SURVEYING PARTS, TYPES, PURPOSE OF SURVEYING.pptx

surveying types, parts, purpose and technique

1. SURVEYING KAVI MALAR 2 ND YEAR MDS DEPT. OF PROSTHODONTICS 1

2. CONTENT INTRODUCTION DEFINITIONS OBJECTIVES HISTORY AND DEVELOPMENT OF SURVEYOR- PART I HISTORY AND DEVELOPMENT OF SURVEYOR- PART II TYPES OF SURVEYOR PARTS OF SURVEYOR PURPOSE OF SURVEYING SURVEY LINES AND HEIGHT OF CONTOUR SURVEYING RECENT ADVANCES LITERATURE REVIEW ON TRIPODING TECHNIQUES REFERENCES 2

3. INTRODUCTION A partial denture will not succeed unless it is designed and constructed in harmony with all the physiological and mechanical problems present in the patient’s mouth. Surveying and designing are important steps towards achieving a successful restoration. A well executed design serve 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. 3

4. DEFINITIONS – { GPT – 9 } 4

5. DEFINITIONS – { GPT-9 } 5

6. OBJECTIVES 6

7. HISTORY AND DEVELOPMENT OF DENTAL SURVEYOR 1.) Before the invention of dental surveyor “ visual survey” of dental casts were in use. W.M. RANDALL’S TECHNIQUE{ 1890} - cast is held at arms length and stabilized on the table top with wax or impression compound. With one eye closed ,a sharp pencil was held perpendicular to occlusal plane and was passed over the axial surfaces of tooth to develop a survey line. 2.) RUDOLPH HANAU{ 1917} – this device was intended for orthodontic research and not for mapping height of contours, showed commercial failure. 7

8. 3.) Dr.A J FORTUNATI (1918) : First to demonstrate advantages of using a mechanical device to map the contours of abutment teeth. Replaced the steel analyzing rod of “ Bridge Parallelometer ” with a graphite rod. 4.) PHILADELPHIA DENTAL CLINIC CLUB { 1918} : Developed Robinson surveyor , which is one of the firsts to be designed for cast surveying for clasp design procedure. 5 ) HERMAN ES CHAYES { 1920}: Chayes Parallelometer was not a surveying instrument, intended to be used for ensuring parallelism of chayes attachment system. Has two mandrels, female components of attachment were held in these. 8

9. 6.) WEINSTEIN AND ROTH { 1923} : NEY SURVEYOR Original NEY SURVEYOR introduced in 1923 Features : palm rest on top of vertical arm . Current model of NEY SURVEYOR introduced in 1937 Mid 1950 – NEY clasp surveyor junior model Mid 1960 modification of NEY , facilitating both surveying and milling Straight handpiece is attached to the surveying arm. 9

10. NOBLE G WILLS { 1929} : WILLS SURVEYOR Original WILLS SURVEYOR which was marketed by J.F. JELENKO and company Preferred by many operators because of its spring loaded arm. Recent design, which still retained the spring loaded surveying arm. 10

11. Original wills surveyor, marketed by Kerr products of Detroit in 1929 Came both with and without light, cast held in place with wax KINGS COLLEGE SURVEYOR : Adjustable cast holder, interesting parallel pivoting horizontal arms Powerful magnet in tilting table. Cast had an iron ring embedded in its base.therefore didn’t require a fixing agent . ELECTRONIC SURVEYOR: Developed by United States Air Force school of Aviaton Medicine Powered by dry battery cells passing a weak current through surveying tool to the cast surface. Phenolphthalein is applied over the cast, and surveying tool when comes in contact marks the red survey line . 11

12. COLUMBIA PARALLELOR , { 1940},similar to Ney surveyor ROACH or DEE SURVEYOR:{1944} : Cast holder is fixed to base,but table could rotate 360 °. Horizontal arm was free to rotate in 360 as well as vertically. MODIFICATION OF ROACH surveyor{ 1950} by Dr. A.D. Rebossio He removed the vertical and horizontal arms Leaving only the cast holder behind . 12

13. NEY dental international and J.F. JELENKO and company dominated the market during the 20 th century. In their 1950 text, McCall and Hugel reported 11 dental surveyors had been featured in scientific exhibits at the American Dental Associations 1948 annual meeting . These were: NEY – 1923 BROWN –MAIER – 1925 WILLS – 1929 LENTZ – 1935 LINEER – 1937 NEY – 1937 FRANZWA – 1937 RINGLE – HIATT- SMITH – 1944 McKAY – 1944 HAGMAN – 1944 ROACH- 1944 13

