DENTAL CAST

SURVEYOR

Presented by:

Dr. Tushar Bhagat

Ref: McCraken’s Removable partial prosthodontics.

CONTENT & REFERENCES

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INTRODUCTION

Before 1918, all RPD were designed arbitrarily.

Turning point came in 1918, Dr. A. J. Fortunati, introduced dental cast

surveyor, which was used to determine the parallelism of surfaces.

After 1918, RPD service becomes from guesswork to an objective,

scientific based procedure.

In 1923, J. M. Ney Company introduced first commercially available

Surveyor.

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1918

DEFINITION

Dental Cast Surveyor : An instrument used to determine the relative

parallelism of two or more surfaces of the teeth or other part of the cast of

dental arch.

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PURPOSES OF DENTAL CAST SURVEYOR

Surveying the diagnostic cast.

Contouring wax pattern.

Surveying ceramic veneer crowns.

Placement of intracoronal retainers.

Surveying master cast.

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Ref: McCracken’s Removable partial prosthodontics. Page.no.168-172

Path of placementGuide planeLocate Area for retentionEliminate bony & tooth

interferences

PARTS OF SURVEYOR

1) Level platform

2) Vertical column / rod

3) Horizontal arm

4) Surveying arm

5) Surveying table / cast holder.

6) Surveying tools.

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Ney dental surveyor

Ref: Stewart’s Removable partial prosthodonics. Page.no.205-206

1. LEVEL PLATFORM

Level platform is parallel to bench top

and on which the cast holder is moved.

Clean with an Acetone or Alcohol swab.

Small amount of polymethylmethacrylate

powder should be placed before

surveying.

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Ney dental surveyor

VERTICAL COLUMN & HORIZONTAL ARM

Vertical column supports the suprastructure.

Horizontal arm that extents at right angle from the

vertical column.

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Ney dental surveyor

SURVEYING ARM & SURVEYING TABLE

Surveying arm extends vertical from horizontal arm.

Surveying arm is capable of movement in a vertical

direction and contains a MANDREL at its lower end.

Mandrel holds surveying tools used in surveying

procedure.

Surveying table holds the cast which permits spatial

reorientation of the cast (ie, tipping or tilting)

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Ney dental surveyor

SURVEYING TOOLS

1) Surveying tools that may be placed in mandrel.

1) Analysing rod (used to determine relative parallelism of

surfaces of dental cast)

2) Carbon marker (mark the height of contour)

3) Undercut gauge (used to identify position of desired

undercut, available in 0.010, 0.020 & 0.030 inch

embodiments.)

4) Wax knife (used during block out procedure & in

construction of surveyed restoration.)

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Ney dental surveyor

Analyzing rod

Carbon marker

Un

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rcu

t ga

ug

e

Wax knife

SURVEY PROCESS

I. Identifying the most favourable tilt. a) Retentive undercut

b) Interferences

c) Esthetics

d) Guiding plane

II. Path of insertion

III. Tripoding the cast

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Ref: Stewart’s Removable partial prosthodonics. Page.no.207-220.

IDENTIFYING THE MOST FAVOURABLE TILT

If anterior of the cast is

lowered, the cast is said to

have anterior tilt, & so on.

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IDENTIFYING THE MOST FAVOURABLE TILT

Four critical factors:

I. Presence of suitable undercuts

(Retentive undercut).

II. Elimination of hard & soft tissue

interferences (Interferences).

III. Creation of desirable Esthetics.

IV. Guide plane establishment.

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Rarely is it possible to be achieve the optimum in all four area.

IDENTIFYING THE MOST FAVOURABLE TILT

a) Retentive undercut:

1. Retentive undercut must be present on the

abutment tooth.

2. If not present than,

1) Tilt of cast or,

2) Recontouring of enamel or,

3) Crowning of tooth.

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IDENTIFYING THE MOST FAVOURABLE TILTb. Interferences:

I. Certain structure may interfere while

constructing RPD like (some teeth, bony

prominences, soft tissue undercuts)

II. Difficulties may be avoided by;

1. Changing the tilt.

2. Altering the design.

3. Surgical intervention.

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IDENTIFYING THE MOST FAVOURABLE TILT

c)Esthetics: for optimum results;

1. Metal component less

visible

2. Selection of artificial teeth

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IDENTIFYING THE MOST FAVOURABLE TILT

d) Guiding plane :guide planes are

parallel surface of abutment teeth

I. When the RPD seated in mouth the

guiding plane are contact in minor

connector.

II. They can be prepare on enamel

surface if needed.

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PATH OF INSERTION

I. Ideally all RPD should

have single path of

insertion, but in class I & II

situation it has more than

one.

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TRIPODING THE CAST

a) Recording the favourable cast tilt for future

references (to re-orient the cast).

b) The procedure is called as tripoding or

tripodization.

c) There are several methods, but two are common.

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TRIPODING THE CASTMethod 1:

Place three widely divergent dots (on

area which is not included in

component)on the tissue surface of the

cast using the tip of undercut gauge or

carbon marker, with vertical arm of the

surveyor in a locked position.

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TRIPODING THE CASTMethod 2:

To score two sides and the dorsal

aspect of the base of the cast with a

sharp instrument held against the

surveyor blade. By tilting the cast until all

three lines are again parallel to surveyor

blade, the original position of cast can

be re-establish.

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Thank you

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Ref: McCraken’s Removable partial prosthodontics.