|Articles about Biomaterials|
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| The fate of transplanted fibrous capsule as an autogenous graft
Sarifakioglu, N., S. Gokrem, et al. (2005), Plast Reconstr Surg 115(4): 1087-94.
Abstract: BACKGROUND: In reconstructive and aesthetic surgery, several autogenous graft materials and biomaterials are available for soft-tissue augmentation, but none has all the properties of the ideal filler material. The common problem is that heterogeneous material is reactive, and the problem for the autogenous grafts is resorption. METHODS: In this experimental study, the authors examined the transformation that the autogenous graft undergoes in a different location when it is used as a capsule tissue in place of silicone. Whole/diced capsule and fat grafts were evaluated at 3, 6, 9, and 12 months for their volume, weight, and histopathologic and statistical bases. RESULTS: The capsule graft was observed at month 12 as a dense collagen bulk. When it had decreased by 25.6 percent in volume at the end of the 12-month period, the decrease in weight was found to be 20 percent. The resorption rates in diced capsule grafts were 14 percent of volume and 8.6 percent of weight. The volume-based rate of resorption was even lower (63 percent) for the capsule than for the fat, and the weight-based rate of resorption was even lower (70 percent) for the capsule. CONCLUSIONS: The low rate of resorption in capsule grafts was attributed to the environmental conditions that triggered the potential cause of resorption, such as inflammation in the localization conditions when it is was carried from the region where it was formed. The results indicate that in the new localization of the capsule tissue that is developed against silicone, it behaves as an autogenous graft that it is resorbed at a lower rate.
| The fibroblast response to tubes exhibiting internal nanotopography
Berry, C. C., M. J. Dalby, et al. (2005), Biomaterials 26(24): 4985-92.
Abstract: The use of three-dimensional scaffolds in cell and tissue engineering is widespread; however, the use of such scaffolds, which bear additional cellular cues such as nanotopography, is as yet in its infancy. This paper details the novel fabrication of nylon tubes bearing nanotopography via polymer demixing, and reports that the topography greatly influenced fibroblast adhesion, spreading, morphology and cytoskeletal organisation. The use of such frameworks that convey both the correct mechanical support for tissue formation and stimulate cells through topographical cues may pave the way for future production of intelligent materials and scaffolds.
| The fluorohydroxyapatite (FHA) FRIOS Algipore is a suitable biomaterial for the reconstruction of severely atrophic human maxillae
Schopper, C., D. Moser, et al. (2003), Clin Oral Implants Res 14(6): 743-9.
Abstract: Grafting of the maxillary sinus is an established treatment modality to provide sufficient bone for the fixation of dental implants. We stated the hypothesis that the porous fluorohydroxyapatitic (FHA) biomaterial FRIOS Algipore could be used as a suitable biomaterial for sinus grafting in severely atrophic maxillae. To investigate the accuracy of our hypothesis, 69 trephine specimens from 26 patients who received maxillary sinus grafting with FRIOS Algipore were retrieved during the installation of dental implants. The specimens were processed undecalcified and subjected to histomorphological and histomorphometrical examination. After a mean healing time of 7 months, 23.0% (+/-8.3) new bone had formed around the implanted particles. Bone formation was also evident within the pores of the particles. Statistical analysis indicated that bone formation originated from the sinus floor. Particles provided scaffolding for the promotion of newly formed bone towards apical sinus portions. Mineral dissolution from the walls of the pores was observed prior to and during bone apposition. Thereafter, portions of the particles were resorbed during bone remodeling and replaced by newly formed bone. The present investigation shows that the biomaterial FRIOS Algipore is a suitable biomaterial for sinus grafting of severely atrophic maxillae.
| The foreign body reaction to a biodegradable biomaterial differs between rats and mice
Khouw, I. M., P. B. van Wachem, et al. (2000), J Biomed Mater Res 52(3): 439-46.
