Surveyor, Surveying and Milling

Dr. Kyaw Tint UDMY

Surveyor

• 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

• dental surveyor is vitally important to the planning, execution, and verification of appropriate mouth modifications for a removable partial denture and restoration

• 1918, it was first introduced• Also known as parallelometer• The surveyor allows a vertical arm to be

brought into contact with the teeth and ridges of the dental cast, thus identifying parallel surfaces and points of maximum contour

• It is the clinician’s responsibility to survey the study cast and then use the information obtained to design the partial denture

Type of Surveyor•Mechanical•Micro-analyser•Electronic

The parts of a surveyor1. Platform on which the base is moved2. Vertical arm that supports the superstructure3. Horizontal arm from which the surveying tool suspends4. Table to which the cast is attached5. Base on which the table swivels6. Paralleling tool or guideline marker 7. Mandrel for holding special tools

The Ney Surveyor

Platform

Vertical arm

Horizontal arm

Table

Base

Paralleling tool

Mandrel

The Jelenko Surveyor

The right hand is braced on the horizontal arm

of the surveyor, and the fingers are used, as illustrated, to raise

and lower the vertical shaft in its spindle.

The left hand holding the cast on the adjustable table slides horizontally

on the platformin relation to the vertical arm.

The right hand must be used to loosen and tighten the tilting mechanism as a suitable anteroposterior and lateral tilt of the cast in relation to the surveyor is being determined

SurveyingObjectives

1. To determine the most desirable path of placement that will eliminate or minimize interference to placement and removal2. To identify proximal tooth surfaces that are or need to be made parallel, so they act as guiding planes during placement and removal3. To locate and measure areas of the teeth that may be used for retention4. To determine whether teeth and bony areas of interference will need to be eliminated surgically or by selection of a different path of placement.

1.Various path of insertion

2.Prepare guide surface ( Guiding Plane)

3.Area of RETENTION

4.Failure to eliminate unwanted undercut (interference)

Objectives Of Surveying5. To determine the most suitable path of placement that will permit locating retainers and artificial teeth to provide the best esthetic advantage.6. To permit accurate charting of the mouth preparations to be made7. 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 out8.To record the cast position in relation to the selected path of placement for future reference

5. The Best Esthetic

6. Diagnostic casts can serve as a visual guide for tooth preparation

7. Block out to Undesirable tooth undercut

8.Recording Relation of Cast to Surveyor

Factors that Determine Path ofPlacement and Removal of Prosthesis

2.Guiding Planes3.Retentive Areas4.Interference5.Esthetics

Guiding Planes

• Thus the denture can be easily placed and removed by the patient without strain on the teeth contacted or on the denture itself and without damage to the underlying soft tissues

• Guiding planes are also necessary to ensure predictable clasp assembly function, including retention and stabilization

Retentive Area

• Retentive areas must exist for a given path of placement and must be contacted by retentive clasp arms that are forced to flex over a convex surface during placement and removal

• Satisfactory clasp retention is no more than the resistance of metal to deformation (within own flexibility)

• however, positive cross-arch reciprocation to retentive elements must be present

Interference• The prosthesis must be designed so that it may

be placed and removed without encountering tooth or soft tissue interference

• Interference may be eliminated during mouth preparations by surgery, extraction, modification of interfering tooth surfaces, or alteration of tooth contours with restorations

Esthetic• 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

• Esthetics also may dictate the choice of path selected when missing anterior teeth must be replaced with the partial denture

• Because the primary consideration should be the preservation of remaining oral tissues, esthetics should not be allowed to jeopardize the success of the partial denture

Step-By-Step Procedures in Surveying

• Guiding Planes• Retentive Areas• Interference• Esthetics

• On Diagnostic, Master, Refractory Casts…

Guiding Plane (step by step)

Relative parallelism of proximal tooth surfaceswill determine anteroposterior tilt of the cast in relation to the vertical arm of the surveyor

When a choice is made between having contact with aproximal surface at the cervical area only or contact at the marginal ridge only, the latter is preferred because a plane may then be established by recontouring

Retentive area

• Undercut area is best accomplished by directing a small source of light .The angle of cervical convergence is best observed as a triangle of light between the surveyor blade and the apical portion of the tooth surface

• Alter the cast position by tilting it laterally until similar retentive areas exist on the principal abutment teeth

• When the cast is tilted laterally to establish reasonable uniformity of retention, it is necessary that the table be rotated about an imaginary longitudinal axis without disturbing the antero-posterior tilt previously established

Undercut & retentive area

DesirableUn-Desirable

Measuring undercut with undercut gauge

Blocking Out Undercut for un-desirable

Interference

• If a mandibular cast is being surveyed, check the lingual surfaces that will be crossed by a lingual bar major connector during placement and removal

• Bony prominences and lingually inclined premolar teeth are the most common causes of interference to a lingual bar connector

• If the interference is bilateral, surgery or recontouring of lingual tooth surfaces, or both, may be unavoidable.

