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PubMed2004

A comparative histological evaluation of the biocompatibility of materials used in apical surgery.

AIM: To evaluate the biological properties of a variety of materials that could be used in apical surgery. METHODOLOGY: The intraosseous implant technique recommended by the FDI (1980) and ADA (1982) was used to test the following materials: zinc oxide-eugenol (ZOE), mineral trioxide aggregate (MTA), and Z-100 light-cured composite resin. Thirty guinea-pigs, 10 for each material, divided into experimental periods of 4 and 12 weeks, received one implant on each side of the lower jaw symphysis. The connective tissue response alongside the lateral wall outside the cup served as a negative control for the technique. At the end of the observation periods, the animals were killed and the specimens prepared for routine histological examination to evaluate their biocompatibility. RESULTS: The reaction of the tissue to the materials diminished with time. The ZOE cement was highly toxic during the 4-week experimental period, but this profile changed significantly after 12 weeks, when it showed biocompatible characteristics. MTA and Z-100 showed biocompatibility in this test model at both time periods. CONCLUSIONS: MTA and Z-100 composite were biocompatible at 4 and 12 weeks in this experimental model.

Aluminum Compounds↗

PubMed2006

Biodegradable polylactide membranes for bone defect coverage: biocompatibility testing, radiological and histological evaluation in a sheep model.

Large bony defects often show a delayed healing and have an increasing risk of infection. Several materials are used for the coverage of large defects. These materials must be biocompatible, easy to use, and must have an appropriate stability to present a mechanical hindrance. Aim of this study was to investigate two different biodegradable membranes for defect coverage in a sheep model. Round cranial defects (1.5 cm diameter) were created in sheep. Six different treatments were investigated: defects without membrane, defects covered with a poly(D,L-lactide) or with a 70/30 poly(L/D,L-lactide) membrane and all defects with or without spongiosa filling. The sheep were sacrificed 12 or 24 weeks postoperatively. Bone formation in the defects was quantified by computer-assisted measurements of the area of the residual defect on CT radiographs. Histomorphometry and host-tissue response were evaluated by light microscopy. The biocompatibility was investigated by analyzing the amount of osteoclasts and foreign body cells. Both membranes served as a mechanical hindrance to prevent the prolapse of soft tissue into the defect. The biocompatibility test revealed no differences in the amount and distribution of osteoclasts at the two investigated time points and between the investigated groups. No negative effect on the tissue regeneration was detectable between the investigated groups related to the type of membrane, but a foreign body reaction around the two membrane types was observed. In the membrane-covered defects, the spongiosa showed a progressing remodeling to the native bony structure of the cranium. The groups without spongiosa partly revealed new bone formation, without complete bridging in any group or at any time point. Comparing the 12 and 24 weeks groups, an increased bone formation was detectable at the later time point. In conclusion, the results of the present in vivo study reveal a good biocompatibility and prevention of soft tissue prolapse of the two used membranes without differences between the membranes. An enhanced remodeling of the spongiosa into native bony structures under the membranes was detectable, but no osteopromoting effect was observed due to the membranes.

Absorbable Implants↗

PubMed1995

Systemic cardiovascular response in hemodialysis without and with ultrafiltration with membranes of high and low biocompatibility.

In order to test whether dialyzer membrane biocompatibility influences systemic cardiovascular function, we treated 8 hemodialysis patients (4 men and 4 women, aged 24-73 years) with a low-biocompatible (cuprophane) and a high-biocompatible (polyacrylonitrile) membrane in a randomized double-blind crossover protocol using bicarbonate hemodialysis without ultrafiltration for the first 60 min and with ultrafiltration for the remaining treatment time. Left ventricular function and systemic hemodynamics were assessed noninvasively at baseline and during treatment by Doppler echocardiography combined with external subclavian artery pulse trace calibrated with oscillometrically measured brachial artery blood pressures. There was no significant difference in the cardiovascular response to the 2 membranes, neither during isolated hemodialysis nor when ultrafiltration was added. Mean arterial pressure increased 10% (p < 0.001) during isolated hemodialysis and returned to baseline levels with ultrafiltration. The cardiac index decreased 22% (p < 0.001) during ultrafiltration, due to the greater decrease in left ventricular stroke index (30%, p < 0.001) than increase in heart rate (9%, p < 0.05). Total peripheral resistance increased 10% (p < 0.05) during isolated hemodialysis and a further 19% (p < 0.01) when ultrafiltration was added. Hence, profound cardiovascular alterations were observed during hemodialysis treatment; however, these changes were not related to the biocompatibility of the membranes.

