Shortened Dental Arch

Question 1

What is meant by the term ‘shortened dental arch’?

Answer 1

• Dentition is which posterior teeth has been lost
• Usually consists of 6 anterior teeth and 4 premolars in each jaw
• 20 in total
• OVD maintained

Question 2

Describe 1 occlusal unit

Answer 2

PAIR of occluding premolars

Question 3

Describe 2 occlusal units

Answer 3

PAIR of occluding molars

Question 4

What are some issues in regards to a lack of posterior support?

Answer 4

• Impaired masticatory function
• Increased occlusal wear
• Alteration in food selection
• Distal tooth migration
• Mandibular displacement
• Occlusal instability
• TMDS

Question 5

What are the clinical indications for a SDA?

Answer 5

1. Loss of posterior support with 3-5 occlusal units remaining
2. Enough occlusal contacts to provide sufficient occlusal table and maintain OVD
3. Good prognosis of remaining teeth
4. Pt not wishing any further dental tx

Question 6

What are the clinical contra-indications for a SDA?

Answer 6

1. Remaining teeth poor prog
2. Untreated/ advanced perio disease
3. TMDS
4. Pathological tooth wear
5. Occlusal instability
6. Sig malocclusion e.g. Class II or III

Question 7

What is assessed in a patient for SDA?

Answer 7

• Full exam

1. TMDS
2. Tooth tissue integrity (caries, heavily rest etc)
3. Tooth wear
4. Perio status (distal drifting, interdent spacing –> made worse but inadeq perio)
5. Occlusal stability (& incisor, skeletal class)

Question 8

When to restore an arch?

Answer 8

• Function problems
• Aesthetics concerns
• Occlusal instability
• Pain due to missing teeth

Question 9

How may a SDA be extended?

Answer 9

• RPD
• Bridge
• Implants

Question 10

What is meant by the term ‘combination syndrome’?

Answer 10

• Lower ant teeth opposing upper edentulous ridge
• Unstable upper complete denture
• Concentration of occlusal force in upper ant region –> flabby ridge