• If the interference is only unilateral, a change in the lateral tilt may avoid an area of tooth or tissue interference

Esthetic

• In some instances, gingivally placed bar clasp arms may be used to advantage; in others, circumferential clasp arms located cervically may be used

• In still other instances, a tapered wrought-wire retentive clasp arm may be placed to better esthetic advantage than a cast clasp arm.

After that

• Mouth Preparation• Individual tray fabrication• 2nd Impression• Making master cast• Surveying again on Master Cast

Surveying again in Master Cast

Relieving master cast

All efforts copy on Refractory Cast

Surveyor with Milling Machine

- It roots for CAD/CAM- One direction + Visual aid-2,3,4,5 direction+ Computer-Essential for all restorations which needs part of insertion and contact point.. e.g.. glaze is produced only after necessary re-contouring is accomplished

Tooth Contact Points & Embrasure

3rd, 4th, 5th

Surveyor and Milling Machine in Dental Implant Treatment & Lab

Single tooth with Angulation Problems(Examples)

Attach relevant hexed UCLA abutment to the analogue on the model,

Trim the plastic pipe so that the post will fall in line with the arch of the existing teeth

• Super-M60• Today topic is milling machine for dental laboratory. This milling machine is one of the products from Dae Young

Precision Company. I would like to explain how to use this machine. First, you see this is milling arm attached to the tool and, this lower one is table. Milling arm, which is connected with the cable to the motor inside. Now we are looking the model cast on the table of the milling machine.………………………………………………………

• Now we see is 2 implant abutments with different degree inclination. We are going to define the path of insertion of the prosthesis by using the milling machine. We have to make same path of insertion for two different inclined abutments.

• Abutments milling for path of insertion• It is checking the path of insertion by tilting the model attached table. If we make constant the front implant,

please check how much we have to cut the second one for path of insertion ... and compare. It is too much to cut … and again if we make constant to second one, we have to cut much on first implant. So we decide to cut little millimeters on each abutment. You can see it is better for each abutment.

• Now going to make most appropriate and correct path of insertion by cutting both abutments by using the straight burs.……………………………………………………. Preparation …………………………..

• After confirmation by straight bur, we are going to use 2 degree tapering bur for tapering of the abutments.• …………………………………………………… Preparation ………………………………………………………………• After cutting by milling, we make the wax jig and check to sure the pathway of insertion. This looks like to be

right milling procedure and correct path of insertion although abutments have different inclination.

• Super-S2• This is the surveyor of our company. You can see this two arms surveyor and this rod attached

with thermostat stick. This is surveying table and now you see the set of tool.……………………………………………………………

• These are undercut gauge. First one is 0.25 mm undercut, second is 0.5 mm and third one is 0.75 mm.

• These are tapering burs. First one is 2 degree taper, second is 4 and last one is 6 degree tapering.

• This is the straight bur and carbon rod (pencil) for marking the survey line.• ……………………………………………………………………………………………………………………• First we are going to fix the model on the surveying table. By adjusting this screw, we can

place the model and by unlocking this tab, we can tilt the surveying table. • Fix a denture model on table

…………………………………………………………………………………………………………………• Then we fix the model and be careful not to move.• By using this tab, it can raise and tilt the table.• Undercut analysis

……………………………………………………………………………………………………………………• We analyze undercut for installation of removable partial denture. There are undercut areas

in 3 abutment teeth. The surveyor helps as a tool which let the RPD into correct path of insertion.

• Model gauges path of insertion • We guess and thinking the average amount of undercut areas on each abutments and path of insertion.

First abutment, … second .. and last one ……• ………………………………………………… Carbon marking • By using the carbon marking rod, we draw the survey line on the three abutments of the model. Below

this survey line is the undercut area. • ………………………………………. Cover with wax …………• Then fill the undercut areas with the wax so as to block this area during the RPD processing. • ………………………………. Remove extra wax with heating tool ……………..• Then we use straight heating tool to remove excess wax. ……………………..• ………………………… And remove from table and make fine touch……• These are undercut areas and become the guiding plates on the RPD framework. So RPD insertion has no

disturbance and correct path of insertion.• ……………………………………………………… Undercut gauges ……………………….• Then I would like to show how to use the undercut gauges after surveying. This is the 0.75 mm undercut

area at this point and then it move upward direction. Here we change the 0.25 mm gauge as it is lesser to tooth contact…

• Credit to Dr. Aung Thu Hein for translation from Korea to English

Credit to Dr. Kyaw Htwe

Milling Machine found in UDMY

Happy at the same time sorrowful

When you deliver a prosthesis

If you consider survey line , undercut and

contact point

I will be very happy

Great Thanks for

your time and attention