14. HISTORY AND DEVELOPMENT OF SURVEYORS – PART II Basic dental surveyors which were redesigned and accessorized to improve its accuracy and versatility. RETENTOSCOPE: Produced by saddle lock company It has a rotating head which supports 3 horizontal arms 1 of the arm is a conventional surveying arm. 2 nd arm is for a handpiece for milling. 3 rd arm supports a dial undercut gauge . Working light is attached to vertical arm. Surveying table is moved upward and downward instead of the surveying arm 14

15. B) STRESSOGRAPH Manufactured by Ticonium company Consist of 2 horizontal arm assemblies. 1 st arm is conventional surveying arm . 2 nd arm is the dial gauge to measure undercuts. 15

16. C)BROKEN-ARM SURVEYORS A surveyor in which the horizontal arm is hinged . This allows surveying tool to be used in all the regions of the cast. Also allows for attachment of handpiece to the horizontal arm for milling purpose. Examples : william’s surveyor, Nesor broken-arm , Torit broken – arm surveyor, Ticonium broken arm surveyor WILLIAMS BROKEN –ARM SURVEYOR: Features the gimbal stage, adjustable to any tilt in any direction. Has a spring loaded surveying arm. A straight handpiece could easily be clamped to the surveying arm 16

17. TICONIUM COMPANY BROKEN- ARM SURVEYOR Has a spring loaded surveying arm NESOR BROKEN –ARM DENTAL SURVEYOR TORIT BROKEN – ARM SURVEYOR 17

18. D) BLOCKOUT INSTRUMENTS The dental surveyor has proven indispensable during the laboratory task of blocking out undercuts on a master cast before fabrication of RPD. 1 ] PENDULUM SURVEYORS: novel approach. Had a surveying arm of at least 3 feet long , that could pivot at some predetermined point but well above the cast holder. Surveying arm can be moved laterally, and the attached waxing instrument is heated in open flame. It is then returned back to the apparatus and used to shape and trim the blockout wax. AUSTENTAL PENDULUM BLOCKOUT SURVEYOR , with 42 inch long surveying arm. 18

19. 2 ] ELECTRICALLY HEATED BLOCKOUT INSTRUMENTS : AUSTENTAL MICRO- ANALYZER: Measures undercuts electronically. Dial indicator : shows desired amount of undercut Flash light : signals when the exact undercut is reached. PARATHERM: It is a surveying and blockout waxing instrument. Surveying arm moves in all 3 axes. Waxing tools are heated electrically {140° celsius }to contour wax patterns according to Path of insertion. Ideal tool for blocking out undesirable undercuts. 19

20. E) MILLING MACHINES DENTAL SURVEYORS HAVE BEEN DEVELOPED TO FUNCTION AS MILLING MACHINES OR DRILL PRESSES. THESE ARE DEVELOPED FOR : CHAYES MILLING MACHINE AUSTENTAL PRECISION MILLING MACHINE : a)Preparing receptacles for precision attachment placement b) to ensure parallelism of guiding planes into milled castings 20

21. . AUSTENTAL PRECISION MILLING MACHINE PARTS OF MILLING MACHINE: MILLING SPINDLE– motorized unit that receives a drill bit. The spindle can be raised up to 50000 rpm with anti- clockwise up to 30000 rpm. CHUCK – with a bit stop to prevent overpreparation FOOT-SWITCH MODEL TABLE- similar to surveying platform . 21

22. GALLONI ISOPARALLELOMETER KAVO MILLING MACHINE BACHMAN PARALLELOMETER with movable magnetic table 22

23. F) RECENT INNOVATIONS A recently designed surveyor dramatically exposes undercut areas by projecting a beam of laser light. Prototype surveyor made by Intra- Tek , Dallas. A beam of laser light projects vertically downward from distal end of horizontal arm. Laser light is visible only above the height of contour Undercut below the HOC is cast as a dark shadow 23

24. HISTORY AND DEVELOPMENT OF SURVEYOR- PART III These are the additional instruments that did not enjoy commercial success , but nonetheless contributed significantly to the evolution of the dental surveyor. Progenitors of dental surveyor- Paralleling instruments Late twentieth century directions in surveyor design 24

25. Progenitors of surveyor- paralleling instruments 25

26. 26

27. Late twentieth century directions in surveyor design 27

28. TYPES OF SURVEYOR NEY’S SURVEYOR WILL’S SURVEYOR WILLIAM’S SURVEYOR ELECTRONIC SURVEYOR PARATHERM SURVEYOR STRESSOGRAPH BROKEN ARM CAST SURVEYOR OPTICAL SURVEYOR LASER SURVEYOR PARALLELOMETER OTHER SURVEYORS: Austenal microanalyser , Krupp model k3, Anthogyr model, Galloni isoparallelometer , Bachmann parallelometer . 28

