Shortened Dental Arch

Question 1

Problems with rpd

Answer 1

Root caries
Periodontal disease

Question 2

SDA Concept (Kayser 1981)

Answer 2

Dentition where most posterior teeth are missing
Satisfactory oral function without RPD
Priority given to maintaining anterior and premolar dentition in 1 or both jaws
In right circumstances can provide stable and acceptable dentition

Question 3

What is required for sufficient adaptive capacity in SDA?

Answer 3

3 to 5 occlusal units
Molars= 2 units
Premolars= 1 unit

Question 4

Criticisms of Keyser theory?

Answer 4

Loss of molars associated with:
Reduced masticatory efficiency
Mandibular displacement
Alterations in food selection
Aesthetic issues
Loss of occlusal stability
TMJ issues

Question 5

According to WHO, how many teeth do we need

Answer 5

20

Question 6

Indications for SDA

Answer 6

Missing posterior teeth with 3-5 OU
Sufficient occlusal contacts to provide a large enough occlusal table
Favourable prognosis for remaining anterior and premolar teeth
Pt not motivated to pursue complex Rx plan
Limited financial resources for dental care

Question 7

Contraindications for SDA

Answer 7

Unfavourable prognosis for remaining dentition
Untreated or advanced perio disease
TMD
Pathological toothwear
Significant malocclusion- severe class 2/3

Question 8

Why is a severe malocclusion a contraindication

Answer 8

Must be sufficient occlusal contact

Question 9

Negative consequences of failing to establish stable perio in SDA

Answer 9

Drifting of periodontally compromised teeth under occlusal load
Loss of alveolar bone leading to compromised denture bearing area in long term
Loss of neutral zone for denture teeth in long term

Question 10

Consequences of distal tooth migration in SDA

Answer 10

Increases anterior load
Increases number and intensity of anterior occlusal contacts
Increased interdental spacing
Exacerbated by inadequate perio support

Question 11

What is occlusal stability

Answer 11

Stability of tooth positioning relative to its spatial relationship in occluding dental arches

Question 12

5 requirements of occlusal stability

Answer 12

1. Stable contacts on all teeth of equal intensity in centric relation
2. Anterior guidance in harmony with envelope of function
3. Disclusion of all posterior teeth during mandibular protrusive movement
4. Disclusion of posterior teeth on non-working side during mandibular lateral movement
5. Disclusion of posterior teeth on working side during mandibular lateral movement