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INDIRECT RETAINERS

INDIRECT RETAINERS. Definitions. Indications for I. R. Types. Factors Affecting I.R. Tipping (Rocking). Is the Rotation of Partial Denture around a Fulcrum. F. DEFINITIONS.

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INDIRECT RETAINERS

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  1. INDIRECT RETAINERS

  2. Definitions Indications for I. R. Types Factors Affecting I.R.

  3. Tipping (Rocking) Is the Rotation of Partial Denture around a Fulcrum

  4. F

  5. DEFINITIONS

  6. Tooth-tissue supported partial denturesare subjected to vertical displacing forces acting in an occlusal direction. These forces may totally displace the denture if the direct retainers are not functioning adequately. However if the direct retainers are adequate, rotation of the denture around a fulcrum axis rather than total displacement occurs. This rotation is counteracted by the unit of the partial denture called "Indirect retainer".

  7. In tooth supported partial dentures; tissue away movement of the prosthesis is prevented by the action of direct retainers and rests placed on the abutment teeth (self indirect retainer). • In mucosa supported partial dentures;(full palatal coverage) tissue away movement of the prosthesis is prevented by mechanical means (clasps) and by the action of physical means of retention on a well fitting denture base and the connector (direct indirect retention).

  8. Indirect Retainersare “components of removable partial denture that are used to reduces the tendency of the denture to rotate in an occlusal direction about the fulcrum axis”

  9. Fulcrum Lines Retentive fulcrum line is the line joining the retentive tips of the clasps holding the principal abutments (Diagonally placed). Supportive Fulcrum Line Is the Line Joining the Occlusal Rests Supported by Principal Abutments.

  10. F

  11. F This Movement Is Related To Quality Of The Tissue, Extent Of Denture Base And Its Fit And The Amount Of Force Applied

  12. Indirect Retention Components of RPD That Are Used to Reduces Its Tendency to Rotate in an Occlusal Direction About the Fulcrum Axis Supportive Elements (Rests) Used to Retain Far Ends of Partial Dentures

  13. DIRECT RETAINERS Retaining Elements (Clasps) Used to Retain Near Ends of Partial Dentures

  14. F This Movement Is Related To Quality Of The Tissue, Extent Of Denture Base And Its Fit And The Amount Of Force Applied Support

  15. Indications for Indirect Retainers

  16. Tooth-tissue Supported Partial Dentures Are Subjected to Vertical Displacing Forces Acting in an Occlusal Direction. If the Direct Ret. Are Adequate, Rotation of the Denture Around a Fulcrum Axis Rather Than Total Displacement Occurs

  17. F

  18. Class I

  19. Class II

  20. Class IV

  21. Long Span Class III

  22. Factors Influencing the Effectiveness of Ind.Ret. 1-Effectiveness of the Direct R.

  23. 2- Proper Location of I.R • Well-supported I. R. Should Be Placed As Far From the Fulcrum Line As Possible. The Greater the Distance, the More Effective Is the Indirect Retention • A Perpendicular Line Projecting Anteriorly From the Fulcrum Axis Is the Most Effective Location of I. R. And Affords the Best Resistance Against Vertical Dislodging Forces

  24. 3- Effectiveness of the Supporting Structures • Definite, Properly Prepared Rest Seat • Should Never Be Placed on Weak Teeth or on Inclined Surfaces

  25. I.R. In the Form of Rest Should Be Placed in a Definite, Properly Prepared Rest Seat That Allows Transmission of the Forces Along the Long Axis of the Tooth Without Slippage of the Rest or Movement of the Tooth

  26. 4- Rigidity of the Denture Frame • The Minor Connector Joining the I. R. to the Framework Should Be Rigid. Flexing of the Connector Multiplies Rather Than Dissipates the Applied Forces

  27. Factors Influencing the Effectiveness of Ind.Ret. 1- Effectiveness of the D. R. 2- Proper Location of I.R 3- Effectiveness of the Supporting Structures 4- Rigidity of the Denture Frame

  28. Talk slowly but think quickly

  29. Forms of I.R. 1-Rests 2-Connectors

  30. Forms of Ind.Retainers A- R. Used In Mandibular P. D. 1-Auxiliary Occlusal or Canine Rests

  31. 2- Principal Occlusal Rest of Modification Area

  32. 2- Principal Occlusal Rest of Modification Area 2 1

  33. 3- Embrasure Hooks

  34. 4- Auxiliary Rests at the Terminal Ends of Ling. Plate or Kennedy Bar

  35. Forms of Ind.Retainers A- R. Used In Mandibular P. D. 1-Auxiliary Occlusal or Canine Rests 2- Principal Occlusal Rest of Modification Area 3- Embrasure Hooks 4- Auxiliary Rests at the Terminal Ends of Ling Plate or Kennedy Bar

  36. B- Indirect Retainers Used in Maxillary Partial Dentures 1) Cummer Arm 2) Palatal Arm 3) Anterior Palatal Bar 4) Posterior Palatal Bar

  37. 5) Palatal Strap and Rugae Support 6) Direct-indirect Retainer (Full Palatal Coverage) 7) Auxiliary Occlusal or Canine Rests 8) Principal Occlusal Rest of Modification Area

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