7 - Shortened dental arch Flashcards

1
Q

What dental disease is common in RPD wearers?

A
  • root caries
  • periodontal disease
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2
Q

Why is dental disease common in RPD wearers?

A

Patients are already higher risk

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3
Q

What is the Kayser 1981 concept?

A
  • SDA concept
  • dentition where most posterior teeth are missing
  • satisfactory oral function can be achieved without RPD
  • priority is given to maintaining anterior and premolar in one or both jaws
  • sufficient capacity is achieved when 3 to 5 occlusal units are left
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4
Q

What is an occluding unit?

A
  • pair of occluding premolars = 1 unit
  • pair of occluding molars = 2 units
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5
Q

What symptoms are associated with loss of molars?

A
  • reduced masticatory efficiency
  • mandibular displacement
  • alteration in food selection
  • aesthetic issues
  • loss of occlusal stability
  • TMJ problems
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6
Q

What are the indications for SDA?

A
  • missing posterior teeth with 3-5 OU remaining
  • sufficient occlusal contacts to provide occlusal table
  • favourable prognosis for anterior teeth
  • patient not motivated for complex Tx plan
  • limited financial resources
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7
Q

What are the contraindications for SDA?

A
  • poor prognosis for remaining dentition
  • untreated or advanced perio
  • pre-existing TMD
  • pathological tooth wear
  • significant malocclusion
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8
Q

What considerations should be taken before SDA?

A
  • any problems chewing food?
  • any appearance or cosmetic issues with anteriors?
  • any discomfort?
  • any evidence of occlusal instability?
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9
Q

What should be examined EO for an SDA?

A
  • signs of TMD (click/crepitus/pain)
  • hypertrophy of MOM
  • skeletal relationship
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10
Q

What should be examined IO for an SDA?

A
  • signs of bruxism (buccal keratosis/wear)
  • periodontal assessment
  • occlusal assessment
  • teeth of poor prognosis
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11
Q

How should the occlusion be assessed for SDA?

A
  • severe class II and class III are contraindicated as they have few OU
  • edge to edge is okay
  • 3-5 OU ideal
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12
Q

Why does significant periodontal disease contraindicate an SDA?

A
  • drifting of periodontally involved teeth under occlusal load
  • loss of alveolar bone leads to a compromised denture bearing area (long term) and loss of neutral zone
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13
Q

Describe pathological periodontal tooth movement in an SDA.

A
  • distal tooth migration occurs due to anterior load
  • increased occlusal intensity
  • increased interdental spacing
  • exacerbated by inadequate periodontal support
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14
Q

Why is progressive tooth wear a contraindication for SDA?

A
  • long term threat to prognosis of teeth
  • gradual loss of occluding contacts and stability (loss of centric relation)
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15
Q

Define occlusal stability.

A

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

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16
Q

What are the five requirements of occlusal stability for SDA?

A
  • stable contacts on all teeth in centric relation
  • anterior guidance in harmony with envelope of function
  • disclusion of all posterior teeth during mandibular protrusion
  • disclusion of posterior teeth on non-working side during lateral excursion
  • disclusion of posterior teeth on working side during lateral excursion
17
Q

What is occlusal stability determined by?

A
  • absence of pathology
  • periodontal support
  • number of teeth
  • ID spacing
  • occlusal contacts
  • mandibular stability
18
Q

What are manifestations of a traumatic occlusion?

A
  • fracture of restorations or teeth
  • mobility
  • pain not explained by infection
  • tooth wear
  • TMD
19
Q

How can the SDA be extended?

A
  • distal cantilever RRB
  • conventional distal cantilever bridge
  • implants (+/- cantilever bridge)
  • RPD (no longer SDA)
20
Q

Where are RRB more successful in extending the SDA?

A
  • distal cantilever
  • lower more successful
  • light occlusal load and less load during excursion
  • max one unit
21
Q

What causes a flabby ridge?

A

Concentration of forces in anterior causes resorption of bone

22
Q

What is combination syndrome?

A
  • edentulous upper
  • SDA lower
  • maintaining the SDA in the lower is usually transitional until lower teeth XLA