The effect of steam sterilization on the properties of set dental gypsum models

• Published in: Australian dental journal Vol. 41; no. 2; pp. 128 - 133
• Main Authors: Whyte, M. P., Brockhurst, P. J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-04-1996
• Subjects: Calcium Sulfate - chemistry; Dental gypsum; Dental Materials - chemistry; Dental Models; Dentistry; Hardness; Hot Temperature; Materials Testing; properties; sodium succinate; Steam; steam sterilization; Sterilization - methods; Stress, Mechanical; Succinates - chemistry; Succinic Acid; Surface Properties; Surface-Active Agents - chemistry; Time Factors
• ISSN: 0045-0421; 1834-7819
• DOI: 10.1111/j.1834-7819.1996.tb05926.x

The aim of this study was to investigate the viability of autoclave sterilization of set dental gypsum models. The effects of autoclaving on the strength, surface hardness and dimensions of specimens of plaster, stone and diestone were investigated. In addition, sodium succinate was used to minimize any changes produced by autoclaving. It has been shown that dental gypsum casts can be successfully steam sterilized.
The results showed that for fully‐dried gypsum products, autoclaving at 132°C for 5 minutes rendered the casts unacceptable for use. Autoclaving at 121°C for 16 minutes had less effect although casts were still not satisfactory, with the main problems being excessive expansion for plaster and significant strength and surface hardness loss for stone and diestone.
The effect of three additional treatment procedures was examined and the least degradation was observed when the casts were soaked in 1 per cent sodium succinate solution and dried prior to autoclaving, then soaked in water immediately after. Using this procedure the averate change in properties for plaster, stone and diestone respectively were: loss of strength 36, 21 and 28 per cent, loss of surface hardness 34, 21 and 33 per cent, and linear expansion 0.05, 0.09 and 0.13 per cent. Further refinement may improve the procedure.