Principles of Surveying Flashcards
What is a dental surveyor?
Paralleling Instrument used in RPD fabrication
What are the components of the dental surveyor?
- Cast Holder
- Surveying Stand
- Vertical Support Post
- Horizontal Arm
- Analyzing Arm
- Mandrel for Surveying Tools
- Cast Holder (A)
- Surveying Stand (B)
- Vertical Support Post (C)
- Horizontal Arm (D)
- Analyzing Arm (E)
- Mandrel for Surveying Tools (F)
What are the different surveyor tools/styli?
A: Analyzing Rod
B: Carbon Marker
C: Carbon Sheath
D: Undercut Gauges
* 0.010”
* 0.020”
* 0.030”
What are three ways to “fix” a tooth with an undercut?
- enameloplasty
- composite
- surveyor crown
What is the function of a dental surveyor?
- Survey diagnostic cast
- Contour wax patterns
- Contour ceramic & cast restorations
- Place attachments requiring parallelism
- Survey master cast
What are the objectives of surveying diagnostic cast?
- Determine the most acceptable path of insertion
- Identify proximal tooth surfaces that can function as guiding planes
- Locate & measure areas of teeth that may be used for retention
- Determine if soft or bony areas of interference (undercuts) exist
- Determine most suitable path of insertion to satisfy esthetics
- Delineate height of contour on abutment teeth
- Record cast position to selected path of insertion
How is the path of insertion determined during survey procedure?
Guiding Planes, Retentive Undercut, Interferences, Esthetics
What is the path of insertion?
The direction in which the RPD is inserted & removed from the abutment teeth.
What are guiding planes?
Parallel, flattened surfaces at proximal or axial surfaces of teeth
What is the purpose of guiding planes?
Increase RPD stability & retention
What is good about having a greater number of GPs?
Path of insertion more specific
How do you find the guiding planes?
Identified by tilting cast in anterior-posterior direction until maximum parallelism of proximal surfaces
What is the analyzing rod used for?
to identify potential surfaces that can be converted to guiding planes by selective grinding in occlusal 1/3-1/2
RPD mechanical retention provided by clasp that engages __________ ________
retentive undercut
What does the retentive undercut do?
Resist RPD dislodging forces
Clasp needs to be more than ______ away from the gingiva
1 mm
Undercut area lies between survey line and _________ margin
gingival margin
What is the height of contour/survey line?
Line encircling a tooth that designates its greatest diameter at a selected position determined by a dental surveyor
What is the suprabulge area?
Portion of tooth above the height of contour
What is the infrabulge area?
Portion of tooth below the height of contour in relation to path of insertion
Where are the usual areas of retentive undercut?
- Mesiofacial, Mid-facial, Distofacial
- Mesiolingual, Distolingual (less preferred)
What is a false undercut?
- Illusion of undercut due to excessive cast tilt
- Will not exist clinically
- Awkward path of insertion
- Patient unable to place RPD
What are typical interference areas when surveying for RPD?
- Lingually-inclined mandibular teeth
- Buccally-inclined maxillary teeth
- Bony buccal exotoses, tori
- Height of contour too high, clasp placement too high
- Tissue undercut area of bar clasp
How do you locate/eliminate interferences when surveying for RPD?
- Alter tilt of cast/Change path of insertion
- Maintain cast tilt, eliminate by surgery or recontouring of teeth
How can you change teh esthetics of an RPD?
- Alter mediolateral cast tilt
- Recontour proximal surfaces to restore lost dimension if inadequate space for natural tooth width
How do you mark the height of contour/survey line?
Side of carbon marker indicates survey line of abutment teeth at chosen path of insertion
All components of RPD, except terminal 1/3 of retentive clasp should be _______ survey line
above
Ideally, survey line located at junction of…
middle & gingival 1/3
Retentive terminal 1/3 in what area of tooth?
gingival 1/3
Proximal 2/3 of retentive clasp & Reciprocal clasp in what area of tooth?
middle 1/3, above survey line
If survey line is too near occlusal surface (clasp too high on the tooth) what can happen?
- May interfere with occlusion
- Increased leverage on tooth
- Tooth recontoured to lower survey line
If survey line is too low (no undercut exists) what can happen?
- Survey line at or near gingival margin
- No undercut exists for clasp retention
- Cannot use enamoplasty to change
- Requires surveyed crown
What are options if there is inadequate retentive undercut?
– Enamoplasty to create undercut = “Dimple”
–Addition of composite at site to create undercut
–Surveyed crown
Why do you need to tripod your cast?
- Record tilt of cast at chosen path of insertion
- Clinician or Lab technician can re-establish path of insertion
What are the two methods for tripoding the cast?
- Method 1
- Adjust height of vertical arm: marker touches 3 widely separate tissue surface areas (in one plane)
- Circle each tripod mark
- Method 2 (UMKC method)
- Draw vertical lines parallel to analyzing rod on 3 sides of cast (Lines widely separated)
What does blue, red, and black mean on RPD design?
- Blue:
- Metal framework outline
- Wrought wire clasp
- Red:
- Indicate retentive undercut
- Indicate tooth modification areas
- Guiding planes, Survey line reposition, Rest seat areas
- Black:
-Survey line, tripod marks and soft tissue
undercuts
What mouth preparation is needed for RPDs?
- Perform indicated tooth modifications according to RPD diagnostic cast design
- guiding planes, Survey line reposition, Rests
What do you need to do after mouth preparation for a RPD?
Impression for master cast after mouth preparation
What is the general overview for RPD survey and design?
- Survey Diagnostic Cast
* Path of Insertion Determined (Four Factors)
* Mark Survey Line
* Mark Retentive Undercut
* Tripod Cast - RPD Design/Tooth Modifications
* Draw on Diagnostic Cast - Mouth Preparation: Tooth Modifications
- Master Cast
* Resurvey: guiding planes, Survey line, Retentive undercut, Tripod
* Framework made
