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Mechanical properties of acrylic cement and its interface characteristics with cancellous bone have been described. Applications and techniques for optimal use of the cement in joint replacement, treatment of pathologic fractures, and implant revision procedures are presented.
A long term follow-up (10 divided by 12 years) of Charnley total hip arthroplasties fixed with radiopaque acrylic cement is reported. Clinical results and X-rays features have been correlated and discussed with reference to the bone reaction and to the diagnostic possibilities of standard radiographs. A radiographic diagnosis of loosening preceding relevant clinical symptom may allow revision arthroplasty before anatomical situation becomes too deteriorated.
Loosening of the prosthetic stem is one of the most frequent problems in arthroprosthetic replacement. Fixation at the bone/cement interface is therefore of crucial importance. This can be affected by several factors, one of which is the heat generated in the acrylic cement, which may exceed the level at which tissue viability is affected. The authors therefore investigated this phenomenon in theoretical models. These were related to the level and duration of temperature changes at four levels - inside the cement and at the interfaces between cement, implant, spongy bone and cortical bone. Graphs showing temperature peaks and duration are constructed in all the varying conditions and their implications discussed. These concern the viability of osteocytes and vascular tissue, and the mechanical strength of the cement. The implications on design and surgical technique are obvious and point to the need to use the thinnest layer of cement compatible with firm fixation.
In this paper, succeeding the study of the part 1 on the thinning of the upper acrylic resin complete denture with the reinforced palate, it was investigated to keep the same stiffness and strength as the normal resin dentures, and to make the patient comfortable. Besides, many different palate forms exist in the patient's mouth in clinical cases, and so, influence of these forms on the thin plate dentures comes into question. Therefore, 3 types of the palate forms (the standard shape, the extremely large torus and the generally shallow shape) were established, and then the flexural stiffness and strength, and the deformation of the denture bases were scrutinized in this paper. The results obtained in this investigation are as follows: 1) The maxillary torus with sheer bulk had little influence on the flexural stiffness and strength. But, about the generally shallow-shaped denture bases, the mechanical properties dropped a little as compared the normal resin denture bases. The reinforced thin denture bases of which thickness was 60% of the normal one, showed the excellent mechanical properties in spite of the difference of the palate forms. 2) In the upper complete denture base, in spite of the palate forms, anteriority and posteriority of the one were deformed against the load direction around the frontal section through the bilateral canines, and the bilateral ridges of the one were deformed to the load direction around the midline of the denture base. The deformation was extremely decreased by not only the palate but also the whole of the denture base as the reinforced one.
In the literature dealing with causes of denture sore mouth (D.S.M.) a review is given of some possible allergenic factors in acrylic dentures and of testing procedures, as well as of the incidence of allergy. A report is presented of a patient with D.S.M., the cause of which was allergy to the denture material. Skin tests showed that the surface of the upper denture in contact with the hard palate was allergenic, but not the vestibular surface in contact with the cheeks. The lingual surfaces of the lower denture were not allergenic (the other surfaces were not investigated at this sitting). It could not be ruled out that the resin might be inhomogeneous as regards the allergenic factor. The allergenic properties were verified with test castings in the form of discs made under similar conditions to those for the palatal surface. A test casting made in the same way as the vestibular side of the upper denture showed allergenic properties before polishing. The absence of allergenic properties at this point of the denture could be explained by means of another experiment with a test casting in which the allergenic properties disappeared after polishing of the surface of the resin. The working theory was set up that both the palatal and vestibular surfaces of the denture are allergenic, but that this is eliminated by polishing of the latter. The theory was tested in Part III. It was ruled out that the impression material and insulating material could be allergenic. This study is continued in Parts II and III.
The authors propose a method for osteosynthesis of mandibular fractures in a stable and even solid manner, to avoid the inconveniences of mandibulomaxillary fixation. These include: -- the duration of the operative period, -- the necessary close supervision to avoid secondary displacement, -- desmodontous lesions, -- the adverse effects on mouth hygiene, -- the nutritional disturbances with subsequent loss of weight. There is also the ever-present risk of infection, particularly in the dentulous zone where a fracture line crossing a dental alveolus is permanently exposed to the risk of infection from the buccal flora. Three cases are described in which gentamicin acrylic cement pellets were employed to treat bone infections after osteosynthesis of mandibular fractures, with subsequent healing of the septic foci.
This article describes a technique for fabricating a custom acrylic resin shell that will ensure a properly designed amalgam core for the coronally debilitated, endodontically treated posterior tooth. A few simple procedures result in a core foundation for root protection, an ideal crown preparation, and a more predictable final restoration.
This study evaluated the effect of disinfection methods on the dimensional stability, flexural properties, and microhardness of a heat-polymerized denture acrylic resin. A 1- and 12-hour immersion period in 2% alkaline glutaraldehyde, and 3- and 15-minutes exposure to microwaves were employed as disinfection or sterilization procedures. Storage in water for 1 and 12 hours were used as the control. For each procedure 10 specimens were used. The results indicated that the linear changes observed were of no clinical importance. The same conclusion can be drawn for flexural properties and microhardness. The microwave method is a useful alternative to immersion disinfection.
Bonding of different soft lining materials has been widely investigated, but there is little work on the effect of using different denture base resins. This study investigates the bonding of Molloplast-B (a heat-cured, silicone soft lining material) and five commercial acrylic denture base materials of different types (Pacton, Lucitone, Meliodent, Ivocap and Compresin). The lining was processed against all the resins cured and Pacton, Lucitone and Meliodent uncured. In the cured specimens, Lucitone, Meliodent and Compresin demonstrated cohesive failure, whereas Pacton and Ivocap demonstrated part-adhesive and part-cohesive failure. All three sets of uncured specimens demonstrated adhesive failure. It was concluded that pre-curing, roughening and treating with Primo adhesive gives a better bond.
