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Dental surveying of Removal partial denture


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Seminar of surveying of Removal partial denture

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Dental surveying of Removal partial denture

  1. 1. TEAM WORK : Ali Alarasy Afaf Attam Ali Almoliki Lena Abdullah Kais Alhetar Maees Manssor Mohammed Alraei Supervision : Dr. Ali Alsorory Dr. Radoan Aljabri
  2. 2. Dental surveyor : Is an instrument used to survey the abutment teeth and the associated structures. • Or : It's an instrument used to determine the relative parallelism of two or more surfaces of the teeth or other parts of the cast of the dental arch (McCracken) Surveyor also called parallelometer.
  3. 3. Types of surveyor : Many types of surveyor exist from the simple mechanical to the complicated electronic.
  4. 4. Mechanical surveyors :  Are relative inexpensive and easy to use.  Types of mechanical surveyors :  These types have a slightly difference in their constructions.  They are basically the same and produce identical results. 1. Ney. 2. Jelenko. 3. Williams. 4. Retentoscope. 5. Ticonium. 6. The micro analyzer.
  5. 5. Ney william Retentoscope Ticonium The micro analyzerJelenko
  6. 6. Electronic surveyors:  Are complicated and expensive.  Their use restricted to research and large commercial laboratory.
  7. 7. The choice of surveyors depends on : 1. Availability. 2. Personal preference.
  8. 8. Batterfein divided the buccal and lingual surfaces of the tooth adjacent to edentulous space in to two halves : 1. Near zone :  The area closer to the edentulous space. 2. Far zone :  The area lies away from the edentulous space.
  9. 9. Parts of the dental surveyor : 1. Horizontal arm. 2. Vertical arm. 3. Surveying arm. 4. Base. 5. Adjustable table. 6. Surveying tools (Accessories) : A. Analyzer rod. B. Carbon (graphite) marker. C. Undercut gauge. D. Wax trimmer (chisel).
  10. 10. A. Analyzer rod : Metal rod placed against the teeth and ridge during the initial analysis of the cast to identify undercut areas and areas of parallelism without marking the cast.
  11. 11. B. Carbon marker : The graphite marker is moved along the teeth and alveolar ridge to identify and mark the position of the maximum convexity (survey line).
  12. 12.  Survey line are classified to : 1. High survey line :  Found near the occlusal surface of the tooth often parallel to the gingival margin.  It result from abnormal inclination of the tooth and frequently found on the lingual surfaces of the lower teeth and on the buccal surfaces of the upper teeth. 2. Medium survey line :  It’s situated across the central of the tooth and exhibits a slight occluso-gingival incline from the near zone to the far zone. 3. Low survey line :  It’s situated close to the parallel to the gingival margin. 4. Diagonal survey line :  It travels diagonally from the occlusal surface in the near zone to the gingival in the far zone.
  13. 13. high medium low diagonal
  14. 14. C. Undercut gauge :  They are provided to measure the horizontal undercut.  available in these size :  0.25 mm (0.01 inch)  0.5 mm (0.02 inch)  0.75 mm (0.03 inch)
  15. 15. Undercut gauge
  16. 16. D. Wax trimmer (chisel) :  Is used to remove the excess wax, that added to block the unwanted undercut.
  17. 17. Purposes of surveyor : The main purpose of surveyor is to identify the modification of the oral structures that are necessary to fabricate R.P.D. 1. Surveying diagnostic cast. 2. Contouring wax patterns. 3. Surveying ceramic veneer crowns. 4. Placement of intracoronal retainers and internal attachment. 5. Placement of internal rest seat. 6. Machining cast restoration. 7. Surveying the master cast.
  18. 18. • Wax contouring Surveying ceramic crowns Surveying and blocking the master cast
  19. 19. Objective of surveying : 1. Locate proximal tooth surfaces that are parallel to act as guiding surfaces. 2. Locate and measure recesses or undercut for mechanical retention. 3. Identify areas of potential hard or soft tissue interferences. 4. Determine the path of insertion with aesthetic requirements. 5. Determine the most advantageous path of insertion or removal of R.P.D. 6. Delineate the height of contour of the abutment teeth and identify the areas of undercut that must be avoided, reduced or blocked out. 7. Help in planning restorative procedure. 8. Record the most ideal cast position for future reference. 9. Establish a formal plan for R.P.D design and the required mouth preparation.
