Dental physical properties

Plaster is the rehydrated calcined gypsum. The American Dental Association classifies five types of dental plaster according to the physical properties type 1, impression plaster type 11, model plaster type 111, dental stone type IV, high-strength dental stone and type V, high-strength. 

Dental stone is generally used at a water—powder volume ratio of about 30 parts water to 100 parts of stone. The mix is not easily poured, but can flow readily under mechanical vibration. The physical property requirements include a setting time of 10 3 min fineness of powder, where 98% should pass a number 100 sieve (ca 0.15 mm) and 90% pass a number 200 sieve (ca 0.07 mm) linear setting expansion at 2 h of <0.20% compressive strength at 1 h of 20.6 MPa (2987 psi) and consistency such that the slump test disk is 30 2 mm diameter. 

Mixes of improved dental stone (type IV) using 22 parts of water to 100 parts of powder produce a mass that is not fluid and pourable but can be easily vibrated into place. The physical properties of the improved dental stone include a setting time 10 3 min, fineness of powder such that 98% passes a 100 sieve (ca 0.15 mm) and 90% passes a 200 sieve (ca 0.07 mm) setting expansion at 2 h limited to a max of 0.10% compressive strength at 1 h of at least 34.3 MPa (4974 psi) and a disk formed in the slump test for consistency of a 30 2 mm diameter. 

Copper [7440-50-8] Cu, produces a reddish color and reduces the melting pokit of the alloy. It produces heat-treatable compositions with gold, platinum, and palladium that result ki kicreased hardness, strength, and generally improved physical properties. The tarnish resistance of the alloy is usually decreased. The gold—copper, Au—Cu, system is the fundamental system of many dental gold alloys. Copper has a useful range of 0—20 wt %. 

Poetschke, P. (1916). Physical properties of dental cements. Journal of Industrial Engineering Chemistry, 8, 302-9. 

Swanson, E. W. (1936). Effect of particle size on the physical properties of silicate cements. Journal of the American Dental Association, 23, 1620-31. 

Tuenge, R., Sugel, I. A. Izutsu, K. T. (1978). Physical properties of a zinc phosphate cement prepared on a frozen slab. Journal of Dental Research, 57, 593-6. 

Civjan, S. Brauer, G. M. (1964). Physical properties of cements based on zinc oxide, hydrogenated resin, o-ethoxybenzoic acid and eugenol. Journal of Dental Research, 43, 281-99. 

Norman, R. D., Phillips, R. W., Swartz, M. L. Frankiewicz, T. (1964). The effect of particle size on the physical properties of zinc oxide-eugenol mixtures. Journal of Dental Research, 43, 252-62. 

Though these may provide a standard for screening production quality, they are merely representative. The flexural properties will be a consistent test of the many possible mechanical property testing modalities. Other areas of physical properties that are important to the success of a composite dental restorative are radiopacity, polymerization shrinkage and thermal interactions, e.g., thermal expansion and thermal diffusivity. 

TABLE 2. Physical Properties of Cured Dental Compositions Containing Step 1 Hybrid Monomer 1... 

R. Rushforth, Superior physical properties make palladium an ideal dental metal,... 

W. Souder and G.C. Paffenbarger, Physical Properties of Dental Materials (Natl Bur. Standards (U.S.), Gaithersburg, MD, 1942), Circ. No. C433. 

MPa, compressive strength 245-303 MPa, water sorption 0.5-0.7/cm ) considerably exceeded the minimum requirement of the specification for dental composite resins (37). If low concentrations are employed in the formulations especially with DEAPAA as accelerator, the cured composites are nearly colorless. No perceptible change occurs in the color of the specimens containing a UV absorber after 24 hours exposure to a UV light source. Because of the excellent overall physical properties, nearly colorless appearance and the potentially better biocompatibility, compositions using these accelerators should yield improved restoratives. 

Corrosion of metallic surgical implant materials used in orthopedic, cardiovascular, and dental devices resulting in the release of metal ions to tissues, and degradation of the physical properties of polymeric implant materials due to interactions with tissue fluids and/or blood... 

Synthetic pol)mieric materials have been widely used in medical disposable supply, prosthetic materials, dental materials, implants, dressings, extracorporeal devices, encapsulants, polymeric drug delivery systems, tissue engineered products, and orthodoses as that of metal and ceramics substituents [Lee, 1989]. The main advantages of the polymeric biomaterials compared to metal or ceramic materials are ease of manufacturability to produce various shapes (latex, film, sheet, fibers, etc.), ease of secondary processability, reasonable cost, and availability with desired mechanical and physical properties. The required properties of polymeric biomaterials are similar to other biomaterials, that is, biocompatibility, sterilizability, adequate mechanical and physical properties, and manufacturability as given in Table 40.1. 

An alloy is a solution of two or more metals. Amalgams are alloys which involve mercury as one component. A silver amalgam as used in dental work is a solution of silver and mercury. The pewter used to make silverware in Revolutionary War times is an alloy with the composition 85.5% tin, 6.8% copper, 6% bismuth, and 1.7% antimony. Most alloys usually have Physical properties which are different from those of the individual components. In contrast, the chemical properties of the alloy are related to those of the individual components. 

ID. Siderou, M.M. Karabela, E.Ch. Vouvoudi, Physical properties of current dental nanohybrid and nanofill hght-cured resin composites. Dent. Mater. 27 (2011) 598-607. 

Table ld.l0 Physical Properties of precious dental alloys (Ref. 5, 8)... 

Yu, R., Koran, A., 3rd Craig, R G. (1980) Physical properties of maxillofacial elastomers under conditions of accelerated aging. Journal of Dental Research, 59, 1041-1047. 

Precise dosage of reactive components is essential for the reproducible hardening of dental cements, without adversely affecting the physical properties of the hardened product. Cellulose acetate butyrate microcapsules containing poly(acrylic acid) prepared by phase separahon when mixed with glass ionomer powder result in single-phase, free-flowing powders [64]. The contents of microcapsules can be released and become mixed with the solid phase by mechanical stress, vibration microwaves, and/or sonicahon. 

We learned in Section 12.2 that polymers can be characterized by their physical properties. Elastomers are used as biomaterials in flexible tubing over leads for implanted heart pacemakers and as catheters (tubes implanted into the body to administer a drug or to drain fluids). Thermoplastics, such as polyethylene or polyesters, are employed as membranes in blood dialysis machines and as replacements for blood vessels. Thermoset plastics find limited but important uses. Because they are hard, inflexible, and somewhat brittle, they are most often used in dental devices or in orthopedic applications, such as in joint replacements. To fill a cavity, for example, the dentist may pack some material into the cavity, then shine an ultraviolet lamp on it. The light initiates a photochemical reaction that forms a hard, highly cross-linked thermoset polymer. 

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