Acrylic Resins↗

PubMed1995

Biocompatible intermittent hemodialysis.

Since intermittent hemodialysis was first used systemically during the Korean war, the mortality of acute renal failure (ARF) in critically ill patients has remained high ( > or 50%). The lack of improvement may be a result of better resuscitation techniques and intensive care management that allow more severely ill patients to survive long enough to develop ARF. The concept that those patients with ARF die with, but not of, renal failure was challenged recently by the results of three prospective randomized trials. Each tested the hypothesis that the course of ARF and the fate of critically ill patients may be affected adversely by bioincompatibility reactions due to the dialysis membrane used (activation of complement and neutrophils). Schiffl and colleagues were the first to publish a full report on the results of their investigation comparing bioincompatible cuprophane (CUP) and biocompatible acrylonitrile AN 69 (Hospal, Lyon, France) membranes in 52 patients with ARF following cardiovascular surgery. The AN 69 group had a lower death rate (38% vs. 65%, p = 0.052), a lower proportion of patients dying from Gram-negative sepsis (40% vs. 71%, p = 0.0162), and an improved recovery of renal function. A similar trial comparing the use of CUP with biocompatible polymethyl-methacrylate (PMMA) was performed in 72 patients with medical categories of ARF. Again, the use of a biocompatible membrane resulted in an improved survival rate (57% vs. 37%, p = 0.11) and better recovery of renal function (62% vs. 37%, p = 0.04). Of the 20 patients in each group who initially had nonoliguric ARF, the survival rates were 80% with PMMA and 40% with CUP (p = 0.01). The preliminary results of another multicenter study including 121 patients dialyzed with either bioincompatible cellulosic membranes or PMMA or polysulfone membranes seem to confirm these findings. The management of critically ill patients is sophisticated and expensive. The use of biocompatible membranes adds little to the overall costs and appears to be justified.

Acute Kidney Injury↗

PubMed2005

Bioactive and biocompatible pieces of HA/sol-gel glass mixtures obtained by the gel-casting method.

Hydroxyapatite (HA)/glass mixtures have shown a faster bioactive behaviour than HA itself. On the other hand, the gel-casting method is a simple and reproducible colloidal method to produce ceramic pieces with complex shapes. In this work, pieces of HA/glass mixtures were prepared by the gel-casting method. A study for obtaining concentrated slurries of these mixtures is reported; the bioactivity and biocompatibility of the obtained pieces have been studied also. The influence of pH, dispersant concentration, the content and milling of glass, and the way to prepare the suspensions were investigated. The lowest viscosity and better rheological properties were achieved with the lowest glass content, when the glass was added after the dispersion of the HA powder and when the glass was not milled after calcination. Fluid suspensions with a high solid content (50 vol.%) could be prepared and well-shaped pieces were obtained from these slurries. These pieces showed in vitro bioactive behavior in simulated body fluid; additionally, the proliferation and spreading assays with osteoblastic cells (HOS) showed that the pieces are biocompatible. The results obtained indicate that the gel-casting of HA/glass mixtures produces bioactive and biocompatible pieces with the required shapes. Therefore, these materials could be good candidates for clinical applications and scaffolds for tissue engineering.

Biocompatible Materials↗

PubMed2006

Staining ability and biocompatibility of brilliant blue G: preclinical study of brilliant blue G as an adjunct for capsular staining.

OBJECTIVE: To evaluate the effectiveness and biocompatibility of brilliant blue G (BBG) for capsular visualization for continuous curvilinear capsulorrhexis. METHODS: The capsular staining ability of BBG was evaluated at graded concentrations of 10.0, 1.0, 0.5, 0.25, 0.1, and 0.01 mg/mL in enucleated pig's eyes. The biocompatibility of BBG was assessed in rat's eyes for 2 months. The eyes were analyzed using light, fluorescence, transmission electron, and scanning electron microscopy. TUNEL (terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling) was used to detect apoptotic cells, and endothelial cell counts were analyzed using scanning electron microscopy. The results were compared using indocyanine green and trypan blue. RESULTS: The BBG improved capsular visualization, and a complete capsulorrhexis could be performed. In the rat model, no apparent toxic effect was observed using biomicroscopy during 2 months. Histologically, BBG showed satisfactory biocompatibility. Apoptotic cell death of the endothelial cells was detected in only the trypan blue group. In contrast to BBG, indocyanine green and trypan blue showed degeneration of corneal endothelial cells using transmission and scanning electron microscopy. CONCLUSION: The BBG contributed to better capsular visualization and caused no apparent complications to the corneal endothelium.Clinical Relevance The BBG is effective and safe capsular staining for continuous curvilinear capsulorrhexis.