  20. 20. The advantages of surveying the diagnostic (study) cast : 1. Permit an accurate charting of the required of the mouth preparation. 2. Determine the desirable and undesirable undercuts. 3. Determine proximal tooth surfaces used as guiding planes. 4. Determine the best path of placement and removal of the prosthesis.
  21. 21. The advantages of surveying the master cast : 1. Determine the most acceptable path of placement and removal which is free from any interference. 2. Determine soft, bony or tooth undercuts and areas of interference that should be blocked out or eliminated. 3. Determine the relative parallelism of teeth surfaces that act as guiding planes. 4. Identify and measure tooth undercuts that may be used for retention. 5. Aid in determining restorative procedures and mouth preparation. 6. Delineate height of contour (survey line) on the abutment. 7. Trimming block out material parallel to the path of placement. 8. Recording the cast position in relation to a selected path of placement for future reference.
  22. 22. Principles and rules for surveying : 1. By surveying, the prosthesis goes smoothly into place without interference. 2. All cast are originally surveyed with the occlusal-plane parallel to the base of the surveyor (zero tilt). 3. When the surveyor blade contacts a tooth on the cast at its greatest convexity, a triangle is formed, the apex of the triangle is at the point of contact of the surveyor blade with the tooth, and the base is the area of the cast representing the gingival tissues. The apical angle is called the angle of cervical convergence. This will indicate the areas available for retention and the existence of tooth and other tissue interference to the path of placement.
  23. 23. 4. A cast in a horizontal relationship to the vertical arm represents a vertical path od insertion; a cast in a tilted relationship represents a path of placement toward the side of the cast that is tilted upward. 5. Any areas cervical to the height of contour may be used for the placement of retentive clasp components, whereas areas occlusal to the height of contour may be used for placement non-retentive, stabilizing or reciprocating components. 6. Wherever possible, undesirable undercut and areas of interference are removed during mouth preparation by recontouring teeth or making necessary restoration. 7. The location of the undercut area can be changed by tilted the cast anteriorly or laterally.
  24. 24. 8. Deciding the tilt of the cast depends in path of placement and removal of the denture. 9. A combination between two tilts could be used. 10. An anterior tilt is sometimes preferred in distal extension bases this increases resistance to vertical displacement by the denture base by engaging undercut distal to the abutment teeth. 11. The retentive tips of clasps must engage undercut, which are present,when the cast is surveyed with the occlusal plane parallel to the base of the surveyor, i.e. undercut areas should be present at both zero tilt and new tilt. 12. The retention on all principles abutments should be as nearly equals as possible. 13. Without guiding planes, clasp retention will either be detrimental or practically nonexistent.
  25. 25. Path of insertion Definition of path of insertion : Is the direction of movement in which the prosthesis moves from the point of initial contact with the supporting teeth to the terminal resting position without injury and interference. Definition of path of removal :  The direction of movement of the prosthesis from its resting position to the last contact with supporting teeth without injury and interference.
  26. 26. Types of path of insertion : 1. Single : It’s most likely to exist when bounded edentulous areas are present. 2. Multiple : Exist where guide surfaces are not utilized.  Ex : where abutment teeth are divergent. 3. Rotational :  Two distinct paths of insertion will be employed for a sectional or two part denture.
  27. 27. Rotational path of insertionun Multiple path of insertionSingle path of insertion
  28. 28. Factors that determine the path of insertion : 1. Guiding planes. 2. Interference. 3. Healthy of the abutment teeth. 4. Retentive undercut. 5. Aesthetic.
  29. 29. Factors that determine the path of insertion : 1. Guiding planes : Definitions :  Are vertically parallel axial surfaces on the abutment teeth oriented to contribute to the direction of the placement and removal of R.P.D  Proximal tooth surfaces that bear a parallel relationship to one another, Must be either found or created to act as guiding planes during placement and removal of the prosthesis.
  30. 30. Advantages of guiding planes : A.It’s flat surface without undercut so it makes the insertion and removal of the prosthesis easy. B.It attaches the surface of the abutment teeth thus provide bracing that aid in the stability of the prosthesis. C. Prevent clasp deformation.
