clasp assembly dentistry

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factors to consider

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  • The position of undercut is very important factor for selecting clasp in removable partial dentures, especially in distal extension cases. A simple technique for selecting clasp in distal extension partial dentures is introduced in the article: Hakkoum, M. A. (2015), New Clasp Assembly for Distal Extension Removable Partial Dentures: The Reverse RPA Clasp. Journal of Prosthodontics. doi: 10.1111/jopr.12313 http://onlinelibrary.wiley.com/doi/10.1111/jopr.12313/abstract
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clasp assembly dentistry

  1. 1. DISCUSS THE FACTORS THAT NEED TO BE CONSIDERED IN SELECTING THE RIGHT CLASP ASSEMBLY FOR A REMOVABLE PARTIAL DENTURE (RPD) WELLINGTON J. NII DARKO
  2. 2. OUTLINE • INTRODUCTION • FACTORS TO CONSIDER • CONCLUSION
  3. 3. INTRODUCTION • A CLASP ASSEMBLY IS THE PART OF AN RPD THAT ACTS AS A DIRECT RETAINER AND/OR STABILIZER FOR THE PROSTHESIS BY PARTIALLY ENCOMPASSING OR CONTACTING AN ABUTMENT TOOTH
  4. 4. INTRODUCTION • COMPONENTS • FUNCTIONS • TYPES OF CLASPS
  5. 5. FACTORS • POSITION OF UNDERCUT • HEALTH OF THE PERIODONTAL LIGAMENT • SHAPE OF SULCUS • OCCLUSION • HYGIENE • AESTHETICS/ APPEARANCE • BRACING • LENGTH OF THE CLASP
  6. 6. POSITION OF UNDERCUT • Diagonal survey lines • Larger undercut furthest away • Typical designs
  7. 7. POSITION OF UNDERCUT • Larger undercut nearer to saddle • Ring clasp • ‘I’ bar
  8. 8. POSITION OF UNDERCUT • Tilted • Low survey line on buccal surface • High survey line on lingual surface • Ring clasp
  9. 9. POSITION OF UNDERCUT • High survey line • Alter crown shape • Flexible gingivally approaching clasp • Occlusally approaching clasp(more flexible platinum-gold-paladium wrought wire clasp)
  10. 10. HEALTH OF THE PERIODONTAL LIGAMENT • RETENTIVE CLASP TRANSMITS EXTRA FORCE TO THE PERIODONTIUM • THE HEALTH OF THE PERIODONTIUM AS WELL AS THE AREA OF ATTACHMENT AND MAGNITUDE OF THE FORCE IS KEY TO THE REACTION TO THESE FORCES • RPD SHOULD NOT BE PROVIDED FOR PEOPLE WITH ACTIVE PERIODONTAL DISEASE
  11. 11. HEALTH OF THE PERIODONTAL LIGAMENT • OCCLUSALLY APPROACHING CLASPS ARE CONTRAINDICATED IN TEETH WITH REDUCED PERIODONTAL SUPPORT- IRRITATES THE TISSUES • GINGIVALLY APPROACHNG CLASPS MORE SUITABLE FOR PERIODONTALLY COMPROMISED TEETH- MORE FLEXIBLE
  12. 12. HEALTH OF THE PERIODONTAL LIGAMENT • Periodontal attachment loss • Arrested disease process • More damage if relatively inflexible clasp system used • More flexible gingivally approaching clasp • CAUTION- root caries. Wrought wire occlusally approaching clasp
  13. 13. SHAPE OF THE SULCUS • Anatomical obstacles • Prominent frenal attachment- trauma • Surgical excision of frenal attachment
  14. 14. SHAPE OF THE SULCUS • Undercut in the sulcus • Arm spaced from ridge to prevent trauma
  15. 15. OCCLUSION • OCCLUSALLY APPROACHING CLASP LOCATED ABOVE THE SURVEY LINE- SUFFICIENT SPACE NEEDED (TOOTH PREPARATION) • GINGIVALLY APPROACHING CLASPS HAVE NO ROLE IN OCCLUSION
  16. 16. HYGIENE • GINGIVALLY APPROACHING CLASP CROSSES THE GINGIVAL MARGIN • ONE CLASP ENCOURAGES MORE PLAQUE THAN THE OTHER? • GINGIVALLY APPROACHING CLASP COULD POSE GREATER THREAT IN PATIENTS WITH POOR ORAL HYGIENE • INCREASED RISK OF ROOT CARIES ESPECIALLY WITH RECESSION
  17. 17. AESTHETICS/ APPEARANCE • Either type can detract from appearance(anterior teeth) • Gingivally approaching clasp has potential for being hidden in the disto buccal aspect of the tooth provided there is suitable undercut area
  18. 18. AESTHETICS/ APPEARANCE • Tooth coloured polyoxymethylene occlusally approaching clasp as alternative • Bulkier • Require deeper undercut • Less adjustable • High cost
  19. 19. BRACING • Occlusally approaching clasp more rigid and has more contact with tooth above survey line • Transmits more horizontal force • More efficient bracing component
  20. 20. LENGTH OF THE CLASP • Only terminal third • Too much of clasp arm • High force required • Strain on periodontal ligament fibres • Exceeds proportional limit of alloy- distortion of clasp
  21. 21. LENGTH OF THE CLASP • Only at tip • Length not restricted by the dimensions of the clasped tooth • Can be increased to give greater flexibility • Advantageous in tooth with reduced periodontal attachment
  22. 22. CONCLUSION • CLASP ASSEMBLY,FUNCTIONS, TYPES • FACTORS INFLUENCING THE CHOICE OF CLASP ASSEMBLY Position of undercut Health of the periodontal ligament Shape of the sulcus Occlusion Hygiene Aesthetics/ Appearance Bracing Length of clasp
  23. 23. REFERENCES • BRITISH DENTAL JOURNAL, VOLUME 189, NO. 12, DECEMBER 23 2000 • DEEPAK, N.V., KARTHIKEYAN, R. TEXTBOOK OF PROSTHODONTICS. 4TH EDITION. JITENDAR P V. 2007. why go to college?......there is Google

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