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Effect of sterilization on the cutting efficiency of PVD-coated nickel-titanium endodontic instruments.

AIM: To investigate alterations in cutting efficiency when conventional and titanium nitride (TiN) coated nickel-titanium (NiTi) K-files were exposed to repeated sterilization using an autoclave. METHODOLOGY: A total of 96 NiTi K-files (size 35) were randomly divided into two groups (A and B) of 48 instruments each. Whilst the instruments of group B were exposed to physical vapour deposition (PVD) creating a coating of a TiN layer, the files of group A were not coated. The instruments of groups A and B were randomly divided into four subgroups of 12 instruments each. A.1/B.1: Instruments were exposed to five cycles of sterilization. A.2/B.2: Instruments were exposed to 10 cycles of sterilization. A.3/B.3: Instruments were immersed in NaOCl for 30 min, rinsed in water, and exposed to five cycles of sterilization. A.C/B.C: Instruments were not sterilized (controls). The cutting efficiency of all files was determined by means of a computer-driven testing device. Special plastic samples with cylindrical canals were used and the maximum penetration depth of the files into the lumen was assessed. RESULTS: The TiN-coated instruments of groups B.1, B.2 and B.3 showed no significant difference in comparison with the penetration depths of the controls (P> 0.05). The uncoated files of groups A.1, A.2 and A.3 displayed significantly lower maximum penetration depths (P< 0.05) when compared to the control files. CONCLUSIONS: Repeated sterilization under autoclave or exposure to sodium hypochlorite (NaOCl) prior to sterilization did not alter the cutting efficiency of PVD-coated NiTi K-files.

Analysis of Variance↗

Effects of lactose and mode of sterilization of a lactose diet on mineral metabolism in germ-free and conventional rats.

Mineral balances of Ca, P, Mg, K, Na, Zn, Mn, Cu were carried out on 6-week old Fisher rats for 14 consecutive days. Four lots of germfree (GF) and 4 lots of conventional (CV) rats were fed a semi-synthetic diet at weaning containing either 0 or 10 p. 100 of lactose (L). The diet was sterilized either by irradiation (I) or by autoclave (Au). Lactose, when added to the diet, caused very variable modifications of the mineral metabolism, depending on the mineral studied and the mode of sterilization. Thus, retention and apparent absorption of iron were hardly changed by the presence of lactose. On the other hand, those of Mn were strongly enhanced by the lactose. The action of the other minerals was complex; it was modulated either by the mode of diet sterilization, the flora, or by both factors simultaneously. The IL diet increased retention of most of the minerals; in some cases (Na, Zn, P, Ca) it was only evidenced in CV rats; in other cases (Mn, Mg, Cu) its action was visible in both CV and GF animals. Steam-sterilized lactose (AuL) considerably reduced this effect and even reversed it. This change in lactose action under the effect of steam sterilization especially affected absorption, which declined for all the minerals, except Zn and Mn. It was accompanied by a drop in the digestive efficiency ratio which was particularly pronounced in GF rats. The destruction of 1/3 of dietary lactose by steam sterilization could not alone explain the differences between the effects of IL and AuL. Other factors, such as the products of the Maillard reaction formed by steam sterilization of the diet, might be implicated.

Animals↗

Effect of glucose concentration, osmolality, and sterilization process of peritoneal dialysis fluids on cytokine production by peripheral blood mononuclear cells and polymorphonuclear cell functions in vitro.

