bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methods of osseous reconstruction of the mandible following surgical resection
Authors: Boyne Philip J. 
Published: May 2005

AbstractOsseous reconstruction of the surgically resected mandible has presented, for some time, a considerable surgical problem. This paper presents the results of a series of experimental investigations evaluating the various morphologic and immunologic types of autogenous bone grafts in the reconstruction of the surgically resected mandible. The osteogenic inductive effect of hemopoietic marrow in combination with autogenous cancellous bone is reviewed and examples of this inductive effect are cited. The application of the particulate graft of cancellous bone and marrow to the restoration of large areas of lost mandibular bone is described. In this application, the particulate graft is used with a compatible metal implant designed to offer an optimal grafting system for the reconstruction of large areas of the mandible. The metallic implant, in addition to containing the bone graft, serves to control and fix the host bone fragments and lessens the period of intermaxillary immobilization necessary for healing. Normal aesthetic mandibular contour is restored and routine dental prosthesis may be constructed over the reconstructed mandible. It is felt that this system offers the optimal approach, through the combination of implant metals and highly osteogenic graft tissues, to the reconstruction of the mandible following surgery.
Development of the self‐supporting polymer tooth implant
Authors: Hodosh Milton , Povar Morris , Shklar Gerald 
Published: May 2005

AbstractThe central theme of our studies is concerned with finding a better means of tooth replacement. This goal is being realized for a “tailor‐made” polymer and associated techniques of usage have been developed for this purpose. In the course of doing this, we have introduced the polymer implant concept by which materials can be tailor made to serve different functions.The polymer composition currently considered best for these studies contains clear polymethacrylate powder and liquid monomer, blowing agent (dinitrosopentamethylene tetramine), anorganic bone, and N‐tributyl phosphate. This mixture is heat processed in a plaster mold at 300° F for 30 min. The processed implant is sandblasted to remove its outer skin and to open the pores on the implant's surface to the host's tissues when implanted. This formulary has resulted in the totally self‐supporting replica implant becoming a reality in baboons. Two Papio‐Anubis baboons', both with 8 incisors (4 upper and 4 lower) were replaced with polymer replicas, and after 3 months the splints were severed and the 16 implants remained totally self‐supporting. Metals have been coated with this polymer formula, and polymer coated pins have been used successfully as supports for fixed prostheses and as endodontic stabilizers. The internal metal piece imparts increased strength without bulk, while the polymer coating allows for attachment to the implant. The untoward effects of metals, such as heat transfer, electrical and corrosive phenomena are diminished or eliminated. This “happy union” of the two materials allows the implant to be strong and well integrated into the host. The Polymer Implant Concept holds a genuine hope for the future. In this instance it provides for a better means of tooth replacement: one which is cosmetically and functionally excellent. Most probably it will have an important place in the neurosurgical, orthopedic, and medical fields as well.
Implantable ceramic teeth
Authors: Hamner James E. , Reed O. M. 
Published: May 2005

AbstractIdentification of an appropriate biomaterial which would allow an artificial tooth implant to function in a stable manner without eliciting a toxic response is one of the major challenges facing dentistry today, and has been the subject of an increasing number of investigations in recent years.Because of questions which still remain regarding the biocompatibility of candidate materials, extensive animal research in tooth implantation is an absolute necessity. Primates, providing dental models closely approximating the human condition, are especially valuable for undertaking that systematic scrutiny of experimental implant materials which is so clearly prerequisite to human clinical trials.In the current study, 26 jaw block sections, containing calcium aluminate root implantations, were surgically removed from 13 baboons. The implantation time periods ranged from 2 weeks to 10 months. The controlled porosity of the ceramic roots varied from 50 to 200 μ.Ingrowth of periodontal tissues into the porous ceramic root implants was demonstrable clinically, with light microscopy, and with the scanning electron microscope. Implant retention and stability, resulting from adequate ingrowth of fibrous/vascular elements into the ceramic pores, were optimal when the calcium aluminate root implants had a porosity of 100–150 μ. The problems of toxicity and biodegradability were not encountered using calcium aluminate.
The anchor oral endosteal implant
Authors: Cranin A. Norman , Dennison Thomas A. , Schnitman P. , Piliero S. , Pentel L. 
Published: May 2005

