Ceramic debinding with possible pre-conditioning can require a week of time, but it is an essential and carefully controlled processing step necessary to prevent part deformation and cracks caused by pressure gradients from evaporating substances. The use of ceramics in dental applications, which require unique characteristics from ceramic forming, has been limited due to the difficulty of manufacturing parts with minor deviation in properties. Nowadays, ceramic dental replacements are mostly milled into final shape from ceramic blocks, which is cost effective, but the material waste percentage can be even 95 %. Additive manufacturing (AM) methods, such as stereolithography, have become an alternative to milling providing better user safety, lower waste production, and increasingly lower price range due to increasing popularity of AM methods.
The thermal debinding of dental restorations could be made more economical by extracting some of the slurry substances prior to thermal debinding, creating flow channels for gases to exit. Supercritical carbon dioxide (scCO2) extraction was used for different polymeric and ceramic stereolithography prints to find out which substances dissolve from the stereolithographically printed part without cracking and part deformation. The scCO2 extracted samples were characterized with thermogravimetric analysis, optical microscopy, and the sample mass and dimensions were measured before and after the extraction test. The scCO2 extraction testing time, pressure, temperature, and monomer fractions and slurry contents in recipes were varied. PEG400, PEG200 difunctional methacrylate, uncured 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and uncured 1,10-decanediol diacrylate were successfully extracted. Increase of pressure in extraction parameters resulted in faster extraction rate and increase in temperature resulted in decrease of extraction rate and part deformation in polymeric prints. The same was studied with ceramic alumina samples.