Surveyor and technique of Surveying in Removable partial denture

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SURVEYING IN
REMOVABLE PARTIAL
DENTURES
Dr Farah Ahmed

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SURVEY
• To examine as to condition,value or situation , to
appraise.
• To determine the form and position of a given
entity by taking linear and angular
measurements

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SURVEYING
An analysis and comparison of the prominence
of intraoral contours associated with the
fabrication of a dental prosthesis.

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SURVEYOR
A surveyor is essentially a parallelometer, an
instrument used to determine the relative
parallelism of surfaces of teeth or other areas on
a cast of the jaws.
(Stewart)

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A paralleling instrument used in the construction
of a dental prosthesis to locate and delineate the
contours and relative positions of abutment teeth
and associated structures.
-(GPT-8)

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“Intelligent use of a dental surveyor is the best
way to prevent the occurrence of countless
problems frequently related to oral rehabilitation
with RPDs”
-Dr O C Applegate

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The History and Development of the Dental
Surveyor (Robert L Engelmier)-JOP vol 11(march)
2002
“Reduced to its simplest terms , surveying a tooth
is a mechanical method of obtaining its height of
contour accurately. If a vertical plane is brought
into contact with a curved surface it will touch at
the greatest bulge on the convexity and nowhere
else.”
–Dr A H Schmidt (1953)

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Manual Surveying
• Visual survey
• Eyeballing
• Dr W M Randall’s
technique for
surveying.(1890)

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Early Paralleling instruments
THE CHAYES PARALLELOMETER (circa 1920)

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THE CHAYES PARALLELOMETER
SYSTEM

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Paralleling device used as a jig for the Grisworld Attachment System

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The First Dental Surveyor
• Dr Rudolph Hanau (1917)
• Dr A J Fortunati (1918)
• Dr Edward Kennedy
• The Philadelphia Dental Clinic club
• Noble G Wills
• Weinstein and Roth(1923)

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THE ROBINSON SURVEYOR (circa
1918)

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DENTAL SURVEYING APPARATUS – HANAU
(1917)

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The Basic Dental Surveyor
1. Level platform
2. Cast holder
3. Vertical arm
4. Horizontal arm
5. Surveying arm
6. Interchangeable
Surveying tools

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Scientific Exhibits American Dental
Association (1948)
1. Ney (1923)
2. Brown Maier (1925)
3. Wills (1929)
4. Lentz –Circa (1935)
5. Lineer (1937)
6. Ney (1937)

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7. Franzwa (1937)
8. Ringle-Hiatt-Smith (1944)
9. McKay (1944)
10. Hagman (1944)
11. Roach (1944)

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A. Original Ney’s Surveyor (1923)
B. Current model of Ney’s Surveyor (1937)
C. Modified Ney’s Surveyor (mid 1960s)

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Will’s Surveyor 1937 Recent Design Of The Will’ Surveyor

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The Roach Surveyor (1944)

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RECENT INNOVATIONS

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Austenal 42 inch blockout
surveyor
Austenal Micro Analyser

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PARTS OF A SURVEYOR
British dental journal, volume 189, no. 10, november 25 ,2000
1. Level platform
2. Vertical arm
3. Horizontal arm
4. Surveying arm
5. Cast holder
6. Accessory tools

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Accessories/surveying tools
1.Analyzing rod
2.Carbon(graphite) marker
3.Undercut gauges
4. Wax knife
5.Milling devices (with handpiece holder)

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Analysing Rod

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Identifies undercut areas and to determine the
parallelism of surfaces without marking the cast.

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Graphite Marker

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• moved around the tooth and along the alveolar
ridge
• the tip of the marker should be level with the
gingival margin.

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False Survey Line

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Undercut Gauges

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the shank and head should contact the cast
simultaneously.
• more sophisticated, types of undercut gauge are
available such as dial gauges and electronic
gauges.