AbstractSince the accidental rediscovery of the endosteal implant by Formaggini in the late 1940's, the field has witnessed a tremendous evolution in theory and clinical application. Chercheve, in his efforts to improve on earlier spiral designs, proposed several theories on the relationship of the metallic endosteal implant to its osseous environment. Some of the problems he experienced still have not been overcome in our present designs.The development of the blade implant marked a true advancement in endosteal design. This implant proved to be much more functional and reliable than the spiral concept; however, it too had certain disadvantages which became obvious after a relatively short period of clinical trial. The anchor endosteal implant was developed as a result of efforts to correct the various problems associated with the blade.Preliminary animal research using both anchor and blade implants was begun. Four dogs had each type of implant inserted in edentulous areas. The animals were sacrificed four months post insertion for histologic examination. More sophisticated animal implant studies are being performed at the Brookdale Hospital Medical Center.Clinical evaluation of the anchor implant over a 3‐year period has been very encouraging. Results have indicated a higher level of clinical success than previously achieved with blade or spiral designs.
History and philosophy of attachment of prostheses to the musculo‐skeletal system and of passage through the skin with inert materials
Authors: Murphy Eugene F. 
Published: May 2005

AbstractThe history of passage through the skin and of attachment to bone to treat fractures is briefly sketched since the work of Malgaigne in 1843. Attachment of metal to bone for many months is now routine after open reduction of fractures and is quite successful for many years for completely buried hip prostheses. Passage through the skin, the gums, or the cornea has been used in many specialties. At least half a dozen investigators have attempted skeletal attachment of artificial limbs.Even if absolute solutions are impossible, perhaps temporary successes might be extended by one or two orders of magnitude (adequate for a lifetime) by increased attention to engineering details. The role of ASTM Committee F–4, Surgical Implants, is noted. An important principle may be matching of stiffness, or at least tapering of the transition in stiffness, between implant and tissue. This precaution should reduce local stress concentrations tending to loosen attachment to bone or to reopen mechanical adherence of tissue to implant, opening a pathway for infection.
The fracture mechanics of bone—another look at composite modeling
Authors: Cooke Francis W. , Zeidman Howard , Scheifele Stephen J. 
Published: May 2005

AbstractThe energy absorbed in the impact fracture of bovine metatarsal and metacarpal bone was shown to depend on the aspect from which the inpact specimen was obtained. In a majority of cases caudad specimens were more than an order of magnitude tougher than cephalad specimens and the fracture surfaces of the tough specimens were fibrous or woody in appearance due to osteon pull out. This pull out phenomenon was identified as a major factor in determining the toughness of bone and is analogous to the toughening effect produced by fiber pull out in synthetic composites. Whenever a substantial component of the applied stress was resolved across the osteons, the fracture cracks were seen to propagate in an interosteonal mode similar to the delamination of synthetic composites with weak interfaces. Plastic deformation of the matrix is the third mechanism commonly employed to effect toughening in synthetic composites. Although no similar phenomenon was demonstrated in this study, it is probable that this also makes some contribution to the work‐to‐fracture of bone.
Design considerations in a rolamite knee joint prosthesis
Authors: Thornton A. W. , Predecki Paul 
Published: May 2005

AbstractProblems encountered with existing total knee prostheses are briefly summarized. Existing prosthesis designs giving anatomically correct relative planar motion between femur and tibia are reviewed. A design incorporating a Rolamite suspension is proposed and evaluated. The design has the advantages of being closely anatomical in its motion having negligible friction or wear and requiring no lubrication. If substantial tendon damage is present the Rolamite design is easily modified to include a gear and rack.
Structure ‐ biocompatibility relationship of condensation polymers
Authors: Imai Y. , Watanabe A. , Masuhara E. , Imai Y. 
Published: May 2005

