EVALUATING THE STRENGTH OF DIFFERENTLY PROCESSED DENTAL PLASTERS

Abstract

This study examined the prospect of using three different mixing techniques using Plaster of Paris (Dental SP) and whether or not one would be revealed to have greater strength than the others. This project was carried out by constructing three differently processed groups of dental plaster: the first vacuum-mixed, the second mixed using a mechanical vibrator at a high level of amplitude (8) and the third hand-mixed. The samples consisted of the same water to powder ratio according to the manufacturer’s instructions and were tested using a Universal testing machine (Lloyd strength machine) for their strength. Data analysis of the total of 60 samples (20 samples in each group) showed that according to the mean values the vacuum-mixed plaster had the greatest strength of the three. Hand-mixed and mechanically vibrated plaster had similar results, however the strength of the hand-mixed plaster was slightly higher. Moreover, the standard deviations of the vacuum-mixed group identified this as the group with the smallest discrepancies compared to mechanically vibrated and hand-mixed groups. These findings, in conjunction with previous studies, suggest that the vacuum mixer has the potential to produce plaster of greater strength. However, this cannot be supported as none of the three groups emerged as having a statistically significant difference in strength. This information is also evidence that plaster’s strength does not appear to increase after using a mechanical vibrating table at a high level of amplitude.