OBJECTIVE To investigate the variation of the strength of gypsum-bonded dental investments with burnout temperature. METHODS The disc-rupture test was employed at burnout temperatures ranging from 450 to 800 degrees C for four products (Beauty Cast, Cristobalite, Novocast (all WhipMix) and Deguvest California (Degussa)). In this test, an investment disc is created inside an investment mold su...

Late Quaternary soils in southern New Mexico support previous work that suggested pedogenic gypsum accumulates in successive stages as a function of time, similar to pedogenic carbonate. However, gypsum also occurs as small (0·5}1 mm), powdery spheres that we term snowball morphology. The snowball morphology represents one of the initial stages of pedogenic gypsum development. Scanning electron...

Abstract Fly ash (FA) is pozzolanic, while blast furnace slag (GGBS) latent hydraulic. These two materials react slowly in the presence of water to harden. Adding an alkali activator such as strong hydroxide could boost hardening process, but safe handling highly corrosive primary concern. Therefore, present work prescribed various types gypsum activate FA and GGBS a binder phase for making mor...

Casts with a high surface hardness and abrasion resistance are essential for conventional dental prosthesis construction procedures. The water/powder ratio is critical factor determining the physical chemical properties of gypsum casts, any modification to this may alter these properties.

RATIONALE Dental Dam is the safest and most efficient isolation technique in endodontics and restorative dentistry, but it also used in esthetics, orthodontics, prosthetics, pedodontics and periodontology (for teeth immobilization). While in most cases the standard clamps are efficient, in some clinical situations clamp adaptation is mandatory in order to assure a tight contact on the tooth. ...

Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast mad...

With the rapid development of economic, gypsum is widely used in casting and other industry areas. In this paper, the result is obtained that the performance of plaster mold is better when gypsum-water ratio is 0.5. If the composition of gypsum slurry mixture ( -hemihydrate, mullite powder, zirconium powder, reinforcing fibers) is mullite powder: zircon flour: enhancing fiber = 1:0.25:0.2:0.02-...

Time-resolved energy dispersive X-ray diffraction (EDXRD) data have been measured in situ from cast blocks of gypsum, CaSO(4) x 2 H(2)O, in the presence of reactive phosphate solutions under hydrothermal conditions (100 < or = T < or = 180 degrees C) in order to understand the formation of hydroxyapatite monoliths, for applications such as in artificial bone or dental materials. Measurement of ...