Retention and stability of complete dentures

Question 1

Define retention.

Answer 1

Resistance of denture to vertical movement away from tissues

Question 2

Define stability.

Answer 2

Resistance of denture to lateral displacement (by functional forces)

Question 3

Define adhesion.

Answer 3

• physical attraction of unlike molecules for each other (saliva and mucous membrane/saliva and denture base)
• “suction”

Question 4

How does adhesion affect denture design?

Answer 4

• more important in the maxillary than the mandibular
• extension over denture bearing area

Question 5

Define cohesion.

Answer 5

Physical attraction between similar molecules (salivary molecules)

Question 6

What is the role of saliva in denture wearing?

Answer 6

• buffering
• cleaning (antimicrobial)
• adhesion and cohesion

Question 7

How does atmospheric pressure affect denture design?

Answer 7

Border seal ensures good “suction”

Question 8

Describe a post dam seal.

Answer 8

• bevelled edge at the beginning of the soft palate
• only in maxillary denture
• ensure fovea palatine are not covered
• 0.5mm is typical depth

Question 9

Describe adequate extension of a lower denture.

Answer 9

• base extends over retromolar pads
• should extend into lingual pouch (where you can palpate the vertical part of the mandible)

Question 10

Where are soft tissue undercuts common?

Answer 10

• anterior 4-4 maxillary region
• uncommon in lower

Question 11

List factors that can make retention difficult.

Answer 11

• atrophic ridges (down to basal bone)
• incomplete palate (cleft palate or cancer patients)
• fibrous ridges
• damaged alveolar ridges (soft tissue graft)
• gagging patients
• insufficient saliva

Question 12

How should teeth be positioned?

Answer 12

• teeth in neutral zone
• over ridge in mandible
• slightly buccal in maxilla
• narrower teeth are better

Question 13

How does the tongue affect denture wearing?

Answer 13

Teeth that are placed too lingually cause the denture to lift