Saddles and Support Flashcards

1
Q

What are saddles?

A

The part of the denture that covers the alveolar ridges and includes artificial teeth and gum work

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2
Q

Name 6 things to consider when designing a saddle

A
  1. Which spaces to fill
  2. Occlusal surface design
  3. Base extension
  4. Polished surface
  5. Fitting surface (acrylic / metal)
  6. Junction between saddle and tooth (open / closed)
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3
Q

Name 4 considerations when deciding which spaces to fill with an RPD

A
  1. Appearance
  2. Mastication
  3. Speech
  4. Maintaining oral health
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4
Q

Describe the occlusal surface design on RPDs

A
  • As few teeth as required especially on lower DES (only 1 molar replaced)
  • Narrower teeth
  • Tapered towards occlusal surface
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5
Q

Describe the extension of lower DES

A

Cover at least 2/3 of the retromolar pad and to the full functional width and depth of the buccal and lingual sulci

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6
Q

Describe the extension of upper DES

A

Full extension to the hamular notch and full functional width and depth of the buccal sulcus

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7
Q

Describe polished surfaces when designing saddles

A
  • Lingual polished surface concave
  • Buccal polished surface convex
  • Palatal contour follows underlying palate
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8
Q

Name 2 functions of polishing surfaces

A
  1. Aid muscular control

2. Improve stability

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9
Q

What is the most common fit surface used?

A

Acrylic embedded in spaced CoCr meshwork

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10
Q

When may metal fit surfaces be used?

A

When the space between opposing teeth and the alveolar ridge is minimal, usually due to over eruption

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11
Q

Describe closed and open saddle designs

A
  • Combined design usually used
  • Closed means close contact between saddle and teeth and usually used anteriorly as no spaces present
  • Open means spaces present between saddle and teeth and used when possible as tends to be healthier
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12
Q

What is support?

A

Resistance to vertical load applied to prosthesis during function and ultimately borne by bone

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13
Q

Name 2 ways vertical load is ultimately borne by bone

A

Teeth - via PDL which is tensile force and perceived as healthy
Mucosa - directly to bone which is compressive and perceived as unhealthy

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14
Q

Why is mucosal support seen as more unhealthy than tooth support?

A

Bone can become resorbed if put under compressive forces

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15
Q

Name 5 denture components which can give support

A
  1. Occlusal rests
  2. Occlusal onlays
  3. Embrasure hooks
  4. Denture base
  5. Any components contacting above survey lines on teeth
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16
Q

What is an occlusal rest?

A

A metal projection attached to RPD which extends over and bears on occlusal or prepared surface of a tooth

17
Q

What is the best way to produce an occlusal rest?

A

Cast (not wrought) as it must fit surface accurately to not interfere with occlusion

18
Q

Name 6 functions of an occlusal rest

A
  1. Transmits vertical load along the long axis of the tooth
  2. Provides some bracing and reciprocation
  3. Maintains components in correct position
  4. Prevents tooth over eruption
  5. May improve occlusion
  6. May act as indirect retainer
19
Q

Name 3 functions of rest seat preparations

A
  1. Provide more suitably inclined bearing surface for occlusal rest than those existing on the natural teeth
  2. Provide shape of surface giving desirable amount of bracing (saucer shaped)
  3. Provide space between occlusal surface of upper and lower teeth to allow a rest of adequate thickness and strength
20
Q

What should the dimension of occlusal rests be?

A

One half of the buccolingual cusp-cusp width and about one third of the mesiodistal width of the tooth

21
Q

What is an occlusal onlay?

A

Essentially an occlusal rest but extended to cover all the occlusal surface to increase occlusal vertical dimension and bring into occlusal contact

22
Q

What are 2 materials used for construction of occlusal onlays?

A
  1. CoCr

2. CoCr + acrylic

23
Q

What is an embrasure hook?

A

Metal attachment placed in the embrasure between two contiguous anterior teeth

24
Q

Name 3 advantages of embrasure hooks

A
  1. Support
  2. Indirect retention
  3. Bracing
25
Q

Name 3 ways to optimise mucosal support

A
  1. Ensure good base extension
  2. Use broader connector
  3. Reduce load on lower mucosa by using less teeth