  31. 31. Importance of the guiding planes : A.Guiding planes are necessary to ensure the passage of rigid parts of the prosthesis. B.Guiding planes are necessary to ensure predictable clasp function, including retention and stability. C. Guiding planes are necessary to give a positive direction to the prosthesis to and from its terminal position.
  32. 32. 2. Interference : Feature of the mouth which interfere with the easy insertion and removal of the prosthesis. Interference in the mandible may because of : A.Bony prominence. B.Mandible tori. C. Lingual inclined teeth (particularly the premolars). D.Undercut alveolar ridge. E.Interference with surfaces of the abutment teeth.
  33. 33. Interference in the maxilla May found in this areas : A.Buccally inclined posterior teeth. B.Bony areas on the buccal aspect of edentulous spaces. C. Surface of the abutment teeth.
  34. 34. Interference can be eliminated by : A.Surgical removal in the case of severe bony interference. B.Changing the design of R.P.D. C. Changing the path of insertion. D.Contouring or reshaping tooth surface. E.Extraction the tooth that cannot be restored or that is away from the occlusal plane.
  35. 35. 3. Healthy of the abutment : The clasp of the R.P.D should be placed on strong and healthy abutment teeth.
  36. 36. 4. Retentive undercut : Undercut :  Is the convexity and bulbous of the tooth below the height of contour. Location of undercut : Undercuts are located on the lingual a buccal surfaces of the abutment.
  37. 37. Types of undercut : 1. Desirable: • Undercut that is used in the design of R.P.D 2. Non desirable : • Any undercut that is not used in the design.
  38. 38. The amount of retention existing below the height if convexity can be determined by this method : • By directing a small source of light toward the cast from the side away from the dentist, the angle of cervical convergence is best observed as a triangle of light between the surveyor blade and the apical portion of the teeth.
  39. 39. Retention of the clasp arm can be determined by the angle of convergence. The undercut should be equal in depth and should permit the location of clasp tip in the gingival third of the abutment tooth. • The undercut should be posterior and lateral in order the prosthesis not to be displaced during function.
  40. 40. Tooth without undercut we must create undercut by contouring or dimpling.  Dimpling : Creation of undercut on the buccal surface of the abutment teeth.
  41. 41. 5. Aesthetic : Chosen the design of R.P.D in which the display of metal which has ugly appearance is minimized. Clasp design that will provide satisfactory aesthetic for any given path of insertion must selected. Tapered wrought wire retentive clasp arm is more aesthetic than cast clasp. The use of attachment is more aesthetic than clasp. The preference of the aesthetic against other factors depends on the location of the prosthesis. When anterior replacement is involved, aesthetic must be given the primary consideration. The objective should always to obtain an appearance as natural as possible.
  42. 42. Surveying procedure This may be divided into the following distinct phases: 1. Initial survey. 2. Analysis. 3. Final survey.
  43. 43. The initial survey :  The cast is positioned with the occlusal plane horizontal.  The teeth and ridges are then surveyed to identify undercut areas that might be utilized to provide retention in relation to the most likely path of displacement.  The position of the survey lines and the variations in the horizontal extent of undercut associated with them should be noted.  The amount of undercut can be judged approximately from the size of the ‘triangle of light’ between the marker and the cervical part of the tooth, or measured more precisely by using an undercut gauge.  An assessment can then be made as to whether the horizontal extent of undercut is sufficient for retention purposes.
  44. 44. Initial survey and measuring the undercut
  45. 45. The Analysis :  An RPD can be designed on a cast which has been surveyed with the occlusal plane horizontal (i.e. so that the path of insertion equals the path of displacement).  However, there are occasions when tilting of the cast is indicated so that the paths of insertion and displacement differ.  The analysis of the cast continues with the occlusal plane horizontal and the following aspects, one or more of which might necessitate a final survey with the cast tilted, are considered: 1. Appearance. 2. Interference. 3. Retention. 4. Guiding planes
  46. 46. Appearance  When a maxillary cast, containing an anterior edentulous area, is surveyed with the occlusal plane horizontal it will often be found that there are undercuts on the mesial aspects of the abutment teeth.
  47. 47.  The mesial gap can be avoided by giving the cast a posterior (heels down) tilt so that the analyzing rod is parallel with the mesiolabial surface of the abutment tooth.
  48. 48.  With this posterior path of insertion the saddle can be made to contact the abutment tooth over the whole of the mesiolabial surface and a much better appearance results.