Abstract: Before a biomaterial can be applied in the clinic, biocompatibility must be tested in in vivo models, by monitoring the foreign body reaction. In this study, we compared the foreign body reaction (FBR) to the biodegradable biomaterial hexamethylenediisocyanate crosslinked dermal sheep collagen (HDSC) between several strains of rats and mice. HDSC disks were implanted subcutaneously on the backs of AO, BN, F344, LEW, and PVG rats and on the backs of 129 SVEV, BALB/c, and C57BL/6 mice. Materials were explanted after 7, 14, 21, and 28 days and processed for (immuno) light and transmission electron microscopic evaluation. In all rat strains, giant cell formation and phagocytosis of HDSC bundles were comparable. In addition, in the PVG rat, many plasma cells infiltrated the HDSC disks. Only a few T cells were present in AO and PVG rats, whereas, in F344 and LEW rats, the presence of T cells was more pronounced. BN rats showed an intermediate T-cell infiltration. In mice, the FBR to HDSC was comparable between the different strains. Compared with rats, giant cell formation was limited, whereas stroma formation was more abundant. Phagocytosis of HDSC bundles rarely occurred in mice, whereas calcification was observed more often. It is concluded that the FBR to HDSC clearly differs between rats and mice. This has consequences for assessment studies on biocompatibility and also on fundamental biomaterial research.
| The formation of supported lipid bilayers on silica nanoparticles revealed by cryoelectron microscopy
Mornet, S., O. Lambert, et al. (2005), Nano Lett 5(2): 281-5.
Abstract: The controlled fabrication of biocompatible devices made of lipid bilayers deposited onto flat solid supports presents interest as models of cell membranes as well as for their biotechnological applications. We report here on the formation of supported lipid bilayers on silica nanoparticles (nanoSLBs). The successive steps of the adsorption of lipid vesicles on nanoparticles and the formation of nanoSLBs are revealed in detail by cryotransmission electron microscopy (cryo-EM). The formation of nanoSLBs was achieved for liposomes with positive, neutral, and low net negative charge, while liposomes with a high net negative charge adsorbed to silica nanoparticles but did not rupture. The nanoSLBs were found to follow faithfully the surface contours of the particles, information yet unavailable for SLB formation on planar solid substrates.
| The frontier of substitution medicine: integrating biomaterials and tissue engineering
Sterkman, L. G. and J. Riesle (2000), IEEE Eng Med Biol Mag 19(3): 115-7.
| The future of biomaterials
Jones, D. W. (1988), J Can Dent Assoc 54(3): 163-73.
| The future of spinal arthroplasty: a biomaterial perspective
Oskouian, R. J., R. Whitehill, et al. (2004), Neurosurg Focus 17(3): E2.
Abstract: Both total hip and knee arthroplasty have demonstrated outstanding clinical results. The functional spinal unit composed of the intervertebral disc and facet joints is at least as complex. The intricacies of the coupled motions of the functional spinal unit have made development of an artificial disc a challenge. There have been several failed attempts to create a disc replacement that recapitulates normal motion while providing significant longevity and a low incidence of complications. Better understanding of the biomechanics of the intervertebral disc complex and improvements in implant material have made successful intervertebral disc replacement a likely reality, now that several artificial discs have completed Food and Drug Administration clinical trials. In this manuscript the authors detail the biomaterials used in disc arthroplasty and discuss joint wear and the host response to wear debris.
| The golden anniversary of titanium biomaterials
Williams, D. (2001), Med Device Technol 12(7): 8-11.
Abstract: Titanium has become the leading structural metallic biomaterial and 50 years of clinical performance has proven its value. However, it is wise not to forget the basic laws of materials science upon which its reputation has been based.
| The history of injectable biomaterials and the biology of collagen
Matton, G., A. Anseeuw, et al. (1985), Aesthetic Plast Surg 9(2): 133-40.
Abstract: The authors discuss the history and use of injections of paraffin, silicone, and collagen for soft-tissue contouring. The structure and uses of collagen are described with particular reference to Zyderm Collagen Implant, a highly purified bovine collagen.
| The human bone-oxidized titanium implant interface: A light microscopic, scanning electron microscopic, back-scatter scanning electron microscopic, and energy-dispersive x-ray study of clinically retrieved dental implants
Schupbach, P., R. Glauser, et al. (2005), Clin Implant Dent Relat Res 7 Suppl 1: S36-43.
