Surveyor and technique of Surveying in Removable partial denture

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SURVEYING IN REMOVABLE PARTIAL

DENTURES Dr Farah Ahmed

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SURVEY

• To examine as to condition,value or situation , to appraise.

• To determine the form and position of a given entity by taking linear and angular measurements



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SURVEYING

An analysis and comparison of the prominence

of intraoral contours associated with the fabrication of a dental prosthesis.



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SURVEYOR

A surveyor is essentially a parallelometer, an

instrument used to determine the relative parallelism of surfaces of teeth or other areas on a cast of the jaws.

(Stewart)



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A paralleling instrument used in the construction of a dental prosthesis to locate and delineate the contours and relative positions of abutment teeth and associated structures.

-(GPT-8)



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“Intelligent use of a dental surveyor is the best

way to prevent the occurrence of countless problems frequently related to oral rehabilitation with RPDs”

-Dr O C Applegate



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The History and Development of the Dental Surveyor (Robert L Engelmier)-JOP vol 11(march) 2002

“Reduced to its simplest terms , surveying a tooth is a mechanical method of obtaining its height of contour accurately. If a vertical plane is brought into contact with a curved surface it will touch at the greatest bulge on the convexity and nowhere else.”

–Dr A H Schmidt (1953)



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Manual Surveying

• Visual survey• Eyeballing• Dr W M Randall’s

technique for surveying.(1890)



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Early Paralleling instruments

THE CHAYES PARALLELOMETER (circa 1920)



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THE CHAYES PARALLELOMETER SYSTEM



11Paralleling device used as a jig for the Grisworld Attachment System



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The First Dental Surveyor

• Dr Rudolph Hanau (1917)• Dr A J Fortunati (1918)• Dr Edward Kennedy• The Philadelphia Dental Clinic club• Noble G Wills• Weinstein and Roth(1923)



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THE ROBINSON SURVEYOR (circa 1918)



14DENTAL SURVEYING APPARATUS – HANAU (1917)



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The Basic Dental Surveyor

1. Level platform2. Cast holder3. Vertical arm4. Horizontal arm5. Surveying arm6. Interchangeable

Surveying tools



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Scientific Exhibits American Dental Association (1948)

1. Ney (1923)2. Brown Maier (1925)3. Wills (1929)4. Lentz –Circa (1935)5. Lineer (1937)6. Ney (1937)



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7. Franzwa (1937)8. Ringle-Hiatt-Smith (1944)9. McKay (1944)10. Hagman (1944)11. Roach (1944)



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A. Original Ney’s Surveyor (1923)B. Current model of Ney’s Surveyor (1937)C. Modified Ney’s Surveyor (mid 1960s)



19 Will’s Surveyor 1937 Recent Design Of The Will’ Surveyor



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The Roach Surveyor (1944)



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RECENT INNOVATIONS



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Austenal 42 inch blockout surveyor

Austenal Micro Analyser



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PARTS OF A SURVEYORBritish dental journal, volume 189, no. 10, november 25 ,2000

1. Level platform2. Vertical arm3. Horizontal arm4. Surveying arm5. Cast holder6. Accessory tools



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Accessories/surveying tools1.Analyzing rod2.Carbon(graphite) marker3.Undercut gauges4. Wax knife5.Milling devices (with handpiece holder)



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Analysing Rod



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Identifies undercut areas and to determine the

parallelism of surfaces without marking the cast.



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Graphite Marker



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• moved around the tooth and along the alveolar ridge

• the tip of the marker should be level with the gingival margin.



29False Survey Line



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Undercut Gauges



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the shank and head should contact the cast simultaneously.

• more sophisticated, types of undercut gauge are available such as dial gauges and electronic gauges.



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Wax Knife



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• To blockout undesirable undercuts

• To prepare guiding planes



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1. Survey line2. Undercut3. Guiding planes4. Path of insertion5. Path of displacement



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SURVEY LINE

Survey line is a line drawn on a tooth/teeth of a cast by means of a surveyor for the purpose of determining the various parts a clasp/clasps.