AbstractVarious condensation polymers including polyamides, polyesters, polyethers, polysulfonamides, polysulfonate, polyphosphonate, polyimide, polyamide‐imides, polyester‐amides, etc. have been prepared and evaluated for their biocompatibility by a cell culture method. Cell attachment and cell growth are influenced by the chemical structures of the tested polymers. Aliphatic polyamides exhibited considerably different cell growth behavior than aromatic polyamides.
Acrylate and methacrylate esters: Relationship of hemolytic activity and in vivo toxicity
Authors: Dillingham E. O. , Lawrence W. H. , Autian J. , Schmalz G. 
Published: May 2005

AbstractQuantitative hemolysis assays of acrylate and methacrylate esters provided estimates of the intrinsic hemolytic activity (Hi the slope of the concentration‐response curve) and the concentrations effecting 5% (H5) and 50% (H50) hemolysis. The dependence of hemolytic activity and LD50 (mice) on physical properties (lipophilicity, molar refraction, and molecular volume) of the esters was determined by multiple regression analysis. The observed correlations were: Hi, R2 = 0.94; H5, R2 = 0.95; H50, R2 = 0.94; and LD50, R2 (all compounds) = 0.80, R2 (all compounds less the methyl esters) = 0.94. The difference of the methyl esters was associated with the smaller steric volume of the methyl ester substituent and the presence (methacrylates) or absence (acrylates) of the branched methyl group. Associative steric contributions of the branched methyl group and the ester substituents were probably responsible for greater variability in the methyacrylate series. The results were consistent with the conclusion that the mechanism of the action of the esters is membrane mediated and relatively nonspecific and that in vivo biotransformation was not a significant factor. Also, long‐term toxic liability of the esters may be more closely related to intrinsic toxicity than acute toxicity.
Stiffness and inelastic deformation in acrylic‐titanium composite implant materials under compression
Authors: Schnur D. S. , Lee D. 
Published: May 2005

AbstractA variety of acrylic bone cement‐metal composite materials were prepared and tested in simple compression at 37°C in order to evaluate the mechanical behavior of these materials for possible use in bone replacement. The stiffness of the composite was of particular concern, and a simple rule of mixture was used to raise the modulus of acrylic bone cement. The reinforcement of the cement was accomplished by titanium and Ti‐6A1‐4V in different forms, e.g., wire, sheet, wire mesh, and powder. Test results demonstrated that the stiffness of the bone cement could indeed be increased by a desired amount to that of bone. A 16% volume fraction consisting of 25 0.10 cm diam Ti‐6A1‐4V wires increased the modulus of the bone cement by 380% to a value comparable to the modulus of cortical bone. Titanium sheet was nearly as effective as wires in increasing the modulus of bone cement, while titanium mesh was not a significantly effective reinforcing material. The amount of titanium powder added to the bone cement did not alter the compliance of the matrix material. In addition, as the flow strength increased, the strain to the point of load instability decreased. It was concluded that the extent of stiffening was governed by nonuniform deformation in the metal and the adjacent matrix which could be explained on the basis of geometrical considerations. Some of the limitations of the test results as well as methods of predicting the composite implant material behavior are also outlined.
Hyaluronan solution as a cartilage antidesiccant
Authors: Bloebaum R. D. , Rubman M. H. , Merrell M. , Thacker K. , Hofmann A. A. 
Published: May 2005

AbstractDuring arthrotomy, desiccation of the articular cartilage of synovial joints by the ambient environment of the operating room causes chondrocyte death and may promote degenerative changes within the joint. This study documents the efficacy of a biomaterial, hyaluronan (HY) solution, to maintain chondrocyte viability during desiccation. Rabbit patellar articular cartilage was air‐dried for 2 h with and without application of the HY solution. As assessed by 35S04 uptake and autoradiography, the HY solution helped maintain chondrocyte viability, when compared to air dried specimens (p ≤ 0.02). HY solution applied to the articular surfaces of joints undergoing arthrotomy may offset the detrimental effects of desiccation, such as chondrocyte death and degenerative joint changes.
Preparation of poly (D, L) lactide microspheres by emulsion–solvent evaporation, and their clinical applications as a convenient embolic material
Authors: Grandfils C. , Flandroy P. , Nihant N. , Barbette S. , Jérome R. , Teyssié Ph. , Thibaut A. 
Published: May 2005

