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Wear of combinations of acrylic resin and porcelain, on an abrasion testing machine.

Wear tests of various combinations of acrylic resin and porcelain were made using a machine which was designed to test materials under conditions similar to those of masticatory function by simulating the loads, sliding distances, and contact times encountered in the human masticatory cycle. The results showed that the amount of wear of the two materials worn in combination depended on the nature of the surrounding medium and on the surface roughness of the opposing material. Acrylic resin showed good wear resistance provided no third party abrasive or opposing hard, rough surface was present. When a mild abrasive was incorporated in the system, the acrylic resin vs acrylic resin combination wore almost seven times more than porcelain vs porcelain. Clinical experience would suggest that this is a reasonably sound order of wear.

Acrylic Resins

Processing factors affecting the clarity of a rapid-curing clear acrylic resin.

The difficulty in repeatedly producing unblemished, clear acrylic resin in the dental laboratory has hindered its wider use, despite its many advantages over coloured material. Recently, rapid-cure dental acrylics have been introduced, which are available in both clear and coloured forms. This investigation examined various factors which may influence the production of unblemished, rapid-curing, clear acrylic resin. Utilizing a quantitative assessment of clarity, the most important factor influencing the clarity of the resin is shown to be the choice of separating medium. Tin-foil produces extremely high clarity, but alginate mould separator causes surface blanching. However, this surface blanching can be removed by polishing. Porosity, caused by too rapid curing, and stone model dryness are of only secondary importance. Possible water contamination of the monomer liquid due to accidental exposure only affects clarity at very high levels of contamination.

Acrylic Resins

[Hydrogen peroxide, chloramine T and chlorhexidrine in the disinfection of acrylic resin].

The effectiveness of 3% h drogen peroxide, 5% chloramine T and 0,5% chlorhexidine gluconate solutions in disinfection of acrylic resine plates massively infected with oral flora was analysed. The acrylic resine plates used for investigations, were infected in vitro with mixed salivary flora characterized by small numbers of yeast-like fungi (1st group), or great number of these microorganisms (2nd group). Infected plates were exposed to solutions of analysed disinfectants during various time periods. After rinsing or inactivation of disinfectant residues, acrylic plates were put into bacteriological medium and incubated during 7 days period in 37 degrees C. The results of this study indicated the effectiveness of acrylic plates disinfection to be dependent on used disinfectant, time of exposition, and microorganisms present on the surface of acrylic resine. The solutions of disinfectants were less active in the cases of plates infected with material containing great numbers of yeast-like microorganisms. Among analysed disinfectants 0,5% solution of chlorhexidine was characterized by most effective and rapid activity, whereas 3% solution of hydrogen peroxide was found to be the least effective.

Acrylic Resins

Acrylic resin blockout for interim removable partial dentures.

A technique using autopolymerizing acrylic resin as a blockout material has been described. This technique greatly simplifies the laboratory construction and insertion phases of the complex interim removable partial denture. It is not suggested that the acrylic blockout replace the wax blockout if a heat-cured denture base is not indicated. Wax should be used if a "sprinkle-on" autopolymerizing acrylic resin is used for the denture base.

Acrylic Resins

[Long-term results of plastic skull repairs with acrylic resins].

In the period from the beginning of 1956 until June 1978, we closed 312 skull gaps with acrylic resin. We used Palacos G (group I) 205 times and Refobacin Palacos R (group II) 107 times. Owing to the antibiotic action of Palacos, the infection rate, which was 6.8 per cent in the first group, could be lowered to 1.07 per cent even with a larger range of indications. The cosmetic results were very satisfactory. Owing to only slight changes in consistency and elasticity, a good protection of the brain was ensured. With the exception of one patient who temporarily showed psychic alterations, the acrylic resin was not felt as a foreign body. Disagreeable sensations, especially in case of the action of heat and cold such as are occasionally mentioned by wearers of metal plates, did not occur in our patients. Formation of neoplasms caused by polymethyl methacrylate has been found in none of the patients during the observation period of 20 years. The plastic repair with acrylic resin can be carried out quickly and in a simple manner. It may be used in all regions of the cranium. Even larger defects can be closed in this way.

Acrylic Resins

Fabrication of interim acrylic resin removable partial dentures with clasps.

An orderly sequence of steps for construction of an interim acrylic resin partial denture has been presented. The technique allows the dentist to fabricate an effective restoration that has a definite path of insertion and removal that can be placed in the patient's mouth with little time spent on adjustment and correction. This technique may be used with heat- or cold-curing acrylic resin.

Acrylic Resins

[External fixation with autopolymerizing acrylic resin].