We sought to investigate the effects of high glucose concentration, osmolality, and heat sterilization of peritoneal dialysis fluids on tumor necrosis factor-alpha (TNF-alpha) production by peripheral blood mononuclear cells (PBMC) and polymorphonuclear cell (PMN) functions. Blood samples were obtained from eight healthy volunteers. PBMCs and PMNs were harvested by centrifugation with Ficoll-Hypaque (Sigma, St Louis, MO). PBMC were incubated with an equal volume of test fluids and RPMI for 4 hours (pH equilibrated), followed by incubation for 20 hours in RPMI with or without endotoxin (10 ng/mL). Total TNF-alpha production was measured by radioimmunoassay. PMNs were incubated with pH-adjusted test fluids for 30 minutes. After incubation, phagocytosis was determined by the uptake of 14C-labeled Staphylococcus aureus, oxidative burst by reduction of ferricytochrome C to ferrouscytochrome C on stimulation with phorbol myristate acetate, and enzyme release by measurement of endotoxin-stimulated bactericidal/permeability increasing factor. To study the effects of increasing glucose concentration and osmolality on PBMC and PMN functions, we compared conventional 1.5% Dianeal (1.5%D), (Baxter Healthcare Corp, Deerfield, IL) 2.5% Dianeal (2.5%D), 4.25% Dianeal (4.25%D), and control (RPMI for PBMCs and Hank's balanced salt solution for PMNs). PMNs exposed to 4.25%D exhibited an inhibition of phagocytosis, phorbol myristate acetate (PMA)-stimulated oxidative burst, and bactericidal/permeability increasing factor release compared with control, 1.5%D, or 2.5%D. To study the effects of increased osmolality when controlled for glucose concentration, we compared 1.5%D with 1.5%D in which osmolality was increased to that of 4.25%D with the addition of either sodium chloride (1.5%D+NaCl) or mannitol (1.5%D+M). High osmolality induced higher TNF-alpha production by unstimulated PBMCs and decreased TNF-alpha production by endotoxin-stimulated PBMCs. PMN functions were also inhibited by high osmolality. To study the effects of increased glucose concentration when controlled for osmolality, we compared 4.25%D with 1.5%D+NaCl and 1.5%D+M. High glucose concentration induced an increase in TNF-alpha production by unstimulated PBMCs, a decrease in TNF-alpha production by endotoxin-stimulated PBMCs, and an inhibition of PMN functions. Finally, to investigate the effects of heat sterilization, we compared 4.25%D (heat sterilized) to a filter-sterilized 4.25%D (4.25%D-F). The filter-sterilized fluid induced less changes in PBMC and PMN functions compared with the heat-sterilized fluid. These data suggest that the high glucose concentration, high osmolality, and heat sterilization of peritoneal dialysis fluids adversely affect PBMC and PMN functions. These effects could predispose continuous ambulatory peritoneal dialysis patients to peritonitis, compromise host defense during infection, and jeopardize long-term survival of the peritoneal membrane.

Biocompatible Materials↗

[Suitability of different procedures for the sterilization of microsurgical instruments. A review of current and future procedures].

A review of common methods of sterilization is presented. The principles of operation of steam, hot-air, and gas sterilizers, as well as that of a completely new method which uses H2O2 plasma, are described. The suitability of these methods for sterilizing microsurgical instruments was studied. This paper deals in particular with hot-air sterilization, which is preferred because of the low humidity involved. This method was investigated by recording temperature curves during sterilization. Sterilization with hot steam (autoclaving) has been shown to damage instruments by causing corrosion, to which the types of steel used to make these instruments are highly susceptible. A H2O2 plasma sterilization method is described which operates at low temperatures and with very low humidity. Its suitability for microsurgical instruments has been investigated.

Forecasting↗

Effect of tubal sterilization on ovarian follicular reserve and function.

OBJECTIVE: Tubal ligation may reduce the ovarian blood flow and lead to tissue damage to the ovary. If so, this may also result in a significant decrease of the total follicular pool. We performed a long-term evaluation of ovarian reserve and function after tubal sterilization in a longitudinal prospective comparison cohort. STUDY DESIGN: In an university tertiary-care center, 26 women undergoing laparoscopic tubal sterilization with the use of bipolar coagulation, and 26 matched control subjects underwent measurement of follicle-stimulating hormone, luteinizing hormone, 17beta-estradiol, and inhibin on menstrual cycle day 3 before (baseline) and at 6, 12, 18, 24, and 60 months after the sterilization for ovarian reserve evaluation. At baseline and 12 and 24 months after tubal ligation, women who underwent sterilization were sampled every other day across an entire menstrual cycle for follicle-stimulating hormone, luteinizing hormone, 17beta-estradiol, inhibin, and progesterone determination to evaluate ovarian function. RESULTS: No significant changes were observed either within or between groups for any parameter, despite the fact that a 45% and 30% increase in follicle-stimulating hormone concentration from baseline to the 60-month control was detected in tubal sterilization and control groups of women, respectively. No significant changes were observed in the mean area under the curve of follicle-stimulating hormone, luteinizing hormone, estradiol, inhibin, and progesterone per menstrual cycle at baseline and 12 and 24 months after sterilization. CONCLUSION: This 5-year follow-up study suggests that there is neither an accelerated decline of ovarian follicular reserve nor ovarian dysfunction after tubal sterilization by electrocoagulation.

Adult↗

Effect of steam sterilization on the rheology of polymer solutions.