29. COMPARISON 29

30. SURVEYING PLATFORM SURVEYING TABLE: CAST HOLDER AND BASE {Ball and socket joint} 3. VERTICAL ARM 4. HORIZONTAL ARM: Ney surveyor- Fixed Jelenko surveyor – Swivels Williams surveyor – Split and jointed 5. SURVEYING ARM : Ney: passive Jelenko : spring loaded 6. SURVEYING TOOLS PARTS OF A SURVEYOR 30

31. ANALYSING ROD A cylindrical metal rod that contacts the convex surface of teeth to be analyzed Helps determine “ height of contour” and “relative parallelism” of one surface to another. CARBON MARKER Used to draw the “ survey line “ NEY- Circular in cross-section JELENKO – Triangular in cross section SURVEYING TOOLS 31

32. UNDERCUT GAUGE used to determine the location and amount of retentive undercut present in the abutment tooth. Vertical rod contacts the height of contour while the circular metal plate detects undercut CHROME ALLOYS GOLD AND WROUGHT ALLOYS WAX TRIMMER Used to trim excess wax from block out areas to make it parallel to path of insertion To trim waxed crown restorations 32

33. 33

34. SURVEYING THE DIAGNOSTIC CAST : To determine the “ path of insertion” or the most favourable tilt which is further influenced by: - Guiding planes, Aesthetics, Retentive Undercuts, Interferences. TRIPODING: After the final tilt of cast is determined, the position is recorded by tri- poding which helps re-orienting the cast back in surveyor as well as transferred to the master cast. SURVEYING THE MASTER CAST: By tri- poding the master cast, it is positioned in the same position as that of a diagnostic cast. Then it is surveyed to perform following procedures: A) BEADING B) BLOCK OUT C) RELIEF 34

35. 4. CONTOURING WAX PATTERNS Indicated when the proposed abutment needs to be crowned. wax pattern of crown is prepared and the working cast is placed in the surveyor. Using the wax trimmer desirable guiding planes parallel to path of placement are prepared. Height of contour is adjusted as well to get the right amount of undercut for the placement of retentive arm. 35

36. 5. CONTOURING CROWNS Followed by casting and ceramic application, wax patterns undergo varied degree of changes. So the metal crowns or unglazed ceramic crowns are placed back in the surveyor using tripod marks. Desirable guiding planes and height of contour are re-established. Finishing , polishing and glazing is done after this. Equipment : handpiece holder suspending a straight handpiece with mounted cylindrical stones are used, this is attached to the surveying arm. 36

37. 6.PLACING INTERNAL ATTACHMENTS: Surveyor is first used to assess the space available in the abutment for placement of internal attachments without encroaching pulp Done by creating a recess in the abutment teeth in diagnostic cast. If space available is adequate it is transferred to the wax pattern , which is defined following casting. Absolute parallelism among the attachments is necessary. 37

38. 7. PLACING INTERNAL RESTS : Internal rests placed on crowns provide good support and stabilization. Box shaped occlusal rests with vertical walls and flat floors are placed in wax patterns , in harmony with path of insertion. Done using straight handpiece of surveyor with appropriate tools. Contraindication: distal extension partial dentures { more torque applied on abutment due to interlocking rests.} 38

39. SURVEY LINES DEFINITION: A line produced on a cast by a surveyor making the greatest prominence of contour in relation to the planned path of placement of a restoration. BLATTERFEIN divided the abutment tooth into two halves by a vertical line passing through the centre of tooth. Near zone Far zone E 39

40. Blatterfein’s classification of survey lines HIGH SURVEY LINE: Placed in occlusal third in both near and far zone Seen in inclined teeth and teeth with larger occlusal diameter. Deeper undercuts Solution : wrought combination clasp and ring clasp for lone standing tilted tooth. MEDIUM SURVEY LINE: NEAR ZONE: middle third FAR ZONE: gingival third Preferable survey lines. Both Aker’s clasp and Roach’s clasp can be used, however Aker’s is preferred. 40

41. 3. LOW SURVEY LINE NEAR AND FAR ZONE: Gingival third Seen in opposite side of a tilted tooth with a high survey line. Difficult to place retentive arm , because the arm will be very close to gingiva . SOLUTION: change contour by either Tilting, Recontouring , Crown placement. Place reciprocal arm in these survey lines. 4. DIAGONAL SURVEY LINE NEAR ZONE: Occlusal third FAR ZONE: Gingival third Commonly seen in buccal surfaces of canine and premolars. SOLUTION: Place Reverse Circlet clasp, Hair-pin clasp,” T” or Modified T- bar clasp . 41

42. NEY’S CLASSIFICATION OF SURVEY LINES 42

43. HEIGHT OF CONTOUR {HOC} Term coined by KENNEDY. Represents the greatest bulge of diameter of a crown when viewed from a specific angle or changes as the vertical position of tooth changes. Tipping or tilting the cast will cause the HOC to move accordingly. 43