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Wax Knife

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• To blockout
undesirable undercuts
• To prepare guiding
planes

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1. Survey line
2. Undercut
3. Guiding planes
4. Path of insertion
5. Path of displacement

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SURVEY LINE
Survey line is a line drawn on a tooth/teeth of a
cast by means of a surveyor for the purpose of
determining the various parts a clasp/clasps.
-GPT 8

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TYPES OF SURVEY LINES
• Blatterfein classified survey lines as:
1. High survey Line
2. Medium Survey Line
3. Low Survey line
4. Diagonal Survey Line

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•Found near the occlusal
surface of a tooth often
parallel to the gingival
margin
• It results from abnormal
inclination of the teeth
• lingual surfaces of the
lower teeth and buccal
surfaces of the upper teeth.
•Wrought wire clasp used
High Survey Line
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•It is situated across
the center of the tooth
• Exhibits a slight
occlusogingival incline
from the near zone to
the far zone.
•Aker’s or Roach clasp
Medium Survey Line
39

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•It is situated close to and
parallel to the gingival
margin.
• It frequently occurs as a
result of marked
inclination of the tooth and
may also occur on
conically shaped tooth.
•Modified T clasp
Low Survey Line
40

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It travels diagonally
from near the occlusal
surface in the near
zone to the gingiva in
the far zone.
Diagonal Survey Line
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Reverse circlet clasp

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Class I:
•Survey line runs diagonally
across the tooth surface.
•The type of clasp indicated
is occlusally approaching
cast clasp with terminal third
engaging the undercut.
Ney’s Classification
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Class II: Survey line also runs
diagonally across the tooth
surface but as a mirror
image of Class I line. Here a
gingivally approaching clasp
arm is suggested.
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.

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Class III:
Survey line is parallel to
the occlusal surface and
lies just below it

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Undercut
the portion of the surface of an object that is below
the height of contour in relationship to the path of
placement
-(GPT 8)

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Types Of Undercuts
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Tooth Undercuts (Proximal
undercuts)
Soft Tissues or bony
Undercuts(on lingual side
of ridge)

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• 0.25 mm - 0.01” chrome cobalt
• 0.5 mm – 0.02” cast gold
• 0.75 mm – 0.03” stainless steel

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Guiding Planes
vertically parallel surfaces on abutment teeth
or/and dental implant abutments oriented so as
to contribute to the direction of the path of
placement and removal of a removable dental
prosthesis.

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Two or more parallel axial surfaces on abutment teeth which can
be used to limit the path of insertion and improve the stability of a
removable prosthesis. Guide surfaces may occur naturally on
teeth but more commonly need to be prepared.

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PATH OF INSERTION
Surveying removable partial dentures:the importance of guiding planes
and path of insertion and stability –O L Bezzon et al (JPD October 1997
vol 78 no.4 )
the specific direction in which a prosthesis is
placed on the abutment teeth or dental
implant(s)
• path of withdrawal (reverse of path of insertion)
• path of placement

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The RPD path of insertion and withdrawal is the
direction in which the prosthesis moves in
relation to the support system when it is seated
in or removed from the mouth, guided by the
contact of its rigid parts with the abutments.
(GPT-8)

5252
A single path of insertion

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Multiple Paths of Insertion

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Two paths of insertion Rotational path of insertion

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Potential Path of Dislodgement
Regardless of the path of insertion the path of
dislodgement results from masticatory function that pulls
the prosthesis in a direction perpendicular to the occlusal
plane.

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USES OF A SURVEYOR
1. Surveying the diagnostic cast
2. Tripoding the cast
3. Transferring tripod marks to another cast
4. Contouring wax patterns

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5. Contouring cast restorations
6. Placing internal attachments and rests
7. Surveying the master cast

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Process Of Surveying
1. Preliminary visual assessment of the study
cast.
2. Initial survey.
3. Analysis.
4. Final survey

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Visual assesment:
• Eyeballing
• Form and arrangement of teeth
• Potential problem areas

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Anterior tilt (‘heels up’) Posterior tilt (‘heels down’).

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Left and Right Tilts

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Initial survey
• Cast positioned with
the occlusal plane
horizontal.
• The position of the
survey lines.
• ‘Triangle of light’
between the marker
and the cervical part
of the tooth.
• Undercut gauges

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Analysis
• Occlusal plane horizontal
• Consider:
1. Appearance.
2. Interference.
3. Retention

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Appearance:
• Undercuts on the
mesial aspects of the
abutment teeth.
• Unsightly gap
between the denture
saddle and the
abutment teeth
gingival to the contact
point.