-GPT 8



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TYPES OF SURVEY LINES

• Blatterfein classified survey lines as:

1. High survey Line2. Medium Survey Line3. Low Survey line4. Diagonal Survey Line



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•Found near the occlusal surface of a tooth often parallel to the gingival margin• It results from abnormal inclination of the teeth• lingual surfaces of the lower teeth and buccal surfaces of the upper teeth. •Wrought wire clasp used

High Survey Line

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•It is situated across the center of the tooth

• Exhibits a slight occlusogingival incline from the near zone to the far zone. •Aker’s or Roach clasp

Medium Survey Line

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•It is situated close to and parallel to the gingival margin.

• It frequently occurs as a result of marked inclination of the tooth and may also occur on conically shaped tooth. •Modified T clasp

Low Survey Line

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It travels diagonally from near the occlusal surface in the near zone to the gingiva in the far zone.

Diagonal Survey Line

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Reverse circlet clasp



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Class I: •Survey line runs diagonally across the tooth surface.

•The type of clasp indicated is occlusally approaching cast clasp with terminal third engaging the undercut.

Ney’s Classification

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Class II: Survey line also runs

diagonally across the tooth surface but as a mirror image of Class I line. Here a gingivally approaching clasp arm is suggested.

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.



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Class III: Survey line is parallel to

the occlusal surface and lies just below it



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Undercut

the portion of the surface of an object that is below the height of contour in relationship to the path of placement

-(GPT 8)



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Types Of Undercuts

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Tooth Undercuts (Proximal undercuts)

Soft Tissues or bony Undercuts(on lingual side of ridge)



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• 0.25 mm - 0.01” chrome cobalt• 0.5 mm – 0.02” cast gold• 0.75 mm – 0.03” stainless steel



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Guiding Planes

vertically parallel surfaces on abutment teeth

or/and dental implant abutments oriented so as to contribute to the direction of the path of placement and removal of a removable dental prosthesis.



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Two or more parallel axial surfaces on abutment teeth which can be used to limit the path of insertion and improve the stability of a removable prosthesis. Guide surfaces may occur naturally on teeth but more commonly need to be prepared.



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PATH OF INSERTIONSurveying removable partial dentures:the importance of guiding planes and path of insertion and stability –O L Bezzon et al (JPD October 1997 vol 78 no.4 )

the specific direction in which a prosthesis is

placed on the abutment teeth or dental implant(s)

• path of withdrawal (reverse of path of insertion)• path of placement



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The RPD path of insertion and withdrawal is the

direction in which the prosthesis moves in relation to the support system when it is seated in or removed from the mouth, guided by the contact of its rigid parts with the abutments. (GPT-8)



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A single path of insertion



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Multiple Paths of Insertion



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Two paths of insertion Rotational path of insertion



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Potential Path of Dislodgement

Regardless of the path of insertion the path of dislodgement results from masticatory function that pulls the prosthesis in a direction perpendicular to the occlusal plane.



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USES OF A SURVEYOR

1. Surveying the diagnostic cast2. Tripoding the cast3. Transferring tripod marks to another cast4. Contouring wax patterns



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5. Contouring cast restorations6. Placing internal attachments and rests7. Surveying the master cast



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Process Of Surveying

1. Preliminary visual assessment of the study cast.

2. Initial survey.3. Analysis.4. Final survey



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Visual assesment:

• Eyeballing• Form and arrangement of teeth• Potential problem areas



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Anterior tilt (‘heels up’) Posterior tilt (‘heels down’).



61Left and Right Tilts



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Initial survey

• Cast positioned with the occlusal plane horizontal.

• The position of the survey lines.

• ‘Triangle of light’ between the marker and the cervical part of the tooth.

• Undercut gauges



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Analysis

• Occlusal plane horizontal• Consider:1. Appearance.2. Interference.3. Retention



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Appearance:

• Undercuts on the mesial aspects of the abutment teeth.

• Unsightly gap between the denture saddle and the abutment teeth gingival to the contact point.



