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PubMed1995

Impact strength of denture polymethyl methacrylate reinforced with continuous glass fibers or metal wire.

The impact strength of heat-cured acrylic resin test specimens that had been reinforced in various ways was compared in this study. Ten rectangular test specimens were fabricated for each test group. The strengtheners included 1.0-mm-diameter steel wire and continuous E-glass fibers. Both notched and unnotched test specimens were tested in a Charpy-type impact test. In a further analysis the concentration of glass fibers in the test specimens was determined and plotted against the impact strength of the test specimens. The results showed that, compared with the unreinforced specimens, both types of reinforcement increased the impact strength of the test specimens considerably (p < 0.001). There was no clear difference between the mean impact strength value of the test specimens reinforced with metal wire and that of the specimens reinforced with glass fiber. The correlation coefficient between the fiber concentration of the test specimens and their impact strength was 0.818 (p < 0.005). Specimens with fiber concentrations greater than 25 wt% yielded to the higher impact strength more readily than those with metal wire reinforcement did.

Dental Stress Analysis↗
PubMed2004

Fatigue strengths of particulate filler composites reinforced with fibers.

The aim of this study was to evaluate the dynamic fatigue strengths at 10(5) cycles and the strains of particulate filler composite resins with and without reinforcing fibers. An UHMWPE (Ribbond), a polyaromatic polyamide fiber (Fibreflex), and three glass fibers (GlasSpan, FibreKor, Vectris Frame) were used to reinforce the particulate filler composite resins. The fatigue properties were measured in three-point bending mode using a servohydraulic universal testing machine at a frequency of 5 Hz, until failure occurred or 10(5) cycles had been completed. The fatigue strengths at 10(5) cycles were determined by the staircase method. The fractured aspects of specimens were evaluated by an optical and scanning electron microscope. The fatigue strengths of particulate filler composite resins were 49-57 MPa, and those of fiber-reinforced were 90-209 MPa. Unidirectional glass fibers showed higher reinforcing effects on the fatigue strengths of composite resins. The strain of UHMWPE-reinforced composite was largest.

Analysis of Variance↗
PubMed2004

Light-curing reinforcement for denture base resin using a glass fiber cloth pre-impregnated with various urethane oligomers.

The purpose of this study was to investigate the flexural properties of denture base resin reinforced using glass fiber cloth and a urethane oligomer. The five types of oligomer used in this study were S5, S9, S3, U4, and U6, which have varying functional groups and viscosities. The flexural properties of S9 with glass fiber cloth could not be measured because S9 is elastic. In the heat-cured resin reinforced with S9, the reinforcement peeled away from the resin. In the self- and light-cured resins reinforced with S9, the flexural properties increased significantly. When reinforced with the other four oligomers (S5, S3, U4, and U6), the flexural strength and flexural modulus of the self-, heat-, and light-cured resins increased significantly (p<0.01).

Acrylic Resins↗
PubMed2006

Mechanical properties of woven glass fiber-reinforced composites.

The aim of this investigation was to measure the flexural and compressive strengths and the corresponding moduli of cylindrical composite specimens reinforced with woven glass fiber. Test specimens were made by light-curing urethane dimethacrylate oligomer with woven glass fiber of 0.18-mm standard thickness. Tests were conducted using four reinforcement methods and two specimen diameters. Flexural strength and modulus of woven glass fiber-reinforced specimens were significantly greater than those without woven glass fiber (p < 0.01). Likewise, compressive strength of reinforced specimens was significantly greater than those without woven glass fiber (p < 0.01), except for specimens reinforced with woven glass fiber oriented at a tilt direction in the texture (p > 0.05). In terms of comparison between the two specimen diameters, no statistically significant differences in flexural strength and compressive strength (p > 0.05) were observed.

Analysis of Variance↗
PubMed1996

Transgenic superoxide dismutase mice: Increased mesolimbic µ-opioid receptors results in greater opioid-induced stimulation and opioid-reinforced behavior.

