No abstract available.
Polyethylene*

No abstract available.
Concanavalin A* ; Polyethylene Glycols* ; Polyethylene*

From September 1973 to October 1975, author had experienced two cases of congenital canaliculus atresia and eight of traumatic canalicus lacerations, and repaired them by means of the Pigtail probe of Worst inserted through a polyethylene tube (size of which being 46, I.D. 016" O.D. 031"). The length of time to leave the polyethylene tube in place had been six to eight weeks. Z plasty was performed to prevent cicatrical contraction of the lower lid. Two cases of congenital canaliculus atresia became reobstructed two weeks after removal of the tube which were accidentally slipped out. In a single case in which Z pIasty was not performed, the patient continued to complain of lacrimation due to cicatrical contraction in the lower lid margin medial to the punctum. The canaliculus, however, demonstrated the patency as evidenced by nasal drainage of fluid syringed into the punctum.
Drainage ; Humans ; Lacerations ; Polyethylene

There has been many researches aimed at reinforcing the strength of resin, and these have led to the development and use of numerous materials in recent years. A case in point, is the recent development of plasma-treated polyyethylene fiber which has been used mainly in fixed provisional restoration to reduce the incidence of fractures. This study aims at assessing whether plasma-treated polyethylene fiber as applied to composite resin is effective in increasing the flexural strength and how applied portions affect this. Twenty-four applied and eight unapplied composite resin bars were fabricated. Twenty-four applied specimens were divided into three groups. Plasma treated polyethylene fiber was applied to the groups each with different portions of composite resin. In the first group, plasma-treated polyethylene fiber was not applied. In the second group, fiber was applied to the compression side of composite resin. Fiber was applied to the tension side in the third group, while fiber was embedded in the tension side of the compositeresin in the fourth group. Each specimen was tested by use of a three-point bending strength test with an instron testing machine, and the flexural strength was calculated. The following results were obtained. : 1. Under the conditions of this study, the third and fourth groups demonstrated a statistically greater flexural strength compared to the first and second groups. 2. But there was no statiscally significant difference, not only between the first group and the second group, but also between the third group and the fourth group. Taken together, it can be concluded that plasma-treated polyethylene fiber applied to composite resin is an effective method in increasing flexural strength, and the best way of increasing the flexural strength is by application of plasma-treated polyethylene fiber to the tension side, or the embedding of same in composite resin. It must be mentioned however that this test used a static single-load test method. This method determined the maximum stresses that could be tolerated, but this might not be valid where the prediction of clinical failure is concerned. In order therfore to clinically utilize plasma-treated polyethylene fiber to reinforce the composite resin, it is suggested that a further study which considers the various loads be undertaken.
Incidence ; Plasma ; Polyethylene*

No abstract available.
Bone Substitutes* ; Polyethylene*

OBJECTIVE: Rod-screw fixation systems are widely used for spinal instrumentation. Although many biomechanical studies on rod-screw systems have been carried out, but the effects of rod contouring on the construct strength is still not very well defined in the literature. This work examines the mechanical impact of straight, 20° kyphotic, and 20° lordotic rod contouring on rod-screw fixation systems, by forming a corpectomy model. METHODS: The corpectomy groups were prepared using ultra-high molecular weight polyethylene samples. Non-destructive loads were applied during flexion/extension and torsion testing. Spine-loading conditions were simulated by load subjections of 100 N with a velocity of 5 mm min⁻¹, to ensure 8.4-Nm moment. For torsional loading, the corpectomy models were subjected to rotational displacement of 0.5° s⁻¹ to an end point of 5.0°, in a torsion testing machine. RESULTS: Under both flexion and extension loading conditions the stiffness values for the lordotic rod-screw system were the highest. Under torsional loading conditions, the lordotic rod-screw system exhibited the highest torsional rigidity. CONCLUSION: We concluded that the lordotic rod-screw system was the most rigid among the systems tested and the risk of rod and screw failure is much higher in the kyphotic rod-screw systems. Further biomechanical studies should be attempted to compare between different rod kyphotic angles to minimize the kyphotic rod failure rate and to offer a more stable and rigid rod-screw construct models for surgical application in the kyphotic vertebrae.
Molecular Weight ; Polyethylene ; Spine*