44. De Van 1935 44

45. SURVEYING SURVEYING DIAGNOSTIC CAST: Mounting diagnostic cast Identifying the most favourable tilt Path of insertion Tripoding Placing survey lines Locating and marking measured undercuts. DESIGNING MOUTH PREPARATION : ABUTMENT TOOTH PREPARATION SURVEYING MASTER CAST Retripoding master cast Design transfer to master cast Block out 45

46. SURVEYING DIAGNOSTIC CAST This is done before the treatment plan is formulated. OBJECTIVE: To determine the most favourable tilt To determine the most favourable path of insertion . 46

47. 1)Mounting of diagnostic cast The cast to be surveyed is attached to the cast holder. Its occlusal plane should be parallel to the base. Anterior teeth should be facing the vertical arm of surveyor. Horizontal tilt or 0° tilt is the starting point of surveying procedure. 47

48. 2) Identifying the most favorable tilt. Tilting changes the position of the cast, which in turn changes the long axis of each tooth on the cast relative to the horizontal plane. Possible because of the ball and socket design . Tilt of cast is described as a viewpoint of person looking at its posterior surface or rear view . Tilting more than 10° from horizontal plane should be avoided. Antero-posterior tilt influences : Guiding Plane Right and Left tilt : Undercuts 48

49. Rear view of tilted casts Anterior tilt Posterior tilt A B Left tilt Right tilt A B 49

50. 2a) Four critical factors determining most favourable tilt In the order of importance: presence of suitable retentive undercuts elimination of hard and soft tissue interferences creation of desirable esthetics establishment of appropriate guiding planes. It is not possible to achieve optimum in all 4 areas, so a compromise must be made weighing the factors against one another. 50

51. RETENTIVE UNDERCUTS IDEALLY: Proposed abutment should have undercut of 0.010 inch undercut for cast alloys and o.015 inch for wrought alloys in horizontal tilt. Location : apical third of clinical crown { esthetic and mechanical advantage} Location : mesiobuccal , distobuccal line angle or midfacial surface depending upon practitioners philosophy. CHECKED USING ANALYSING ROD 51

52. Why the retentive undercut must be present in horizontal or 0° tilt ??????? Dislodging forces are always directed perpendicular to patient’s occlusal plane. Therefore resistance to dislodging forces must be there when the dental arch is in horizontal position. 52

53. RETENTIVE UNDERCUTS-must be present in horizontal tilt. If present If absent Tilt may be changed to optimize the undercut. So that a retentive clasp will be positioned no farther occlusally than the junction of gingival and middle third of tooth. Tilting will create only an illusion. Solution : a) Recontouring enamel surfaces. b ) Fixed restorations ( crown, inlays, ceramic veneers) 53

54. What happens when it’s not present???????? 54

55. INTERFERENCES Certain structures such as the teeth, bony prominences, soft tissue undercuts etc. interfere with path of insertion. INTERFERENCES IN MAXILLARY ARCH: Palatal torus Exostoses and undercuts Facial tipping of posterior teeth Edentulous maxillary anterior ridge with noticeable undercut. 55

56. Interferences Interferences in mandibular arch Mandibular tori Mandibular posterior teeth with lingual tipping Areas adjacent to pear -shaped pads Bony prominences 56

57. MAXILLARY INTERFERENCES PALATAL TORUS Interferes with Mx Major connector placement. Tilting will not solve the problem. Solution : Design alteration : Surgical removal 57

58. B ) EXOSTOSES AND UNDERCUTS Common on the buccal surfaces of maxillary arch. Solution: surgical correction Prevents intimate contact between the RPD and patient’s soft tissue. This leads to food accumulation and denture instability. 58

59. C) FACIAL TIPPING OF POSTERIOR TEETH : Change in Height Of Contour a) As the tooth tilts, survey line moves occlusaly in buccal surface and apically on lingual surface b) High survey lines are often associated with soft tissue undercuts An infrabulge clasp should not be used. C} Tipping present on both sides: Tilting- not beneficial Solution - Recontouring or crown placement D} Tipping seen only on one side E} Tilting can be beneficial 59

60. D) Edentulous maxillary anterior ridge with noticeable undercut . SOLUTION: Giving the cast a slight posterior tilt SOLUTION:- Modifying or eliminating the anterior flange and butting the replacement teeth directly against the edentulous ridge. -Provided the sufficient ridge height is present 60

61. Mandibular interferences A} MANDIBULAR TORI Difficult to avoid. Design modification: sufficient amount of relief should be provided. But this compromises thickness of major connector and causes tongue interference Best solution: surgical removal 61