AbstractThe aim of preoperative embolization is to facilitate surgical removal by reducing tumor volume and vascularity, thereby decreasing blood loss during surgery. In a search for a better embolic material, compared to heterogeneous commercial products, we describe here in detail the preparation of poly (D,L) lactide microspheres by an emulsion‐solvent evaporation process. The size distribution of the microparticles and their aggregation state‐critical parameters in view of such application‐have been investigated. Their effectiveness, as an embolic material, has been evaluated by some preliminary experiments undertaken on humans. The results were assessed on clinical and histological grounds.
Mechanical properties of fibrin adhesives for blood vessel anastomosis
Authors: Flahiff C. , Feldman D. , Saltz R. , Huang S. 
Published: May 2005

AbstractVarious methods have been used for anastomosing, or attaching, two ends of a severed blood vessel together. The most common method, suturing, is tedious, can be time‐consuming, and requires special training in microvascular surgery. Other methods, such as mechanical devices and lasers, have some problems as well. The use of fibrin adhesives for blood vessel anastomosis might eliminate some of the current problems by allowing a quicker, simpler, and more reliable method of attachment. Although mechanical studies have been conducted to determine fibrin glue properties in shear, tensile, and burst tests; most of these studies have used skin or intestinal tissue. Therefore, to evaluate the feasibility of using fibrin glue as an adhesive for blood vessel anastomosis, the mechanical properties of blood vessels joined with fibrin glue were examined using tensile and burst tests. High and low fibrinogen concentrations were tested after 5‐ or 45‐min time periods. In addition, three clinical methods of attachment were compared: end‐to‐end anastomosis, vessel overlapping, and suturing. In this study, because the adhesive strength was not found to increase significantly after 5 min, setting times for fibrin glue may be short enough to make it a clinical option when compared to suturing. In addition, the higher fibrinogen concentration did not result in a significantly higher adhesive strength, indicating that the lower concentration fibrin adhesives may be of comparable strength to the higher concentrations for clinical applications.
The role of connective tissue in inhibiting epithelial downgrowth on titanium‐coated percutaneous implants
Authors: Chehroudi B. , Gould T. R. L. , Brunette D. M. 
Published: May 2005

AbstractIdeally, the surface of epithelium‐pene‐ trating implants should impede apical epithelial migration. Previous studies have shown that micromachined grooved surfaces can produce connective‐tissue ingrowth, which inhibits epithelial downgrowth on percutaneous implants [Chehroudi et al., J. Biomed. Mater. Res., 24, 9, (1990)]. However, in those studies, connective tissue and epithelium interacted with the same surface so that the effects of the surfaces on each population could not be determined separately. The objectives of this study were (a) to examine cell behavior on implants in which connective tissue contacted surfaces of various topographies and epithelium encountered only a smooth surface, and (b) to compare one‐ stage and two‐stage surgical techniques. Implants had a base component (BC) which was either smooth or had a surface with 19‐pm‐ or 30‐pm‐deep grooves or 120‐pm‐ deep tapered pits, and a skin‐penetrating component (SPC) which was smooth. In the two‐stage technique, the BC was implanted subcutaneously for 8 weeks, which permitted the healing of the periimplant connective tissue. In the second stage the SPC was connected to the BC. For one‐stage implants, BC & SPC were connected and implanted percutaneously. Implants (BC & SPC) were removed 1, 2, or 3 weeks after percutaneous implantation and histological sections were measured for recession, connective tissue and epithelial attachment as well as capsule thickness. Light microscopy indicated that both grooved and tapered pitted surfaces encouraged connective tissue ingrowth. On the grooved surfaces, the orientation of fibroblasts changed from an oblique to a more complex pattern which included cells having round nuclei within the grooves, as well as cells oriented oblique or perpendicular to the grooves. In the tapered pits a hammock‐like arrangement of fibroblasts was observed. In some cases, foci of mineralization and formation of bonelike tissue were found on the grooved and pitted surfaces. The apical migration of the epithelium was significantly (p < 0.05) inhibited by those micromachined surfaces which produced connective tissue ingrowth to the BC. This study found that placing the implants in two stages improved the performance of percutaneous devices, and that a further improvement was achieved if the implant had a surface promoting connective tissue ingrowth.
Human gingival tissue response to HTR polymer
Authors: Yukna R. A. , Greer R. O. 
Published: May 2005

