gypsum products -dental materials
GYPSUM PRODUCTS DENTAL MATERIALS Gypsum was found in mines around city of Paris so its called plaster of Paris. ADA SPECIFICATION NUMBER: 25 Gypsum is classified into 5 types : Type1: Dental plaster for impression Type2: Dental plaster ,class 1- mounting,class 2-for moulds Type3: Dental stone for model Type4: Dental stone -high strength and low expansion Type5: Dental stone - high strength and high expansion 1 MOLE= 6.02214076×10 23 . Gaughing water: Excess water mixed with plaster ,makes manipulation quite easier . mechanism of setting in gypsum is explained through 3 theories out of which dissolution precipitation theory is widely accepted. Advantage: 1)record fine details with least pressure 2)dimensional changes very minimal 3) economical Disadvantage: 1)g...