Dental Surveyor

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INTRODUCTION

- A partial denture will not succeed unless it is designed and constructed in

harmony with all the physiologic and mechanical problems present in the

patients mouth.

- The surveying procedure is an integral part of planning process which helpsthe dentist to determine which teeth most desirable as abutment for placing the

rest seats for maximum support and distribute stresses without excessive

clasping and tooth coverage.

- The procedure of surveying requires enormous amount of learning, but time

spent in study is worth, the reward of success that will follow.

DEFINITION

The surveyor is a paralleling instrument used in construction of a prosthesis to locate

and delineate the contours and relative positions of abutment teeth and associatedstructures. It is an instrument used to determine the relative parallelism of two or

more surface of teeth or other parts of a cast of a dental arch. The idea of the dental

surveyor was introduced in !" and the first surveyor developed specifically for use

in prosthodontics was made commercially available in !#$.

PARTS OF AN SURVEYOR. %ori&ontal arm

#. 'ertical arm

$. (urveying arm

). (urveying table

*. +ast holder . (urveying tools

Surveying plate form

It is metal plate parallel to the floor where a cast holder can be placed


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Surveying tale

It is stand placed over the surveying plate form

The stand has place and table to place a cast

The cast can be loced in any position on the table with help of a locing

device The table is attached to the base with help of ball and socet facilitate the tilt

the table oint

Verti!al arm

Arises vertically from

the surveying plate form

/ae a support for

hori&ontal and surveying arm


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"ori#ontal arm

0xtend hori&ontally from the top

of vertical arm

(upport the surveying arm at

it is free end

Surveying arm

It extends vertically from the free end of the hori&ontal arm it is parallel to the

vertical arm

the lower end of this arm has a mandrel into which tools used for surveyingcan be loced in

Analy#ing ro$

It is solid cylinder metal rod

It is a first tool to be used during surveying It is used to determine the parallelism of tooth surface


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Act as lie tangent to the convex surface of obect being surveyed

It help to analy&e the location of height of contours

!aron mar%er&

It is used for draw surveying line which determined the height of contour ofthe teeth

un$er!ut guage& undercut gauge are used to measure the depth and


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the location of the undercuts on the analy&ed tooth in

three dimensions

(tewart states the availability of undercut gauges in three standard si&e

namely 1.11inch , 1.1* inch and 1.1#1 inch

/c +racen states the availability of undercut gauge at

1.11 , 1.1#1 and 1.1$1

'a( trimmer)%nife*

2sed to directly trim the excess wax while surveying the wax patterns

0liminate and bloc out undercut parallel to path of insertion


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Type& of &urveyor

3ney surveyor

#34eleno surveyor


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$3williams surveyor

Purpo&e& of &urveyor

+&urveying of t,e $iagno&ti! !a&t

3 To determine the most desirable path of placement that will eliminate or minimi&e

interfernece to placement and removal.

5ath of placement is the direction in which a resoration moves from the point of initial

contact of its rigid parts with the supporting teeth to its terminal resting position.

5ath of removal is the direction of resoration movement from its terminal resting

position to the last contact of its rigid parts with the supporting teeth.

#3 to identify proximal tooth surfaces that are or need to be made parallel so they act

as guiding planes during placement and removal.

$3 to locate and measure areas of teeth that may be used for retention.

)3to determine whether teeth and bony areas of interferences will need to be

eliminated surgically or by selcetion of a different path of placement.


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*3to determine the most suitable path of placement that will permit locating retainers

and artificial teeth to provide the best esthetic advantage.

3to permit accurate charting of the mouth preparations to be made.This includes the

preparation of the proximal tooth surfaces to provide guiding planes and the reduction

of excessive tooth contours to eliminate interferences and to permit a more acceptablelocation of reciprocal and retentive clasp arms.

63to delineate the height of contour on abutment teeth and to locate areas of

undesirable tooth undercut that are to be avoided eliminated or bloced out.

"3to record the cast position in relation to the selected path of plav7cement for future

reference. This may be done by locating three dots or parallel lines on the cast thus

establishing the hori&ontal plane in relation to the vertical arm of the surveyor.

+!ontouring t,e -a( pattern

3The surveyor blade is used as a wax carver during this phase of mouth preparation

so that the proposed path of placement may be maintained throughout the preparation

of cast restorations for abutment teeth.

+&urveying t,e !erami! veneer !ro-n&

3ceramic veneer crown are often used to restore abutment teeth on which

extracoronal direct retainers will be placed

#38efore the final gla&e is accomplised the abutment crowns should be returned to the

surveyor on a full arch cast to ensure the correct contour of the veneered portions or to

loctae those area that need recontouring.

$3the final gla&e is accomplised only after the crowns have been recontoured.

+ma!,ining !a&t re&toaration&

3with a handpiece holder attached the axial cast and ceramic restorations may be

machining with a suitable cyclindrical carborundam point.

#3 proximal surfaces of crowns and inlays which will serve as guide plane 7s and

vertical surfaces above the crown ledges may be improve by machining.

