Rpd Flashcards
Prostho rpd
Partial edentulousness
The dental status, when one or more teeth are missing from
the dental arch, but there is at least one tooth/root present.
Torque
is moment or moment of force, is the tendency of a force to rotate an object
about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be
thought of as a twist to an object. The torque is the product of the applied force and the
length of the lever. Mathematically, torque is defined as the product of force and the
lever-arm distance, which tends to produce rotation. Loading force x length of loading
arm = resistance force x length of resistance arm.
Axis of rotation/ fulcrum line is
a connecting line between the supporting points on
the abutment teeth adjacent to the edentulous ridge around which the denture can
rotate or rock
Primary rotation axis
a connecting line between the supporting points on the
abutment teeth adjacent to the edentulous ridge. After inserting the denture it may
become a real or actual rotational axis.
Secondary rotation axis
a line between the supporting points of a tooth neighboring
and a tooth non-neighboring the edentulous ridge
Real, actual rotation axis
is that primary rotation axis around which the inserted
denture may sink, tilt or rock
Fábián-Fejérdy classification class 1A
There can be one or more primary fulcrum
lines, but after the prosthesis is inserted none of these becomes an actual rotational
axis, torque does not arise on the axis of rotation, and the prosthesis doesn’t sink in
any direction. Dental support is possible.
Fábián-Fejérdy classification class 1B
There can be one or more primary fulcrum
lines from which one can become a real axis of rotation after the prosthesis is inserted.
The moment of rotation is small, so the sinking of the tooth supported denture can be
compensated for. There is a torque, but it can be compensated for, if we use more
abutments for the anchorage. Fix prosthesis can be made
Fábián-Fejérdy classification class 2A
There can be only one primary fulcrum line,
but one or more secondary fulcrum lines. After inserting the denture, the primary axis
of rotation may turn in an actual axis of rotation, and the denture rotating around this
axis may sink in one direction. Tooth and mucosa support. The remaining teeth or the
edentulous ridge is in one block. A removable partial denture can be made
Fábián-Fejérdy classification class 2A/1
There is only one fulcrum line, and this
primary fulcrum line becomes a real axis of rotation after the denture is inserted, the
denture rotating around this axis, may sink in one direction. Mucosa and tooth
supported. Long edentulous ridge, subtotal edentulousness. A removable partial
denture can be made.
Fábián-Fejérdy classification class 2B
There can be two or more primary fulcrum
lines, from which one may become a real axis of rotation after the denture is inserted.
The denture rotating around this axis may sink in one direction. The remaining teeth
aren’t situated in one block, combination of free end saddle and short span ridges. A
removable partial denture can be made.
Fábián-Fejérdy classification class 3
There can be one or more primary fulcrum
lines from which one or more may become a real axis of rotation after the denture is
inserted, the denture rotating around them can sink in two directions, and it may rock. Mucosa and tooth supported. Very long edentulous ridges, teeth are situated diagonal.
A removable partial denture can be made.
Removable partial denture definition
: It is a dental device that restores one or more,
but not all the natural teeth and associated structures, its retention and support are
provided by the natural teeth (dental implants) and/or mucosa (and under it the bone).
It occupies more space in the mouth then the teeth, the mucosa and the edentulous
ridge are also covered, it is connected to the natural teeth, and the patient himself can
remove and insert it.
. Support of the prosthesis
The transmission of vertical components of chewing force
to the tissues of the mouth, and the resistance of these tissues to this force. With other
words: The foundation on which the denture rests, and which resists displacement
towards the tissues. It comprises the hard and soft tissues that bear the loads of
mastication and clenching applied to the denture.
Dental, periodontal support
is, when the vertical components of masticatory force
are transmitted only to the tooth/periodontium
Mucosal support
is, when the vertical components of masticatory force are
transmitted only to the mucosal bony basement
Mixed, dento-mucosal or muco-dental support
In this case the teeth and the
mucosa-bone base take part together in the support and retention of the RPD. When
the number and/or position of the remaining teeth doesn’t allow dental support, the
vertical components of the masticatory force are transmitted to the teeth and the
mucosal bony base (also the hard palate in the upper jaw).
Retention of the RPD
Means the fixation of the RPD against the forces that would
provoke the dislodgement, or lift of the prosthesis from its place. Retention is that
property of a denture which resists the outward displacement of the denture, away
from the tissues
Rigid retainer
Means that the load affecting the denture is transmitted to the abutment
tooth in the same size, because the connection between the saddle and the retainer is
stiff, there is no movement of the denture independent from the abutment tooth. The
denture can move neither in vertical, horizontal, nor in sagittal direction. Forces from
any direction affecting the denture reach the abutment teeth immediately. Retention
acts at the moment of load. There is no force transmission to the abutment tooth
without chewing; it is the appropriate retention form
Elastic retainer
In this case a decreased load is transmitted to the abutment teeth,
because the connection between the saddle and the abutment teeth is elastic/non rigid
(drought wire clasp), the partial denture can move/dislodge independent from the
abutment tooth. The fixation is not activated immediately at the time of the load
Clasp line, line of support
a line connecting two occlusal rests of the RPD in an arch
segment)
Load line
connects the centric stops in an arch segment. It should be orally from the
line of support to avoid the generation of lifting forces on the prosthesis
Area/poligon of support
The area that is bounded by the occlusal rests, or the area
determined by the lines of support. Line of support connects the occlusal rests of an
arch segment. The polygon of support connects all lines of support. The supporting
area must be as big as possible.
Area of load
The edentulous ridge outside of the supporting area. The smaller the
loading area is the more stable the RPD is