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posterior tilt so that the analysing rod is parallel with the mesiolabial surfaces of abutment teeth.

contact of abutment tooth over the whole of the mesiolabial surfaceand a much better appearance results.



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Interferences:



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Interferences in the maxillary arch

Maxillary tori



68Exostoses and undercuts on maxillary buccal surfaces



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Interferences in the mandibular arch

Mandibular tori



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Lingually tilted premolars



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Undercuts adjacent to pear shaped pads

Bony prominences on facial surface of mand canines



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Retention:



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Final Survey

• The aims for optimum retention should be to provide:

• Resistance along the path of displacement.

• Resistance along the path of withdrawal



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•guide surfaces are used to provide resistance to displacement•retentive portion of the clasp needs only to resist movement along the path of withdrawal• positioned solely with reference to the red survey line.



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Gingivally approaching clasp positioned at the cross-over point of the survey lines.

•survey lines converge mesially or distally•the tip of an occlusally approaching clasp can engage the common area of undercut.



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Tripoding the cast



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Other Methods of Tripoding

• Pin cemented in the centre of the cast• Use of protractor fixed on surveyor• Use of dental bur in place of pin• Use of position recorder device on a surveyor• Use of plastic plate and impression of cusp tip• Device with adjustable arms• Use of plastic tray and impression• Smooth or threaded pin with sleeve• Use of inclinometer• Key and keyway system• Tripoder attachment



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Transferring tripod marks to another cast

• 3 anatomical points marked on diagnostic cast

• Same points marked on 2nd cast with analysing rod



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Contouring the wax patterns

• With cast on surveying table , tilt adjusted to original tilt.

• Guiding planes• Height of contour



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Contouring Crowns & cast restorations

• Shape of wax pattern altered during casting & finishing.

• Working cast with restorations placed at original tilt

• Cylinder stone.• Guide planes refined.



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Placing internal attachments/rests

• Intracoronal retainers.• Surveyor acts as a drill press



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OBJECTIVES OF SURVEYING

1. Path Of insertion2. Guiding planes3. Height of contour4. Dental and osseous contours5. Soft tissue contours



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6. Cast position and relation to path of insertion7. Transfer of design to master cast8. Blockout9. Develop axial contours10. Machine guiding planes11. Intracoronal retainers



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Maintenance of Surveyor• Wipe the base of surveying table and surveying platform with alcohol or acetone soaked gauge pad.• Acrylic resin powder can be sprayed for smooth gliding.• Machine oil should be applied to vertical arm before and after use, each time.



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SUMMARY

Surveying is undertaken to obtain information that will help us decide:

(1) The optimum path of insertion of the denture

which in turn is influenced by:

• the need to use guiding surfaces to achieve a pleasing appearance.



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• the need to avoid interference by the teeth or ridges with correct positioning of denture components.

• the need to use guide surfaces for retention.

(2) The design, material and position of clasps.



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MICROSURVEYOR



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1. O. L. Bezzon, M. G. C. Mattos, R. F. Ribero, Surveying removable partial dentures: the importance of guiding planes and path of insertion for stability.J Prosthet Dent 1997;78:412-18.

2. J. C. Davenport, R. M. Basker, J. R. Heath, J. P. Ralph, and P-O. GlantzSurveying.British Dental Journal 2000, vol.189(10):532-42

3. Robert L. Engelmeier The History and Development of the Dental Surveyor: Part I

Journal of Prosthodontics, Vol 11 No 1, 2002: pp 11-18.



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4. Robert L. Engelmeier The History and Development of the Dental Surveyor: Part II

Journal of Prosthodontics,VOL11,No 2, 2002: pp122-30.5. Robert L. Engelmeier The History and Development of the Dental Surveyor: Part III

Journal of Prosthodontics,VOL13,No 3,2004: pp 195-202. 6. Stewart’s Clinical Removable Partial Prosthodontics,3rd Edition,

Survey and design 7. McCracken’s Removable Partial Prosthodontics,11th Ed



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Surveyor and technique of Surveying in Removable partial denture

Health & Medicine

Transcript of Surveyor and technique of Surveying in Removable partial denture