5 Dr.

Azad Almuthaffer

DENTAL SURV EYOR

Dr. Azad Almuthaffer

The ideal requirements for successful Recommended method for manipulating the
removable partial denture are: dental surveyor
1. Be easily inserted and removed by the patient. The right hand is braced on the horizontal arm of
2. Resist dislodging forces. the surveyor, and the fingers are used to raise and
3. It should be aesthetically pleasing. lower the Paralleling tool. The left hand holding
4. Avoid the creation of undesirable food traps. the cast on the adjustable table slides horizontally
5. Minimize plaque retention. on the platform in relation to the paralleling tool.
These objectives are achieved by a careful The right hand must be used to loosen and tighten
evaluation of a patient’s study casts. The the tilting mechanism as a suitable
instrument used to aid the examination of the anteroposterior and lateral tilt of the cast.
study casts is called a dental surveyor and the
procedure is known as surveying. A B
SURVEYOR

It is an instrument used to determine the

relative parallelism of two or more surfaces of
the teeth or other parts of the cast of a dental
arch.

A. Ney surveyor: surveyor with non-swiveling

horizontal arm. It is widely used because of its
simplicity and durability.
B. Jelenko surveyor: surveyor with swiveling
horizontal arm at top of vertical arm and has
spring mounted paralleling tool. Horizontal
arm may be fixed in any position by tightening
nut at top of vertical arm.

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Platform on which the base is moved.

Vertical column that supports superstructure.
Horizontal arm from which surveying tool
suspends.
Table which holds the cast in a fixed relation
to the vertical arm.
Base on which the table swivels.
Paralleling tool or guideline marker
Mandrel for holding special tools.
Survey tools:
The tools which are used for surveying are:
Analyzing rod
It is a rigid metal rod used for diagnostic
purposes in the selection of the path of
placement and to determine the undercut areas
prior to scribing the height of contour with the
carbon marker. Wax trimmer
Carbon marker It is a knife used to trim excess wax which
It is used for the actual marking of the survey blocks out undesirable undercut in such away
line on the cast. A metal shield is used to to be parallel to each other and to the pre-
protect it from breakage. determined path of insertion to obtain the
proper form of the wax pattern.

Undercut gauge
They are used to measure the extent of the
undercut on abutment teeth that are being used
for clasp retention. Usually there are available
in three gauges: 0.25, 0.5, and 0.75 mm. The relationship of the paralleling tool and the
Undercut dimensions can be measured on vertical arm to the table (cast) represents the
teeth by bringing the vertical shaft of the path of placement that the partial denture will
gauge in contact with a tooth and then moving ultimately take when inserted or removed
the surveying arm up or down until there is from the mouth.
also contact with the terminal disc (two points
touch).

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Surveying a tooth consisted of locating

To determine whether tooth and bony areas of accurately the height of its maximum contour
interference will need to be eliminated in relation to the plane in which the cast is
surgically or by selecting a different path of positioned.
placement, that done to determine the most Whenever possible, cast should be surveyed
desirable single path of placement that will with the occlusal plane parallel to the base of
eliminate or minimize interference to the surveyor so that the path of insertion is
placement and removal. vertical to the occlusal plane.
A partial denture should have a single path of The fact that the majority of the natural teeth
insertion, this is only possible for dentures crowns are bulbous in shape (have a
with bounded saddle, for dentures with free suprabulge area); this suprabulge point could
end saddles two or more paths of insertion will occur anywhere between the occlusal surface
be possible. and the gingival margin. When a vertical arm
is brought into contact with the convex
Advantages of single path of placement: surface, they will contact only at one point that
a) Allows insertion and removal of is the point of maximum convexity. When this
prosthesis without interference. surface is rotated, and is still in contact with
b) Help to direct the force along the long the vertical arm, an imaginary line will be
axis of the tooth. traced at the greatest circumference, when we
c) Provide frictional retention. substituted this vertical analyzing rod with a
d) Minimize torque on the abutment teeth. carbon marker then an actual line will be
e) Cross arch stabilization. produced at the level of the maximum tooth
f) Equalize retention. bulge, this line is called survey line.