Consequent to the insertion of the human Cu/Zn-superoxide dismutase (SOD) transgene, SOD transgenic mice (SOD-Tg) show higher concentrations of the primary receptor thought to be involved in opioid reinforcement (µ). These increases are observed in areas specifically associated with the primary neurotransmitter thought to be involved in addiction (dopamine), and in neuroanatomical regions thought to mediate substance abuse (mesolimbic). In the present study we have tested the idea that these increases in µ-receptors are associated with parallel changes in µ-mediated behaviors. Baseline and morphine-induced locomotor activity were significantly altered in the SOD-Tg mice. A qualitative change in the nature of acute and chronic morphine-induced locomotor activity was demonstrated by a significant change in the slope of the dose-effect curve. SOD-Tg mice were significantly more sensitive to the locomotor stimulant effects of morphine. Intravenous morphine-reinforced behavior was also altered in the SOD-Tg mice. SOD-Tg mice showed significant dose-related changes in operant lever-press responding maintained by morphine injection and significantly greater amounts of behavior were maintained by the drug than by vehicle under an intermittent schedule of reinforcement. In addition, SOD-Tg mice increased operant responding for the drug when the amount of behavior required to maintain drug intake increased 10-fold under a PR schedule of reinforcement. In contrast, in wild-type mice morphine injections failed to maintain greater amounts of behavior than vehicle, there were no dose-related changes in behavior, and when response requirements increased under the PR schedule, morphine intake decreased significantly. Thus, SOD transgene insertion significantly enhanced the efficacy of morphine as a reinforcer.

Journal Article↗
PubMed2001

Bronchial stump reinforcement in right pneumonectomy with fascia lata and gelatin resorcin formalin (GRF) glue: case report.

We reinforced the bronchial stump with fascia lata and Gelatin Resorcin Formalin (GRF) glue in a right pneumonectomy. This method was found to be simple and useful. We describe our case and the method herein. A 62-year-old woman had a malignant polypoid lesion which completely occluded the introitus of the right main bronchus and deviated to the introitus of the left main bronchus. Right pneumonectomy was done but materials (pleura, pericardium, intercostal muscle, etc.) obtained from the thoracic cavity were insufficient for bronchial stump reinforcement due to severe adhesion caused by prior tuberculosis. Therefore, we reinforced the bronchial stump using the fascia lata and GRF glue. Fascia lata is a superior material for reinforcement in terms of strength and ease of molding, as well as harvesting. GRF glue is a superior adhesive with rapid and strong fixation. We consider this method of reinforcing the bronchial stump with fascia lata and GRF glue to be feasible, in particular, for pneumonectomy or lobectomy without adequate material in the thoracic cavity because of severe adhesion or lesions.

Drug Combinations↗
PubMed2001

Expansion and bioabsorption of the self-reinforced lactic and glycolic acid copolymer prostatic spiral stent.

PURPOSE: Self-reinforced bioabsorbable stents can be made self-expanding due to the viscoelastic memory of the oriented bioabsorbable materials. A new self-expandable self-reinforced copolymer of lactic/glycolic acid, lactic/glycolic molar ratio 80:20 stent was developed to prevent postoperative urinary retention after procedures that induced prostatic edema. In in vitro experiments the expansion rate has been up to 100% during the first few hours at body temperature. We investigated the expansion rate and biodegradation of the self-reinforced lactic and glycolic acid copolymer prostatic spiral stent in vivo in the prostatic urethra. MATERIALS AND METHODS: A total of 39 men, 52 to 84 years old, with lower urinary tract symptoms due to benign prostatic enlargement underwent interstitial laser coagulation of the prostate. A self-reinforced copolymer of lactic/glycolic acid, lactic/glycolic molar ratio 80/20 stent was inserted into the prostatic urethra at the end of the operation. The stent lumen diameter was 4.5 mm. The location and diameter of the lumen and degradation of the stent were studied with transrectal ultrasound at 1, 2, 4 and 6 months postoperatively. At 6 months patients underwent cystoscopy. RESULTS: All except 1 patient voided on postoperative day 1. Mean lumen diameter was 7.4 mm. (range 6.2 to 8.2) at 1 month and 7.2 mm (range 6.2 to 7.5) at 2 months. At 4 months the stent was degraded into small pieces. No pieces of stent were found in the prostatic urethra on ultrasound or cystoscopy at 6 months. However, a portion of the spiral stent was found at the bottom of the bladder in 2 patients. CONCLUSIONS: The speed and expansion rate of the self-reinforced copolymer of lactic/glycolic acid, lactic/glycolic molar ratio 80/20 stent was sufficient to lock the stent in place and ensure voiding in cases of edema induced bladder outlet obstruction. Strength retention greater than 2 months was long enough to avoid later impairments of voiding.