  49. 49. Interference :  While examining the cast with the occlusal plane horizontal, it sometimes becomes apparent that an undercut tooth or ridge would obstruct the insertion and correct placement of a rigid part of the denture. By tilting the cast, a path of insertion may be found which avoids this interference.  For example, if a bony undercut is present labially, insertion of a flanged denture along a path at right angles to the occlusal plane will only be possible if the flange stands away from the mucosa or is finished short of the undercut area. This can result in poor retention as well as a poor appearance.
  50. 50. • If the cast is given a posterior tilt so that the rod, and thus the path of insertion, is parallel to the labial surface of the ridge it is possible to insert a flange that fits the ridge accurately.
  51. 51. • Lingually tilted premolars can make it impossible to place a sublingual, or lingual, bar connector sufficiently close to the lingual mucosa. Such a problem would occur lingually to LR4. • If interference from a tooth is present and cannot be avoided by selecting an appropriate path of insertion, consideration should be given to the possibility of eliminating the interference by tooth preparation.
  52. 52. Guiding plans :  Analyze the proximal abutment tooth surfaces with the surveyor-analyzing rod. Alter the cast position anterioposteriorly until their proximal surfaces are in parallel relation to one another or near enough that they can be made parallel by recontouring. The end result should provide parallel proximal surfaces that may act as guiding planes.
  53. 53. Retention :  To obtain retention, undercuts must be present on teeth relative to the horizontal survey.  It is a misconception to believe that changing the tilt of the cast will produce retentive undercuts if none exist when the cast is horizontal.
  54. 54.  The principle of tilting the cast to enhance retention is that by so altering the path of insertion; so a rigid part of the denture can enter an area of the tooth surface or an area of the ridge which is undercut relative to the path of displacement.
  55. 55. The Final Survey • If it is decided that the cast should be tilted, the analysing rod is exchanged for a marker different in colour from that used in the first survey, and the final survey is carried out. It will then usually be found that the teeth to be clasped have two separate survey lines which cross each other. In order to obtain optimum retention it is necessary to understand how to position the clasps correctly in relation to the two survey lines.
  56. 56.  The aims for optimum retention should be to provide: • Resistance along the path of displacement. • Resistance along the path of withdrawal.  The former can be achieved by the use of guide surfaces or clasps while the latter is provided by clasps alone. • When guide surfaces are used to provide resistance to displacement of the denture in an occlusal direction, the retentive portion of the clasp needs only to resist movement along the path of withdrawal and therefore can be positioned solely with reference to the red survey line.
  57. 57. • It does not matter if, as in this example, the clasp engages too deep an undercut relative to the path of displacement. Movement of the denture in an occlusal direction is prevented by contact with the guide surface, therefore permanent deformation of the clasp will not occur.
  58. 58. • A gingivally approaching clasp positioned at the cross-over point of the survey lines resists movement along both the path of withdrawal and the path of displacement without being permanently deformed by movement along either path.
  59. 59.  If the survey lines converge mesially or distally, the tip of an occlusally approaching clasp can engage the common area of undercut to provide resistance to movement along both paths.
  60. 60. Recording the cast position and tilting : 1. The tripod method.  Tripoding is done by drawing three widely separated cross marks on the tissue side of the cast lingualy or palatal to the remaining natural teeth while the cast and the vertical arm is locked at a certain vertical height.  The cast can be repositioned to the same tilt by allowing the analyzing rod to touch one of the cross marks, the spindle is then locked at this vertical height and the tilt of the cast is modified until the rod touches the three cross marks. Then locking the surveyor table to its original position.
  61. 61. 1. The analyzing rod method (scoring).  Two sides and dorsal aspect of the base of the cast are scored with a sharp instrument held against the surveyor blade.  By tilting the cast until all three lines are parallel to the surveyor blade, the original tilt be re-established.
  62. 62. References : McCracken’s removable partial prosthodontics 12th Edition. Deepak Nallaswamy, Text book of prosthodontics Jaypee. J. C. Davenport, R. M. Basker, J. R. Heath, J. P. Ralph, and P-O. Glantz (2000): A Clinical Guide to Removable Partial Denture Design (ISBN 0- 904588-637). J. C. Davenport, R. M. Basker, J. R. Heath, J. P. Ralph, and P-O. Glantz,(2000): Surveying; British Dental Journal ; 189: 532–541.