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posterior tilt so that the analysing
rod is parallel with the mesiolabial
surfaces of abutment teeth.
contact of abutment tooth over the
whole of the mesiolabial surface
and a much better appearance
results.

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Interferences:

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Interferences in the maxillary arch
Maxillary tori

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Exostoses and undercuts on maxillary buccal surfaces

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Interferences in the mandibular arch
Mandibular tori

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Lingually tilted premolars

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Undercuts adjacent to pear
shaped pads
Bony prominences on facial surface
of mand canines

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Retention:

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Final Survey
• The aims for optimum
retention should be to
provide:
• Resistance along the
path of displacement.
• Resistance along the
path of withdrawal

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•guide surfaces are used to provide resistance to displacement
•retentive portion of the clasp needs only to resist movement along the path of
withdrawal
• positioned solely with reference to the red survey line.

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Gingivally approaching clasp
positioned at the cross-over point
of the survey lines.
•survey lines converge mesially or
distally
•the tip of an occlusally approaching
clasp can engage the common area of
undercut.

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Tripoding the cast

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Alternate method of tripoding

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Other Methods of Tripoding
• Pin cemented in the centre of the cast
• Use of protractor fixed on surveyor
• Use of dental bur in place of pin
• Use of position recorder device on a surveyor
• Use of plastic plate and impression of cusp tip
• Device with adjustable arms
• Use of plastic tray and impression
• Smooth or threaded pin with sleeve
• Use of inclinometer
• Key and keyway system
• Tripoder attachment

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Transferring tripod marks to
another cast
• 3 anatomical points
marked on diagnostic
cast
• Same points marked
on 2nd cast with
analysing rod

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Contouring the wax patterns
• With cast on
surveying table , tilt
adjusted to original
tilt.
• Guiding planes
• Height of contour

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Contouring Crowns & cast
restorations
• Shape of wax pattern altered during
casting & finishing.
• Working cast with restorations placed at
original tilt
• Cylinder stone.
• Guide planes refined.

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Placing internal attachments/rests
• Intracoronal retainers.
• Surveyor acts as a drill press

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OBJECTIVES OF SURVEYING
1. Path Of insertion
2. Guiding planes
3. Height of contour
4. Dental and osseous contours
5. Soft tissue contours

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6. Cast position and relation to path of insertion
7. Transfer of design to master cast
8. Blockout
9. Develop axial contours
10. Machine guiding planes
11. Intracoronal retainers

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Maintenance of Surveyor
• Wipe the base of surveying table and surveying
platform with alcohol or acetone soaked gauge
pad.
• Acrylic resin powder can be sprayed for smooth
gliding.
• Machine oil should be applied to vertical arm
before and after use, each time.

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SUMMARY
Surveying is undertaken to obtain information
that will help us decide:
(1) The optimum path of insertion of the denture
which in turn is influenced by:
• the need to use guiding surfaces to achieve a
pleasing appearance.

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• the need to avoid interference by the teeth or
ridges with correct positioning of denture
components.
• the need to use guide surfaces for retention.
(2) The design, material and position of clasps.

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MICROSURVEYOR

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1. O. L. Bezzon, M. G. C. Mattos, R. F. Ribero,
Surveying removable partial dentures: the importance of guiding
planes and path of insertion for stability.
J Prosthet Dent 1997;78:412-18.
2. J. C. Davenport, R. M. Basker, J. R. Heath, J. P. Ralph, and P-O.
Glantz
Surveying.
British Dental Journal 2000, vol.189(10):532-42
3. Robert L. Engelmeier
The History and Development of the Dental Surveyor: Part I
Journal of Prosthodontics, Vol 11 No 1, 2002: pp 11-18.

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The History and Development of the Dental Surveyor: Part II
Journal of Prosthodontics,VOL11,No 2, 2002: pp122-30.
The History and Development of the Dental Surveyor: Part III
Journal of Prosthodontics,VOL13,No 3,2004: pp 195-202.
6. Stewart’s Clinical Removable Partial Prosthodontics,3rd Edition,
Survey and design
7. McCracken’s Removable Partial Prosthodontics,11th Ed

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