthroplasty (A. Toni et al.). From X-rays to quantitative computed tomography in experimental orthopaedic research: qualitative and quantitative data analysis (J. Cordey et al.). Application of radiographic image reconstruction and simulation analysis for preoperative planning in 'mint reconstructive surgery (E.Y.S. Chao, M.J. Vanderploeg). Fundamentals of thermoelasticity spate 9000 technique (R. Bourgois, L. Reymen). Application of thermoelasticity to orthopaedic implants - case study: pelvis (R. Bourgois, L. Reymen). Application of non-invasive techniques in the determination of fracture callus property and bone strength (E.Y.S. Chao et al.). Quantitative analysis of the histological reactions at the interface and the surrounding bone tissue following the implantation of hip endoprostheses (M. Hahn). Dynamic optical pedobarography in diabetic foot problems (L. Serra, M.B. Serra, M.H. Cardoso). Image processing techniques for measuring back surface asymmetry in scoliotic patients (A. Merolli, P. Tranquil]] Leali, P.L. Guidi). Maximum functional occlusion in molars with a computer integrated scan/CAD/CAM-system (J.M. van der Zel). List of participants.
Review:
From Book News, Inc. (1st October 1994)
Presents the available knowledge on imaging techniques applied to biomaterials, especially in the orthopedics field. The volume includes basic and practical aspects of recent techniques, with particular emphasis on the study of materials, biological tissues (including bone), and tissue/implant interfaces. Chapter 1 addresses fundamental aspects of image processing and chapter 2 the question of 3-D visualisation. Chapters 3 to 6 deal with techniques used for the study of materials surfaces, while the application of imaging techniques to the study of cells, tissue, and bone is covered in chapters 7 to 12. Chapters 13 to 22 cover the use of computer graphics. Finally, chapter 23 deals with the technological aspects of fabrication, including the subject of crown reconstruction by CAD/CAM.
Abstract: severely atrophied and/or when no period without denture is requested. Many grafting
materials are used to gain bone volume for implant placement. Autogenous bone grafting
has been widely used despite increased morbidity. Bone substitutes avoid problems related
to bone harvesting at secondary surgical sites but are reported to undergo a slow
regeneration process. Until now, platelet-rich fibrin (PRF) has been proposed as substitution
grafting material with simultaneous implantation (Diss et al. 2008, Mazor et al. 2009).
Aim: A patient asked for maxillary implant placement to support a full prosthesis with the
least invasive shortest treatment; he requested no period without denture during the
treatment. Sinus grafting was performed with only PRF through a crestal approach and
implant placement was delayed. The 1-year clinical performance of implants was assessed.
Material and methods: A 69-year-old woman presented for maxillary full rehabilitation.
Posterior to the maxillary bicuspids, the residual bone height was ≤ 5mm. PRF grafting was
prepared from the patient’s centrifuged blood (Choukroun et al. 2001). Through crestal sinus
floor elevation, osteotomy sites were enlarged and the membrane integrity was controlled.
PRF pieces were introduced, and flaps sutured. Twelve weeks later, Bone Level® (sites #13,
14, 23 and 24; Ø4.1mm, length 10mm, Straumann AG) and TE® implants (sites #16 and 26;
Ø4.8-6.5mm, length 10mm, Straumann AG) were placed without tapping in a submerged
manner. The 4-month healing period was uneventful. After exposure, implants were restored
with an overdenture relying on six implants connected with two bars. Computed tomography
scans and radiographs were performed before surgery and during the 1-year follow-up after
loading.
Results: All implants achieved primary stability although bone density was poor. They were
successfully loaded. After one year, they were clinically stable with a functional load. In the
sinuses, newly formed mineralized tissue was visible but regenerated bone volumes were
limited. Implants #26 and #16 showed a residual protrusion into the sinus of 2 and 4mm
respectively.
Conclusions: This case report has shown that sinus grafting via a crestal approach can be
managed within duration of 3 months using PRF. The introduction of PRF has contributed to
maintain space for bone regeneration; however, bone density was poor and peri-implant
bone formation was low.
Abstract: We have covalently grafted on chitosan an oligopeptide containing the RGDS sequence specific to endothelial cell attachment, via a water-soluble agent, the 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride. Immobilization of GRGDS was confirmed by ATR-FTIR analysis, and the yield of the grafting reaction, calculated from UV spectroscopy measurements, reached approximately 90%.
