The shortened dental arch Flashcards

1
Q

What is the SDA Concept?

A
  • Proposed by Kayser 1981
  • A dentition where most posterior teeth missing
  • Satisfactory oral function without use of RPD
  • Priority given to maintaining anterior and premolar dentition in one or both jaws
  • In right circumstances , non replacement of posterior missing teeth can provide stable and acceptable dentition
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2
Q

What is the definition of occlusal stability?

A
  • Absence of the tendency for teeth to migrate other than the normal physiological compensatory movements occuring over time
  • Or The stability of tooth positioning relative to its spatial relationship in the occluding dental arches
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3
Q

What factors determine Occlusal stability?

A
  • Periodontal support
  • Number of teeth in dental arches
  • Interdental spacing
  • Occlusal contacts
  • Tooth wear
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4
Q

In the SDA concept what gives sufficient adaptive capacity?

A
  • Gives sufficient adaptive capacity when 3-5 occlusal units are left
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5
Q

What classifies as 1 unit in SDA concept?

A
  • Pair of occluding premolars
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6
Q

What classifies as 2 units in SDA concept?

A
  • Pair of occluding molars
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7
Q

What are loss of molars associated with (in terms of problems)?

A
  • Reduced masticatory efficiency
  • Mandibular displacement
  • Alterations in food selection
  • Aesthetic issues
  • Loss of occlusal stability
  • TMJ problems
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8
Q

What is the 1992 World Health Organisation statement on amount of teeth we need?

A
  • “the retention, throughout life, of a functional, esthetic, natural dentition of not less than 20 teeth and not requiring recourse to prostheses should be the treatment goal for oral health”
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9
Q

What are the indications for a txt plan with application of SDA?

A
  • Missing posterior teeth with 3-5 OU remaining
  • Sufficient occlusal contacts to provide large enough occlusal table
  • Favourable prognosis for remaining anterior and premolar teeth
  • Pt not motivated to pursue complex txt plan
  • There are limited financial resources for dental
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10
Q

When will SDA work long term?

A
  • Only work long term if remaining natural dentition can be preserved for remainder of lifetime of pt
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11
Q

What are the contraindications for application of SDA concept in txt plan?

A
  • Poor prognosis for the remaining dentition
  • Untreated or advanced periodontal disease
  • Pre-existing temporomandibular joint dysfunction
  • Signs of pathological tumour
  • Pt has significant malocclusion i.e. Severe Class II or Class III
    If any one of these are met then consider replacing posterior teeth
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12
Q

If you have broken down dentition what are the two options for txt plan?

A
  • Restore complete dental arches (28 teeth)
  • Restore reduced dental arches (SDA:20-24 teeth)
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13
Q

What are the pros and cons of restoring complete dental arches?

A
  • More complicated txt
  • Higher cost
  • Too expensive for many pt or health care systems
  • Better results?
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14
Q

Pros and cons of restoring reduced dental arches?

A
  • Less complicated txt
  • Lower cost
  • Applicable for more pt
  • Txt result worse perhaps?
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15
Q

What are some considerations you have to make about pt when deciding to adopt the SDA concept or restore full dentition?

A
  • Does pt have any problems chewing food?
  • Does pt have appearance or cosmetic concerns from missing teeth?
  • Does pt have discomfort arising from missing teeth?
  • Any evidence of occlusal instability as result of missing teeth?
    If yes to any one of these then consider replacing missing teeth
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16
Q

Upon extra oral examination what are some keys things to look out for?

A
  • Check for signs of TMJ dysfunction like click/crepitus/deviation/pain
  • Hypertrophy/tenderness of MOM
  • Skeletal relationship
17
Q

Upon intra oral examination what are some key things to look for?

A
  • Signs of Bruxism like buccal keratosis/ scalloping/ trauma/ wear facets/ restorations
  • Signs of tooth wear
  • Periodontal assessment
  • Occlusal assessment
  • Teeth of poor prognosis
18
Q

What is the course of action if pt has periodontal problems?

A
  • Course of non-surgical peridontal management should be planned
  • Therpay aimed at stabilising periodontal condition of remaing teeth
  • Evaluate response
  • Must be able to maintain perio health
19
Q

What are the negative consequences of failure to establish stable periodontal health?

A
  • Drifting of periodontally compromised teeth under occlusal load
  • Loss of alveolar bone leading to compormised denture bearing area in long term
  • Loss of space (neutral zone) for denture teeth in long term
20
Q

What type of tooth migration occurs in SDA and what does this have an effect on?

A
  • Distal tooth migration
  • Increases anterior load
  • INcreased number and intensity of anterior occlusal contacts
  • INcreases interdental spacing
  • Exacerbated by inadequate perio support
21
Q

Why is progressive tooth wear a contraindication to application of SDA concept?

A
  • Long term threat this poses to survival of teeth (endo txt - can it withstand forces e.g.)
  • Gradual loss of occluding contacts and occlusal stability
22
Q

What can occur if stabilising occluding contacts were to fail in SDA?

A
  • Unplanned tooth loss may happen
  • This can lead to loss of occlusal stability
  • Undermines SDA and may require extensive prosthetic rehab
23
Q

What are the 5 requirements of occlusal stability?

A
  • Stable contacts on all teeth of equal intensity in centric relation
  • Anterior guidance in harmony with the envelope of function
  • Disclusion of all posterior teeth during mandibular protrusive movement
  • Disclusion of posterior teeth on the non-working side during mandibular lateral movement
  • Disclusion of posterior teeth on the working side during mandibular lateral movement
24
Q

What are some consequences of traumatic occlusion?

A
  • Fracture of restorations and/or teeth
  • Tooth mobility
  • Dental pain not explained by infection
  • Tooth wear
  • May also contribute to TMD
25
Q

What is a stable dentition?

A
  • If pt can achieve reproducible ICP without evidence of pathological manifestations of trauma (prev card)
26
Q

How can the SDA be extended?

A
  • Resin retained bridgework
  • Conventional bridgework
  • Implants
  • RPD
27
Q

How would you incorporate a Resin retained bridgework or conventional bridgework in extension of SDA?

A
  • Distal cantilever
  • Max one unit on each side of arch
  • Light contact on cantilevered pontics in ICP
  • Minimal contact in excursive movements
  • Heavy contacts may lead to failure
28
Q

How would you incorporate implants in extension of SDA?

A
  • Single tooth in molar/premolar position
  • Cantilever bridge
29
Q

How would you incorporate RPD in extension of SDA?

A
  • Bilateral free end saddle
  • RPI design
  • Consider with CU
  • Non compliance be aware
30
Q
A