Animals↗

PubMed1996

Biocompatibility testing of NiTi screws using immunohistochemistry on sections containing metallic implants.

NiTi is one of the most innovative concepts to have appeared in the field of metallic biomaterials in recent years but its biocompatibility remains controversial. We evaluated the biocompatibility of Nitinol screws using immunohistochemistry to observe the distribution of bone proteins during bone remodeling process around NiTi implant. Results were compared with screws made of Vitallium, c.p. titanium, Duplex austenitic-ferritic stainless steel (SAF), and Stainless Steel 316L. Screws were implanted in rabbit tibia for 3, 6, and 12 weeks. Embedding was performed in the hard resin Technovit, and for the immunohistochemical procedure undecalcified sections with bone-anchored implants could thus be used. The immunostaining method developed seemed to be a reliable technique to stain proteins in undecalcified sections. Biocompatibility results of the NiTi screws compared with the other screws showed a slower osteogenesis process characterized by no close contact between implant and bone, disorganized migration of osteoblasts around the implant, and a lower activity of osteonectin synthesis.

Alloys↗

PubMed1998

Subconjunctival biocompatibility of a viscous bioerodable poly(ortho ester).

The biocompatibility of a viscous poly(ortho ester) (POE) intended for prolonged intraocular drug delivery was studied. This hydrophobic and bioerodable carrier was subconjunctivally injected in rabbits and evaluated both clinically and histologically. To assess the cause of the triggered transient acute inflammatory reaction, the two monomers, the intermediate and final degradation products, and the local toxicity of different solvents used during the polymer preparation were tested. Since the two initial monomers and the intermediate degradation products induced only moderate inflammation, the main acute inflammatory reaction is attributed to the formation of an acidic by-product which has been monitored in vitro by measuring the progressive decrease of the environmental pH. The influence of the sterilization procedure on tissue biocompatibility was established by comparing two polymers of similar molecular weight: one after gamma-sterilization, and an aseptically synthesized one. The biocompatibility was significantly improved by avoiding irradiation of the polymer.

Animals↗

PubMed1998

Biocompatibility analysis of different biomaterials in human bone marrow cell cultures.

A cell culture system for biocompatibility testing of hip implant materials is described. Human bone marrow cells have been chosen because these cells are in direct contact with the biomaterial after implantation in situ. The sensitivity of this method is evaluated for materials which are already being used as implants in humans and animal, e.g., hydroxyapatite (HA) ceramic, pure titanium, and ultra-high-molecular-weight polyethylene (UHMWPE). As indicative parameters of biocompatibility primary cell adherence, cell number, cell proliferation, production of extracellular matrix, cell vitality, and cell differentiation are described. After 2 weeks in culture, obvious differences between the biomaterials with respect to the indicative parameters could be observed. Cell numbers were greatest on the HA specimens. In the case of titanium alloys, we observed a decreased number of cells. The production of extracellular matrix was high for the HA ceramics but reduced for titanium specimens. The polymers allowed only a few adherent cells and showed no signs of extracellular matrix production. The results can be correlated astonishingly well to animal experiments and clinical experiences. Therefore, we suggest that this cell culture system seems to be a useful tool for biocompatibility testing of bone implantation materials. It also helps reduce animal experiments. With the help of flow cytophotometry, we analyzed the influence of biomaterials on large numbers of cells with respect to differentiation. There were similar populations of T cells and monocytes on all specimens tested. Extended B-cell and granulocyte populations, however, were observed with titanium and UHMWPE. Most osteocalcin-containing cells adhered to the HA ceramics.

Aged↗

PubMed1998

In vivo biocompatibility evaluation of nickel-titanium shape memory metal alloy: muscle and perineural tissue responses and encapsule membrane thickness.