+&urveying t,e ma&ter !a&t

3 to select the most suitable path of placement by following mouth preparations that

satisfy the requirements of guiding planes ,retention , non interference and esthetics.

#5ermit measurement of retentive areas and to identify the location of clasp terminals

in proportion to the flexibility of the clasp arm being used.


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$3 9ocate undesirable undercut areas which must be eliminated by blocout.

)3To trim blocout material parallel to the path of placement before duplication.

Fa!tor& t,at $etermine pat, of pla!ement an$

removal.+Retentive un$er!ut&+Interferen!e&

+E&t,eti!&

+/ui$ing plane&

Retentive Un$er!ut&

The first, unchangeable rule to remember when surveying diagnostic casts for

removable partial dentures is that retentive undercuts must be present on the abutment

teeth at the hori&ontal tilt.

- The surveying procedure is always started with the cast to be analy&ed

positioned in the cast holder so that the occlusal surface of the remaining teeth

are parallel to the surveying table or base of the surveyor.

- The occlusal surface of the teeth must be viewed first in the hori&ontal plane

because dislodging forces applied to the partial denture are alwaysperpendicular to the occlusal plane. :esistance to this dislodging force must be

present when the cast is at a hori&ontal position.

- If retentive undercuts are not present, they must be created.

- 0namel surfaces may be contoured in limited circumstances to produce or

improve retentive undercuts, but this procedure should not be embraced in

favor of other potentially less dangerous approaches. +areful analysis of the

teeth on the diagnostic cast will usually reveal whether an undercut can be

prepared without penetrating the enamel surface.

- Ideally, proposed abutment teeth should have 1.11 inch of undercut at the

most desired location, either the distobuccal or mesiobuccal line angle and inthe gingival third of the clinical crown of the tooth.


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- ;nce retentive undercuts have been found at the hori&ontal tilt, the tilt may be

changed to alter the amount of undercut on any given tooth. It must be ept in

mind that changing the tilt to alter the amount of undercut on one tooth will

affect the undercuts on the remaining teeth. The tilt is normally changed to

lower the height of contour on an abutment tooth so that a clasp either

retentive or reciprocal can be positioned no more occlusal than the unction of

the gingival and /iddle third of the tooth. This position not only produces

amore esthetic result but also improves the mechanical advantage by lowering

the torquing or rotational forces the clasp transmits to the tooth the lowering of

the in effect shortens the length of the lever arm acting on the tooth thus

reducing instead of magnifying the applied force.


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INTERFERENCE

+ertain areas of the mouth-the teeth, soft tissue undercuts, and bony exostoses

frequently interfere with the insertion of the partial denture. These areas have to be

eliminated by altering the tilt of the cast on the surveying table or by surgery.

INTERFERENCES IN 0ANDI12E

- ;ne of the greatest errors in treatment planning is attempting to position the

maor connector to avoid a lingual torus, especially if a lingual bar is planned

as the maor connector

- This thicness of the lingual bar may also be compromised, resulting in a non

rigid maor connector that is damaging to the remaining teeth. (urgery must be

seriously considered in case of lingual tori.

- The remaining teeth in the mandible are frequently lingually inclined. These

unsupported or partially supported remaining premolar and molar teeth tend to

drift in a mesio-lingual direction.

- 5lan a labial bar maor connector in place of the lingual one.

- Another area of the mandible that frequently causes interference to the path of

insertion is the area lingual to the pear shaped pad. A lateral tilt of the cast on

the surveying table may help to eliminate some if not all, of a unilateral

undercut in this area.

INTERFERENCES IN 0A3I22A

- ;ne of the maor sources of interference in the maxilla is a torus palatines.

The torus interferes with the placement of the maor connector.

- +hanging the tilt of the cast on the surveying table will not give the needed

relief.


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- 8ony exostoses or undercuts buccal to the posterior edentulous ridge are

encountered frequently. Their surgical removal is not a complicated procedure

and should be done to provide better support for the denture base.

- If there buccally inclined teeth are located on one side of the arch only, tilting

the surveying table away from the teeth may lower the height of contour

sufficiently to permit the clasps to be located in a nearly ideal position.

- If these inclined teeth are located on both sides of the arch, changing the tilt of

the cast will have no helpful effect. If the tipping is not too severe, contouring

the enamel surfaces to lower the survey line may be attempted.


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EST"ETICSTo obtain optimum esthetics.

. The metal, usually in the form of clasp arms must be concealed as much as

possible without compromising the necessary support and stability of the

prosthesis and

#. The artificial anterior teeth must be placed in the most natural position

possible.

- To satisfy the first requirements of avoiding unnecessary display of metal, the

tilt of the survey table should be such the survey lines on teeth that will be

visible be as close to the gingival margin as is compatible with maintaining

periodontal health.

- The ideal clasp position for retentive clasps is in the gingival third of the

clinical crown.

-


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- The surveyor is used to locate existing or potential surface of teeth that can be

converted to guiding planes by selective grinding. These planes are always

developed parallel to the path of insertion.

CONC2USION

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Dental Surveyor