Absorbable Implants↗
PubMed2001

Reinforced sternal closures for prevention of sternal dehiscence in high risk patients.

BACKGROUND: Sternal dehiscence is still a frequent complication after cardiac surgery procedures, performed through midline sternotomy. Its cumulative incidence has been reported to be around 2.5%, but several risk factors for increased incidence have also been identified. In past years several techniques have been proposed to achieve reinforced sternal approximation, mainly considered for the treatment of sternal dehiscence, more than for its prevention. The objective of this paper is the evaluation of the results, in terms of prevention of sternal dehiscence in high-risk patients, using reinforced closure techniques compared to standard technique. METHODS: Our study population included 212 patients who underwent cardiac surgery procedure and presented at least one of the increased risk factor for sternal dehiscence. Fifty-six patients (26.4%) received a reinforced sternal closure technique (RC group), 156 patients (73.6%) received a conventional sternal closure (CC group). RESULTS: The cumulative incidence of sternal refixation, in this selected population, was 5.6% with a statistically significant difference in favour of the RC group. The results of this study clearly show that the appropriate utilisation and selection of one of the several techniques of reinforced sternal closures can be effective in the reduction of sternal dehiscence in high risk patients. CONCLUSIONS: A reinforced technique should therefore be utilised in all patients undergoing cardiac surgery, presenting one or more risk factors for increased incidence of sternal dehiscence.

Cardiac Surgical Procedures↗
PubMed2003

[Obstruction of an reinforced endotracheal tube due to dissection of internal tube wall during total intravenous anesthesia].

We report here a case of obstruction of an reinforced endotracheal tube during laryngomicrosurgery under total intravenous anesthesia. In this case, we used a 6.0 mm ID reinforced endotracheal tube that had been used previously for other patients and sterilized two times by ethylene oxide gas. During the operation, the peak airway pressure increased gradually and eventually reached to 35 cmH2O. After the exchange of the endotracheal tube, ventilation was improved immediately. The endotracheal tube was occluded by dissection of internal wall. Several cases of reinforced tube obstruction have already been reported and in most of these cases the obstruction was related to their repeated use and nitrous oxide anesthesia. However, the present case showed that dissection of reinforced endotracheal tube could also occur during general anesthesia without using nitrous oxide. We should bear in mind that repeated use of reinforced endotracheal tube could induce a critical airway obstruction.

Airway Obstruction↗
PubMed2004

[Mechanical property analysis of polyethylene fiber reinforced polymethyl methacylate].

