Supporting fulcrum axis

Definition
Denture relation about
an axis
Factors influencing
effectiveness of
indirect retainers
Forms of indirect
retainer

It is the component of RPD that
assists direct retainers in
preventing displacement of the
distal extension denture base by
creating resistance on the
opposite side of the fulcrum line

It is the line about which the distal
extension partial denture tends to
rotate towards or away from the
tissues.
This axis is an imaginary line passing
through the teeth(occlusal rests) and
direct retainers( retentive tips)

The fulcrum axis passes between
the two main occlusal rests
called (Supporting fulcrum axis)
This movements is resisted by
the ridge& its overlying mucosa

The fulcrum axis passes between
most posterior and bilaterally
located retentive terminals of
primary direct retainer
It is called (Retentive fulcrum
axis)
This movements is resisted by
Indirect retainers

1. Distance between the fulcrum line & the
indirect retainer
The greater the distance the more the
effective will be the indirect retainer
The indirect retainer must be
perpendicular& midway to the fulcrum
axis

2.Effectiveness of tooth support
Indirect retainer must be placed on a
definite rest seat.
It should be perpendicular to the
long axis of tooth upon which it rest
to prevent tooth movement
Weak teeth should not be used to
support indirect retainer

3.Effectiveness of direct retainer
Unless the principle occlusal rests
are held in their seats by the action
of the direct retainers
If displacement of the base away
from the tissues will occur, Indirect
retainer does not resist
displacement

4.Rigidity of connectors supporting
Indirect retainers
All connectors must be rigid, to
allow indirect retainer to be in
function
5. Indirect retainer must be rigid
If arm of indirect retainer were to
flex indirect retainer will not be
effective

• - Occlusal rests .
• - Canine extension from occlusal
rest.
• - Cingulum rest.
• - Continuous bar
• - Lingual plate

1. -Indirect retention.
2. - Distribution of load over many teeth.
3. -Give strength and rigidity to the
appliance.
4. "-Can form point of attachment for incisal
rests

• - Palatally or lingually inclined teeth.
• - Short clinical crown.

• Poor tolerance.
• Interference with speech when used
in the upper jaw.

-Palatal arm.
-Anterior palatal bar
-Posterior palatal bar
-Extension of the palatal plate
(horse shoe).