Dental surveyor

describes different types of surveyors along with the history, advancements, parts of surveyor, brief on surveying procedure of each, surveying tools, difference between ney and jelenko surveyor, broken arm surveyor, spring loaded surveyor, william suveyor.
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1. Surveyor Presented by – Piyali Bhattacharya 1 st year PGT Dept. of Prosthodontics and Crown & Bridge HIDSAR

2. Definition : (GPT 9) An instrument used for determining the exact parallel relationships of lines, structures, and surfaces in dental casts and prostheses ; an apparatus used for making one object parallel with another object, as in paralleling attachments and abutments for fixed dental prostheses or precision attachments for removable dental prostheses

3. HISTORY OF DENTAL SURVEYOR In 1890, Dr. W . M. Randall’s technique for surveying a cast before the advent of the dental surveyor

4. The cast was stabilized on the table top with wax or impression compound after the path of placement had been determined. In principle, this technique was very similar to that used with a dental surveyor. Its accuracy, however , was completely dependent on the operator’s ability to keep the pencils parallel and steady.

5. Early Paralleling Instruments:

6. This device was intended for orthodontic research and not for mapping the “heights of contour of the teeth.” There is no evidence that the “Stanton-Hanau” surveyor was ever commercially available. Hanau’s 1917 design for a “dental surveying apparatus.”

7. Dr . Herman E. S. Chayes , an early pioneer in both fixed and removable prosthodontics, wrote extensively about precision attachments . As a result , he is generally credited with first recognizing and describing the importance of parallelism in the fabrication of passive fixed and removable partial denture restorations.

8. Around 1920, Dr. Chayes developed the Parallelometer This instrument could be used both intraorally and at the laboratory to ensure parallelism of precision attachments. The instrument also could be used to identify non-parallel and/or undercut surfaces of prepared teeth

9. Evolution In 1918, Dr.A.J.Fortunati introduced the dental surveyor at a dental clinic in Boston. Fortunati’s surveyor was a parallelometer Fortunati replaced the steel analyzing rod of a “Bridge Parallelometer ” with a graphite rod, then accurately traced survey lines of the greatest convexities of the teeth.

10. The Robinson surveyor (circa 1918) developed by the Philadelphia Dental Clinic Club is perhaps the first surveyor designed for cast surveying as part of the clasp design procedure.

11. In 1923, J.M.Ney Corporation introduced the first commercially available surveyor .(Designed by Roth and Weinstein) The current model of the Ney surveyor was introduced in 1937. This instrument can be converted into a milling machine by clamping a straight hand-piece to the surveying arm.

12. Schwartz cited Noble G. Wills as another early pioneer of removable partial denture design Wills surveyor was the original surveyor marketed by the J. F. Jelenko Company It had spring-loaded surveying arm

13. The Original Wills surveyor The Kings College surveyor (circa 1940) had an adjustable cast holder and interesting parallel, pivoting, horizontal arms. It also featured a powerful magnet in the tilting table. The cast had an iron ring imbedded in its base, so there was no need for a fixing agent.

14. Difference Between Ney And Jelenko Surveyor Ney Horizontal arm is fixed Vertical arm retained by friction Shaft remains in any vertical position until moved Jelenko Fixed horizontal arm Vertical arm is spring mounted Vertical arm when released returns to its original position. And it should be held against spring tension Cast table is fixed with magnet with the Surveying platform Cast table is moved around surveyor platform

15. William Surveyor It has a gimbal stage table adjustable to any degree of tilt. Superstructure of this surveyor has a joint arm with a spring loaded surveying arm Best suited for placing intracoronal attachment

16. This electronic surveyor, developed at the United States Air Force School of Aviation Medicine at Randolph Air Force Base, was powered by dry cell batteries and was capable of passing a weak current through the surveying tool to the cast surface. Casts were treated with phenolphthalein, and contact with the surveying tool produced a fine, red survey line.

17. The Columbia Parallelor The Roach surveyor, developed in 1944 , the smallest surveyor ever developed. The cast holder was fixed to the base, but the table could freely rotate through 360°. The horizontal arm was free to rotate 360° as well as to move vertically on the vertical arm.

