Biomaterial Database

[Correct timing of work on a hard plaster of Paris model]. 1979

G Franz

Of the individuals in Hamburg questioned, 48% waited an average of 1 to 2 hours after making a stone cast before proceeding with work on it; 38%, 1 day; and only 2%, more than 1 day. The material test however showed that 5 or 6 days of storage at room temperature are necessary before optimal values are obtained for compressive strength, ball-thrust hardness, and abrasive hardness. The greatest amount of expansion with type IV stone plaster, removed from the cast after 30 minutes, was measured between 8 and 24 hours at room temperature, after the plaster had been mixed. The least changes in dimension were recorded after a 5-day contractive phase. Given these results, the stone cast should be stored for 5 to 6 days at room temperature before work is resumed on it if precision work is to be done.

UI	MeSH Term	Description	Entries
D002133	Calcium Sulfate	A calcium salt that is used for a variety of purposes including: building materials, as a desiccant, in dentistry as an impression material, cast, or die, and in medicine for immobilizing casts and as a tablet excipient. It exists in various forms and states of hydration. Plaster of Paris is a mixture of powdered and heat-treated gypsum.	Dental Gypsum,Dental Stone, Artificial,Gypsum,Plaster of Paris,Alabaster,Anhydrous Sulfate of Lime,Artificial Dental Stone,Calcium Sulfate (1:1), Dihydrate,Calcium Sulfate (1:1), Hemihydrate,Calcium Sulfate (2:1),Calcium Sulfate Dihydrate,Calcium Sulfate, Anhydrous,Calcium Sulfate, Dihydrate,Calcium Sulfate, Hemihydrate,Calcium Sulphate,Drierite,Gypsite,Gypsum, Dental,Karstenite,Stone, Artificial Dental
D003765	Models, Dental	Presentation devices used for patient education and technique training in dentistry.	Dental Models,Dental Model,Model, Dental
D006244	Hardness	The mechanical property of material that determines its resistance to force. HARDNESS TESTS measure this property.	Hardnesses
D006813	Humidity	A measure of the amount of WATER VAPOR in the air.	Humidities
D013674	Technology, Dental	The field of dentistry involved in procedures for designing and constructing dental appliances. It includes also the application of any technology to the field of dentistry.	Dental Technology
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D013995	Time	The dimension of the physical universe which, at a given place, orders the sequence of events. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Effects, Long-Term,Effects, Longterm,Long-Term Effects,Longterm Effects,Effect, Long-Term,Effect, Longterm,Effects, Long Term,Long Term Effects,Long-Term Effect,Longterm Effect
D014867	Water	A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Hydrogen Oxide