Surveying Procedures Flashcards
what is the function of the study model?
Analysis of mounted models in the articulator
Interim RPD production
Surveying (design the framework of the RPD)
Fabricate the custom tray
What is the aim of the surveying process?
Define the shape, form, and contours of the teeth and associated structures that will influence RPD design
Identify modifications of dental structures required to
optimize RPD design
Allows selection of Path of Insertion most compatible
with:
- Aesthetic requirements
- Guiding plane location
- Retention - location and depth of undercut
- Hard & soft tissues interferences
What are the steps of the surveying process?
- Preliminary visual assessment
- Determine the path of insertion
- Mark the height of contour of teeth (identifying the
retentive area) - Define the position of rest
- Identify the desired undercut
- Draw the outline of the framework
- Adjust the height of contour and create guiding
planes
What is observed during the preliminary visual assessment?
Kennedy classification
Fulcrum lines
Potential rest seat location
Indirect retention
Consider the relative parallelism of the proximal tooth surfaces
Consider problems relating to interference, contour, undercuts.
Decide potential rest seat locations - mark on study model.
How is the path of insertion chosen using the roach technique?
Three points are chosen: Marginal ridge of the molars and the tip of the icisors
How is the path of insertion chosen when there is no incisors?
Marginal ridge of the premolars and the marginal ridge of the molars
How is the path of insertion chosen when the molars are missing?
Create a reference using wax
How is height of contour found?
Using a carbon marker that is placed parallel to the path of insertion the undercuts are marked.
What is required for an infrabulge retainer?
3mm of attached gingivae from free gingival margin to the top of the undercut
How can soft tissue undercuts be avoided?
Change POI
Use a major connector design that avoids the bulky area
Pre-prosthetic surgery
What is the purpose of tripodization of the cast?
Procedure that allows the casts to be placed back on the survey table in the same orientation as when the original survey and design has been carried out.
How is tripodization in the horizontal plane done?
Vertical arm of the surveyor is locked and 3 different tissue points are selected and marked for future identification
How is tripodization in the vertical plane done?
Analyzing rod as a guide ruler
Create three parallel divergent markings on the dorsal and the two lateral sides of the cast.
These lines can then be used to reorientate the cast to the original plane
What is the aim of adjusting the height of contour?
All reciprocating arm is above the height of the contour and 1/3rd of retention arm is in the undercut
Why are guiding planes created?
The natural bulge of the tooth needs to be flattened by preparation
Single POI is provided
Limits instability of the RPD
Reduced food impaction