The authors report on 40 cases using acrylic-metal prosthesis after ablative cancer surgery and compare them with the literature. The long-term complications (prosthesis extrusion or infection) are important, but the short-term follow-up (3 months) is more than 80% of success, any material used. The prosthesis keep a physiological position to the mandible, against scar sequelae. The use of soft tissue closure without post-operative radiotherapy increase the success of a simple-used and low-priced device of mandibular reconstruction.
The present study was designed to investigate methyl-[2,3-14C]acrylate (MA) distribution, excretion, and metabolism. Data presented here show that the radioactivity derived from MA is rapidly absorbed after i.p. and p.o. administration and distributed into all major tissues of rats. The highest concentration of MA-derived radioactivity was detected mainly in the liver and kidneys at 1 (i.p.) or 2 (p.o.) hours after dosing. There were only slight differences observed in the dynamics of tissue distribution and excretion in relation to the route of administration. The major route of MA excretion was CO2 exhalation (approximately 54% of the administered dose in 48 h) followed by urinary excretion. Two metabolites were identified in the urine, namely, N-acetyl-S-(2-methylcarboxyethyl)cysteine and N-acetyl-S-(2-carboxyethyl)cysteine, and ratio between those was about 1:1.
This study investigated the fracture load and deflection of acrylic resin specimens with different types of metal inserts. A metal adhesive denture resin (Meta Dent) and a conventional denture resin (Meliodent) were used with round metal, braided wires and mesh as inserts. There were eight groups and each group contained ten specimens. Each specimen was broken on a Monsanto testing machine using a three point load after storage in water at 37 degrees C for 48 hours. The results indicated that metal inserts enhanced the fracture resistance of both denture resins. No significant differences were found between the metal adhesive and conventional denture resin.
After outlining the problem of pathological fractures in patients suffering from malignant tumours, a recent acrylic cement osteosynthesis technique is presented. This makes immediate immobilization of the fracture possible, alleviation of pain and so early use of the fractured extremity. The personal series is illustrated and it is concluded that the technique also offers suitable prophylaxis when radiography of the skeleton points to osteolytic areas in which pathological fracture can be foreseen.
Acrylic cement, used to fixate total hip arthroplasty (THA), creeps under dynamic and static loading conditions. As a result, THA stems which are debonded from the cement, may gradually subside, depending on their shape and surface roughness. The purpose of this study was to evaluate the relationship among dynamic load, creep characteristics, interface friction, and subsidence patterns. A laboratory model consisting of a metal tapered cone, surrounded by a cement mantle, was developed. The cone was gradually compressed in the cement by a dynamic, sinusoidal axial force, cycling between 0 and 7 kN for 1.7 million cycles at a frequency of 1 Hz. Subsidence and cement strain were monitored. Two tapers were tested in this way. The relationships among subsidence, creep properties and interface friction were evaluated from a finite element (FE) model, used to simulate the experiments. In this model, the creep properties obtained in dynamic and static, tension and compression experiments measured earlier, were used. The subsidence patterns of both tapers were similar, but one subsided more than the other (380 vs 630 microns). Both subsided stepwise instead of continuous, with a frequency much smaller than that of the applied load. The characteristics of the subsidence and cement-strain patterns could be reproduced by the FE model, but not with great numerical precision. The stepwise subsidence could be explained by slip-stick mechanisms at the interface starting distally and gradually working towards proximal. Variations in friction from 0.25 to 0.50 reduced the total subsidence and the step frequency by about 50%. It was concluded that FE-models used to simulate the mechanical endurance characteristics of THA reconstructions, extended to incorporate cement creep, produce realistic results. These results showed that prosthetic subsidence under dynamic loads occurs due to cement creep. The extent of the subsidence is extremely sensitive to interface friction, hence to small variations in surface roughness and cement constitution. This may explain the relatively large variation of in vivo prosthetic subsidence rates reported in the literature.
During the period between 1972-1992 32 patients with calvarial bone defects were treated by 35 reconstructions. The paper presents early and late results of various methods of reconstructions. Very good late results were achieved in all 5 patients in whom the defects were reconstructed with autogenic split cranial bone graft. There were equally good results in 19 from 22 patients in whom acrylic and propylene-polyester implants were applied. Total resorption of autogenic split iliac and split rib bone graft were observed in all 5 patients in whom skull defects were filled with this tissue.
We describe a hemiarthroplasty of the shoulder with an acrylic Judet hip prosthesis, inserted after the excision of a giant cell tumour of the head of the humerus, which functioned well for 39 years.
Injection of acrylic glue, especially in its watery phase, remains difficult, even with small syringes. The use of a pressure regulator similar to those used for balloon inflating in vascular radiology makes this procedure easier, reducing the risk of glove perforation, with optimal precision and safety.
We report a difficult case of recurrent carotid blowout syndrome in a patient who had a rupture of the common carotid artery with formation of a large pseudoaneurysm. Conventional management of this emergency, consisting of composite occlusion of the internal and common carotid arteries, was not possible owing to prior clinical failure of balloon test occlusion. This led to an initial attempt to cover the site of rupture with overlapping self-expanding stents, which was only temporarily successful in controlling the hemorrhage. When a subsequent episode of carotid rupture with life-threatening hemorrhage occurred, percutaneous direct-puncture acrylic embolization with temporary flow arrest was used to successfully obliterate the pseudoaneurysm.