Nickel-titanium shape memory alloy (Nitinol) has properties that could be very useful in surgical applications. Thermal shape memory, superelasticity, and high damping properties make such alloys behave differently compared to other implant metals. There has previously been a lack of sufficient evidence on the biocompatibility of Nitinol. The purpose of this study was to evaluate general soft tissue response and biocompatibility to Nitinol in vivo, and to clarify neural and perineural responses, previously unreported. Seventy-five rats were randomized into three groups. Test specimens were implanted into paravertebral muscle and near the sciatic nerve. A comparison was made between Nitinol, stainless steel, and Ti-6Al-4V. The animals were euthanized at 2, 4, 8, 12, and 26 weeks after implantation. General morphologic and histologic observations were made under light microscopy. Semiautomatic computerized image analysis was used to measure the encapsule membrane thickness around the implants. The muscular tissue response to Nitinol was clearly nontoxic, regardless of the time period. The overall inflammatory response to Nitinol was very similar to that of stainless steel and Ti-6Al-4V alloy. There were no necroses, granulomas, or signs of dystrophic soft tissue clacification. The immune cell response to Nitinol remained low. Only a few foreign-body giant cells were present. The detected neural and perineural responses were also clearly nontoxic and nonirritating with Nitinol. No qualitative differences in histology between the different test materials could be seen. At 8 weeks, the encapsule membrane of Nitinol was thicker than that of stainless steel (mean 62 +/- 25 microns vs. 41 +/- 8 microns). At the end of the study, the encapsule thickness was equal to all the materials tested. We concluded that Nitinol had good in vivo biocompatibility after intramuscular and perineural implantation in rats in the 26-week follow-up. Based on the results of the present study, Nitinol appears to have good potential for clinical use.

Animals↗

PubMed1999

Characterization and biocompatibility of epoxy-crosslinked dermal sheep collagens.

Dermal sheep collagen (DSC), which was crosslinked with 1, 4-butanediol diglycidyl ether (BD) by using four different conditions, was characterized and its biocompatibility was evaluated after subcutaneous implantation in rats. Crosslinking at pH 9.0 (BD90) or with successive epoxy and carbodiimide steps (BD45EN) resulted in a large increase in the shrinkage temperature (T(s)) in combination with a clear reduction in amines. Crosslinking at pH 4.5 (BD45) increased the T(s) of the material but hardly reduced the number of amines. Acylation (BD45HAc) showed the largest reduction in amines in combination with the lowest T(s). An evaluation of the implants showed that BD45, BD90, and BD45EN were biocompatible. A high influx of polymorphonuclear cells and macrophages was observed for BD45HAc, but this subsided at day 5. At week 6 the BD45 had completely degraded and BD45HAc was remarkably reduced in size, while BD45EN showed a clear size reduction of the outer DSC bundles; BD90 showed none of these features. This agreed with the observed degree of macrophage accumulation and giant cell formation. None of the materials calcified. For the purpose of soft tissue replacement, BD90 was defined as the material of choice because it combined biocompatibility, low cellular ingrowth, low biodegradation, and the absence of calcification with fibroblast ingrowth and new collagen formation.

Animals↗

PubMed2000

In vitro and in vivo biocompatibility of chitosan-xanthan polyionic complex.

A novel hydrogel, CHITOXAN(TM) (CH-X), has potential as a vehicle for controlled drug delivery. The hydrogel is obtained by complexation of two polysaccharides, chitosan and xanthan. In the present work we investigated the biocompatibility of the complex using in vitro and in vivo models. The cytotoxic effects of CH-X microspheres as well as their degradation products at different concentrations were assessed on fibroblasts (fibroblast cell line L-929) using 3-(4,5-dimethylthiazole-2yl)-2,5-triphenyl tetrazolium) (MTT). The test is based on mitochondrial dehydrogenase cell activity as an indicator of cell viability. Interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) cytokines as well as nitric oxide (NO) production by macrophages (macrophage cell line J-774) were examined as indicators of cell activation. In vivo biocompatibility assessment was performed for 1 to 12 weeks. This study was performed using tablets obtained after compression of CH-X particles implanted at the subcutaneous level in male Wistar rats. CH-X biocompatibility and degradation were investigated using histological studies. Light and transmission electron microscopy (TEM) analyses were used to determine the foreign-body reaction and phagocytosis of the implants by macrophages. Fibroblast exposition to CH-X particles and degradation products did not show cytotoxic effects as measured by MTT test. TNF-alpha production was dependent on CH-X particles concentration, whereas IL-1beta production was found to be dose independent. CH-X extract products stimulated TNF-alpha secretion when used at the highest concentration (10 mg/mL), notably after 28 days' degradation time. No effect was observed on IL-1beta production when CH-X extracts were used in comparison to the control. The effects of CH-X particles on NO secretion were similar as on TNF-alpha. Histological studies showed that CH-X tablets broke down into particles which progressively degraded into smaller fragments. A significant fraction of the fragments was ingested by the macrophages after 12 weeks of implantation. Light microscopy studies showed a weak foreign-body reaction as a function of time and the fibrous layer thickness decreased with time of implantation.