62. B} LINGUAL TIPPING OF MANDIBULAR POSTERIOR TEETH PROBLEMS: No undercuts on facial surface and large undercuts on lingual surface Suprabulge clasps given for lingual retention are short and rigid exerting destructive forces. SOLUTION: For lingual tipping present on both sides Labial bar major connector { poor patient acceptance} Recontouring Restorations Orthodontic movement 62

63. C} AREA ADJACENT TO PEAR SHAPED PADS PROBLEM: exhibit significant undercut unilaterally or bilaterally. SOLUTION:- Unilateral undercut : slight lateral tilt Bilateral undercut: tilting is not effective, acrylic denture base extending in this area can be modified to provide patient comfort. 63

64. D} BONY PROMINENCES Seen mostly in relation to the buccal surfaces of mandibular canine and premolar PROBLEM: Bony prominences produce soft tissue undercuts SOLUTION: Either Tilting the cast or surgical recontouring depending upon severity. 64

65. ESTHETICS To obtain optimum esthetics in RPD Metal components must be concealed Prosthetic teeth must selected, contoured and properly positioned . 65

66. CONCEALING THE METAL COMPONENTS 66

67. PROBLEM: mesial drifting SOLUTION: surveying is done to determine how much recontouring is needed PROBLEM: triangular spaces with large undercuts SOLUTION: optimum tilt given or recontouring done. TOOTH SELECTION : shade, size contour and functional demands. ESTHETIC CONCERNS: 67

68. GUIDING PLANES These are planes prepared on axial surfaces of teeth. Minor connector and other rigid components of RPD come in contact with the prepared proximal tooth surface. It should be parallel to the determined path of insertion. Analysing rod in the surveyor is used to locate surfaces that are parallel to the planned POI, or those that can be made parallel are determined by antero -posterior tilting and then prepared or crowning can also be done. 68

69. Guiding plane FORM: Width- 2/3 rd the distance between buccal and lingual cusp tips OR 1/3 rd the buccolingual width of tooth. Height- 2/3 rd the length of the crown from marginal ridge cervically . 69

70. PATH OF INSERTION The tilt of cast determines its path of insertion. For practical purposes , the path of insertion and removal will always be parallel to the vertical arm of the surveyor. Components of RPD that govern the path of insertion : MINOR CONNECTORS : which connects clasps to major connector. BODY AND SHOULDER OF CLASP ASSEMBLY : may exhibit some effect. RECIPROCAL ARMS: where guiding planes have been prepared on lingual surfaces of remaining teeth. 70

71. Understanding the concept of path of insertion, withdrawal and displacement POI{ PATH OF INSERTION} : The path followed by denture from its first contact with teeth until it is fully seated. POW{ PATH OF WITHDRAWL} : This coincides with path of insertion, but is in reverse. POD{ PATH OF DISPLACEMENT} : The path taken when the denture is dislodged in function.This is always seen perpendicular to occlusal plane or horizontal plane. In 0 °tilt: POI = POW= POD { a retentive clasp will be enough to resist POW and POD} When tilt is given : POI = POW ≠ POD{ retentive clasp will resist POD while the retentive clasp plus the guiding plane will be required to limit the POW Davenport et al,Surveying , British dental journal,november 25 ,2000 71

72. Sufficient guiding surfaces- single POI Divergent guiding surface- multiple POI Converging guiding surface with only point contact- multiple POI Two distinct POI- sectional dentures Rotational POI – one of the teeth showing tipping How do we limit POI???????????? GUIDING PLANES ARE THE ANSWER Davenport et al,Surveying , British dental journal,november 25 ,2000 72

73. PATH OF INSERTION Kennedy class I: Multiple POI Kennedy class II: Multiple POI Kennedy class II with modification: Single POI Kennedy class III: Single POI Kennedy class IV: Single POI 73

74. TRIPODING DEFINITION: Those marks or lines drawn on a cast in a single plane perpendicular to the surveying rod to assist with repositioning the cast on dental surveyor in a previously defined orientation. Two commonly used methods of tri- poding are: Tissue surface indexing Art portion indexing 74

75. Tri- poding methods: Tissue surface indexing The 3 points marked should be in the same horizontal plane After ensuring that, cast should be locked in the surveying table. 75

76. Surveying arm is adjusted such that the 0.030inch undercut gauge used here comes in contact with 3 easily identifiable locations on the lingual surface of cast Surveying arm is then fixed, in the horizontal plane, surveying table is then moved to bring the cast in contact with undercut gauge, producing a shallow groove. A red pencil is used to mark the groove, line should be approximately 4mm long and relatively narrow. 76

77. Each horizontal line is crossed and then circled to get a crosshair configuration. Tripod marks should be placed at 3 widely spaced anatomic areas of the cast and should be readily identifiable. 77

78. ART PORTION INDEXING 3 Lines and marks are scribed on the art portion or base of the cast One on posterior surface, one on each side of lateral surface. Analyzing rod are held against the side of cast and a mark is made with a sharp instrument. 78