Abstract: BACKGROUND: Surface modification of titanium implants by anodic oxidation may lead to enhanced bone integration. For instance, in vivo studies have demonstrated formation of more bone contacts in less time than for turned control implants. In addition, oxidized implants have shown a higher resistance to torque forces, indicating a strong interlock between bone and the oxide layer. However, the structure of the oxidized titanium-bone interface in high resolution is not known. PURPOSE: The aim of the study was to analyze the human bone-oxidized titanium interface at a high-resolution level. Of particular interest was the relationship between bone tissue and the pores of the surface oxide. MATERIALS AND METHODS: Twelve clinically retrieved implants with an oxidized surface (TiUnite, Nobel Biocare AB, Goteborg, Sweden) were used. Seven were regular dental implants and five were experimental mini-implants and had been subjected to immediate, early, or no loading. They were retrieved after 5 to 9 months of healing and were processed and analyzed using light microscopy, scanning electron microscopy (SEM) in normal and back-scatter (BS-SEM) modes, and energy-dispersive x-ray (EDX) analysis techniques. RESULTS: Bone formation was observed to occur from adjacent bone structures toward the implant surface, and it was evident that bone formation had occurred at the implant surface. SEM, BS-SEM, and EDX revealed that mineralized bone had grown into the pores of the surface oxide layer, including pores with small diameters (< 2 microm). CONCLUSIONS: The clinically retrieved oxidized implants showed evidence of bone growth into the pores of the surface oxide layer. The findings indicate the establishment of a strong interlock between the bone and the oxidized titanium implant, which is suggested to be beneficial for clinical performance.
| The human macrophage response during differentiation and biodegradation on polycarbonate-based polyurethanes: dependence on hard segment chemistry
Labow, R. S., D. Sa, et al. (2005), Biomaterials 26(35): 7357-66.
Abstract: Human monocytes, isolated from whole blood, were seeded onto tissue culture grade polystyrene (PS) and three polycarbonate-based polyurethanes (PCNUs) (synthesized with either 1,6-hexane diisocyanate (HDI) or 4,4'-methylene bis-phenyl diisocyanate (MDI), poly(1,6-hexyl 1,2-ethyl carbonate) diol (PCN) and 1,4-butanediol (BD) in different stoichiometric ratios (HDI:PCN:BD 4:3:1 or 3:2:1 and MDI:PCN:BD 3:2:1) (referred to as HDI431, HDI321 and MDI321, respectively). Following their differentiation to monocyte-derived macrophages (MDMs) the cells were trypsinized and reseeded onto each of the PCNUs synthesized with either 14C-HDI or 14C-BD and degradation was measured by radiolabel release (RR). When the differentiation surface was MDI321, there was more RR from 14C-HDI431 than from any other surface (p < 0.0001) whereas the amount of esterase (identified by immunoblotting) as well as the esterase activity was the greatest in MDM differentiated on PS, reseeded on 14C-HDI431 (p < 0.0001). The effect of potential degradation products (methylene dianiline (MDA) and BD) from the PCNUs was carried out to determine possible links between products and substrate-induced activation of MDM. MDA was found to inhibit RR 60% from MDM seeded on 14C-MDI321B (p < 0.0001), approximately 20% from 14C-HDI431 (p = 0.002) and no effect from 14C-HDI321B. MDA inhibited esterase activity 30% from MDM only on 14C-MDI321B (p = 0.003), but no effect on esterase activity was observed for the other two polymers. BD had no inhibitory effect on RR from any PCNU, but did inhibit esterase activity in MDM on 14C-HDI431 (p = 0.025). This study indicates that the degradation of a specific material is a multi-factorial process, dictated by its susceptibility to hydrolysis, the effect of specific products generated during this course of action, and perhaps not as well appreciated, the material's inherent ability to influence enzyme synthesis and release.
| The impact of biomaterials and research on dentistry
Nathanson, D. (2000), Pract Periodontics Aesthet Dent 12(1): 68, 70.
| The impact of heparin-coated circuits on hemodynamics during and after cardiopulmonary bypass
de Vroege, R., R. Huybregts, et al. (2005), Artif Organs 29(6): 490-7.