18. In their 1950 text, McCall and Hugel reported that 11 dental surveyors had been featured in scientific exhibits at the American Dental Association’s 1948 Annual Meeting

19. Ney—1923 Brown-Maier—1925 Wills—1929 Lentz—circa 1935 Lineer —1937 Ney—1937 Franzwa —1937 Ringle -Hiatt-Smith—1944 McKay—1944 Hagman —1944 Roach—1944

20. MODIFICATIONS IN SURVEYOR

21. Types Of Dental Surveyor Ney Jelenko William Retentoscope A 2000- Buchnann Surveyor Micro Analyzer Stress O Graph Austenal Surveyor Optical Surveyor Computerized Surveyor Ticonium Surveyor Intraoral Surveyor

22. Broken-Arm Surveyors: The broken arm not only facilitated surveying, but also allowed the surveyor to function as a milling machine through the adaptation of a straight hand-piece to the surveying arm

23. Retentoscope The Retentoscope , produced by the Saddle-Lock Company. A rotating head supports 3 horizontal arms, 1 of which was a conventional surveying arm. A second arm supports a handpiece for milling, and the third supports a dial undercut gauge. A work light is attached to the vertical arm. The table , rather than the surveying arm, can be raised and lowered during surveying.

24. The Stressograph produced by the Ticonium Company, features 2 horizontal arm assemblies. The first arm is designed to be a conventional surveying arm, and the second arm supports a dial gauge to measure undercuts.

25. Buchnann Surveyor : Used for placing precision attachment parallel to the path of insertion Ticonium Surveyor : in this surveyor, the marking point will make vertical line on the abutment tooth until desired depth of infrabulge has been reached. Ticonium Surveyor

26. Bego Paraflex surveyor The Bego Paraflex surveyor has a solid horizontal arm and a “parameter” dial undercut depth gauge

27. The Austenal Micro Analyzer Measures undercuts electronically. A dial indicator shows the desired amount of undercut, and a flashing light signals when the exact undercut is reached. The Austenal Flexseal preformed clasp patterns are used as a standard of measurement.

28. The Austenal Surveyor includes an electrically heated waxing tool. This device had a surveying arm at least 3 feet long that could pivot at some predetermined point well above the cast holder. the operator could move the surveying arm laterally, heat the attached waxing instrument in an open flame, and then return the apparatus to the master cast Blockout Instruments

29. The Paratherm surveying and blockout waxing instrument heats its waxing tools electrically. The surveying arms move in 3 axes. Paratherm also offers the Paraline , a non-electrical surveyor based on the Paratherm design.

30. Milling Machines

31. Recent Innovations Dramatically exposes undercut areas by projecting a beam of laser light

32. Optical Surveyor Parallel light beams with light bulbs with dense filaments . Changes in survey lines and unddercuts can be surveyed easily Better visualization Disadvantage: Requires dark room Light beams reflecting from cast can cause illumination

33. Intraoral Surveyor For checking tooth preparation of abutment teeth in FPD/RPD Accurately indicates path of insertion Visual guide during tooth preparation Inexpensive, practical and readily available

34. THREE DIMENSIONAL COMPUTER AIDED SURVEYING 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

35. 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.

36. Purpose Of Surveyor Surveying the diagnostic cast Tripoding the cast Surveying the master cast Contouring the wax pattern Placement of internal rest seats Machining the restoration

37. Use of Surveyor: To determine the most desirable paths of insertion and removal for removable partial dentures. To identify proximal surfaces that must be prepared to serve as guiding planes. To delineate the heights of contour for all of the teeth and to locate and measure retentive areas. To locate both dental and osseous contours that could interfere with insertion and removal of a partial denture framework and to allow accurate charting of the necessary mouth preparation. To record the cast position and its relation to the path of placement.

38. To transfer the partial denture design to the master cast in the laboratory. To block out the master cast and to trim the blockout material. To develop the axial contours of wax patterns. To machine guiding planes. To facilitate the placement of intra-coronal retainers.

39. PARTS OF A SURVEYOR A- Surveying Platform B- Vertical Arm C- Horizontal Arm D- Surveying Arm E- Mandrel F- Surveying Tools G- Surveying Table

40. Surveying Tool: Analyzing Rod- To determine relative parallelism of surfaces on dental cast Carbon Marker- to mark the greatest circumference of teeth

41. Surveying Tool: Undercut Gauges- To accurately locate retentive undercuts on proposed abutments According to stewart’s size of undercut gauge - 0.010, 0.015, 0.020 inches respectively. According to Mc Cracken the undercut gauge size- 0.010, 0.020 , 0.030 inches.

42. Ney surveyor has a circular beaded undercut gauge Jelenko surveyor has a fan shaped bead with gauges of different dimensions

43. A surveying Wax Knife- for blocking out the surveying restorations

44. References: The History and Development of the Dental Surveyor : Part I, Engelmeier , Journal of Prosthodontics, Vol 11, No 1 (March), 2002: pp 11-18 The History and Development of the Dental Surveyor : Part II, Engelmeier , Journal of Prosthodontics, Vol 11, No 2 ( June), 2002: pp 122-130 Stewart’s clinical removable partial prosthodontics , 4 th edition Mc Cracken’s Removable Partial Prosthodontics 11 th edition