Animals↗

PubMed2000

Biocompatibility of electroactive polymers in tissues.

The biocompatibility of ethylene-vinyl acetate copolymer (EVAc), polyethylene (PE), and polyaniline (PANi) films in the emeraldine (EM), nigraniline (NA) and leucoemeraldine (LM) intrinsic oxidation states were assessed through subcutaneous implantation into male Sprague-Dawley rats beneath the dorsal skin, for a period ranging from 19 to 90 weeks. Histological examination, interstitial pressure measurement, and X-ray photoelectron spectroscopy (XPS) were employed to determine the biocompatibility of the polymers. The polymers did not provoke inflammatory responses in the subcutaneous tissues over the entire implantation period. Characteristics features associated with tissue-implant incompatibility were not evident near the implantation. Interstitial pressure was measured to evaluate the development of tissue. Low interstitial pressure readings on the region of implantation confirmed the biocompatibility of these polymer types. The surface composition of the electroactive aniline polymers before and after the implantation was characterized by XPS.

Aniline Compounds↗

PubMed2001

Biomaterial properties and biocompatibility in cell culture of a novel self-inflating hydrogel tissue expander.

The aim of this study was to investigate the swelling properties and the biocompatibility of a novel tissue expander material. The self-inflating material is a hydrogel consisting of a modified copolymer of methylmethacrylate and N-vinyl-2-pyrrolidone, which takes up water by osmosis. To increase the swelling volume, the primarily neutral gel material was modified by converting it into an ionized gel. To study the swelling and pressure behavior of the material, the anhydrous gel cylinders were equilibrated in distilled water, saline, and sugar solutions. The biocompatibility was investigated in cell culture. We tested the hydrogel eluate after swelling for cytotoxicity and mutagenicity using the cell lines MRC-5 and P3X63 Ag8 653 (Ag8). Furthermore, particles of the material were added to cell cultures to induce foreign body reactions and to verify its influence on monocyte differentiation. The material has a swelling capacity (Q = maximum swelling volume/anhydrous volume) of 5 to 50 depending on the degree of ionization of the polymer network. In this study, two polymer modifications with a swelling equilibrium of Q = 11.1 and 30 in water were tested. The swelling ratio also depends on concentration and ion content of the equilibration medium. The highest swelling capacity was found in water, the lowest in Ringer's solution. The swelling of the anhydrous material with the swelling capacity of Q = 11.1 fits best the average purpose of material properties for tissue expansion and generates a maximal hydrostatic pressure of approximately 235 mmHg. Effects on cell proliferation were detected only at the highest eluate concentration tested (i.e., eluate: culture medium = 1:1), which was far beyond physiological values, whereas mutagenicity was absent. Monocytes neither migrated nor tightly attached to the hydrogel. They neither phagocytose the material nor did they show any sign of a foreign body reaction, e.g., formation of multinucleated giant cells or monocyte proliferation. In the presence of hydrogel material, the differentiation processes of monocytes to macrophages or dendritic cells, respectively, were found to be undisturbed. From these results, we conclude that there is a high biocompatibility of the expander material, which may be a favorable and interesting candidate for further clinical applications.

Animals↗

PubMed2001

In vitro biocompatibility assessment of naturally derived and synthetic biomaterials using normal human urothelial cells.

The reconstruction of urinary tissues often employs various types of biomaterials, and adequate material biocompatibility is essential for the successful reconstruction of urinary tissues. In this study we utilized a primary normal human urothelial cell culture system to evaluate the in vitro biocompatibility of a number of naturally derived biomaterials [i.e., bladder submucosa, small intestinal submucosa, collagen, and alginate] and polymeric biomaterials [i.e., poly(glycolic acid), poly(L-lactic acid), poly(lactic-co-glycolic acid), and silicone] that are either experimentally or clinically used in urinary reconstructive surgery. To determine the cytotoxic and bioactive effects of these biomaterials, the cell viability, metabolic activity, apoptotic properties, and DNA-synthesis activity were measured with four types of assays [Neutral Red, 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide, apoptotic activity, and tritiated thymidine incorporation assays] using extract and direct contact methods. Most of the biomaterials tested did not induce significant cytotoxic effects and exhibited normal metabolic function and cell growth in vitro. This normal primary human urothelial cell culture model is suitable for in vitro biocompatibility assessments and is able to provide information on the cell-biomaterial interactions and the ability of biomaterials to support bioactive cell functions.

