What should be the primary consideration when deciding to use a base in a restoration?

The primary consideration when deciding to use a base in a restoration is the depth of preparation. This aspect is crucial as a deeper cavity preparation exposes the dental pulp to potential irritation or injury, necessitating adequate protection. A base serves to insulate the pulp from thermal changes, provide a barrier against chemical irritants, and support the restoration material. When the cavity preparation is deeper, it increases the likelihood of pulp exposure, which emphasizes the need for a base to safeguard the tooth structure and the pulp.

Other factors, such as the type of restoration or the patient's age, are also important in the overall decision-making process but are secondary to the depth of the preparation. For instance, while the type of restoration may dictate certain material properties, it doesn't directly address the immediate protective needs of the dental pulp in deeper preparations. Understanding the relationship between cavity depth and the potential risk to pulp health underscores the reason depth is the primary consideration.