Prosthetics 5 - Support and indirect retention

Question 1

what is the definition of support?

Answer 1

it is the resistance to vertical load directed through the denture to the underlying mucosa.
one example of vertical load is occlusal forces during chewing.

Question 2

the force transmitted through the prosthesis is ultimately resisted by?

Answer 2

bone

Question 3

support for the removable prosthesis can be achieved through the use of?

Answer 3

• teeth (tooth-borne)
• mucoperiosteum (mucosa borne)
• both teeth and mucosa (tooth/mucosa borne)

Question 4

mucosal support can be gained from?

Answer 4

• saddles

- connectors

Question 5

tooth support gained through the use of? how is the force transmitted?

Answer 5

• periodontal ligament.

- force is transmitted through tooth to the PDL, and ultimately to the underlying bone

Question 6

tooth support can be gained from using which devices?

Answer 6

• occlusal or cingulum rests
• onlays
• overdenture abutments
• connectors

Question 7

what is the advantage of using an overdenture abutment?

Answer 7

if crown is carious and removed + tooth is root treated, denture can be supported over the root. this preserves the alveolar bone and allows patients to receive feedback from the PDL

Question 8

support: why should we beware of periodontally compromised teeth?

Answer 8

if there is less PDL left, this means that there is less support the tooth can offer. when there is less support, the increased load on the tooth may further compromise its periodontal health

Question 9

saddles - what types of support do each of these provide?

1. bounded saddles
2. free ended saddles
3. large saddles

Answer 9

1. tooth support possible
2. tooth/mucosa borne at best
3. mucosa borne

Question 10

what is indirect retention?

Answer 10

it is the prevention of displacement of saddle away from ridge, by extension of the denture

Question 11

indirect retention: movement of one end can only occur if?

Answer 11

movement can only occur if the other end is free

Question 12

indirect retention: if both ends are supported, e.g. in class 3 denture, movement can only occur if?

Answer 12

movement can only occur if there is a displacement of the central pivot, in this case the disengagement of a clasp

Question 13

indirect retention: the removable prosthesis should aim to? how does it achieve its aim?

Answer 13

• reduce the effect of the displacing force
• can be done by placing the clasp as close as possible to the saddle, and by placing the indirect retainer as far as possible from the saddle

Question 14

denture components: what do saddles provide?

Answer 14

retention, support, bracing

Question 15

denture components:

what do connectors provide?

Answer 15

support, indirect retention, bracing

Question 16

denture components:

what do clasps provide?

Answer 16

retention, support, bracing

Question 17

denture components:

what do rests provide?

Answer 17

support and indirect retention