To determine the most suitable path of

placement that will permit locating retainers
and artificial teeth to the best esthetic
advantage.
To identify proximal tooth surfaces those are
made parallel to act as guiding planes during
placement and removal.
To locate and measure areas of the teeth that
may be used for retention.
To permit an accurate charting of the mouth
The area of a tooth occlusal to the survey line
preparation to be made.
is a non-undercut area, while the area
To delineate the height of contour on abutment
gingival to the survey line is undercut area.
teeth (survey line) and to locate areas of
When a tooth is tilted or rotated in relation to
undesirable tooth undercuts, to be avoided,
the analyzing rod, another survey line will be
eliminated, or blocked out.
traced, as result, the extent of non-undercut
To record the cast position in relation to the
area and the undercut area are consequently
selected path of placement for future
changed. That means that the survey line can
reference.
vary according to the angle formed by contact

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of the vertical analyzing rod with the tooth

surface. Alteration of undercut area can be The undercut areas cannot be created or
done by tilting the dental cast. produced by tilting the cast.
All casts are originally surveyed with the
POSSIBLE SURVEY LINE OUTCOMES occlusal plane is parallel to the base of
It is better to name the survey line as survey surveyor; this is what we called zero tilt, in
mark as mention below. which the retentive undercut must be present
• Continuous survey line: When there is on the abutment teeth.
continuous contact between the carbon marker
and smooth tooth surface.
• Complete circumference interrupted survey
line: When continuous contact between the
marker and irregular tooth surface especially
the buccal surface of molar teeth (presence of
buccal groove) makes the height of contour
with different levels.
• Incomplete circumference interrupted Most patients will tend to seat the partial
survey line: When there is error in surveying denture under force of occlusion. If the path of
procedure, when there is area not surveyed. insertion is other than vertical to the occlusal
• Double survey lines: When there are two plane such seating may deform the clasps.
levels of same height of contour, especially Also dislodging forces are always directed
occur when there is abrasion of the facial tooth perpendicular to the occlusal plane.
surface. In sound tooth surface this is not
appeared unless there is error in surveying Only the retentive tip of the clasp must engage
procedure, when the technician makes two the undercut area, which are present when the
surveying with two levels of carbon marker. cast is surveyed in certain position.
• Survey area: When the tooth height of what are the properties of this
contour appears as a plane especially in the certain position?
labial surface of the incisor teeth.
• Incisal edge survey line: When the incisors Wherever possible, the undesirable undercut
have labial proclination, or even normal labial and area of interference are removed during
inclination but with anterior tilt surveying. mouth preparation by recontouring teeth or
making necessary restoration.
Anteroposterior tilt: anterior tilt will increase
the mesial undercut, while the posterior tilt
will increase the distal undercut. Such as in
free end extension partial denture, tilting the
cast anteriorly will decrease or eliminate the
distal undercut, where the path of insertion
will be changed, thus getting rid of
undesirable undercut located distally, therefore
the tilting of the cast is to minimize or
equalize the undesirable undercut.

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2- Allow more favorable path of insertion.

3- Allow the use of a desired type of clasp for
better function and esthetic.
4- Allow the use of a design to minimize food
impaction, food entrapment and plaque
accumulation.

Types of undercuts established by surveyor

Contour: due to natural contour of the tooth.
Anterior tilt Posterior tilt
Positional: due to tilting of cast on surveyor.
(Heel up) (Heel down)
Desirable undercut: used for retaining the
Lateral tilt: dealing with retentive undercut
removable partial denture against dislodging
situated buccally or lingually on posterior forces by incorporating retentive flexible clasp
teeth. arm.
Undesirable undercut: undercuts other than
those used for retention are considered
undesirable and should be eliminated by:
Tilting the cast and change the path of
insertion.
Tooth recontouring by tooth reshaping, filling
restoration, or undercut releveling.
The effect of tilting a cast on the surveyor Placing properly contoured crown restoration
will be: on the tooth.
1- Redistribution of undercuts to the desired Blocking out the undercut with wax on the
areas. master cast.

COMPUTER AIDED DIGITAL SURVEYING

1- Determine the initial path of insertion perpendicular to the plane of occlusion.

2- Adjust the initial path of insertion according to guiding planes, retention, interference, and esthetic.

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3- Notice the undercuts labeled by different colors according to their gauge.

4- After determine the definite path of insertion do parallel block out for the undesirable undercuts.

5- Remove of wax from desirable undercuts (the retentive terminus area).

