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DENTAL SURVEYOR The tool for perfect planning of Removable Partial Denture

DENTAL SURVEYOR The tool for perfect planning of Removable Partial Denture. Dalhousie continual education McCracken’s Removable Prosthodontics , 11 th Edition. Lecture Outline. Description of Dental Surveyor Purposes of Surveyor Discussing some related terms

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DENTAL SURVEYOR The tool for perfect planning of Removable Partial Denture

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  1. DENTAL SURVEYORThe tool for perfect planning of Removable Partial Denture • Dalhousie continual education • McCracken’s Removable Prosthodontics, 11th Edition

  2. Lecture Outline Description of Dental Surveyor Purposes of Surveyor Discussing some related terms Factors That Determine Path of Placement and Removal • Guiding Planes • Retentive Areas • Interference • Esthetics Step-by-Step Procedures in Surveying Diagnostic Cast Recording Relation of Cast to Surveyor

  3. Definition An instrument used to determine the relative parallelism of two or more surfaces of the teeth or other parts of the cast of a dental arch. *

  4. Purposes of Surveying the Diagnostic Cast 1. To determine the most desirable path of placement that will eliminate or minimize interference to placement and removal 2. To identify proximal tooth surfaces that are, or need to be, made parallel so that they act as guiding planes during placement and removal. 3. To locate and measure areas of the teeth that may be used for retention.

  5. Purposes of Surveying the Diagnostic Cast 4. To determine whether tooth and bony areas of interference will need to be eliminated surgically or by selecting a different path of placement. 5. To determine the most suitable path of placemen that will permit locating retainers and artificial teeth to the best esthetic advantage. 6. To permit an accurate charting of the mouth preparation to be made

  6. Purposes of Surveying the Diagnostic Cast 7. To delineate the height of contour on abutment teeth and to locate areas of undesirable tooth undercut that are to be avoided, eliminated, or blocked out. 8. To record the cast position in relation to the selected path of placement for future reference.

  7. Some Important Terms

  8. Height of Contour & Undercut

  9. Height of Contour (HOC) A line encircling a tooth, designating its greatest circumference at a selected position determined by a dental surveyor.

  10. Suprabulge • Undercut = • Infrabulge • Height of contour

  11. Any areas cervical to HOC used for placement of retentive clasp components • Areas occlusal to the HOC used for the placement of nonretentive, stabilizing, or reciprocating components. *

  12. Non-undercut Area Undercut here

  13. Types of undercuts Tooth Undercuts * Soft Tissues or bony Undercuts(on lingual side of ridge) #

  14. Angle of Cervical Convergence An angle viewed between a vertical rod contacting an abutment tooth and the axial surface of the abutment cervical to the height of contour.

  15. Direct Retainers • Retention • Composed of: • rest • retentive element • reciprocal (bracing) element • minor connector Buccal Lingual

  16. Rule: Retentive tip should usually be designed to be placed in the gingival 1/3

  17. Path of Insertion & Removal

  18. Path of Insertion • Path that the prosthesis is • Placed/removed • Usually a single path

  19. Path of Insertion (P.I) The Direction in Which a Restoration/ Prosthesis Moves From the Point of Initial Contact With the Supporting Teeth to the Terminal Resting Position Where the Occlusal Rests Are Seated and the Denture Base Is in Contact With the Tissue Path of Removal (P.R) Reverse of the Path of Insertion *

  20. Advantages of a Single Path of Insertion • Equalizes retention

  21. Advantages of a Single Path of Insertion • Bracing and Cross-arch Stabilization

  22. Advantages of a Single Path of Insertion • Minimizes torque on abutments

  23. Advantages of a Single Path of Insertion • Allows removal without encountering interferences

  24. Advantages of a Single Path of Insertion • Directs forces along long axes of teeth

  25. Advantages of a Single Path of Insertion • Provides frictional retention

  26. Factors Determining Path of Insertion & Removal Guiding planes Retentive areas Interference Esthetics

  27. Guiding Planes • Two or more vertically parallel flat surfaces of abutment teeth shaped to direct a prosthesis during placement and removal *

  28. Proximal Plates • Bracing Arms • Rigid portions of Retentive Arms * Guiding Planes • Where rigid components contact abutments

  29. Effects of Guiding Planes on Retention & Stability • Maintains Retention

  30. Effects of Guiding Planes On Retention & Stability • Minimizes Need for Retention

  31. Guiding Planes Functions • to ensure passage of the rigid parts of prosthesis past existing areas of interference. # • to control & limit directions of movement of RPD as it is being inserted, removed or while in function. • to ensure predictable clasp assembly function, including retention and stabilization *

  32. Effectiveness of Guideplanes • Most effective when: • Prepared on several teeth • Cover a large surface area (proximal & lingual)

  33. Prep. Of Guiding Planes Prepare Guiding Planes First *

  34. Use Finger Rest

  35. Burs • Long Cylindrical Carbide or Diamond (8837K 014) 8837K-014

  36. Guiding Plane Dimensions *

  37. Guiding Plane Dimensions *

  38. Polish Prepared Surfaces • Rubber wheels or points

  39. If Axial Surface Already Parallel to Path of Insertion? • NO Preparation !

  40. Retentive Areas

  41. Retentive Areas • Retentive arm should have a different path of escapement than guiding plane (path of removal), so retentive arm must be forced to flex over a convex surface during placement and removal (retention) *

  42. Optimal Path of Insertion • Retentive undercuts equalized • Ideally, retentive arms should oppose each other on opposite sides of the arch with fairly even retention *

  43. Retentive Areas To obtain fairly even retention: --change the path of placement to increase or decrease the angle of cervical convergence of opposing retentive surfaces of abutment teeth. OR --alter flexibility of retentive clasp arm

  44. Optimal Path of Insertion (Interference) * Prosthesis must be designed so that it may be placed and removed without encountering toothorsoft tissue interference

  45. Interference Bony prominences and lingually inclined premolar teeth are the most common causes of interference to a lingual bar connector *

  46. Interference If the interference is bilateral, surgery or recontouring of lingual tooth surfaces, or both, may be unavoidable. If it is only unilateral, a change in the lateral tilt may prevent an area of tooth or tissue interference.

  47. Interference Bony undercuts • to remove them surgically; • to change the path of placement at the expense of modifying or restoring teeth to achieve guiding planes and retention; • to design denture bases to prevent such undercut areas.

  48. Interference Generally, interference that cannot be eliminated for one reason or another will take precedence over the factors of retention and guiding planes.

  49. Optimal Path of Insertion (Esthetics) • Esthetics • Minimize display of clasps, metal components *

  50. Esthetics • Esthetics dictates the choice of path selected only when missing anterior teeth must be replaced with RPD *

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