Final answer:
In a deep cavity preparation, zinc phosphate cement is the appropriate base material choice due to its strength and protective properties for the dental pulp. Proper mixing and application techniques are crucial for the cement's effectiveness.
Step-by-step explanation:
When selecting a base for a deep cavity preparation due to extensive decay, it is important to choose a material that provides protective properties for the dental pulp and supports the restoration. Zinc phosphate cement is one such material that can be used as a base under restorative materials. It has a long history of use due to its strength and its ability to insulate the tooth from thermal changes.
When mixing zinc phosphate cement, it is critical to follow the manufacturer’s instructions to achieve the correct consistency and working time. The mixing technique typically involves adding the powder to the liquid in small increments on a cool, glass slab to control the exothermic reaction and lengthen the working time.
After thorough removal of the decayed area, following the process described in Figure 24.8 (e), a proper base of zinc phosphate cement should be placed to protect the pulp before the final restoration. The procedure must ensure all cavity is removed and the base is applied without any voids or gaps to prevent future bacterial invasion and tooth sensitivity.