The effect of steam sterilization (dwell@121 degrees C) on the apparent viscosity of solutions of carbomer 940P, guar gum, hydroxyethylcellulose (HEC), and xanthan gum was studied. Guar gum and carbomer 940P could be steam sterilized for 30 min without any change in the apparent viscosity. Steam sterilization of HEC and xanthan gum resulted in a substantial decrease in the apparent viscosity and the desirable shear-thinning rheology. The addition of sodium chloride to either polymer prior to steam sterilization diminished the effect of sterilization on the rheology. The apparent viscosity of xanthan solutions was not significantly affected if the solution was made isotonic with sodium chloride (0.15 M). The addition of sodium chloride to xanthan gum after steam sterilization resulted in full recovery of the initial rheological properties. Carbomers, guar gum, and xanthan (in 0.15 M NaCI) are candidates for use in pharmaceutical solutions/suspensions that are subjected to steam sterilization.

Pharmaceutical Solutions↗

High-level disinfection or "sterilization" of endoscopes?

Controversy has surrounded the use of liquid chemical germicides to reprocess medical instruments that are damaged by heat sterilization. A review of the literature was performed to assess and compare the efficacy of disinfection and sterilization processes. The results of this review demonstrate that high-level disinfection of thoroughly cleaned endoscopes is not associated with a higher infection rate than is "sterilization". While there may be a theoretical distinction between the highest level of disinfection and sterilization, thorough cleaning eliminates clinical differences between the two. High-level disinfection is quick, effective, inexpensive, and recommended whenever heat sterilization is not feasible. A low-temperature sterilization process should be considered only if it is comparable in cost to disinfection or if it offers demonstrated advantages without damaging the instrument. Neither disinfection nor sterilization is likely to be effective if the instrument is not cleaned thoroughly after use.

Cross Infection↗

Toxicity of heat sterilized peritoneal dialysis fluids is derived from degradation of glucose.

Heat sterilization makes peritoneal dialysis (PD) solutions cytotoxic. Two compounds in the solutions, lactate and glucose, can be degraded by heat. This study's goal was to discover which of the compounds was responsible for the cytotoxicity. The influence of sterilization temperature on degradation of the compounds was also subjected to investigation. Solutions of glucose and lactate and a mixture of lactate and glucose were prepared. These were sterilized in glass ampules in an oil bath at different temperatures for varying times. Toxicity was determined as inhibition of cell growth with a fibroblast cell line (L929), and ultraviolet (UV) absorbance was measured at 284 nm. Lactate solutions did not show cytotoxicity after heat sterilization. Glucose solutions that were heat sterilized showed an increase in UV absorbance at 284 nm and were cytotoxic. The mixture of lactate and glucose exhibited the same cytotoxicity as glucose alone. Lower sterilization temperatures lead to increased cytotoxicity and an increase in UV absorbance at 284 nm. Results indicate that the toxic products formed during heat sterilization of PD fluids are derived from glucose.

Animals↗

Effects of human milk pasteurization and sterilization on available fat content and fatty acid composition.

BACKGROUND: Human milk is frequently heat treated in hospitals to reduce bacterial contamination, particularly in banked milk fed to preterm infants. Pasteurization and sterilization may induce oxidative losses of unsaturated lipids and vitamins and may inactivate enzymes and immunologic factors. This study was designed to examine the effects of pasteurization and sterilization on milk fat content available to the recipient infant and on fatty acid composition. METHODS: In fresh, pasteurized (62.5 degrees C for 30 minutes), and sterilized (120 degrees C for 30 minutes) milk samples (5 ml) of 12 mothers (days 5-35 of lactation), fat content was determined gravimetrically and the contribution of 30 fatty acids was determined by gas-liquid chromatography. RESULTS: The coefficients of variation for measurements of milk fat content were 0.7% and of fatty acids accounting for more than 0.09% of weight, 0.1-3.0%. Available fat content was 3.1+/-1.4 g/dl (mean +/- SD) in fresh human milk and 3.1+/-1.4 g/dl (not significant) in pasteurized human milk. Fat content declined to 2.7+/-1.1 g/dl (p < 0.001 vs. fresh) in sterilized human milk, because of increased fat adherence to the container surface after sterilization. The percentage composition of saturated, monounsaturated, and polyunsaturated fatty acids of the n-6 (C18:3, C20:2, C20:3, and C22:4) and the n-3 series (C18:3 C20:5, C22:5, and C22:6) was not affected by thermal treatment. Milk sterilization caused a slight decrease of linoleic (-0.7% vs. fresh milk; p = 0,006) and arachidonic (-2,6%; p = 0.045) acids. CONCLUSIONS: Pasteurization of human milk does not influence fat content and composition, but sterilization may reduce available fat content by more than 10%, whereas there are only slight changes in fatty acid composition.

