The posterior seal in the upper complete denture serves the following functions.. Retention of the maxillary denture

The posterior seal in the upper complete denture serves the following functions:

• A. It reduces Pt discomfort when contact occurs between the dorsum of the tongue and the posterior end of the denture base.
• B. Retention of the maxillary denture.***
• C. It compensate for dimensional changes which occur in the acrylic denture base during processing.
• D. B & C are correct.

The correct answer is D. B & C are correct.

The posterior seal is a crucial component of a complete denture that serves two primary functions:

- Retention:

The posterior seal provides resistance to vertical movement of the denture, preventing it from lifting off the palate. This is achieved by creating a seal between the denture base and the soft tissues of the palate, particularly the soft palate and the fovea palatina, a small depression at the junction of the hard and soft palates. The seal is maintained by the suction forces created when the denture is seated and the tongue presses against the posterior denture border.

- Dimensional Compensation:

The posterior seal helps to compensate for dimensional changes that occur in the acrylic denture base during processing and wear. As the denture is subjected to temperature changes and occlusal forces, it can shrink or expand slightly. The posterior seal helps to accommodate these changes by providing a flexible and dynamic seal that can adapt to the denture's movement.

- Option A, "It reduces patient discomfort when contact occurs between the dorsum of the tongue and the posterior end of the denture base,":

is partially correct. While the posterior seal can reduce tongue discomfort to some extent, its primary function is retention and dimensional compensation.

- Option C, "It compensates for dimensional changes which occur in the acrylic denture base during processing,":

is also correct. The posterior seal helps to ensure that the denture maintains a stable seal even as the acrylic base undergoes dimensional changes.

Therefore, the posterior seal serves two essential functions in a complete denture: retention and dimensional compensation. By providing a tight seal between the denture and the palate, it helps to keep the denture in place and maintain a stable fit over time.