79. Transfering tripod marks to another cast Transfering marks from master cast to refractory cast : Scoring or scribing the cast rather than just marking it with a pencil helps. Transfering marks from diagnostic cast to master cast: cast is repositioned in surveyor using the tripod marks and additional anatomical landmarks are used and are: 1) Distal marginal ridge of 1 st premolar on one side 2) Lingual cusp tip of 1 st premolar on other side. 3) Incisal edge of lateral incisor . 79

80. PLACING SURVEY LINES Carbon marker positioned in mandrel and tightened Surveying arm is unlocked to allow free supero -inferior movement Surveying table is moved until the cast comes into light contact with the carbon marker. This is accomplished by controlling surveyor arm with one hand while guiding movement of surveying table with opposite 80

81. Placing survey lines Survey lines are transferred to teeth as a result of contact between dental cast and side of carbon marker. Survey lines transferred to soft tissue areas which may be contacted by components of RPD 81

82. LOCATING AND MARKING MEASURED UNDERCUTS To permit correct placement of retentive clasps. The depth and position of desired undercut varies with material and clasping system used. Undercut gauge is selected according to the aforementioned criteria. 82

83. An appropriate undercut gauge is selected and placed into mandrel Dental cast is brought into light contact with the shank of the undercut gauge. Head of the gauge does not contact the surface of the cast 83

84. Surveyor arm is raised until the undercut gauge contacts the infra-bulge area of tooth The point of contact is scraped very lightly. Apical border of the contact scribed is clearly marked using a red pencil . It should be a thin horizontal line approximately 2mm in length 84

85. DESIGNING A completed design serves as a blueprint for a RPD framework construction, keeping in mind the mechanical characteristics. Certain principles and philosophies are to be followed before proceeding with designing. The three main philosophies are: Stress equalization Physiologic basing Broad stress distribution 85

86. Stress equalization : a stress director in the form of hinge is used Physiologic basing : tissue recorded in compression Broad stress distribution : distributing forces over as many teeth and as much of soft tissue as possible. 86

87. COLOR CODING USED FOR DESIGNING b RED- tripod marks - rest seats: in solid red - recontouring areas : outline with red with spaced diagonal lines filling it - relief in soft tissue : outline with red accompanied by the word relief BROWN: Metallic portions of RPD BLUE: Denture base resins BLACK: survey lines in teeth and tissue area : enter information on the base of the cast 87

88. Kennedy class I and II designing DIRECT RETENTION: retention should not be considered as a primary objective. Primary objective: function,appearance , comfort and preservation of remaining structures. Provided mainly by: clasp assembly, but other than that close adaptation of guiding plane and framework , proper adaptation of denture base also plays crucial roles. 88

89. CLASP ASSEMBLY: Simplest clasp, having good stabilizing qualities,passive unless activated and accommodate minor movements without transmitting torquing forces to abutment teeth. 89

90. KENNEDY CLASS I: 2 CLASPM ASSEMBLY KENNEDY CLASS II: 3 CLASP ASSEMBLY 90

91. RESTS: Should be placed adjacent to edentulous space Rest seats prepared should allow the forces to be transmitted along the long axis . INDIRECT RETENTION: To neutralize the unseating forces and should direct forces along the long axis of tooth. it should be placed as far away from fulcrum line, but not beyond canine anteriorly . class I: 2 indirect retainers. Class II: 1 is adequate. lingual plating may be used to augment indirect retention. 91

92. MAJOR CONNECTORS: Select the simplest connector that accomplishes the treatment objectives. It must be rigid , must not impinge gingival tissues . Greater the palatal coverage greater is the support derived, so for maxillary arch a broad major connector may be used. MINOR CONNECTORS: Must be rigid and enhance comfort, cleanliness and the placement of artificial teeth. DENTURE BASES: Broad coverage , but this should not interfere with functional movements of surrounding tissues. Selective pressure impression techniques are recommended. Cameo surface should be polished and should enable the patient to exercise maximum neuromuscular control. 92

93. OCCLUSION: MIP if possible should coincide with Centric relation. A harmonious occlusion should be established. All eccentric movements should be dictated by the remaining natural teeth. Prosthetic teeth should be selected and positioned to minimize stresses on the prosthesis. Fewer teeth and teeth that are narrower bucco-lingually . Teeth placement: crest of the ridge. Teeth s hould display sharp cutting edges and ample escapeways . 93

94. KENNEDY CLASS III DESIGNING DIRECT RETENTION: CLASPS Quadrilateral positioning Simple circlet clasps , while considering tooth contours, soft tissue contours and esthetics. Reciprocal element must be rigid . RESTS: Should be positioned adjacent to edentulous space. Rests should be used to support major connectors and lingual plating . 94