Arachidonic Acid↗

Race, insurance status, and tubal sterilization.

OBJECTIVE: To examine the independent effects of race or ethnicity and insurance status on use of tubal sterilization rates. METHODS: This study used cross-sectional data collected by the 2002 National Survey of Family Growth. The survey is designed to represent women and men aged 15-44 years in the household population of the United States. Our main outcome measure was tubal sterilization at any time before interview. A multivariable logistic regression model was used to estimate the effects of race or ethnicity and insurance status on rates of tubal sterilization after adjusting for important confounders. RESULTS: The sample consisted of 7,643 women: 66% were white, 15% were Hispanic, and 14% were African American; 68% had private insurance and 32% had public or no insurance. After adjusting for age, insurance status, parity, income, education, marital status, and religion, African-American women were more likely than white women to undergo tubal sterilization (adjusted odds ratio 1.43, 95% confidence interval 1.08-1.88). After adjusting for age, race or ethnicity, parity, income, education, marital status, and religion, women with public or no insurance were more likely to undergo sterilization compared with women with private insurance (adjusted odds ratio 1.38, 95% confidence interval 1.09-1.74). CONCLUSION: African-American women and women with no or public insurance were more likely to have undergone tubal sterilization compared with white women and women with private insurance, respectively. Additional research to identify factors that influence women's decision to undergo sterilization is warranted. LEVEL OF EVIDENCE: II.

Adolescent↗

Effect of heat sterilization on surface characteristics and microstructure of Mani NRT rotary nickel-titanium instruments.

AIM: To evaluate the effect of repeated dry heat sterilization on surface characteristics and microstructure of Mani nickel-titanium rotary instruments. METHODOLOGY: Thirty-three new Mani NRT instruments, size 30, taper 0.04 and 25 mm in length were examined. Twenty-seven instruments were divided into three groups for surface characterization by scanning electron microscopy (SEM). In the first group (n = 3), instruments were examined in the 'as-received' condition and after they had been subjected to 11 sterilization cycles. In the second and third subgroups (n = 12), 12 instruments were prepared for cross-section and a further 12 for longitudinal sectional analysis and evaluated in subgroups of three, after 0, 1, 6 and 11 sterilization cycles. The remaining six instruments were analysed with differential scanning calorimetry (DSC), three in the 'as-received' condition and three after being subjected to 11 cycles of sterilization. RESULTS: Scanning electron microscopy observations indicated the presence of debris, pitting and deep milling marks in both new and sterilized files. After 11 sterilization cycles, debris remained and surface roughness was increased significantly (P = 0.05). DSC analyses showed that the specimens in the 'as-received' condition and after 11 sterilization cycles were in the austenite phase or a mixture of austenite and R-phase at 37 degrees C. CONCLUSIONS: The machining defects and structural imperfections of new Mani instruments are indicative of the difficulty in manufacturing nickel-titanium endodontic instruments. DSC measurements suggest that Mani instruments are capable of superelastic behaviour under clinical conditions.

Calorimetry, Differential Scanning↗

Systemic levels of tumor necrosis factor alpha during hemodialysis with cellulosic membranes: no effect of the sterilization procedure.

Extractable constituents of dialyzer membranes (e.g., monomers and beta-glucans) may induce the production of cytokines in vitro. We therefore studied circulating tumor necrosis factor alpha (TNF alpha) levels in 23 stable hemodialysis patients during treatment with dry Cuprophan membranes (ETO-sterilized n = 10, steam-sterilized n = 13) longitudinally over a period of 4 weeks. After 4 weeks, those 5 patients of each group showing the highest TNF alpha levels were switched to steam-sterilized, wet Cuprophan membranes. No significant increase in plasma TNF alpha was observed during hemodialysis with either ETO- or steam-sterilized dry Cuprophan membranes. A substantial TNF alpha increase (> or = 100% compared to pre-HD values), however, was observed during 14 of 84 treatment sessions. In 5 selected patients with ETO-sterilized, dry Cuprophan dialyzers, TNF alpha rose from (mean +/- SEM) 17.2 +/- 3.0 (pre-HD) to 20.9 +/- 6.2 (120 min) and 21.9 +/- 4.5 pg/ml (240 min). Corresponding levels in patients with steam-sterilized, dry Cuprophan were 16.2 +/- 5.4 (pre-HD), 21.9 +/- 6.8 (120 min), and 16.0 +/- 3.7 pg/ml (240 min), respectively. There was no difference between ETO- and steam-sterilized dialyzers. No significant reduction in mean TNF alpha plasma levels or in frequency of elevated peak levels was achieved when these patients were switched to wet Cuprophan dialyzers for another 4 weeks. It is suggested that an induction of elevated TNF alpha levels during hemodialysis is possible but is not observed regularly during treatment with Cuprophan membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellulose↗

