introduction to dental surveyor and surveying technique in prosthodontics

1. Year 2
2019
Dental Surveyor &
Surveying
Dr Chu Seng Boon
DDS (USM), MClinDent (Pros) (King’s College London), MProsRCS (Edinburgh)

2. Dental Surveyor
First introduced to dentistry
in 1918
It is a fundamental aspect for
effective removable partial
denture (RPD) design &
construction

3. Dental Surveyor
It allows a fixed vertical arm to
be brought into contact with the
teeth & ridges of the dental cast
outlining parallel surfaces &
points of maximum contour

4. Dental Surveyor
The clinician/student
should be the one to carry out
this procedure of the preliminary
survey on the primary cast in
preparation for a design

5. Dental Surveyor
This is because it is the
clinician/student who has the
clinical knowledge & experience
of the patients & their oral
circumstances

6. Dental Surveyor
The clinician/student can then
proceed to consult their
technician on their findings,
opinions can be expressed from
both clinician & technician prior
to any planned adjustment (i.e.
rest seats/guide planes)

7. Purpose of surveying
Select a single path where denture can be inserted
(PATH OF INSERTION) and removed (PATH OF
WITHDRAWAL) without obstruction
Once in position, denture should be able to resist falling
out by itself or during function
The selected path must also attempt to be aesthetically
pleasing

8. Purpose of surveying
To locate proximal tooth surfaces that are or can be
made parallel (guide planes)
To identify the height of contour on abutment teeth

9. Purpose of surveying
To identify areas of desirable undercuts (can be used
for retention) & undesirable undercuts (must be
eliminated/blocked out)
This includes areas of teeth and mucosa that will be
contacted by rigid connectors
Failing to eliminate such undercuts will prevent the
denture from seating

10. •Ney surveyor
•Jelenko surveyor
•Williams surveyor
•Retentoscope surveyor
•A 2000 - Buchanann surveyor
•Micro analyser
•Stress-O-Graph
•Austenal surveyor
•Optical surveyor
•Computerized surveyor
•Ticonium surveyor
•Intra oral surveyor
Types of surveyors

11. 1890
1905
1920
1923
1890

12. 1937
Ney
surveyor
1929
The original Wills
surveyor by G Wills
1937
Wills surveyor - current model
1942
King’s College Surveyor
1944
The Roach Surveyor

13. Electro-stress-o-graph
Retentoscope
Broken arm

14. Jalenko
Ney

15. Surveying Terminology
Guide planes
1
Also referred to as guide surfaces.
Two or more parallel vertical surfaces on abutment teeth
which can be used to dictate the path of insertion & improve
stability
They govern the direction of movement of the RPD during
insertion & removal

16. The green
arrows in both
diagrams
illustrate the
guide planes

17. In practice, guide planes are
found with the aid of surveyor

18. Surveying Terminology
Undercuts
2

19. Surveying Terminology
Undercuts
2
hat lies between the height of contour & the gingivae (area below the greate

20. Surveying Terminology
Undercuts
2
Desirable
undercut
Undesirable
undercut
Soft tissue
undercut
Undercuts

21. Surveying Terminology
Undercuts
2
Desirable
undercut
area of abutment surface that is suitable for
the location of a retentive clasp terminal,
which in order to escape the undercut, the
clasp would be forced to flex & thus
generate retention

22. Surveying Terminology
Undercuts
2
the area of abutment tooth/soft tissue which
the RPD must pass without interference &
hence must be blocked out (filled with
wax/plaster) before master cast is
duplicated.
Undesirable
undercut
Use of the surveyor with a trimming knife
produces a surface that is parallel to the
proposed path of insertion and removal.

23. Surveying Terminology
Undercuts
2
an undercut in a residual ridge or soft
tissue covering of a dental arch that would
prevent or influence the placement & design
of a RPD.
Soft tissue
undercut
These undercuts are relative to the selected
path of insertion

24. an undercut (in red) on
the overhang of a cliff
edge
h are shown in green. The lines in orange represent the height of contour or

25. Surveying Terminology
Path of insertion
3
Path taken by the denture from its initial contact with the teeth
until it is completely seated
this path coincides with the path of withdrawal but NOT
necessarily the path of displacement

26. Surveying Terminology
Path of insertion
3
a single path of insertion may be used if sufficient guide
surfaces are available to be contacted by the denture - most
likely in bounded edentulous regions, this would be the most
favorable path
Multiple paths may exist where guide surfaces are not used
because the abutment teeth are divergent making it impossible to
gain two parallel surfaces

28. There are also instances
where a rotational path of
insertion can be used
Path of displacement
this is the direction the denture
tends to be displaced in function
- i.e. when the patient is eating
sticky foods, and is normally at
right angles to the occlusal
planes

29. Components of surveyor
Horizontal arm
Surveying arm
Cast holder
surveying table platform
Vertical arm

30. Components of surveyor
Surveying table
Cast holder

31. Components of surveyor
Surveying arm

32. Components of surveyor
Surveying tools
Analyzing rod
surveying tool

33. etermine the relative positions of parallel surfaces & undercuts without ma
it is placed against the teeth & ridges during the initial analysis for
available undercuts & potential guide planes.
Analyzing rod