Insecticidal effects of Agnique MMF were investigated in the coastal brackish water shrimp farms in the Tan Thuan commune, Dam Doi district of Ca Mau province in 2000. The investigations were made in terracotta jars and shrimp ponds with the surface area 30m2 and 1000m2 each. Agnique MMF was found to have a high and fast killing effect on larvae of An.sundaicus at all three testing doses of 0.3ml/m2, 0.4ml/m2 and 0.5ml/m2. Especially larvae at instars of III, IV and pupae. However, the insecticide produced a low effect on Culex sitiens killing larvae of IV ins tar and only retarding larvae of I, II, III instar. The residual effect of Agnique MMF was found to be 14 days in the terracotta jars and 6 days in the ponds. In the direct observations, Agnique MMF was found to have no negative effects on rearing shrimps
Fatty Alcohols ; Polyethylene Glycols

In 1971, for purpose of reduction of peak stress occuring in cement and trabecular bone of the acetabulum, Harris reported a series of metal-backed acetabular components with removable polyethylene liners that could be replaced if excessive wear occured. Modular designs of hip prostheses have become popular recently, but they introduce the risk of disassembly of the components postoperatively. And introduce of loosening and infection of femoral or acetabular components by debris of polyethylene liner. We report a case of mechanical disassembly of polyethylene liner in cementless metal backed cup, and review previously reported articles.
Acetabulum ; Hip Prosthesis ; Polyethylene

PURPOSE: The purpose of this study was to examine the effects of change of polyethylene resin type and manufacturing method on the wear of polyethylene tibial component. MATERIALS AND METHODS: Thirteen MG I and 10 MG II components were retrieved at revision surgery. Each polyethylene tibial component was graded for surface wear damage. Density profiles of the polyethylene were measured to examine the extent of oxidative degradation of the polyethylene. RESULTS: The primary damage mode of the MG I retrievals was scratching and metallic debris, but the primary damage mode of the MG II was delamination (P<0.05). For the implants with implantation time of 5 years or more, the MG II polyethylene had a higher density value (0.959+/-0.002 g/cc, n=7) compared with the MG I (0.948+/-0.004 g/cc, n=11). Both delamination and polyethylene degradation increased with length of implantation time for the MG II components (P<0.01). Even after gamma sterilization, the directly molded 1900 MG I components experienced significantly less delamination and degradation than the machined GUR 415 MG II tibial components. CONCLUSIONS: This study suggests that delamination of polyethylene tibial components is influenced by resin type and/or manufacturing method
Fungi ; Polyethylene* ; Sterilization

PURPOSE: The purpose of this study was to compare the two-dimensional with three-dimensional radiographic measurements of polyethylene liner wear in the Harris-Galante II acetabular cup. MATERIALS AND METHODS: We measured the polyethylene liner wear amount and the wear rate of 64 hips with Harris-Galante II acetabular cup by two methods: Livermore's method and modified Devane's method. We evaluated the relationships between the two methods. RESULTS: The average total amount of wear and the average wear rate are 0.86+/-1.01 mm and 0.18+/-0.20 mm/year using the two-dimensional method and 0.99+/-1.01 mm and 0.21+/-0.2 mm/year using three-dimensional method respectively. The amount of wear and the wear rate by the three-dimensional method was larger than those by the two dimensional method. CONCLUSION: The amount of polyethylene liner wear can be measured by the two-dimensional method because it is highly correlated with the amount that is measured by the three-dimensional method, since there was no differences between the two methods.
Acetabulum* ; Hip ; Polyethylene*