Alternative splice acceptor site in MSH4 gene is responsible for male sterility conferred by ms5 in soybean.

In soybean breeding, using the recessive male-sterile ms5 gene, derived from fast neutron mutagenesis, for recurrent selection is advantageous because of the d2 locus, which controls cotyledon color in mature seeds and can be used as a phenotypic selection marker for ms5 male sterility. However, occasional self-fertilization occurs because of the elimination of d2 linkage and instability of male sterility. Elucidating the mechanism and the gene responsible for ms5 male sterility may resolve these problems. Using fine mapping with 15 simple sequence repeat (SSR) markers, we narrowed down the candidate ms5 locus to a 54-kbp region. Bulked-DNA analysis using next-generation sequencing revealed a deletion as a candidate variation in the region. This 15-bp deletion and a nucleotide substitution were identified in intron 1 of MutS homolog (GmMSH4), which modulates chromosomal recombination in meiosis. The ms5 transcript contained a novel exon with a premature termination codon. This exon originated from an alternative splice acceptor site caused by the deletion and nucleotide substitution, disrupting gene function. Co-segregation of male sterility with five independent mutations in GmMSH4 was confirmed using progeny of mutant lines. Mutations in GmMSH4 led to biased DNA partitioning during meiosis, resulting in collapsed or enlarged pollen and suggesting that ms5 male sterility is caused by the failure of pollen formation during meiosis due to the loss of function of GmMSH4. These findings could help explain the mechanism of instability of ms5 male sterility and improve the efficiency of recurrent selection using DNA markers in soybean breeding.

Glycine max↗

Sterile-male method of population control.

The principle of animal population control through the use of sexually sterile males has been demonstrated for insects. Sexually sterile males that retain their sexual vigor and behavior will exert greater influence in regulating animal populations than can be achieved by destroying or removing the same number of individuals from the population. This hypothesis is supported by calculations showing theoretical population trends in assumed insect and animal populations subjected to treatments that destroy or eliminate certain percentages of the individuals as compared with a procedure that retains or replaces the same number of males in the population after sterilization. The maximum regulating effect that can be achieved is in direct proportion to the ratio of sterile to fertile males competing for mates. The advantages of inducing sexual sterility in a natural population of an insect species by chemical or other treatment over the method of rearing and releasing a dominating population of sterile males are considered. It is suggested that the sterile-male method may have practical application for undesirable populations of certain wild animals as well as for insects.

Animals↗

Limitations of thioglycolate broth as a sterility test medium for materials exposed to gaseous ethylene oxide.

Although ethylene oxide is a reliable sterilizer, the process may be limited by diffusion. Thus, situations may exist where microorganisms are protected from the sterilizing gas. It is possible that the exterior of a substance may be sterilized, whereas the interior is not. We investigated three general types of materials in which this limitation of diffusion could occur: the bore of glass and plastic tubing, the center of cotton balls, and plastic adhesive film/paper backing interface. These materials were contaminated as close to their geometric center as possible with Bacillus subtilis var. niger spores occluded in crystals of sodium chloride. After exposure of the contaminated materials (except aluminum foil) to ethylene oxide, thioglycolate broth (a standard sterility-test medium) indicated sterility, whereas Trypticase Soy Broth indicated nonsterility. It is likewise possible that aerobic microorganisms, surviving in or on material after exposure to dry heat or steam sterilization processes, would not be recovered by thioglycollate broth. Entrapped aerobic organisms will probably not grow out in the low oxygen tension zone of an anaerobic medium such as thioglycollate broth. It is recommended than an aerobic medium such as Trypticase Soy Broth be used concurrently with thioglycolate broth for sterility testing.

Bacillus subtilis↗

Use of AmpliWax to optimize amplicon sterilization by isopsoralen.

