SHORTENED DENTAL ARCH

Question 1

What are some problems associated with RPDs?

Answer 1

• root caries
• periodontal disease
• patients find them annoying!

Question 2

What is loss of molar teeth associated with?

Answer 2

• reduced masticatory efficacy
• mandibular displacement
• alterations in food selection
• aesthetic issues
• loss of occlusal stability
• TMJ problems

Question 3

What are some indications for treatment planning with a shortened dental arch in mind?

Answer 3

• missing posterior teeth with 3-5 OU remaining
• sufficient occlusal contacts to provide a large enough occlusal table
• favourable prognosis for remaining anterior/premolar teeth
• patient not motivated to pursue complex Tx plan
• limited financial resources for dental care

Question 4

What are some contraindications for treatment planning with a shortened dental arch in mind?

Answer 4

• poor prognosis for remaining dentition
• untreated or advanced perio disease
• pre-existing TMD joint dysfunction
• signs of pathological toothwear
• significant malocclusion ( class II or III)

Question 5

When deciding for potential shortened dental arch treatment, what is important to examine intra-orally?

Answer 5

• signs of bruxism
• signs of toothwear
• periodontal assessment
• occlusal assessment
• teeth of poor prognosis

Question 6

Why is it important to assess skeletal class when deciding if shortened dental arch is suitable for a patient?

Answer 6

Must be sufficient occlusal contact

Question 7

If periodontal disease is not managed in patients with a shortened dental arch, what can happen?

Answer 7

• drifting of periodontally compromised teeth under occlusal load
• loss of alveolar bone leading to compromised denture bearing area in long term
• loss of space for denture teeth in long term

Question 8

What does inadequate periodontal support exacerbate in shortened dental arch patients?

Answer 8

• anterior load due to distal tooth migration
• interdental spacing

Question 9

If teeth are heavily restored, how might this affect a patient with a SDA?

Answer 9

Heavily restored teeth are naturally more structurally weak —> unable to withstand increased occlusal load of SDA

Question 10

Why is progressive tooth wear a contra-indication to application of SDA?

Answer 10

• long term threat to survival of teeth
• gradual loss of occlusal contacts & occlusal stability

Question 11

What are the 5 requirements of occlusal stability?

Answer 11

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 the working side during mandibular lateral movement

Question 12

What factors is occlusal stability determined by?

Answer 12

• absence of pathology: toothwear, perio disease
• periodontal support
• number of teeth in dental arches
• interdental spacing
• occlusal contacts
• mandibular stability

Question 13

What are some manifestations o a traumatic occlusion?

Answer 13

• fracture of restorations/teeth
• tooth mobility
• dental pain not explained by infection
• tooth wear

Question 14

What can loss of posterior support drive?

Answer 14

TMD

Question 15

What does Kayser 1981 define as the ‘SDA concept’?

Answer 15

• a dentition where most posterior teeth are missing
• satisfactory oral function without use of RPD
• priority given to maintaining an anterior and premolar dentition in one or both jaws
• in the right conditions this can provide a stable & acceptable dentition

Question 16

What must be present for SDA to be feasible?

Answer 16

Sufficient adaptive capacity in subjects with 3-5 occlusal units are left

Question 17

What constitutes as an occlusal unit in SDA patients?

Answer 17

A pair of occluding premolars = 1 unit

A pair of occluding molars = 2 units

Total must equal between 3-5 for sufficient SDA