EVALUATION OF CONSISTENCY AND SETTING TIME OF IRANIAN DENTAL STONES
Abstract
Introduction. Dental stones are widely used in dentistry and the success or failure of many dental treatments depend on the accuracy of these gypsums. The purpose of this study was the evaluation of Iranian dental stones and comparison between Iranian and foreign ones. In this investigation, consistency and setting time were compared between Pars Dendn, Almas and Hinrizit stones. The latter is accepted by ADA (American Dental Association). Consistency and setting time are 2 of 5 properties that are necessitated by both ADA specification No. 25 and Iranian Standard Organization specification No. 2569 for evaluation of dental stones.
Methods. In this study, the number and preparation of specimens and test conditions were done according to the ADA specification No. 25 and all the measurements were done with vicat apparatus.
Results. The results of this study showed that the standard consistency of Almas stone was obtained by 42ml water and 100gr powder and the setting time of this stone was 11±0.03 min. Which was with in the limits of ADA specification (12±4 min). The standard consistency of Pars Dandan stone was obrianed by 31ml water and 100 gr powder, but the setting time of this stone was 5± 0.16 min which was nt within the limits of ADA specification.
Discussion: Comparison of Iranian and Hinrizit stones properties showed that two probable problems of Iranian stones are:1- Unhemogrnousity of Iranian stoned powder was caused by uncontrolled temperature, pressure and humidity in the production process of stone.
2- Impurities such as sodium chloride was responsible fo shortening of Pars Dendens setting time.
Methods. In this study, the number and preparation of specimens and test conditions were done according to the ADA specification No. 25 and all the measurements were done with vicat apparatus.
Results. The results of this study showed that the standard consistency of Almas stone was obtained by 42ml water and 100gr powder and the setting time of this stone was 11±0.03 min. Which was with in the limits of ADA specification (12±4 min). The standard consistency of Pars Dandan stone was obrianed by 31ml water and 100 gr powder, but the setting time of this stone was 5± 0.16 min which was nt within the limits of ADA specification.
Discussion: Comparison of Iranian and Hinrizit stones properties showed that two probable problems of Iranian stones are:1- Unhemogrnousity of Iranian stoned powder was caused by uncontrolled temperature, pressure and humidity in the production process of stone.
2- Impurities such as sodium chloride was responsible fo shortening of Pars Dendens setting time.
Keywords
Dental stone, Consistency, Setting time