Surveying

* A dental surveyor has been defined as an instrument used to determine the relative parallelism of two or more surfaces of the teeth or other parts of the cast of a dental arch.

* Prof. Dr. S.Venugopal.

Ney Surveyor Jelenko Surveyor
Dental Surveyor

Parts of a Dental Surveyor

PARTS OF A SURVEYOR
Surveying Table

PARTS OF A SURVEYOR

Surveying Arm

* Surveying Tools

3- Undercut Gauge
1- Analyzing Rod
4- Wax Trimmer
2- Carbon Marker

* Analyzing Rod

Surveying Tools
Analyzing rod : a thin straight metal rod used to analyze contours and undercuts . this is the principal tool used in surveying . the side of analyzing rod is brought into contact with surfaces of the proposed abutment teeth to analyze their axial inclination. this rod is easily bent and once bent is difficult to straighten. use it carefully.

* Carbon Marker

Carbon Markers
Carbon marker : rods similar to pencil leads which can be used to mark the location of the height of contour on a dental cast. some surveyors use a protective sheath to prevent or reduce breakage of the carbon markers.

* Undercut Gauges

0.01 0.02 0.03
Undercut Gauge Metal rods with terminal ledges of various widths (the most commonly used are 0.01 inch and 0.02 inch).undercut dimensions can be measured on teeth by bringing the vertical shaft of the gauge in contact with a tooth and then moving the surveying arm up or down until there is contact with the terminal ledge.



UNDERCUT GAUGES

* Undercut Gauge

* Wax Trimmer

Wax Trimmer

Wax trimmer : a tool with straight sharp edge,which parallels the surveying arm.it is used to contour waxed crowns for partial denture abutments,or to place blockout for a partial denture framework.

Prof. Dr. S.Venugopal.

The Prosthesis Goes Smoothly Into Place Without Interference After Analyzing the Proximal Tooth Surfaces and Making the Necessary Alteration
Principles of Surveying

The location of the undercut area can be changed by tilting the cast anteriorly or lateral

Principles of Surveying



Purposes(uses) of surveyor the surveyor may be used for 1.surveying the diagnostic cast, 2.recontouring abutment teeth on the diagnostic cast,3.contouring wax pattern,4. measuring a specific depth of undercut, 5.surveying a ceramic veneer crowns,6. placing intracoronal retainer, 7.placing internal rests, 8.machining cast restorations,9. surveying and blocking out the master cast.


Surveying the diagnostic cast The objectives are as follows: 1- to determine the most desirable path of placement that will eliminate or minimize interference to placement and removal. 2- to identify proximal tooth surfaces that are or need to be made parallel so that act as guiding planes during placement and removal. 3- to locate and measure areas of teeth that may be used for retention. 4- to determine whether tooth and bony areas of interference will need to be eliminated surgically or by selecting a different path of placement.

5- to determine the most suitable path of placement that will permit locating retainers and artificial teeth to the best esthetic advantage. 6- to permit an accurate charting of the mouth preparation to be made. 7- to delineate the height of contour on abutment teeth and to locate areas of undesirable tooth undercut that are to be avoided eliminated or blocked out. 8- to record the cast position in relation to selected path of placement for future references(Tripoding).

Some Important Terms

Height of contour path of placement and Path of removal undercuts

Height of contour

Undercut =Infrabulge

Suprabulge

HEIGHT OF CONTOUR
Survey line :a line encircling a tooth, designating its greatest circumference at a selected position determined by a dental surveyor.

path of placement is the direction in which a restoration moves from the point of initial contact of its rigid parts with the supporting teeth to its terminal resting position with rests seated and the denture base in contact with the tissue. Path of removal is exactly the reverse



ADVANTAGES OF A SINGLE PATH OF INSERTION
1- Equalizes retention 2-Bracing and Cross-arch stabilization 3- minimizes torque on abutments

4- Allows removal without encountering interferences 5- Directs forces along long axes of teeth
6- provide frictional retention


Non-undercut area Any areas occlusal to survey line used for placement of non- retentive, stabilizing, or reciprocating elements
undercut area Any areas cervical to survey line used for placement of retentive clasp components

RULE: RETENTIVE TIP SHOULD USUALLY BE DESIGNED TO BE PLACED IN THE GINGIVAL 1/3

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

1-Desirable Undercuts : used for retention

2-Undesirable Undercut
Types of undercuts

* PROCEDURES of SURVEYING

Three Tripod Tripoding, and all in the same horizontal plane.


Tripoding the diagnostic cast so that the selected path of insertion may be easily found for future reference.

1.Guiding Planes 2.Retentive Areas 3.Interference 4.Esthetics

GUIDING PLANES
Two or more vertically parallel flat surfaces of abutment teeth shaped to direct a prosthesis during placement and removal where rigid components contact abutments *

PREPARATİON OF GUIDING PLANES Long Cylindrical Carbide or Diamond bur

2.RETENTIVE AREAS
Retentive areas must exist for a given path of placement and must be contacted by retentive clasp arms, which are forced to flex over a convex surface during placement and removal. Retention should be sufficient only to resist reasonable dislodging forces. In other words, it should be the minimum acceptable for adequate retention against reasonable dislodging forces.

RETENTIVE AREAS

Retentive arm should have a different path of escapement than guiding plane (path of removal), so retentive arm must be forced to flex over a convex surface during placement and removal (retention)
For a clasp to be retentive, its path of escapement must be other than parallel to the path of removal of the denture itself.

3.INTERFERENCE

The prosthesis must be designed so that it may be placed and removed without encountering tooth or soft tissue interference. a path of insertion that involves interferences should only be selected if the interferences can be eliminated by tooth preparation or reasonable blockout of the master cast.. If the interferences cannot be eliminated or minimized, then a different path of insertion must be considered.


By One path of placement the most esthetic location of artificial teeth is made possible, and less clasp metal and base material may be displayed. Generally, less metal will be displayed if the retentive clasp is placed at a more distogingival area of tooth surface made possible either by the path of placement selected or by the contour of the restorations

ESTHETIC

Thank You!