About some causes of deformation of removable dentures
G. G. Nasibullin , E. X. Bulgakov , M. V. Sviridov , M. T. Amirkhanov , P. M. Rakhmatullin , T. N. Shestopalova
Kazan medical journal ›› 1984, Vol. 65 ›› Issue (3) : 238 -239.
About some causes of deformation of removable dentures
In the process of manufacturing dentures made of acrylic plastics on plaster models and molds, their deformation during polymerization is often observed. It can be assumed that the plaster mold and counterform cannot withstand the pressure that occurs during the molding of plastic. This is what leads to a violation of the fit of the prostheses, an increase in bite and other complications. Semi-aqueous gypsum (CaSO4*0.5* H2O) is used in dental prosthetic equipment and in the dental prosthetics clinic During transportation, storage and packaging of semi-aqueous gypsum at high relative humidity, the content of adsorbed and chemically bound water increases sharply. In this regard, a significant part of gypsum is hydrated, and in the future its chemical activity decreases sharply. Practice has established that damp gypsum becomes unsuitable both for taking casts and for casting models and molds. Such gypsum does not completely harden for a long time. Models cast from damp plaster are fragile, "smeared". During their long-term storage, shrinkage deformations occur, noticeably changing the original dimensions of dentures
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