AbstractBiopsies secured during reentry surgical evaluation of previously treated periodontal osseous defects were examined for gingival tissue response to HTR polymer. Eleven patients provided biopsies of HTR grafted sites 6‐7 months after initial implantation. Minimal inflammation and infrequent foreign body giant cells were found. Bone was present in about half of the samples and osteogenesis associated with the HTR graft material was seen in about 20% of the biopsies. Serendipitously, biopsies of other graft materials or debridement only sites from 6‐30 months post‐treatment were also available for analysis and comparison, and showed similar tissue response. The results of this study suggest that HTR polymer (and other graft materials) is very biocompatible and elicits no untoward gingival tissue responses when placed in periodontal osseous defects.
Preparation and thrombogenicity of alkylated polyvinyl alcohol coated tubing
Authors: Strzinar Irena , Sefton Michael V. 
Published: May 2005

AbstractA polyvinyl alcohol hydrogel (PVA) was reacted with a CI8 isocyanate at 80°C in dimethyl formamide (DMF) in order to improve the platelet reactivity of the hydrogel through an inf hence on albumin adsorption or retention. A C, isocyanate was used as a control. Surface coverage by XPS appeared to be ∼100% for both C4 and C18 modified surfaces, although the limited solubility of C18 isocyanate in DMF may have resulted in a nonuniform surface. Relative to PVA or the solvent treated control, octadecylation resulted in increased albumin adsorption (from a single protein solution) and increased retention when the adsorbed albumin was exposed to a fibrinogen solution. However, octadecylation did not obviate the platelet reactivity problem in preliminary studies: systemic platelet counts were reduced by about half over 4 days in a canine AV shunt experiment and the initial rate of platelet destruction for C IR‐PVA was greater (36%/ day) even than for the solvent‐treated PVA. Surprisingly in preliminary studies butylation of PVA resulted in little or no thrombocytopenia and did not appear to increase significantly the fractional rate of platelet destruction relative to the shunt only blank. It is presumed that the nonspecific effect of alkylation (independent of chain length) was the dominant contribution to the reduced platelet reactivity. A similar effect of C18‐PVA presumably would have been observed had the limited solubility of C18 isocyanate not precluded a uniform surface coverage.
A fractographic investigation of PMMA bone cenent focusing on the relationship between porosity reduction and increased fatigue life
Authors: James Susan P. , Jasty Murali , Davies Jefrey , Piehler Henry , Harris William H. 
Published: May 2005

AbstractFracture surfaces of both monotonic and fatigue loaded bone cement samples were examined to investigate the fractographic characteristics of PMMA. Classic cleavage step river patterns were observed on all monotonically loaded samples, running downstream in the direction of crack propagation. AH fatigue cracks initiated at internal pores and the direction of crack propagation of many cracks was discernible. Porosity, pore size, and pore size distribution were found to affect the crack initiation and fatigue behavior of bone cement. Statistical analysis revealed a strong negative correlation between twodimensional porosity present on the fracture surfaces and the cycles to failure. The fractographic observations of these fatigue samples elucidate one reason why porosity reduction by centrifugation or vacuum mixing increases the fatigue life of PMMA bone cement.