Surveyors and surveying in RPD

Surveyors and surveying

1. SURVEYORS & SURVEYING IN RPD PRESENTED BY : ANNESHA K. KONWAR MDS II nd YEAR

2. CONTENTS INTRODUCTION TERMINOLOGY HISTORY & DEVELOPMENT TYPES & USES OF SURVEYOR PRINCIPLES IN SURVEYING SIGNIFICANCE OF SURVEY LINES PARTS OF DENTAL SURVEYOR SURVEY PROCESS RECENT ADVANCES CROSS REFERENCES CONCLUSION REFERENCES

3. 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 patient’s mouth. Surveying and designing are important steps towards achieving a successful restoration. A well-executed design serves as a blueprint for fabrication of the removable partial dentures. Lack of plan,haphazard preparation and lack of abutment preparation are a few factors of partial denture failure.

4. TERMINOLOGIES :

5. A line encircling a tooth designating its greatest circumference at a selected position

6. History And Development During the first part of the twentieth century, RPD were designed and constructed using arbitrary techniques “eye balling”. The turning point in the change of partial denture construction from guesswork based on clinical experience to scientifically based procedure was the appearance of the dental surveyor in 1918. Dr. A.J. Fortunati In 1923 the J.M. Ney Corporation produced the first commercially available, the Ney instrument.

7. HISTORICAL PERSPECTIVE : 1860 : Dr. J. Richardson. 1890 : Dr W.M. Randall’s technique. 1905 : Dr Herman E.S Chayes ’ Parallelometer 1920 : Robinson surveyor by Philadephia Dental Clinic club. 1923 : The original ney surveyor by Weinstein & Roth.

8. 1937 : Ney surveyor – the current model. 1929 : The original Wills surveyor by noble G Wills . 1937 : Wills Surveyor-the current model 1942 : King’s College Surveyor. 1944 : The Roach Surveyor.

9. >The Electrome >The Retentoscope > The Stressograph >Broken-arm > Pendulum Surveyor >Optical Surveyor

10. WILLIAMS SURVEYOR It has a Gimbal stage table -adjustable to any desired tilt. Degree of inclination can be recorded for repositioning of cast at any time. Superstructure of this surveyor consists of jointed arm and spring-supported survey rod, all components of which can be locked in fixed position if desired.

11. THE HIGHRISER RPD SURVEYOR A pendulum arm Block out/Survey Instrument. A llows fluid movement. The arm can freely swing back and forth, rotate, or move up or down. Arm can be locked to hold it at a set vertical height. Spring tension is easily adjusted Heating element attachment is designed for easy use and various size tips are available.

12. THE SKYSCRAPER SURVEYOR A dual pendulum Electronic Block out / Survey instrument. The dual arm system has several advantages : -The heating element does not have to be removed when surveying -By simply rotating the column the new tool is ready for use .

13. THE THERMA-SCULPT SURVEYOR ATTACHMENT The Therma -sculpt is an electronically heated arbor that can be easily attached to Ney- Jelenko type surveyor. The design concept allows the technician to perform varied wax sculpting tasks : from block out of RPD, to attachment and implant procedures.

14. PURPOSES OF SURVEYING Determine the most advantageous path of insertion. Locate proximal tooth surfaces - guiding surfaces. Locate and measure undercuts. Identify hard or soft tissue interferences. Determine a path of insertion consistent with esthetic requirements. Delineate the height of contour of the abutment teeth and identify areas of undercut Planning restorative procedures. Record the most ideal cast position for future reference. Plan for the RPD design and the required mouth preparation.

15. PARTS OF A SURVEYOR : PLATFORM CAST HOLDER/ SURVEYING TABLE VERTICAL ARM HORIZONTAL ARM MANDREL SURVEYING ARM

16. SURVEYING TOOLS : Analysing Rod Carbon Marker Undercut Gauge Wax Trimmer

17. Analysing rod : Used for preliminary survey of the cast. Assessment of degree of undercuts on hard & soft tissues. Assessment of angulation of teeth. In distal extension cases,allows judgement of whether the distal abutment undercuts are sufficient to indicate that a tilt may be beneficial.

18. CARBON MARKER Basically allows visualization of the analysing rod’s work. Used for drawing survey lines around all teeth involved in clasp design or that have proximal undercuts to be eliminated. To mark the extent of bony/soft tissue undercuts for prosthetic mouth preparation if required. Light pressure without erosion.

