To increase the working time of glass ionomer cement, it should be mixed on what surface?

Mixing glass ionomer cement on a glass plate is the optimal choice to increase the working time of the material. The reason for this is that glass surfaces are non-porous and provide a smooth, cool environment for mixing the cement. This helps to slow down the setting reaction, giving the dental assistant or dentist additional time to manipulate and place the material effectively before it begins to harden.

In contrast, surfaces like stone slabs, plastic mixing pads, and metal surfaces may not maintain the same temperature and may have porosities that can absorb some of the moisture and components needed for proper working time. This can inadvertently lead to a quicker setting time, making it challenging to achieve the desired results when working with the cement. Thus, utilizing a glass plate is a fundamental practice in dental procedures involving glass ionomer cement to ensure optimal handling and application.