OBJECTIVE: To investigate if the Ribbond polyethylene fiber has the effect of reinforcing polymethyl methacylate. METHODS: 28 specimens were fabricated and divided into 3 groups: group of chemical-cured PMMA, group of chemical-cured PMMA reinforced by stainless steel wire and group of chemical-cured PMMA reinforced by Ribbond polyethylene fiber. A three-point bending test was used to measure the flexural strength and flexural modulus of specimens. Then the data were analyzed with a one-way analysis of variance. RESULTS: The flexural strength of chemical-cured PMMA group was (51.383 +/- 2.761) MPa, the flexural modulus was (1791.2 +/- 113.760) MPa; The flexural strength of stainless steel wire reinforced group was (58.725 +/- 1.218) MPa, the flexural modulus was (2092.76 +/- 120.28) MPa; The flexural strength of Ribbond polyethylene fiber reinforced group was (80.975 +/- 2.58) MPa, the flexural modulus was (2866.53 +/- 107.51) MPa. The one-way analysis of variance showed that the results were significant (P < 0.001). Newman-Keuls method showed that the differences among all groups were significant (P < 0.05). CONCLUSION: The Ribbond polyethylene fiber can raise the flexural strength and flexural modulu of polymethyl methacylate.

Dental Bonding↗
PubMed1992

[The behavior of fiber-reinforced plastics during laser cutting].

The pattern of the organic emissions, which are produced by processing of fibre reinforced plastics (epoxy resins reinforced by aramid and glass fibres and phenol resins reinforced by aramid fibre) with laser beam was studied and the concentrations of the main components determined. Despite the application of plastic materials with different chemical structures, the observed patterns are very similar. Mainly aromatic hydrocarbons are emitted, especially benzene and toluene, as well as some heteroatom-containing aromatic hydrocarbons (e.g. phenol). By use of oxygen as process gas the emissions during cutting of glass fibre reinforced plastics can be reduced, while they will be constantly high with aramid fibre reinforced plastics.

Air Pollution↗
PubMedDate not supplied

Water sorption and dimensional stability of three glass fiber-reinforced composites.

PURPOSE: Water sorption and dimensional stability of three fiber-reinforced composites were studied. Two composites (Vectris, FibreKor) were resin impregnated industrially, and one composite (Stick) was polymer preimpregnated but required further manual impregnation. MATERIALS AND METHODS: Bar-shaped specimens of each material were prepared according to manufacturers' instructions. The water sorption and dimensional change of each specimen were calculated according to the change in its weight and dimension before and after immersion. Specimens were immersed in distilled water for 1, 7, 60, and 180 days. SEMs were taken to examine the quality of the fiber-matrix interface. The volume percentage of fiber content of each fiber-reinforced composite was experimentally estimated. RESULTS: A general trend of increasing water sorption for each immersion period according to the material type was: Vectris < FibreKor < Stick. There were no significant differences in dimensional change among the materials and immersion periods. CONCLUSION: The preimpregnated fiber-reinforced composite (Stick) showed higher water sorption than the industrially impregnated fiber-reinforced composites (Vectris, FibreKor). Despite a variation in the water sorption of the fiber-reinforced composites studied, all were within a 32 microg/mm3 criterion established by the ISO. The magnitude of dimensional change was small enough that it should not raise any significant clinical concern.

Absorption↗
PubMedDate not supplied

Single-tooth replacement with a chairside prefabricated fiber-reinforced resin composite bridge: a case study.

There are many fixed options for replacing a single anterior tooth, including implants; conventional full coverage; porcelain-fused-to-metal, all-ceramic, and fiber-reinforced composite designs; and minimal preparation designs that utilize lingual wing frameworks made from metal, ceramic, or fiber-reinforced composite. All of these approaches require at least two visits; however, it is possible to replace a missing anterior tooth in a single visit by using adhesive techniques with resin composite and fiber-reinforced resin composite materials. This approach has been developed and refined with a bridge created at chairside, using a prefabricated fiber-reinforced composite framework. This framework consists of a pontic substructure that is shaped to support a resin composite pontic, with one or two wings used to attach the pontic substructure to either the lingual or facial surfaces of the abutment teeth. This article describes a chairside technique for replacing a maxillary central incisor by using a prefabricated fiber-reinforced framework.

Aged↗
PubMed2004

Staple-line reinforcement techniques with different buttressing materials used for laparoscopic gastrointestinal surgery: a new strategy to diminish perioperative complications.