Apoptosis↗

PubMed2001

In vivo biocompatibility of carbodiimide-crosslinked collagen matrices: Effects of crosslink density, heparin immobilization, and bFGF loading.

Collagen matrices, crosslinked using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (E) and N-hydroxysuccinimide (N), were previously developed as a substrate for endothelial cell seeding of small-diameter vascular grafts. In the present study, the biocompatibility of various EN-crosslinked collagen matrices was evaluated following subcutaneous implantation in rats for periods up to 10 weeks. The effects of the crosslink density, referred to as the number of free primary amino groups per 1,000 amino acid residues (EN10, EN14, EN18, or EN22), the amount of heparin immobilized to EN14, and the effect of preloading heparinized EN14 with basic fibroblast growth factor (bFGF) on the induced tissue reaction were studied. EN-crosslinked collagen was biocompatible at both early and late time intervals, and matrices with high crosslink densities (i.e., EN14, EN10) especially demonstrated a significantly decreased antigenic response when compared to noncrosslinked collagen. Furthermore, increased crosslinking resulted in a decreased degradation rate. Immobilization of heparin onto EN14 resulted in a similar to EN14 (thus without heparin) or somewhat reduced tissue reaction, but fibrin formation and vascularization were increased with increasing quantities of immobilized heparin. Matrices preloaded with bFGF also demonstrated good biocompatibility, especially in combination with higher amounts of immobilized heparin. The latter matrices [EN14 with high heparin and bFGF, thus EN14-H (0.4)F and EN14-H(1.0)F] demonstrated significantly increased vascularization for periods up to 3 weeks. Neither heparin immobilization nor bFGF preloading induced an increased antigenic response. It is concluded that the results of this study justify further evaluation of bFGF preloaded, heparin immobilized EN14 collagen, as a matrix for endothelial cell seeding in experimental animals.

Animals↗

PubMed2002

Chemistry and biocompatibility of alginate-PLL capsules for immunoprotection of mammalian cells.

Transplantation of encapsulated living cells is a promising approach for the treatment of a wide variety of diseases. Large-scale application of the technique, however, is hampered by insufficient biocompatibility of the capsules. In order to get means to study factors influencing the biocompatibility of capsule for encapsulation of living cells, we have correlated the chemical composition of the surface of commonly applied alginate-PLL capsules with the biological response in rats. Capsules prepared of alginates with an intermediate guluronic (G) acid content proved to be biocompatible, whereas capsules prepared of high-G alginates were overgrown by inflammatory cells. We applied X-ray photoelectron spectroscopy to correlate the biological responses with the chemical compositions of the capsule surfaces. High-G alginate capsules proved to have a higher PLL content but less surface binding sites for PLL than low-G alginates. This study, shows for the first time that biological responses against capsules can be successfully correlated to its chemical characteristics.

Alginates↗

PubMed1988

Biocompatibility of six elastomers in vitro.

The biocompatibility of two silicone rubbers, Silastic and Dow Corning Elastomer, and of a polyether and a polyester urethane, a polyether polyester copolymer, and polypropylene oxide was assessed in vitro. These elastomers were selected for assessment as a possible alloplastic tympanic membrane. For these studies use was made of rat middle ear mucosa explants and serially cultured epithelium. The quantitative results were based on epithelial growth curves, the morphological picture was based on the findings in epithelium, and the aging of a biomaterial was simulated. Epithelium morphology was investigated by scanning and transmission electron microscopy and x-ray microanalysis. Quantitative results showed that on Dow Corning Elastomer and polypropylene oxide, cell proliferation was significantly lower compared to normal growth curves. The morphological findings were negative for polypropylene oxide, and did not discriminate between the other biomaterials under study. The simulation results indicated better biocompatibility for the polyurethanes and the polyether polyester copolymer compared with that of polypropylene oxide and both silicone rubbers. Under the simulation conditions, cells exposed to Silastic showed silicon-containing inclusions. These in vitro results suggest that the biocompatibility of the polyurethanes and the polyether polyester copolymer is better than that of both silicone rubbers and polypropylene oxide.

Animals↗