An interim fixed restoration should establish or maintain proper contacts with which of the following?

An interim fixed restoration plays a crucial role in maintaining proper functional and aesthetic conditions in the mouth. To effectively serve its purpose, it is essential that the restoration establishes or maintains contacts with both adjacent and opposing teeth. Proper contact with adjacent teeth ensures that the alignment and contact relationship within the dental arch is preserved, helping to prevent issues such as tooth over-eruption or shifting of the remaining teeth.

Furthermore, establishing contact with opposing teeth is vital for proper occlusal relationships. It aids in distributing functional forces evenly across the dental arch during biting and chewing, which is important for the comfort and health of the patient’s overall occlusion. This dual contact is critical not only for the function of the interim restoration but also for the integrity of the patient's ongoing dental health, reducing the risk of complications that could arise from improper contact in either area.

The other options do not address both necessary contacts, failing to capture the full scope of what an interim fixed restoration needs to accomplish.