Many techniques have been analysed to reduce the risk of perioperative anastomotic leakage and bleeding. No specific resection technique with either linear or circular stapling devices has been shown to be superior in preventing these complications. Reinforcement of staple lines with various buttressing materials is a new strategy used to diminish or eliminate anastomotic leaks and haemorrhage. In this chapter, varying reinforcement techniques with different materials are compared. The available literature has been reviewed thoroughly for relevant data regarding stapled reinforcement techniques and minimizing anastomotic leaks and haemorrhage. Reported data show non-absorbable, semi-absorbable, and bioabsorbablematerials available for gastrointestinal (GI) resections. Semi-absorbable xenomaterials (Bovine Pericardial Strips and Bovine Collagen Strips; Shellhigh No-Reaction Vascupatch, Milburn, NJ, USA), non-absorbable expanded polytetrafluoroethylene (ePTFE; W.L. Gore, Elkton, MD, USA) and absorbable poly (L-lactic acid-co-epsilon-caprolactomne) film are compared. Non-absorbable and semi-absorbable materials show many differences. Absorbable polymer membranes demonstrate marked benefits. Staple-line reinforcement used for laparoscopic GI surgery is a relatively new strategy, most probably improving perioperative outcome only if proper buttressing material is used. To decrease anastomotic complications, using an absorbable polymer membrane as staple-line reinforcement material is reliable and efficacious.

Biocompatible Materials↗
PubMed2005

[Observation on clinical therapeutic effect of "mother-son" reinforcing-reducing method on stroke at restoration stage].

OBJECTIVE: To probe into the role of "mother-son" reinforcing-reducing method of five Shu points in clinical treatment of stroke at restoration stage. METHODS: Sixty-six cases of stroke were randomly divided into a treatment group (n = 34) and a control group (n = 32). The treatment group were treated by acupuncture at acupoints of The Hand-Yangming and The Foot-Yangming Channels, and "mother-son" reinforcing-reducing method of the five Shu for reinforcing deficiency and reducing excess according to deficiency and excess of channels differentiated by Cunkou Renying diagnosis; the control group were treated only by acupuncture at acupoints of The Hand-Yangming and Foot-Yangming Channels with uniform reinforcing-reducing method. Blood flow velocity in Cunkou and Renying Vessels before and after treatment were determined with transcranial Doppler ultrasono-blood flow meter and their clinical therapeutic effects were compared. RESULTS: There was a very significant difference before and after treatment in blood flow velocity in Cunkou and Renying vessels in the treatment group; the clinically basic recovery and markedly improving rate after treatment in the treatment group was significantly superior to that in the control group (P < 0.01). CONCLUSION: The acupuncture therapy of "mother-son" reinforcing-reducing method of five Shu points based on differentiation of yin, yang and deficiency and excess of channels by Cunkou and Renying Vessel methods can increase clinical therapeutic effect on stroke at restoration stage.

Acupuncture Points↗
PubMed2005

Polyethylene fiber-reinforced composite inlay fixed partial dentures: two-year preliminary results.

PURPOSE: Polyethylene fiber-reinforced composite inlay fixed partial dentures (FPDs) have been under development for some time. There is a lack of data on the clinical performance of such prostheses. This prospective clinical study evaluated the clinical performance of polyethylene fiber-reinforced composite FPDs over two years. MATERIALS AND METHODS: Twenty-eight polyethylene fiber-reinforced composite inlay FPDs were fabricated for 19 patients. The treatment plan included removal of the existing restorations, placement of an ultrahigh molecular weight polyethylene (UHMWP) fiber ribbon, and final restoration with a light-curing hybrid resin. The 28 polyethylene fiber-reinforced composite inlay FPDs were examined clinically after 2 years. RESULTS: All 28 FPDs were intact at the 2-year examination. There were no signs of fracture, debonding, or discoloration. CONCLUSION: Based on the results of this descriptive study, the polyethylene fiber-reinforced composite inlay FPDs were considered clinically successful at the 2-year examination.

