Shortened Dental Arch

Question 1

what are problems with RPDs?

Answer 1

high incidence of dental disease in RPD wearers:
- root caries
- periodontal disease

(patients dont clean it properly resulting in more disease)

Question 2

what is the shortened dental arch concept?

Answer 2

• dentition where most posterior teeth are missing
• satisfactory oral function without use of RPD
• priority given to maintaining anterior and premolar dentition

Question 3

how many occlusal units are required for sufficient use in a shortened dental arch?

Answer 3

3-5 occlusal units

Question 4

what is an occlusal unit?

Answer 4

a pair of opposing teeth in maxilla and mandible that support occlusion

Question 5

how many occlusal unit are:
- premolars?
- Molars?

Answer 5

• premolars = 1 unit
• molars = 2 units

Question 6

what are the indications (reasons) for a patient having a shortened dental arch?

Answer 6

• missing posteriors with 3-5 occlusal units remaining
• sufficient occlusal contacts provides stability
• if favourable prognosis for remaining teeth
• pt not motivated to pursue complex tx plan
• limited financial resources for dental care

this is only a good option if pt can preserve remaining dentition for lifetime

Question 8

what are the contraindications for a patient having a shortened dental arch?

Answer 8

• poor prognosis of remaining dentition
• untreated/advanced periodontal disease
• pre-existing TMD
• signs of pathological tooth wear
• patient has significant malocclusion

Question 9

what are considerations you need to take into account if giving a patient a shortened dental arch?

Answer 9

• if pt has problems chewing food
• does pt have any appearance/cosmetic concerns arising from missing teeth
• does pt have any discomfort arising from missing teeth
• any evidence of OCCLUSAL INSTABILITY from missing teeth

[If yes to any of these, maybe replacement of those missing teeth is a good idea]

Question 10

in a patient with a SDA, what would you check in an extraoral exam?

Answer 10

signs of TMJ dysfunction:
- click/crepitus/deviation/pain in TMJ
- hypertrophy/tenderness of MoM

Skeletal relationship

Question 11

in a patient with SDA, what would you check for intra-orally?

Answer 11

Signs of bruxism:
- buccal keratosis/scalloping/trauma/wear/fractured restorations
signs of toothwear

perio & occlusal assessment

Question 12

when looking at a patients with a SDA’s skeletal classification, what are you looking for?

Answer 12

• sufficient occlusal contact (severe malocclusion there may only be 2-3 pairs of occluding teeth)

Question 13

A pt with SDA, what are you looking to do in a perio assessment?

Answer 13

• A course of non-surgical periodontal management should be planned if active disease present
• therapy aimed at stabilising the periodontal condition of all remaining teeth
• if they are engaging in perio tx
• if they can maintain perio health once stable

Question 14

what happens if failure to establish stable perio health in a pt with a SDA?

Answer 14

• drifting of perio compromised teeth under occlusal load
• loss of alveolar bone leading to reduced tooth support & compromised denture bearing area in long term

Question 15

what impacts can compromised teeth have on a patient who has SDA?

Answer 15

• caries must be controlled & stable
• previous caries management -> teeth which heavily restored (structurally weak)
• if tooth is non-vital and has been endodontically treated, can it cope with those forces?

Question 16

what are the 5 requirements of occlusal stability?

Answer 16

1. stable contacts on all teeth of equal intensity
2. anterior guidance in harmony with the envelope of function
3. disclusion of posterior teeth during 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

Question 17

what are the manifestations of a traumatic occlusion?

Answer 17

• fracture of restorations/and or teeth
• tooth mobility
• dental pain not explained by infection
• tooth wear
• may also contribute to TMD