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DIRECT RETENTION.

DIRECT RETENTION. BY : DR. Nora cheta. Intracoronal attachments. Extracoronal attachment. Retentive arm. CLASP ASSEMBLY. Occlusal rest. Bracing arm. Minor connector. SURVEY LINE. NON UNDECUT AREA. Carbon Marker. UNDERCUT AREA. HEIGHT OF CONTOUR. UNDERCUT GAUGE.

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DIRECT RETENTION.

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  1. DIRECT RETENTION. BY : DR. Nora cheta

  2. Intracoronal attachments

  3. Extracoronal attachment

  4. Retentive arm CLASP ASSEMBLY Occlusal rest Bracing arm Minor connector

  5. SURVEY LINE NON UNDECUT AREA Carbon Marker UNDERCUT AREA HEIGHT OF CONTOUR

  6. UNDERCUT GAUGE DESIRABLE UNDERCUT NON DESIRABLE UNDERCUT

  7. DESIRABLE UNDERCUT NON DESIRABLE UNDERCUT

  8. Types of Survey Line Away from the saddle Near the saddle

  9. A-MEDUIM SURVEY LINE Midway between Occlusal surface & Gingival margin in the Near zone Nearer to gingival margin In the far zone We can use occlusally or gingivally approaching clasps

  10. B-DIAGONAL SURVEY LINE Near occlusal surface In the near zone Near gingival margin In the far zone Ging.app. With L bar C clasp Or Or Or Back action & Reverse back Ging.app. With T bar

  11. C-HIGH SURVEY LINE Near to the occlusal surface Back action or reverse back action commonly in inclined teeth Bracing Arm Wrought wire occlusally app.

  12. TILTING THE TOOTH BUCCALLY SENDS THE SURVEY LINE MORE OCCLUSALLY!! BUCCAL BUCCAL

  13. TILTING THE TOOTH LINGUALLY SENDS THE SURVEY LINE MORE CERVICAL!! LINGUAL LINGUAL

  14. D- LOW SURVEY LINE Near the gingival margin Extended arm clasp • Devan clasp engaging proximal undercut • Crowning of the tooth

  15. REQUIREMENTS OF CLASP DESIGN. Retentive arm better located In the gingival 1/3 for better esthetics & mechanics Bracing arm better located In the apical portion of the Middle 1/3

  16. UNDERCUT IS BETTER BE FOUND WITHIN THE GINGIVAL1/3 For mechanical reasons Post Is More Readily Removed by Application of Force Near Its Top Than by Applying Same Force Nearer Ground Level

  17. RECOPRICATION

  18. Each retentive terminal should be reciprocated as retentive arm exerts some orthodontic movement during placement and removal as it flexes about the height of contour.

  19. BRACING

  20. THE DIFFERENCE IS!!!!! • RECOPRICATION IS TO PREVENT THE NATURAL TOOTH MOVEMENT. • BRACING IS TO PREVENT THE WHOLE DENTURE MOVEMENT. • BOTH ARE APPLIED USING THE SAME COMPONENT ---------BRACING ARM-----

  21. OCCLUSAL 1/3, FOR SUPPORT MIDDLE 1/3, FOR BRACING &RECOP. GINGIVAL 1/3, FOR RETENTION.

  22. 180 degrees ENCIRCLEMENT OF THE TOOTH. Tooth can't move horizontally away from the clasp

  23. Amount of retention depends on A- depth of undercut The greater the distance we go into the undercut the greater will be the retention

  24. 2. FLEXIBILITY OF CLASP ARM LENGTH Increasing arm length increases the flexibility ,thus decreasing the retention

  25. SHAPE OF THE CLASP CROSS SECTION Round clasps have universal flexibility thus lowers the retention than ½ round and flat clasps

  26. Degree of taper Retentive arm should be tapered in two dimensions.

  27. The diameter of retentive arm The material of the alloy (gold alloy are more flexible than cobalt chrome alloy ) The type of alloy (wrought wire

  28. C- Angle of cervical convergence

  29. Clasps according to method of approach to undercut Occlusally approaching clasp Gingivally approaching clasp

  30. OCCLUSALLY APPROACHING.

  31. 1-Akers clasp (circlet)

  32. 2-DOUBLE AKER (embrasure) LINGUAL BUCCAL

  33. CROSS ARCH STABILISATION!!

  34. 3-CIRCUMFERENTIAL `C` CLASP

  35. B-DIAGONAL SURVEY LINE Near occlusal surface In the near zone Near gingival margin In the far zone Ging.app. With L bar C clasp Or Or Or Back action & Reverse back Ging.app. With T bar

  36. 4-R.P.A, REST, PROXIMAL PLATE ,AKER.

  37. 5- Multiple clasp

  38. 6- Extended arm clasp Adjacent tooth has a reasonable undercut Abutment has no undercut

  39. D- LOW SURVEY LINE Near the gingival margin Extended arm clasp • Devan clasp engaging proximal undercut • Crowning of the tooth

  40. 7- Half & Half clasp • 2 M.C., 2 O.R. & 2 arms. • Mainly indicated for dual retention commonly in unilateral cases.

  41. SINGLE ARM CLASPS!!! THESE ARE FLEXIBLE CLASPS, DUE TO THEIR ELONGATED SINGLE ARM, AND THEY PROVIDE POOR BRACING.

  42. 7-RING CLASP (ISOLATED, BADLY LINGUALLY TILTED, LOWER MOLAR.)

  43. Distal Buccal Lingual Strut arm Mesial

  44. 8-Reverse Back action clasp. (MANDIBULAR) M.C. originating Mesio-buccally Retentive arm engage Mesio-lingual undercut

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