Adult↗
PubMed1991

Reinforcement of motor evoked potentials in patients with spinal cord injury.

Transcranial magnetic stimulation of the motor cortex has been used to investigate the putative existence of spared motor pathways in spinal cord injured patients with clinically complete paralysis. Particular consideration was given to methods of neurological reinforcement likely to minimize the risk of false negative interpretation of absent motor evoked potentials (MEPs). The principal methods of reinforcement included target and remote muscle contractions and conditioning of MEPs with a brief (20 msec) train of cutaneous stimulation (500 Hz: duration 0.1 msec) delivered 20-150 msec prior to cortical stimulation. Twelve control subjects and 26 patients with severe traumatic spinal cord injury underwent cortical stimulation delivered from a Cadwell MES-10 (70-100% intensity) through a 9-cm focal-point coil. Electromyographic responses were recorded from surface electrodes in bipolar configuration and amplified (3 dB down at 10 Hz-1 kHz) prior to storage. MEPs were recorded, following reinforcement, in muscles with clinically complete paralysis in 4/26 patients. In each case, MEPs were of low amplitude (less than 0.5 mV), polyphasic, and with variable and prolonged latencies. MEPs were evoked in severely paretic (clinically incomplete paralysis) muscles in 6/8 patients only when neurological reinforcement was employed. Conditioning of MEPs in tibialis anterior with preceding cutaneous stimulation to the plantar surface (subthreshold for evoking a flexion reflex) yielded a well-defined modulation of MEP amplitude in control subjects. An early (Conditioning-Test (C-T) intervals 20-45 msec) period of inhibition of MEPs (mean = 60% of control) was followed by a period (C-T intervals 50-90 msec) of facilitation (mean = 345%) and a subsequent (C-T intervals 90-150 msec) period of inhibition (mean = 0%). In spinal cord injured patients the same conditioning paradigm failed to reveal MEPs, but did result in the appearance of suprathreshold flexion reflexes in 2 patients at 20-55 msec C-T intervals. This summation of convergent but subliminal cortical and cutaneous inputs to the target motoneuron pool provided additional evidence of preserved cortical influence on segmental structures that was not detectable by other means. These results extend previous reports of electrophysiological evidence of spared motor pathways in spinal cord injured patients with complete paralysis, and affirm the need for neurological reinforcement as a routine procedure in cortical stimulation studies of spinal cord injuries.

Adult↗
PubMed1991

Reinforcement of linear structure using parametrized relaxation labeling.

An approach for reinforcing underlying linear structure while suppressing unwanted noise, useful for analysis of medical images, has been presented. The method utilizes principles previously presented with regard to relaxation labeling processes, but differ in that the label set is now considered to be continuous and the distribution of label preference values for each object (pixel) parametrized by a single vector. Due to this parametrization, the total number of computations per pixel in the new method is now dependent only on the number of neighbors used in the computation, and not on the number of labels as well, as in previous methods. Thus, for a general reinforcement problem with m labels and n neighbors being considered for each pixel, the time complexity per object (pixel) per iteration goes as O (nm2) for the prototypical algorithm (e.g. (Zucker, et. al., 1977)) and is reduced by the approach presented here to O (n). The method uses a new approach for deciding local neighborhood influence and making a decision between reinforced linear structure with some magnitude and orientation and a no-structure condition based on the nonlinear (sigmoidal) thresholding of a linear vector sum. It should be noted that there is a similarity between this sigmoidal thresholding function and similar functions used in artificial neural networks (Hopfield, 1984). Ongoing work is being performed to further investigate such overlap. Also, it is planned to extend the approach in several ways. These include the ability to reinforce co-circularity, as well as to reinforce underlying planar structure by updating surface normals in true three-dimensional diagnostic imagery.

Image Enhancement↗