Rest: Shortened Dental Arch

Question 1

Loss of molars is associated with what problems ?

Answer 1

Reduced masticatory efficiency.
Mandibular displacement.
TMD.
Aesthetic problems.
Loss of occlusal stability.

Question 2

What are the indications for SDA ?

Answer 2

3-5 occluding units.
Sufficient occlusal contacts providing large enough occlusal table.
Remaining teeth of favourable prognosis.
Patient is not motivated to pursue complex restorative treatment plan.

Question 3

SDA

What are the contraindications for a SDA ?

Answer 3

• Remaining teeth of poor prognosis.
• Untreated or advanced periodontal disease.
• Pre-existing TMD.
• Signs of pathological toothwear.
• Significant Class II or Class III malocclusion.

Question 4

SDA

What is the consequence of distal tooth migration ?

Answer 4

Increases anterior load.
Interdental spacing - results in unfavourable aesthetics.

Exacerbated by inadequate periodontal support.

Question 5

Define occlusal stability.

Answer 5

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

Question 6

What are the 5 requirements of occlusal stability ?

Answer 6

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

Question 7

What are the contributing factors which determine occlusal stability ?

Answer 7

Absence of pathology - TW or PDD.
Periodontal support.
No. of teeth in dental arches.
Interdental spacing.
Occlusal contacts.
Mandibular stability.

Question 8

What are some manifestations of a traumatic occlusion ?

Answer 8

Fracture of restorations/teeth.
Tooth mobility.
Dental pain not explained by infection.
Toothwear.

Question 9

With regard to occlusion, what might contribute to TMD ?

Answer 9

Loss of posterior support.
Traumatic occlusion.

Question 10

What restorative treatment options are there for extension of the SDA ?

Answer 10

RR bridgework.
Conventional bridgework.
Implants.
RPD.

Question 11

What is the consequences of lower SDA opposing edentulous upper arch - ‘combination syndrome’ ?

Answer 11

Instability of complete upper denture in function.

Why ?
Concentration of occlusal force anterior of complete upper.
Accelerated bone resorption of anterior maxillary alveolar ridge and fibrous tissue replacement - flabby ridge.

Question 12

How can ‘combination syndrome’ be managed ?

Answer 12

Extension of SDA - with bridgework, RPD.

Question 13

SDA

What three main factors might lead to failure of SDA ?

Answer 13

Unstable periodontal disease.
Occlusal derangement.
Progressive toothwear.