Ace the California RDA Written Exam 2026 – Drill, Fill, and Thrill Your Way to Success!

An insulating base is a material that is placed under a filling to protect the tooth's pulp. This material acts as a barrier and helps to prevent any potential damage to the pulp. In this case, the base is protecting the pulp from thermal shock, which is a sudden and extreme change in temperature that can cause damage to the pulp. The other options, such as bacterial invasion, chemical irritation, and mechanical damage, do not directly involve changes in temperature and are therefore incorrect answers. Bacterial invasion can lead to decay, chemical irritation can cause sensitivity, and mechanical damage could chip or break the tooth, but these do not specifically protect the pulp from thermal shock. It is important for the base to protect the pulp to maintain the health of the tooth.