Dental surveying

Dental surveyor :- a parallel instrument used in the fabrication of a removable partial denture

what do we mean by

Retention :- ability to resist vertical dislodgment .

Support :- Support is the principle that describes how well the underlying mucosa (oral tissues, including gums and the vestibules) keeps the denture from moving vertically towards the arch

Stability :-the resistance of a denture to movement on it’s tissue foundation on lateral force

Biocompatible :- it will live with the body without causing harm to it

where do I need to do surveying ?

We do it in primary cast step , and secondary cast step mainly and I use it for cr-co RPD

primary cast - I need t determine the area which are parallel to the path of insertion - try to find an area for retention “to make a clasp” - draw our initial design - try to identify which teeth are need preparation inside the patient mouth { i.e a tooth

does not have an under cut one of the alteration that we might do is ENAMEL DIMPLE }

ENAMEL DIMPLE : a small depression on enamel so the clasp goes there when we don’t have a good undercut

Secondary cast - Draw the final design - Countering the block out material which made of wax

Other uses of the surveyor

other use of surveyor

the technician may be using them to countering wax pattern of ceramic crowns for example I want the crown from the beginning “ when it still wax” to have a guide plane so before fabricating that crown the technician make sure that the proximal side is flat in the same characteristic that it should planted inside the mouth

may be I may put an area for reciprocation I may put an internal attachment , or internal rest ,or an external attachment

how do I know that any one of these component are parallel to the other component of the RPD?

We have to use surveyor

So the surveyor is used for RPD but it may be used for other restoration that might be used for RPD production

Internal rest is a tunnel in which the partial denture will go in and out

What does an internal rest do for retention ?

It’s provide retention by friction “ the part which goes in and out it will enter in tight path so it aid in retention

It help in support because it direct the force into the long access of the tooth

It helps in stability because it prevent the RPD from moving laterally

In esthetic … it help us cause we don’t need to clasp so it’s more esthetic to the patient

In external attachment is something else we need to attach it to another teeth

Some the technician has finish all ceramic and he wants to cut it back “it’s not in the wax stage , it’s in the final completed crown stage “ so once again we use the surveyor to make sure that the cut is parallel to the path of insertion he had decided .

surveyor in implantlogy

When I make the implant in the bone later on over it I will add another competent so I want the external component to go in and out smoothly , so issue the surveyor making sure that each implant is parallel to the other

So what do they do aid the surgeon ,,, they place the acryl and make a holes on it <it called surgical guide >and make sure that each implant is parallel to the other , so we use the surveyor to design the holes before doing surgery

Some time we use survivor in complete denture when we have undercuts

For acrylic RPD do we need surveying?

Yes , to find appropriate under cut to place my stainless steal wire in an under cut , this is the main use other uses are followed

Not all the point in the undercut are suitable for utilization

Different type of survivors but the all share the same basic component

There are some other small pieces like the screws in the slide below

Those instrument are basicly to hold another tools which are

Parallel tools : analyzing rod Graphite\ carbon marker Undercut gauges Wax trimmers

Some time we add to it the hand piece and we can use 2 degree or 6 degree taper tool

So we need to do surveying to do a perfect partial denture

The patent when he put his denture he put it to eat to talk , to go around in a good appearance and at night he should remove it to clean it , sleep without it to let the tissue recover so these are the normal event ,,, put the denture and take it out .. but the un usually even will be if the patient ate a stick food “toffee” for example the denture will go out we don’t need that

So we need to differentiate between what is called path of insertion ,,,and the un usual event when the patient eat sticky food ,,, we don’t want the denture to go out when he’s chewing the food we want it to go out when only he decided to take it out “e.g at nigh to sleep”

So the path of insertion it’s the direction of movement , you put your RPD in the patient mouth until the initial contact with the tissue it depend on rest , and denture base

Path of insertion is opposite than path of removal “ opposite”

Path of displacement(POD) is different it’s not parallel to the path of removal it’s in any direction ,, usually when sticky food is there it’s perpendicular to the occlusal table so it’s call PARALLEL DISPLACMENT

When do we have the pass of removal and the pass of displacement the same if the table that we do surveying on it is on level zero

So this is an RPD that could go in and out other direction than the path of insertion I will call it path of displacement but when I but the table that I do surveying at zero tilt it will go in and out only in one direction

The dr played some videos about surveying from YouTube … to watch it just type dental surviong

How do we do a surveying line ?!

First of all before drawing any surveying line I might use the analyzing rod to identify the areas of undercut we need to make sure that the undercut in the both side are almost equal so triangle must be equals if they are not we tilt the cast slightly .

- The we draw a line using a graphite marker “ the graphite marker has a sheet on it to break it from breaking “ and we start rotating to draw a line so we can have a true undercut area so we can place a clasp on it

When we draw a line the graphite marker should touch the margin of the gingival

After that I began gauging the undercut :- from all the area below the line a need to select exactly the area where the undercut is present

The gauge has an horizontal arm which goes .02 inch horizontally

We want to make sure that the vertical part and the horizontal part “ of the gauge “ are touching in the same time

What if the surveyor line is high “ i.e the tooth is to much tilted so the maximum bulge of the tooth is high very much close to the occlusal table “

So if I end my clasp just below the surveyor line I may traumatize the tooth , the best for a retentive arm to be is in the middle just between the middle and gingival third

Some time I don’t have an under cut what is the solution ..

I could reverse may issue and put my retentive arm on the lingual side “if there is a lingual undercut”

Or I can take an under cut from an adjacent tooth using extending clasp

Or I can use a double clasp to obtain the retention from the other side

If I don’t want to change my design I could prepare an enamel dimple “ a small space in enamel just to end my clasp in it “

Not only the denture should go in and out … there shouldn’t be any interferences

DONE by : - mohammad F. elwir