Abstract: This study was performed to investigate if heparin-coated extracorporeal circuits can reduce the systemic inflammatory reaction with the subsequent release of vasoactive substances during and after cardiopulmonary bypass. Fifty-one patients scheduled for coronary artery bypass grafting were perfused with either a heparin-coated or an uncoated circuit. During bypass the mean arterial pressure was maintained as near as possible to 60 mm Hg. Mediators for inflammation, hemodynamic, and oxygen parameters were determined during and after bypass. To reach the target mean arterial pressure in the first hour of bypass the pump flow in the uncoated group had to be increased (P<0.05), consequently the systemic vascular resistance index decreased (P<0.05). After bypass more inotropic support was necessary in this group to reach this pressure. In the coated group less bradykinin, complement activation, and elastase was generated during bypass (P<0.05). The results of this study suggest that heparin coating not only improves biocompatibility, but also ameliorates the hemodynamic instability during and after bypass.
| The impact of nicotine on bone healing and osseointegration
Balatsouka, D., K. Gotfredsen, et al. (2005), Clin Oral Implants Res 16(3): 268-76.
Abstract: OBJECTIVES: To examine the short-term effect of nicotine on bone healing and osseointegration. MATERIAL AND METHODS: Sixteen female rabbits were divided into two groups. The test group was exposed to nicotine tartrate for 8 weeks and the control group was exposed to placebo. Nicotine or placebo was administered via a miniosmotic pump and plasma cotinine levels were measured weekly. The pump delivered 15 mg of nicotine/day for the animals in the test group. All rabbits had three tibial bone preparations. In the proximal and distal bone bed, implants were placed after 4 weeks (right tibia) and after 6 weeks (left tibia). Thus, 2- and 4-week healing groups were created. Removal torque test (RMT) was performed at the distal implants. Ground sections were made from the proximal and the central bone beds. The fraction of mineralized bone in contact to the implant (BIC) and the bone density within the implant threads (BD-i) were determined for the bone-implant specimens. For the central bone beds without implants the bone density (BD-c) in the bone defects was determined. RESULTS: No significant difference in RMT values was found between the test and the control group. Histomorphometric measurements of the BIC and the peri-implant BD-i showed no significant differences between the test and the control group after 2 or 4 weeks. Significant differences were, however, found between the 2- and 4-week samples. In the central bone beds, there was no significant difference in BD-c between the test and the control group. CONCLUSION: Nicotine exposure in a short period of time did not have a significant impact on bone healing or implant osseointegration in rabbits.
| The implantation cyst as a biomaterial assay system
Ligthelm, A. J., E. J. Raubenheimer, et al. (1982), J Dent Assoc S Afr 37(12): 841-4.
| The importance of angiogenesis in the interaction between polymeric biomaterials and surrounding tissue
Rickert, D., M. A. Moses, et al. (2003), Clin Hemorheol Microcirc 28(3): 175-81.
Abstract: The uncomplicated outcome of surgical interventions after biomedical application of biomaterials depends on successful wound healing. Wound healing is a highly complex process compossed of a number of overlapping phases, including inflammation, epithelialization, angiogenesis and matrix deposition. Inadequate angiogenesis limits the transport between the microvasculature and implanted biomaterials. The regulation of angiogenesis is based on numerous growth factors, proteolytic enzymes, extracellular matrix components, cell adhesion molecules, and vasoactive factors. Capillary endothelial cells were grown for different time periods (day 1, 3, 6, 9 and 12) on the surface of a recently developed biodegradable polymeric biomaterial. As control the cells were seeded on the gelatine coated polystyrene surface of commercially available cell cultures dishes. Endothelial cells became adherent and showed confluent cells layers during increasing time period on both surfaces. The total cell number of cells grown on the gelatine coated polystyrene surface was higher in comparison to the polymer surface. The chorioallantois membrane (CAM) assay was used as a sensitive assay to investigate the influence of angiogenesis in vivo. After 48 hours of exposure of the CAM to polymer samples no avascular zones, free of capillaries and/or thrombosis or hemorrhage were detectable. Considering the biofunctionality of our recently developed polymer in these experiments different surface modifications of the polymer are the topic of current investigation to support the biomaterial-microvasculature interactions in vivo.
| The importance of material preparation for the expression of cytotoxicity during in vitro evaluation of biomaterials
Spangberg, L. and E. A. Pascon (1988), J Endod 14(5): 247-50.
| The in vitro morphological effects of some current pre-treatments on dentin surface: a SEM evaluation
Montes, M. A., M. F. de Goes, et al. (2005), Oper Dent 30(2): 201-12.
