Indirect retainer

Question 1

Def , Indirect retainer

Answer 1

Rigid part of RPD resist rotational tissue away movement present in opposite side of retentive
fulcrum line.
used in free end saddle (distal extension (class I,II), mesial extension (long span class IV)

Question 2

Fulcrum line

Answer 2

imaginary line pass between 2 the most posterior principle abutment

Question 3

Rotational movement in free end saddle

Answer 3

1-rotational movement around fulcrum line:
a-rotational tissue ward movement → around fulcrum line.
→ done by mastication ‘‘lodging force’’
→ resisted by rest and denture base
b-rotational tissue away movement→ around fulcrum line.
→ done by dislodging force ‘‘sticky food’’
→ resisted by indirect retainer

2-rotational movement around longitudinal axis of the ridge.
3-rotational movement around vertical axis of the arch.

Question 4

There is vertical tissue ward movement resisted by ….

There is vertical tissue away movement resisted by ….

Answer 4

supporting element

direct retainer

Question 5

Forms of indirect retainer

Answer 5

1-occlusal rest
a-anterior placed occlusal rest, (class I,II)
b-posterior placd occlusal rest , long span class IV

2-anterior and posterior palatal bar

3-continous bar (kennedy bar –continous clasp) , adv act as indirect retainer

4-cummer arm ‘‘canine rest’’

5-palatal arm , When continuous bar is contraindicated

Question 6

2-anterior and posterior palatal bar is …

Answer 6

*it is ring design major connector where anterior palatal bar act as indirect retainer in
distal extension, while Posterior palatal bar act as indirect retainer in mesial extension
“long span class IV”

Question 7

Stress breaker/equalizer def,forms, mechanism

Answer 7

def
Flexible connection between saddle and direct retainer
Forms
1-hinge device
2-flexible major connector ex: split, lingual bar with thinner section.

Mechanism
Allow vertical movement of denture base. So occlusal forces directed more to ridge (primary )
and (secondary) to abutment so decrease tipping of abutments (used in well developed ridge).

Question 8

Stress breaker advantage, disadvantage, indications

Answer 8

Advantages
1-decrease tipping to abutments as direct stress to ridge
2-intermittent pressure give massaging effect to ridge
Disadvantages
1-complex design 2-difficult to repair
3-cause too much movement. So less bracing and indirect retainer
Indications
1-in distal extension with internal attachment as it is rigid
2-in distal extension where weak inherent abutment

Question 9

if use rigid connection between denture base and retainer, the rigid retainer cause torqueing to
abutment.
So there are many solutions: some of them are

Answer 9

1-use rigid connection with flexible /stress breaking clasp (stress breaker like action or stress
breaker like action)
2-use flexible connection with rigid clasp