Why are bases and liners placed in cavity preparations?

Bases and liners are critical components in cavity preparations primarily used to protect the dental pulp. When a cavity is prepared, the underlying structures can be exposed to stimuli such as heat, cold, and acidic materials. These stimuli can potentially harm the pulp, which is the innermost part of the tooth containing nerves and blood vessels.

The placement of a base or liner serves as a barrier between the restorative material and the pulp, helping to minimize sensitivity and prevent damage. Bases are typically thicker and provide thermal insulation, while liners are usually thinner and can also release therapeutic agents that promote pulp health. By providing this protection, bases and liners help to ensure the longevity of the tooth structure and deter any potential complications that could arise from exposure of the pulp to irritants from the restoration.

Enhancing cosmetic appearance, strengthening tooth structure, and improving adhesion of restorative materials, while important aspects of dental restorations, do not directly address the primary function of bases and liners, which is to safeguard the pulp from potential harm during and after the restorative procedure.