Abstract: This in vitro study morphologically evaluated the effect of some current surface pre-treatments on dentin, using scanning electron microscopy, and related these morphological alterations to clinical implications. The labial surfaces of 30 bovine lower incisors were ground to obtain a flat dentin surface and were finished with 600-grit SiC paper to produce standardized smear layers. The teeth were randomly divided into six groups of five each. Group 1 was the control group, smear layer covered dentin; Group 2 was etched with 37% phosphoric acid (PA) for 15 seconds; Group 3, 37% PA for 15 seconds, followed by 10% NaOCl for 60 seconds; Group 4, 10% NaOCl for 60 seconds; Group 5, a self-etching primer (Clearfil SE Bond, CSEB-primer) was applied for 20 seconds; Group 6, CSEB-primer for 20 seconds, followed by NaOCl for 60 seconds. The specimens were fixed, dehydrated, dried and analyzed by SEM. Treatment with 37% PA removed the smear layer, funneled the tubules and resulted in a collagen-rich surface which appeared to have collapsed in its outermost part, producing a dense surface layer covered with silica particles. When 37% PA treatment was followed by 10% NaOCl, the collagen network was removed to reveal an eroded, rough mineral surface with numerous lateral branches and larger than normal tubular orifices. The action of 10% NaOCl on the smear layer-covered dentin showed no significant alteration in surface morphology. The treatment with CSEB-primer dissolved the smear layer but only partially dissolved the smear plugs. The tubules did not present the typical funnel shape seen following PA treatment. These morphological aspects on dentin surface must influence bonding results. The dentin surface alterations produced by PA appeared to be a very severe demineralization pattern, quite irregular and less permeable to monomer infiltration, while the surface provided by the self-etching primer appeared to be a more uniform, less porous surface, and the association with simultaneous monomer infiltration may reduce the occurrence of mistakes in clinical bonding procedures.
| The incidence of microbial keratitis among wearers of a 30-day silicone hydrogel extended-wear contact lens
Schein, O. D., J. J. McNally, et al. (2005), Ophthalmology 112(12): 2172-9.
Abstract: PURPOSE: To estimate the incidence of presumed microbial keratitis with and without loss of visual acuity among wearers of a silicone hydrogel contact lens (Lotrafilcon A, Night & Day, CIBA Vision, Inc., Duluth, GA), recently approved for up to 30 days of continuous wear. DESIGN: Prospective cohort postmarket surveillance study. PARTICIPANTS: Contact lens wearers (recruited from 131 practices) who had been prescribed the lens for intended continuous wear of as many as 30 nights. METHODS: The occurrence of a corneal infiltrate was ascertained through a combination of center report and direct contact with participants at 3 and 12 months. Whenever a corneal infiltrate was suspected, study and treatment medical records were systematically reviewed by an Endpoints Committee using a predetermined classification scheme for corneal infiltration. Cases of presumed microbial keratitis were determined based on the constellation of presenting signs and symptoms and clinical course. MAIN OUTCOME MEASURES: The incidence of presumed microbial keratitis with and without loss of visual acuity. RESULTS: A total of 6245 participants were recruited between August 13, 2002 and July 2, 2003. Of these, 4999 subjects (80%) completed 12 months of follow-up, and these participants contributed a total of 5561 person years of lens wearing experience. Approximately 80% of participants routinely wore their lenses continuously for 3 or more weeks. The overall annual rate of presumed microbial keratitis was 18 per 10,000 (95% confidence interval (CI): 8.5-33.1). There were 2 cases of presumed microbial keratitis with loss of visual acuity, an annual rate of 3.6 per 10,000 (95% CI: 0.4-12.9), and an additional 8 cases without loss of visual acuity, an annual rate of 14.4 per 10000 (95% CI: 6.1-28.4). The rate of presumed microbial keratitis was lower for users reporting typical wear of 3 or more weeks than for those wearing the lens for less than a 3-week continuous period (P = 0.02). CONCLUSIONS: The incidence of loss of visual acuity due to microbial keratitis among users of the silicone hydrogel contact lens was low. The overall rate of presumed microbial keratitis with the wearing schedule of as many as 30 nights was similar to that previously reported for conventional extended-wear soft lenses worn for fewer consecutive nights.
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