95. INDIRECT RETENTION: Usually not required for kennedy class III. Kennedy class III with modification I: that is with a bilateral loss where one or both posterior abutments are used solely for vertical support and not for retention, then the entire design must satisfy the requirements described for kennedy class I and class II. MAJOR AND MINOR CONNECTORS: Must be rigid and meet the requirements as same as that of kennedy class I and II. DENTURE BASES: functional impressions are not required , anatomic impressions are enough. Coverage of residual ridge areas should be determined by appearance, comfort and avoidance of food impaction. OCCULSION: Same as that for kennedy class I and class II. 95

96. KENNEDY CLASS IV DESIGNING Arrangement of anterior teeth to meet esthetic and phonetic need often leads to placement of teeth anterior to crest of ridge. This leads to “tipping” of prosthesis during function, hence the following efforts must be taken:- Every effort must be made to preserve hard and soft tissue components of anterior edentulous ridge. If possible a central incisor or any other tooth should be preserved as an abutment or over-denture. It minimizes harmful rotational forces. 96

97. INDIRECT RETENTION: It should be located as far posterior to the fulcrum line as possible. An ideal quadrilateral configuration of clasping may preclude the need for additional indirect retention. MAJOR AND MINOR CONNECTORS: it should be rigid and a broader palatal coverage should be used in maxillary arch. DENTURE BASE: A functional impression may be indicated if the edentulous area is extensive. DIRECT RETENTION: Quadrilateral configuration is considered ideal, anterior clasp assembly as far anterior and posterior clasp assembly as far posterior as possible. 97

98. ABUTMENT TOOTH PREPARATION OBJECTIVES: Direct stress along the long axis of tooth. Eliminate interferences Create retention Allow placement and removal of prosthesis without transmitting wedging types of stress. SEQUENCE: 1) Preparation of guiding planes. 2) modification of height of contour. 3) preparation of retentive undercuts. 4) rest seat preparation. 98

99. SURVEYING MASTER CAST RETRIPODING: the master cast is tripoded in the same relation as diagnostic cast using the tripoding procedures. DESIGN TRANSFER TO MASTER CAST: With the master cast tripoded and locked in the surveyor , the same procedure used to design diagnostic cast is now used to transfer the design to master cast. 99

100. BLOCK OUT OF MASTER CAST DEFINITION: the process of applying wax or any other temporary substance to undercut portions of a cast so as to leave only those essential to planned construction OR elimination of undesirable undercuts. MATERIAL: One sheet of baseplate wax and one stick of green inlay wax. 41/2 sheets of baseplate wax , 4 ½ sticks of gutta percha , 3 sticks of sticky wax, ½ kaolin and ½ tube lipstick(color) Any commercially available block out material. 100

101. Block out TECHNIQUE: The wax is added to the area to be blocked out by wax spatula. Trimmed parallel to the path of placement by wax trimmer. Trimming is facilitated by slightly warming the wax trimmer. TYPES: PARALLEL BLOCKOUT ARBITRARY BLOCKOUT SHAPED BLOCKOUT 101

102. Parallel block out 102

103. 103

104. RELIEF DEFINITION: The reduction or elimination of undesirable pressure or force from a specific region under a denture base. GPT-8 To provide space: Relief is provided under denture base in case of lattice and meshwork constructions to provide space for acrylic resin. To reduce the pressure on mucosa: Beneath lingual bar and linguoplate . Areas in which major connectors will contact thin tissue eg : mandibular lingual ridge and median palatal raphe 104

105. RECENT ADVANCES 105

106. STEP 1: 3-D SURFACE CAPTURE OF THE DENTAL CAST Optical surface capture device- digital camera with a projected light( comet 250 scanner) captures around 140,000 points in 3-D within the line of sight and these points are termed as “ point cloud” To create 3-D surfaces or a model these points are approximated in connected triangular facets using computer software .( polywork;innovmetric software inc) STEP 2: ELECTRONIC SURVEYING Mathematical softwares ( MatLab ; The MathWorks,Inc,Natick,Mass ) were programmed to read these triangular facetted surface models. 106

107. Barrel shaped representation: the program defines the surface area of teeth apical to survey line by identifying downward facing triangles . Upper boundary of this area defines the survey line. Change in the survey line with tilting can also be seen. These informations are then transferred to surface models of scanned cast. . undercuts electronically identified on surveying cast PROS: survey line captured within a matter of second and are reproducible CONS: cost learning curve. 107

108. LITERATURE REVIEW ON TRIPODING TECHNIQUES 108

109. 1. Kaloyannides , reproduction of tilt of a cast on a surveyor, J Prosthet dent, october 1973 PROTRACTOR TECHNIQUE “a” is a vertical rod used to detect the degree of inclination. “b” is the vertical rod attached to mandrel of surveying arm. “c” is the protractor It can be used to determine inclination in both antero -posterior and transverse direction. Three divergent points are selected either on occlusal surface of teeth or on edentulous ridge Simple, easy technique, reproducibility not effected by change in the shape of cast. 109