In November 1970, a new method of skeletal fixation was devised using self-curing acrylic resin. Manipulative reduction of the displaced fracture is made using screws inserted into the bone fragments under an image intensifier. After reduction, the proximal and distal fragments are joined together with the aid of self-curing acrylic resin. Adjacent joints can be exercised immediately after operation and the fixation is so firm that the use of a plaster cast after operation is not necessary. This simple method can be used in osteosynthesis, compression arthrodesis and various types of osteotomy.

Acrylic Resins

A simplified acrylic resin cast technique.

A simple technique for construction of acrylic resin casts has been described. This procedure utilizes inexpensive and standard supplies found in a dental office.

Acrylic Resins

Bonding of acrylic resins to dentin with 2-cyanoacrylate esters.

Strength and durability of the dentin-acrylic resin joint cemented with 2-cyanoacrylate esters were studied. Maximum adhesion is obtained with isobutyl 2-cyanoacrylate after 1% acid pretreatment of the dentin. Hydrolytic stability is somewhat improved by addition of polymer to the adhesive or coating around the joint.

Acid Etching, Dental

An evaluation of the cure of acrylic resin by three methods.

An investigation was designed and carried out to compare methyl acrylic resin processed by three methods--boiling, in the heat platen press, and a 9 hour, 75 degrees C cure. The material was cured in certain thicknesses in the heat platen press and by boiling without porosity. All samples cured for 9 hours at 75 degrees C had no porosity. The value of the heat platen press as a time-saving device and its applications in a maxillofacial laboratory were discussed.

Acrylic Resins

Acrylic resin copings: an adjunct to fixed restorative dentistry.

A simple technique for fabricating and several uses for acrylic resin copings have been presented. These techniques apply to many aspects of restorative dentistry and often are used in combination with each other. Master cast fabrication, interocclusal registrations, and verification of die accuracy can be done using the copings during a one-appointment sequence. The use of resin copings is especially helpful for the inexperienced dentist, permitting high quality dentistry with a minimum of mistakes and frustations. For the experienced fixed prosthodontist they provide another approach to treatment.

Acrylic Resins

A new skin protecting ointment against acrylic resins.

In order to protect the hands of dentists, dental technicians and dental nurses from direct contacts with acrylic monomer, a new type of protective monoglyceride containing ointment has been introduced. The monoglyceride-based ointment was found to prevent penetration of the monomeric part of an autopolymerising acrylic resin and was also shown to have significantly smaller decreasing influence on the ability to manipulate instruments and materials than a compared silicone-based ointment. Furthermore, even with addition of 1% by volume of the monoglyceride-based ointment there was no marked influence on the mechanical properties (elastic modulous and ultimate tensile strength) of an investigated acrylic tray material.

Acrylic Resins

[Cutaneous manifestations due to acrylic resins used in printing].

In the plant of a large newspaper, the manufacture of printing plates using photopolymer acrylic resins, in the place of lead, resulted in a series of orthoergic and allergic manifestations in the workers. Chemical analysis resulted in the isolation of a tetraethylene glycol diacrylate, the harmful nature of which was proven by allergological studies. Its replacement by tetrathylene glycol dimethacrylate eliminated the problems seen (study based upon 300 allergological tests).

Acrylic Resins

A temporary space maintainer using acrylic resin teeth and a composite resin.

A one-session technique for preparing a temporary space maintainer has been described. The technique consists of attaching an acrylic resin pontic to etched surfaces of natural adjacent teeth by means of a composite resin. The main advantages of this technique are elimination of premature tooth preparation, good esthetics, fair strength, low cost, and rapid completion of the restoration without the need of a dental laboratory.

Acid Etching, Dental

A correlation between abrasion resistance and other properties of some acrylic resins used in dentistry.

This investigation studies the relationship of hardness, elastic modulus and scratch width as dependent variables to the abrasion resistance of twenty-three dental acrylic resins. The multiple correlation R, when all three variables are used as predictors, is 0.727. Because of the significant intercorrelations between the variables themselves a stepwise multiple regression analysis showed hardness as a redundant variable. Abrasive wear can be estimated from the following equation Abrasive wear = 806.1 - 0.1498 modulus + 0.681 scratch width (R = 0.725; standard deviation of estimate +/- 50.8) The deletion of scratch width does not appreciably reduce the standard deviation of the estimate: Abrasive wear = 1063.4 - 0.2055 modulus (r = 0.683; standard deviation of estimate +/- 50.3) The method of curing the specimens conformed to the respective manufacturers' instructions. Abrasion and scratch tests were performed using methods developed by the authors and previously described in the literature, whereas the hardness and elastic modulus results were devised from standard test procedures. Further research is currently in progress to improve the predictive power of abrasion resistance with additional new variables.

Acrylic Resins