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Biomedical subjects

D Nathanson

Publications and source records attributed to D Nathanson.

At least 73 records · Page 4Linked to original sources
PubMed1979

Delayed extraoral hypersensitivity to dental composite material.

Despite their similarities to acrylic resins, composite resins have not been reported to cause allergies. This report documents the case of a patient who experienced several delayed hypersensitivity reactions associated with epoxy-based materials, including dental composite resin. Patch testing confirmed her hypersensitivity to the composite materials. Removal of the composite restorations and replacement with acrylic restorations did not trigger further allergic reactions. Dentists using composite resin materials should be aware of both the possibility of delayed extraoral manifestations of hypersensitivity to those materials and the management of these patients.

Adult↗
PubMed1979

Indications for orthodontic-prosthodontic collaboration in dental treatment.

In dental practice, combined plans of orthodontic and prosthodontic treatment are underused. Indications for a collaborative effort include preservation of integrity of the dental arch, biomechanical factors, limitations in design of prostheses, esthetic appearance, periodontal considerations, prevention of malocclusion, and better retention of position of teeth.

Aged↗
PubMed1978

Histologic response to porous PMMA implant materials.

Poly(methyl methacrylate) as used in polymer replica tooth implants was fabricated into 6 X 6 mm cylindrical specimens and cured in either an air oven, pressure pot, autoclave, or microwave oven. Polymer porosity was achieved by means of either 1) intrinsic foaming agents, or 2) compacting different sizes of large beads with a minimum of monomer, with dense PMMA used as a control. Specimens were then implanted in the long bones of baboons. Histology of thin-sectioned and ground specimens from the sacrificed animals revealed complete tissue ingrowth into implanted material made of medium and large PMMA beads, very superficial ingrowth into material containing foaming agents and anorganic bone chips, and no ingrowth into dense PMMA implants. None of the implants were rejected or caused chronic inflammation. The effect on histologic response of the different curing methods could not be distinguished.

Animals↗
PubMed1978

Preliminary evaluation of the histotoxicity and radiopacity of lead-containing elastic impression materials.

Severe reactions can be caused when elastic impression materials are trapped beneath soft tissues. To develop a rank order of severity of responses, a series of these materials was injected beneath the oral mucosa of a baboon. Alginate and polysulfide rubbers containing lead peroxide produced severe reactions; hydrocolloid, polysulfide without lead, silicone, and polyether produced more mild reactions. The more toxic materials proved to be more radiopaque than the others. Tests for foreign body toxicity should be made a part of future specifications for these materials, and the use of toxic ingredients should be reduced as much as possible. These materials should be made opaque to X rays and of a different color than those of soft or hard tissues.

Abscess↗
PubMed1977

Effect of rapid curing procedures on polymer implant materials.

This investigation of standard curing methods for PMMA implants has demonstrated that alternate means of using the air oven may produce good strength properties along with a considerable degree of porosity, when desired, in a relatively short period of time. Curing of polymers in a pressure pot offers few advantages owing to the length of time required to produce, at best, equivalent strength for the porous materials. The method also poses dangers inherent in the use of superheated salt solution or hot glycerin. The autoclave is widely used in dental offices for sterilizing and will fully and consistently cure polymers within 30 minutes. The best properties for the PMMA resin were achieved with this method (61 MPa or 9,130 p.s.i., tensile strength). The microwave oven has become relatively inexpensive in recent years, and it offers time savings of up to 90 per cent which would be beneficial in implant dentistry or in dental laboratory procedures in general. The exact condition for curing particular polymers must be carefully determined to adjust the time of irradiation in order not to under- or overcure the polymer object. Curing polymers which contain intrinsic foaming agents under pressure conditions slightly reduced the total pore volume. But, pore volume and pore diameter in the large-bead polymers are determined predominantly by packing conditions, not curing conditions. Biologic tolerance to materials cured by these methods in primates is presently being evaluated.

Chemical Phenomena↗
PubMed1975

Porous, heat cured poly (methyl methacrylate) for dental implants.

The use of polyl (methyl methacrylate) for tooth replica implants, as developed by Hodosh, is described as to indications, ingredients, and fabrication technique. Laboratory testing of this material for mechanical and thermal expansion properties, and porosity content were determined as a function of foaming agent and and anorganic bone particle content.

Animals↗