34. Components of surveyor
Carbon marker
surveying tool

35. A chamfered lead marker is moved around teeth & the ridges to
identify & mark areas of maximum convexity or bulbousity - known
as the upper survey line
the tip of the marker indicates the
lower survey line which identifies
the extent of the undercut
These lines separate undercut
areas (located between the two
survey lines) from non-undercut
areas (located above & below these
lines)
Graphite/Carbon Marker

36. e graphite marker should be in contact with the cast as well as the side o
tooth & tissue
undercut identified
Graphite/Carbon Marker

37. Incorrect positioning of the marker can result in a single false
survey line
if this false line is used in the design of an RPD, faults will occur
in the positioning of the components, mainly clasps
Graphite/Carbon Marker

38. Undercut gauges
0.01” 0.02” 0.03”
0.25 mm 0.5 mm 0.75 mm
surveying tool
Undercut Gauges

39. Undercut gauges
surveying tool
Undercut Gauges

40. to measure the extent or depth of horizontal undercut in order to receive re
available in 3 sizes: 0.25mm, 0.5mm & 0.75mm
ch size gauge refers to a specific material in which the clasp will be made fr
different materials can engage different depths of undercut
depending on their elastic modulus (flexibility)
A deeper undercut demands a more flexible clasp material in order
for it to engage & disengage effectively - without fracturing or causing
discomfort
Undercut Gauges

41. 0.25mm for cobalt-chrome (least flexible)
0.5mm for stainless steel
0.75mm for gold (most flexible)
all abutment teeth should be considered for retention when
designing your Co-Cr RPD - unless you are absolutely sure you
will not be looking to clasp a certain tooth i.e. too mobile, too
anterior etc.

42. when measuring & identifying the depth of an undercut you
must adjust the vertical arm of the surveyor down towards the
tooth with the gauge in place until the shank & the ‘head’ of
the gauge contact the tooth simultaneously

43. The point at which the head of the gauge contacts the tooth is
then point marked with a coloured pencil - identifying its exact
location.

44. the tooth is represented by the semi
circle, the horizontal line in the semi
circle depicts the maximum
bulbosity
red vertical line is the shank coming
down the tooth
below the most bulbous line is
undercut & illustrates different depths
as you go lower, the blue, green &
yellow lines are the heads of the
three gauges
Note the distance from the shank in
red to the tooth below the bulbosity
increases as you go lower down the
tooth hence the 0.25mm, 0.5mm &
0.75mm
0.25 co-cr
0.5 SS
0.75 gold

45. Wax trimmer
surveying tool
Wax Trimmer

46. Wax Trimmer
king out unwanted undercut, however we only want to block out what is necessa

47. Wax Trimmer
e in excess, the black line on the right shows the true extent of the undesir
This is where the trimming knife is used

48. rveyor, we can carefully remove the excess was creating parallel surface
of wax is necessary in order to have something to remove with the trimming
Wax Trimmer

49. after this process, the master cast can be duplicated
It is on this duplicated cast that the RPD can be manufactured

50. Diagram (a) the RPD cannot be inserted
because failure to eliminate undesirable
undercut on the cast resulted in acrylic
resin being processed into that area
Such procedure will eliminate the problem as shown below
Diagram (b) the denture has been
processed on a correctly blocked out
cast - as a result there is no interference
with insertion

51. urveying
In Practice

52. Prepare primary casts (study models)
Make sure model is trimmed correctly with the occlusal surface
parallel to the base of the model
1

53. Position the cast on the surveying table -
attach the analysing rod
2

54. 3
Move the cast table (up/down/left/right) with your left
hand whilst holding the movable arm with your right,
offering the analysing rod to the abutment teeth with the
aim to capture guide surfaces

55. A minimum of two will be required on opposite sides of the arch,
this is to establish the path of insertion
Bear in mind that guide surfaces are more aesthetically favourable
in an anterior region rather than posterior, we don’t want
anterior/visible gaps in the finished RPD if we can avoid it

56. The tilt
should not
exceed 10 -
15 degrees

57. 4
Once satisfied, lock the table in this position, swap the
analysing rod for the graphite marker.
the chamfer of the lead facing away from the
tooth, & the upper line being caught on the
shank of the marker
Begin to survey the model making sure the marker is
positioned correctly on teeth & soft tissue
REMEMBER !!! 2 Lines

59. mandible

60. 5
After surveying the model, swap the marker for an
undercut gauge - 0.25mm, 0.5mm or 0.75mm.

61. 6
Check & mark in colour the depth of undercut
required using the measuring gauge on all abutment
teeth, to see where the retention can be achieved

63. 7
Finally, because the cast has been tilted for a path of
insertion, this position must be recorded so that the
position can be reproduced in the laboratory
The way to do this is to place the analysing rod against one side
of the cast and draw a line alongside the rod on the cast -
repeat this on two other sides so that there are 3 widely
spaced lines parallel to the path of insertion

64. Tripoding

65. Completed surveyed models

66. After initial survey, a preliminary design for RPD including any
planned adjustment (i.e. rest seat preparation & guide surfaces)
can be made in consultation with your clinical supervisor
Once approved you can then proceed to make those adjustment
& take a secondary impression with special trays. From these
impressions, a master cast can then be poured