110. 2. Knapp et al; technique for recording dental cast –surveyor relations; journal of prosthetic dentistry march 1979 CEMENTED PIN TECHNIQUE: A hole of around 4-6mm in diameter and 5-8mm in depth are made in the tongue space of mandible and is filled with auto-polymerizing resin in dough stage. A parallel shanked handpiece bur is inserted into surveying arm and lubricated. The bur shank is then lowered to fill the resin and resin is allowed to polymerize. So now we get a cast with cemented pin assembly , the cemented pin with auto-polymerizing resin can also be removed from the cast by slightly twisting using a plier . 110

111. Antony D. Steas , recording and reproducing the tilt of a cast on a surveyor, journal of prosthetic dentistry, january 1987 Aluminium metal sheet strips assembly it consists of two strips 5mm wide and 5.5cm long with 2mm diameter holes placed on either end. The third strip has a longitudinal hole and a slider made of another sheet. 3bolts and 3 pair of nuts Handpiece mandrel slider Handpiece mandrel 111

112. Ansari , A procedure for reorienting a cast on a surveyor, Journal of Prosthet Dent, july 1994 U- shaped plastic tray with a platform and a vertical cylinder which should snuggly fit into stylus of surveyor is fabricated with spacer wax. spacer is removed and the intaglio surface is loaded with putty elastomeric material and is pressed on the cast which is placed in its desirable tilt. 112

113. Dumbrigue and Chingbingyong , A new method for recording and reproducing cast orientation on a survey table. J Prosthet Dent 2003;89:76-8 CAT ( Cast Angle Tool) consists of an inclinometer mounted on a metal plate with a spring loaded swivel arm mechanism. Simplified technique since only 2 positions aligned compared to 3 marks in traditional technique. 113

114. Kamble et al, A magnetic device for recording and reproducing the path of placement for partial removable dental prostheses,( J Prosthet Dent 2013;110: 333-334) A pair of cobalt- samarium magnets of 30mm in diameter and 2.5mm in thickness in required. 2 brass metal of same dimension are secured at each end of magnet using nut and bolt. 1 of the bolt is ground to get a sharp point and on the other one a hole is made to receive straight handpiece mandrel. 114

115. Afsal et al; Putty index for tripoding , journal of prosthodontics , january 15 2017 Diamond disc is attached in the surveying arm and is aligned to center of the cast. putty index is made with addition silicon, not covering anterior teeth and occlusal surface of posterior teeth 115

116. Gali and Lanka, A reproducible 3- point contact device for tri- poding a definitive cast, journal of prosthetic dentistry 2019 116

117. CONCLUSION The introduction of surveyor has changed the removable partial denture service from guesswork to an objective, scientifically based procedure. Each phase in the surveying process is essential to deliver a successful removable partial denture. REMEMBER: Surveying is not an option, it is a necessity. 117

118. REFERENCES Stewart’s clinical removable partial prosthodontics , 4 th edition. McKraken’s removable partial prosthodontics -13 th edition V Rangarajan textbook of prosthodontics - 2 nd edition William et al; A technique for fabricating patterns for RPD framework using digitized cast and electronic surveying. Engelmeier , History and development of dental surveyor, journal of prosthodontics , March 2002,volume 11,number 1. Engelmeier , History and development of dental surveyor, journal of prosthodontics , june 2002,volume 11,number 2. Engelmeier , History and development of dental surveyor, journal of prosthodontics , september 2004,volume 13,number 3. Kaloyannides , reproduction of tilt of a cast on a surveyor, J Prosthet dent, october 1973 Knapp et al; technique for recording dental cast –surveyor relations; journal of prosthetic dentistry march 1979 Antony D. Steas , recording and reproducing the tilt of a cast on a surveyor, journal of prosthetic dentistry, january 1987 118

119. REFERENCES Ansari , A procedure for reorienting a cast on a surveyor, Journal of Prosthet Dent, july 1994 Dumbrigue and Chingbingyong , A new method for recording and reproducing cast orientation on a survey table. J Prosthet Dent 2003;89:76-8 Kamble et al, A magnetic device for recording and reproducing the path of placement for partial removable dental prostheses,( J Prosthet Dent 2013;110: 333-334 Afsal et al; Putty index for tripoding , journal of prosthodontics , january 15 2017 Gali and Lanka, A reproducible 3- point contact device for tri- poding a definitive cast, journal of prosthetic dentistry 2019 Davenport et al,Surveying , British dental journal,november 25 ,2000 119