The photochemical inactivation of amplicons by isopsoralen (IP-10) has been suggested as a possible means to prevent PCR carryover contamination. To evaluate the technique, serial dilutions of amplicons (10(11) to 10(3)) from the Borrelia burgdorferi OSP A gene were amplified in the presence of 0, 25, 50, and 100 micrograms of IP-10 per ml for 45 cycles. The PCR products were exposed to UV light for 15 min to activate IP-10 and sterilize the amplicons. One microliter of each sterilized sample was reamplified for an additional 45 cycles. The PCR products were then resolved in an agarose gel, blotted onto a nylon membrane, and probed with an alkaline phosphatase-conjugated chemiluminescent probe. Although IP-10 at concentrations of 50 and 100 micrograms/ml effectively sterilized up to 10(11) amplicons, the compound was inhibitory to PCR. IP-10 at a concentration of 25 micrograms/ml had slight inhibitory effect on PCR and did not completely sterilized all of the amplicons. Therefore, in subsequent experiments AmpliWax was substituted for mineral oil, and PCR was performed on 10(9) to 10(3) amplicons as described above. Following the amplification, the PCR tubes were cooled to solidify the AmpliWax and inoculated with various concentrations of IP-10. With this technique, PCR products produced from as many as 10(9) target amplicons were effectively sterilized with 200 micrograms of IP-10 per ml. Similarly, the addition of IP-10 (50 micrograms/ml) before and after PCR was evaluated for the detection of B. burgdorferi in 62 ticks from a region of Southern Connecticut where the organism is highly endemic. PCR performed in the presence of 50 micrograms of IP-10 per ml detected B. burgdorferi-specific DNA in 17 of 62 ticks (27%) following gel electrophoresis and in 34 of 62 ticks (55%) following Southern blot hybridization of the PCR products. In contrast, post-PCR addition of IP-10 detected borrelia-specific DNA in 31 of 62 ticks (50%) following gel electrophoresis and in 46 of 62 ticks (64%) following Southern blot hybridization. We conclude that the replacement of mineral oil with AmpliWax can be useful in eliminating the inhibitory effects of IP-10 and other sterilizing agents for post-PCR sterilization of amplicons.

Animals↗

Impact of terminal heat sterilization on the quality of peritoneal dialysis solutions.

In order to meet the sterility requirements imposed by the various regulatory bodies around the world, peritoneal dialysis solutions are terminally heat-sterilized at an acid pH. There is growing concern that both acid pH and the glucose degradation products formed during terminal heat sterilization adversely affect the quality of the therapy provided to the end-stage renal failure patient on peritoneal dialysis. Acid pH and glucose degradation products are thought to contribute to impaired host defense and hence to increased risk of infection, loss of ultrafiltration, and peritoneal fibrosis. On the other hand, peritoneal dialysis solutions prepared by aseptic processing are devoid of in vitro cytotoxicity and hence are considered more biocompatible than heat-sterilized solutions. With new technologies permitting aseptic processing to achieve sterility assurance levels approaching solutions manufactured by terminal heat sterilization, it is possible to produce solutions that are more biocompatible than heat-sterilized products without increasing the risk of microbial contamination.

Abdominal Pain↗

Effect of gamma, ethylene oxide, electron beam, and plasma sterilization on the behaviour of SR-PLLA fibres in vitro.

The aim of this study was to evaluate the effect of various sterilization processes on the physical and mechanical properties of self-reinforced bioabsorbable fibres made out of polylactide (PLLA). The samples were sterilized using plasma, ethylene oxide (one and two cycles), gamma (25 kGy at room temperature, 25 kGy in dry ice, and 2 x 25 kGy at room temperature), and electron beam (15, 25, and 55 kGy) sterilization. The intrinsic viscosity, crystallinity, and mechanical properties (modulus of elasticity, yield strength, and ultimate tensile strength) were tested before and immediately after each sterilization treatment, as well as up to 30 weeks in vitro. Compared with unsterilized fibres, the intrinsic viscosity was markedly decreased after radiation sterilization (gamma and electron beam) and the loss in mechanical properties was accelerated during in vitro degradation. Plasma and ethylene oxide (one and two cycles) did not markedly alter the properties of the samples after sterilization or during in vitro degradation. These data are important for determining the effect of various sterilization processes on the physical and mechanical properties of polylactide-based materials and can be used to predict how fast degradation of the mechanical properties of the self-reinforced PLLA will occur. They can also be used to tailor the degradation kinetics to optimize implant design.

Absorbable Implants↗