Suitability of Dental Stone Preparation Using Local Gypsum and Sodium Chloride

Abstract

The current research included the preparation of dental stones from local raw gypsum and boiling it with a solution of 30% sodium chloride using reflex method. According to the current study, there is no country in the Middle East that produces dental stones. As the details of the method of manufacturing dental stones are not published and are considered very confidential by international companies, and when taking into account that the price of the dental stone is twice the price of plaster, it becomes very important to manufacture dental stones for optimal utilization of the natural wealth in the country. Raw gypsum samples were collected from the Al-Qadisiyah quarry, which is located 19 km southeast of Kirkuk. All samples were subjected to chemical analyses and physico-mechanical tests, including specific weight, particle size, solidification time, longitudinal expansion coefficient, compressive strength, and water-to-powder ratio. The method used for preparing dental stones included the use of a reflex device within a closed system, as there is no loss in sodium chloride solution. The ideal conditions for preparing dental stone were obtained, which are the use of a grain size ranging between -500 and +300 microns and boiling for an hour, followed by drying for an hour at 105 °C, whereby it became possible to prepare dental stone with physiomechanical properties superior to dental stone type III dental stone, according to the American specification for dentists, which indicates that the desired goal of this research has been achieved.