Effect of contact time between alginate impression and type III dental stone on cast model properties

Resumo

To measure the effect of different contact time between
the alginate impression and type III dental stone on cast model
properties in the terms of dimension stability, hardness and surface
details reproduction. Material and methods: Sixty-seven cast
models were obtained from stainless steel cylinder using alginate
impression material and type III dental stone. Thirty-seven cast
models were separated after one hour (control group) and 30 cast
models were separated from impressions after 9 hours. The samples
were evaluated under light microscope for surface details, measured
by digital caliper for dimension stability and hardness was tested
by making indentation on the cast then measuring the depth using
digital caliper. Results: The dimension stability of cast models
was not affected by increasing contact time between type III dental
stone and alginate impression while surface details decreased. In
the meanwhile, hardness was improved with increasing contact
time. Conclusion: According to the results of this study, pouring
of impression up to 9 hours can negatively affect the cast model
properties in the term of details richness.