19. UNDERCUT GAUGES : Used to measure the location and horizontal depth of undercuts on the analysed and marked teeth in three dimensions. Stewert – o.o1”,0.015”,0.02” McCracken-0.01”,0.02”,0.03” Same shank,only the size of the tip/bead v aries (except Neys )

20. WAX TRIMMERS : Used to trim off excessive wax while surveying the wax patterns. To prevent overcontoured blockout of unfavourable undercuts. To demarcate the exact planned clasp arm location to be duplicated. To create a gap/self cleansing area using a 25 trimmer.

21. COMPARISON OF NEY’S & JELENKO SURVEYOR

22. SURVEY LINES :

23. SIGNIFICANCES OF SURVEY LINES :

24. HIGH SURVEY LINE : From occlusal 1/3 rd in NZ to occlusal 1/3 rd in FZ MEDIUM SURVEY LINE : From occlusal 1/3 rd in NZ to middle 1/3 rd in FZ. LOW SURVEY LINE : From cervical 1/3 rd in NZ to cervical 1/3 rd in FZ DIAGONAL SURVEY LINE : From occlusal 1/3 rd in NZ to gingival 1/3 rd in FZ

25. Ney’s Classification 26

26. HEIGHT OF CONTOUR: First termed by KENNEDY. Represents the greatest bulge of diameter of a crown when viewed from a specific angle or changes as the vertical position of the tooth changes. Tipping or tilting the cast will cause the height of contour to move accordingly.

27. DE VAN 1935

28. PATH OF INSERTION : FACTORS AFFECTING

29. RETENTIVE UNDERCUTS : When surveying diagnostic casts for rpd,retentive undercuts must be present on abutment teeth when the cast displays a horizontal tilt. This is necessary because dislodging forces are always directed perpendicular to the occlusal plane.

30. IDENTIFYING THE MOST FAVOURABLE TILT : Tilting is changing the position of the cast,which thus changes the long axis of each tooth on the cast relative to the horizontal plane. Change in the tilt then changes the position of survey line and location and extent of the undercut.

31. The basic position or tilt of the cast on surveyor should be the horizontal tilt. In the horizontal tilt,occlusal surfaces of the teeth are at or near parallel to the horizontal plane.

32. The anterior tilt increases the mesial undercut on the teeth. In the posterior tilt,the occlusal plane is lower in the posterior region. The posterior tilt will increase the distal undercut and decrease the mesial undercut.

33. Interferences I n the maxillary arch – palatal torus exostoses and undercuts on the buccal surfaces of the maxillary arch facial tipping of posterior teeth anterior soft tissue undercuts

34. In the mandibular arch – mandibular tori lingual tipping of the posterior teeth bony prominences often encountered at the facial surfaces of mandibular canines and premolars. Soft tissue undercuts

35. BONY UNDERCUTS

36. ESTHETICS: To obtain optimum esthetics,the metal,usually in the form of clasp arm, must be concealed without compromising necessary support and stability of the prostheses. The artificial teeth must be placed in the most natural position possible. Avoiding unnecessary display of the metal,the tilt of the survey table should be such that the survey line on the teeth that are visible be as close to the gingival margin. The ideal position of the clasp for the retentive purpose is gingival third of the tooth.

37. GUIDING PLANES : Guiding planes are formed from the proximal tooth surfaces of the teeth and are contacted by the minor connectors or other rigid components of the partial denture. These planes guide the prostheses for removal and placement. The guiding planes are in intimate contact with the minor connectors,help to stabilize against the lateral forces.

38. NUMBER OF PATH OF INSERTION:

39. STEP BY STEP PROCEDURES IN SURVEYING A DIAGNOSTIC CAST Orientation of cast Cast tilting Visual analysis using analysing rod Marking of survey lines /soft tissue undercuts using carbon markers Undercut gauges used to measure amount of available retention Interferences Wax Trimmers Tripoding of casts

40. Orientation of Cast Casts oriented such that the anterior part is always toward the vertical member of surveyor and away from the operator Position for description is fixed for either cast. Can be attached to the holding table via: Soft plasticine or wax Locking screws engaging the sides of model Magnetised iron cast into base of model

41. Cast Tilting Tilting is changing the position of the cast, which thus changes the long axis of each tooth relative to the horizontal plane. Alters the contour, positions, location & depth of undercut relative to the new plane. Allows: The most advantageous path of insertion Increase in desirable and decrease in undesirable undercuts Distribution of available undercuts to produce more uniform retention throughout the available teeth & tissues Establishes parallelism & improvises upon esthetics.

