Posterior Palatal Seal

Question 1

What are the 5 purposes of PPS

Answer 1

1. To increase maxillary CD retention by having the posterior aspect of denture base slightly compress the posterior portion of the palatal soft tissue (both soft and hard palates).
2. To compensate for the polymerization shrinkage of the denture base resin, so the denture base has intimate contact with the posterior aspect of the palate and is able to create a seal (suction).
3. To provide contact between the intaglio surface of the denture and the opposing moist, oral mucosa during speech and swallowing to prevent food entrapment between the denture base and mucosa.
4. To decrease the potential for gagging.
5. To minimize the bulkiness of the resin base as it terminates over the soft palate, making the physical presence of the dentre less obvious when the tongue contacts the distal border of a maxillary CD.

Ettinger. (1980). The posterior palatal seal. A review. Aust Dent J.

Question 2

Describe 3 House palatal throat form classifications

Answer 2

1. Class 1: exhibiting a broad shallow palate with minimal “drop” (posterior-inferior movement) of the soft palate in its rest position.
   - Class 1 provides the greatest area for development of a PPS
2. Class 2: less broad shallow palate than a House Class 1 and is often accompanied by a deeper palatal vault with more apparent inferior soft palate deflection at rest.
   - Class 2 presents smaller area for the seal
3. Class 3: soft palate drops off immediately from the hard palate and generally exhibits a deep palatal vault, leaving little area for placement of posterior palatal seal as seen in the other two classes.
   - Class 3 only permits minimal coverage of the soft palate (typically, little more than a line).

Question 3

What is border seal?

Answer 3

1. Border seal: contact b/w the moist moveable mucosa of the upper lip and cheeks and the denture border. The moveable mucosa intimately contacts and encompasses the labial and buccal denture borders which helps to prevent the ingress of air.
2. Peripheral seal: enhanced by contact b/w the moist moveable mucosa of the upper lip and cheeks and the polished surface of the denture base.
3. Posterior palatal seal: located at the posterior aspect of mx CRDP. However there are no soft tissues located posteriorly that can encompass the posterior border of mx CRDP (as in the anterior region of the mouth) to seal a denture and prevent the ingress of air and food. Thus, the intaglio surface of the denture base needs to be elevated slightly for it to compress the moveable soft tissues. These compressible tissues cover both the hard palate and soft palate

Question 4

Describe the significance of PPS - Hardy and Kapur

Answer 4

“A posterior palatal seal is necessary because the distal border of the denture is the least advantageous of all the borders for providing a seal for retention. The labial and bucal denture borders are generally well sealed by the draping of the soft tissues over them, but there is no lip or cheek to drape over the posterior border of the denture.” Thus, a seal is needed at the posterior aspect of a maxillary comlete denture known as PPS.

Hardy and Kapur (1958) Posterior border seal-its rationale and importance. JPD.

Question 5

What did Appelbaum state about PPS?

Answer 5

Appelbaum added to the PPS concept that establishing this posterior seal requires special attention, so mx CD can offer optimal resistance to dislodgement

Appelbaum MB (1979) in Winkler S, Essentials of Complete Denture Prosthodontics. PHILLYYY

Question 6

Who affirmed the importance of PPS?

Answer 6

Avant. (1973). A comparison of the retention of complete denture bases having different types of PPS. JPD.

He compared a mx denture base with no PPS to 4 different types of denture bases where PPS were present.

Avant determined a PPS was indeed necessary for optimal retention of maxillary compete dentures.

Question 7

According to Silverman in 1971, what type of clinical situation requires a special attention when establishing PPS?

Answer 7

1. small residual ridges
2. mobile ridges
3. small and narrow arches
4. high palatal vaults
5. marked mandibular retrusion
6. prognathic mandible that has a larger mandibular denture supporting area than in the maxilla