Condensation silicon is the first silicon material ever used in dentistry. It is commonly used to get impressions in the preparation of crowns, bridges, onlays, and inlays. In some cases, it’s used for an impression in the process of preparation for complete dentures.
The most common uses include getting impressions for metal removable dentures, indirect cast restorations, matrices for indirect and direct restorations and more.
The condensation silicones come in two pastes. The first one is called base paste and it contains polydimethyl siloxane, fillers and color pigments. The second one is called acceleration paste and it includes alkyl silicate, stannous octate, and fillers. The two pastes are mixed and that is when the chemical process begins. They can be found in three types of viscosity including putty 60%-70%, medium 35%-75%, and low 5%-15%. The condensation silicones are mixed for around 45 seconds, according to the brand instructions. The setting time is 8 to 9 minutes.
The impressions with condensation silicones are very accurate. Dentists used this type of silicone for many years. Another great advantage is that these materials are very well accepted by patients. Nice smell and taste is why patents find condensation silicones acceptable. The time for manipulation is good, which makes the job easier for the dentist. They have a low level of distortion when the impression tray is taken out from the mouth. Also, condensation silicones have good elastic characteristics.
Both the condensation and addition silicones are hydrophobic, which means they require a dry oral cavity. A completely dry surrounding is very hard to achieve, but dentists have to be very careful with moist. Unfortunately, the condensation silicones are not as dimensionally stable as the addition type. If they are not proportioned as described, they can show dimensional changes. The condensation silicones show a certain percentage of shrinkage. They are a bit more expensive compared to other materials.