42. Dislodging forces primarily to occlusal plane . Hence, HORIZONTAL or 0 . TILT most common(Not>10˚). Other tilts: Anterior Posterior Lateral

43. Visual Analysis using Analysing Rod Primarily responsible for “eyeballing” of the cast. Once orientation & tilt is established, allows for a general tangential analysis of undercuts, tooth angulations, etc. Also aids the establishment of relative parallelism of various planar surfaces.

44. Marking of Survey Lines /Soft tissue Undercuts using Carbon Markers Analysis by the analysing rod is visualised via the carbon marker. 5H pencil graphites secured with metal reinforcement sheath

45. Undercut Gauges used to measure amount of Available Retention These gauges are used to identify the specific amount and location of desired retentive undercut on the surface of the abutment tooth. The undercut is best viewed against light passing through a triangle bounded by surfaces of abutment tooth, surveyor blade ,apex being the point of contact at the height of convexity and base of triangle being the gingival tissues. 46

46. Undercut utilisation 0.01 → cast retainers 0.02 → wrought wire retention 0.03 → rarely used If no retentive undercuts are present, they must be created by: Gold Crowns Retentive Restorations Creating an undercut by tooth modification

47. Wax Trimmers Once unfavorable undercuts are blocked, to prevent overcontouring , wax trimmers are used. In case of distal extension cases, to create a gap/self cleansing area under the saddle, a 25 . trimmer is used in conjunction. Wax patterns for casting can also be carved accordingly.

48. PRESERVING THE TILT THROUGH TRIPODING : Once tilt has been selected for given rpd design, this tilt should be preserved,so that it can be re-established accurately to the surveying table. This procedure is termed as “ TRIPODING”.This helps in returning the cast to the surveyor for future reference.

49. Methods for tripoding a cast : METHOD 1 : By placing widely spaced dots on the tissue surface of the cast using the tip of the carbon marker, with the vertical arm of the surveyor in a locked position.

50. METHOD 2 Scour 2 sides and the dorsal aspect of the base of the cast with a sharp instrument/ marking pencil held against the surveyor blade. Marks don’t interfere with the design Easy duplication May get smudged upon handling

51. METHOD 3 A hole about 10 mm in diameter and 10 mm deep is prepared in the lingual land area of the mandibular cast with a large acrylic finishing bur. The pin is locked in the vertical spindle and lowered to the bottom of the hole. The vertical spindle with the pin is then locked in this position and the hole is filled with dental plaster. Once the plaster is set, vertical spindle is released from cemented pin.

52. METHOD 4 An instrument reproduces the tilt of a cast on a surveyor using protractor Flat metal strip 5mm wide and 3cm long, one end of which bend upward at 90˚ Metal rod is attached to the end of the flat part of the strip which serves to fit the instrument to the surveyor J Prosthet Dent 1965;34(3)465-471

53. A hole is tapped and threaded in the middle of the bent part of metal strip through which a protractor is screwed The protractor can rotate around the metal rod, acting as a pointer. After determining the path of insertion, the protractor instrument is mounted on the surveyor in place of analyzing rod 3 divergent points are marked, with readings recorded at each tilt

54. METHOD 5 Make a hole in the tongue space on mandibular cast 4-6mm in diameter Hole should create undercut but should not perforate the base of the cast Following normal surveying procedures, a parallel shanked straight handpiece bur is suspended. J Prosthet Dent 1981;41(3):352-354

55. With the bur in place, fill the hole with autopolymerizing acrylic resin For reorientation, reposition the bur in autopolymerizing resin for a parallel tripod record.

56. METHOD 6 Wax deposited on side of cast at 3 widely separated points Analyzing rod used to create imprints of wax This can be transferred by duplication

57. METHOD 7 Make a universal tray on a cast after adapting 2 thickness of baseplate wax over the teeth. Make a platform with a cylinder over the tray and insert analyzing rod into cylinder. Move the tray to and fro vertically during setting of the material to make a smooth vertical perforation in cylinder.

58. Tray loaded with elastic impression material, the cylinder is attached to the rod and locked After establishing tilt, an impression is made Reorientation can later be done by placing the impression on cast and the tilt at which the stylus can enter the cylinder locks the prior position

59. SURVEYING THE MASTER CAST : Surveyed as a new cast Prepared proximal guiding plane surfaces will indicate the correct anteroposterior tilt Any remaining interferences after mouth preparation must be eliminated with block out. Survey lines marked

60. Surveying in Confined Areas J Prosthet Dent 1991;61(5):378-380

61. Orthodontic wire can be used as a horizontal "feeler gauge“ in combination with the vertical analyzing wire to estimate the adequacy of the retentive undercut . Dimensions of the wire allow for finer measurements.