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FACTORS THAT DETERMINE PATH OF PLACEMENT AND REMOVAL

Dr. Azad Almuthaffer

IDENTIFY THE MOST FAVORABLE TILT planes. Proximal tooth surfaces that bear a
parallel relationship to one another must either
1- Guiding Planes be found or be created to act as guiding
Guiding planes are parallel surfaces of planes, to do so this, proximal plates (part of
abutment teeth that direct the insertion and the RPD contact guiding planes) should,
removal of a partial denture. The path of whenever possible, be the initial portions of
insertion should be parallel to the guiding the partial denture to contact the abutments.

The components of the denture that contact the guiding planes during placement of removable partial
denture are:

Tooth surface which acts as Component of the denture which contact these guiding planes
guiding planes
A- Proximal tooth surface 1- Minor connector that joins the occlusal rests and clasp to the
saddle.
2- Proximal plates are used with I-bar or R.P.I. system.
B- Axial or lingual tooth surface 1- Reciprocal clasp arms.
2- Lingual plates that act as reciprocal arm.
3- Minor connector that joins the auxiliary rest to the major
connector.

Function of guiding plane

As a result of this contacting between the
guiding planes and the component of partial
denture guiding planes act as:
Guide the prosthesis in and out of the mouth
easily without strain on the teeth contacted or
on the denture itself and without damage to
2- Retentive Areas
the underlying soft tissue (Assure definite path
Retentive areas must exist for a given path of
of insertion).
placement and must be contacted by retentive
The frictional forces of contact of the
clasp arms, which are forced to flex over a
prosthesis with the guiding plane wall will
convex surface during placement and removal.
contribute to the retention of removable partial
For a clasp to be retentive; its path of
denture.
escapement must be other than parallel to the
Stabilize the prosthesis against lateral forces.
path of removal of the denture itself;
Protect weakened teeth.
otherwise, it would not be forced to flex and
Insure positive clasp action.

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thereby generate the resistance known as path of placement selected or by the contour
retention. Clasp retention therefore depends on of the restorations.
the existence of a definite path of placement 2- Esthetics also may dictate the choice of path
and removal. Retention can increase and selected when missing anterior teeth must be
decrease by change the path of placement to properly positioned in the partial denture. In
increase or decrease the angle of cervical such situations so that neither the artificial
convergence of opposing retentive surfaces of teeth nor the adjacent natural teeth will have to
abutment teeth. be modified excessively.

(A) The first path of insertion (zero tilt), the less

3- Interference
esthetic removable partial denture.
The prosthesis must be designed so that it may
(B) The most esthetic path of insertion, the most
be placed and removed without encountering
esthetic removable partial denture.
tooth or soft tissue interference.
If the interference cannot be avoided by
changing the path of insertion, so the make the second removable denture is
interference must be eliminated during mouth
preparation (by surgery, extraction, modifying
RECORDING RELATION OF CAST TO
interfering tooth surfaces, or altering tooth
contours by restorations) or on master cast by
1- Tripoding method
a reasonable amount of block-out. If the
Place three widely divergent dots on the tissue
interferences cannot be eliminated or
surface of the cast at the same horizontal plane
minimized, then a different path of insertion
using the tip of a carbon marker, while the
must be considered, even if less desirable
vertical arm (paralleling tool) of the surveyor
guiding plane and retentive areas must be
is fixed at given vertical position.
selected.
On returning the cast to the surveyor, it may
4- Esthetics be tilted until the tip of the surveyor blade or
A path of insertion should be selected to diagnostic stylus again contacts the three dots
provide the most esthetic demands. To obtain in the same plane. This will produce the
optimum esthetics in removable partial original position of the cast and therefore the
denture therapy: original path of placement.
1- Metal component must be concealed. This is known as tripoding the cast some
Less metal will be displayed (most esthetic dentists prefer to make tiny pits in the cast at
location of clasps) if the retentive clasp is the location of the tripoding dots to preserve
placed at a more distogingival area of tooth the orientation of the cast and to transfer this
surface made possible either by changing the relationship to the refractory cast.

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Vertical arm (paralleling tool) of the surveyor

is fixed at given vertical position.

2- Analyzing rod method

Score two sides and the dorsal aspect of the
base of the cast with a sharp instrument held
against the surveyor blade.
On returning the cast to the surveyor, tilting
the cast until all three lines are again parallel
to the surveyor blade, the original cast position
can be reestablished.

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