62. Contouring of Wax Patterns Surveyor blade – used as wax carver Proposed path of placement maintained throughout preparation of cast restorations for abutment teeth. Surfaces of restorations that provide reciprocation for clasp arms have to be contoured to permit their location well below occlusal surfaces and on non retentive areas

63. BLOCK OUT After the establishment of path of insertion and the location of undercut areas on the master cast, the areas that shall be crossed by the rigid parts of the denture must be blocked out. Roach carver or No.7 spatula used to adapt the blocking wax. Four types: Parallel Blockout Shaped Blockout /Ledge Blockout Arbitrary Blockout Relief

64. Parallel Blockout : Performed: On interproximal surfaces to be used as guiding planes(0/2/6˚ taper) Beneath all minor connectors On tissue undercuts to be crossed by rigid connectors Beneath bar clasp arms to gingival crevices Materials Used: Hard baseplate wax Hard inlay wax Oil based modelling clay Thickness -Only undercut remaining gingival to contact of surveyor blade with tooth surface

65. Shaped/Ledge Blockout : Performed: On buccal & lingual surfaces to locate plastic or wax patterns for clasp arms Material: Hard Baseplate Wax Thickness: Ledges for location of reciprocal clasp arms to follow height or convexity so that they may be placed as cervical as possible without becoming retentive

66. Arbitrary Blockout : Performed: On all gingival crevices On gross tissue undercuts below areas involved in framework design On tissue undercuts distal to cast framework Labial & buccal tooth undercuts not involved in denture design Material: Oil Based Modelling Clay Hard Baseplate Wax Thickness: Enough to just eliminate gingival crevice, levelled arbitrarily with a wax spatula

67. Relief Provided: Beneath lingual bar connectors or the bar portion of linguoplates On areas in which the major connector will contact thin tissue Beneath framework extensions onto ridge areas for attachment of resin bases Material: Adhesive wax Hard Baseplate Wax Thickness: 32 gauge wax(universally) 20 gauge wax for resin base attachment relief

68. Placement of Internal Rest Seats Large box shaped metallic extensions that function as intracoronal extensions. Carved in wax patterns and refined further with hand piece after casting.

69. Machining of Cast Restorations : Rotary instruments can be attached to the surveyor via a handpiece holder for trimming/machining of restorations. Surveying arm can then be rotated around the restoration to trim excess crown material.

70. SURVEYING CERAMIC VENEER CROWNS Ceramic veneer crowns is used to restore abutment on which an extra-coronal rest is placed Surveyor is used to contour wax pattern except labial or buccal surfaces for esthetic reasons Repositioning on surveyor, reshaping with stones may be required before final Glazing of veneer crowns

71. PLACEMENT OF INTRA CORONAL RETAINERS Surveyor is used to To select a path of placement in relation to the long axes of abutment teeth To cut on diagnostic cast to estimate proximity to pulp To carve wax patterns, to place internal attachment in wax patterns or to cut recesses in casting To place keyway portion of attachment in casting

72. PLACEMENT OF INTERNAL REST SEATS Surveyor used as a drill press Internal rest seats carved in wax pattern, defined in casting or entirely cut in cast restoration It provides positive occlusal support and horizontal stabilization Internal rests may be of Retentive, Non-retentive or Semi-retentive forms

73. WHAT’S NEW?? - THREE DIMENSIONAL COMPUTER AIDED SURVEYING J Prosthet Dent 2004;92(3):408-412

74. Programs were written for this technique using mathematic software ( MatLab:The Math Works, Inc , Natick, Mass) The program identified all downward facing surface triangles on scan as – ve & upward facing as + ve , the junction being the survey line.

75. Tilting the cast allows for accurate re-record of the new survey line. 20˚ tilt This can then be reproduced onto the digitally scanned tooth structure.

76. CONCLUSION Preservation of abutment teeth and supporting structures of the oral cavity depends on accurate and knowledgeable survey and design. To plan, survey, and design a removable partial denture which will provide proper retention, support, stabilization, and esthetics , is essential for the success of the removable partial denture.

77. REFERENCES Stewart’s clinical REMOVABLE PARTIAL PROSTHODONTICS – 4 th Edition and 2 nd edition McCracken’s Removable partial prosthodontics – 11 th Edition An Atlas Of Removable Partial Denture Design – Stratton Dental Laboratory procedures for Removable Partial Denture - Rudd and Morrow

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