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Precision and Semi-Precision Attachments Where? When? Why?

Precision and Semi-Precision Attachments Where? When? Why?. George E. Bambara, MS, DMD FACD, FICD. Objectives of the Program. Understanding how attachments preserve hard and soft tissue Selection of the appropriate attachments Understand the uses of attachments

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Precision and Semi-Precision Attachments Where? When? Why?

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  1. Precision and Semi-Precision AttachmentsWhere? When? Why? George E. Bambara, MS, DMD FACD, FICD

  2. Objectives of the Program • Understanding how attachments preserve hard and soft tissue • Selection of the appropriate attachments • Understand the uses of attachments • Familarization with different attachments • Maintenance and hygiene

  3. Properly Designed Clasps Work ??????Concerns?????? • Uneven distribution of forces • Possible orthodontic movement • Periodontal compression • Clasps can be plaque traps

  4. Removable Partial DenturesPeriodontal Status RPD’s WERE ASSOCIATED WITH • Increased periodontal pathology • Increased plaque and tarter accumulation • Increased gingival inflammation • Increased probing depths • Increased recession • Increased abutment tooth mobility Zlataric’ et.al., The Effect of Removable Partial Dentures on Periodontal Health of Abutment and Non-Abutment Teeth. JPeriodontology, 2002, 73: 137-144

  5. CLASPS: Less expensive. 5 to 6 year life. 30% loss of retention. Poor chewing efficiency. 93% caries rate. 50% compliance. ATTACHMENTS: 15 year + life. More expensive. 99% retention. Excellent chewing efficiency. 8% caries rate. 100% compliance. Clasps vs. Attachments Rantanen, Wetherall and Smales, Feinberg et.al.

  6. CLASSI LEVER

  7. Class II Lever

  8. CLASS III LEVER ClassIII Lever

  9. Indications for Attachments • Aesthetics • Redistribution of forces • Minimize trauma to soft tissue • Control of loading and rotational forces • Non parallel abutments- Segmenting • Future salvage efforts- Segmenting • Retention • Stabilization

  10. Functional Classifications • Class 1A- Solid, rigid, non-resilient • Class 1B- Solid, rigid- lockable • Class 2- Vertical resilient • Class 3- Hinge resilient • Class 4- Vertical and hinge resilient • Class 5- Rotational and vertical resilient • Class 6- Universal, omni-planer

  11. Patient Dexterity and Attachment Wear • Insertion and removal cause wear • Poor dexterity • Avoid multiple attachments with complex a complex path of insertion • Use lingual “guiding arms”

  12. What is a Precision Attachment? • An attachment that is fabricated from milled alloys • Tolerances are within .01mm

  13. Precision AttachmentsThey are Generally • Intracoronal • Rigid = NonResilient

  14. Benefits of Precision Attachments • Consistent quality • Controlled wear • Less wear • Easier repair • Standard parts are interchangeable

  15. What is a Semi-Precision Attachment? • An attachment that is fabricated by the direct casting of plastic, wax, metal, or refractory patterns • Their method of fabrication subjects them to inconsistencies

  16. Benefits of Semi-Precision Attachments • Less costly • Easy fabrication • May be cast in alloy

  17. Semi-Precision AttachmentsThey Are Generally • Extracoronal • Non-rigid = Resilient

  18. 0.1mm – 0.4 mm difference in the displacement of the tissue and the denture base, as opposed to the axial intrusion of the abutment teeth Directs forces to the supporting tissues and the abutment teeth Resilient Attachments

  19. Selection of Attachments • Location • Opposing arch • Function • Retention • Available space ( 3-5mm ) • Cost

  20. Criteria Selection for Resilient and Non Resilient Attachments • Do not oppose two resilient attachments unless teeth are very weak • Opposing distal extensions with strong abutments: upper - non resilient, lower - resilient • Lower distal extension vs. • Natural dentition - resilient • Full denture - non resilient

  21. INTRACORONAL: Placed within the contours of the crown form Needs more tooth reduction Rigid connectors EXTRACORONAL Placed outside the contours of the crown form Needs less tooth reduction Stress redirectors and are considered resilient Coronal Attachments

  22. Stud Attachments A ball and socket type of attachment in which one component is attached to an abutment or implant, and the other element is retained in the prosthesis

  23. Advantages Stud Attachments • Low profile • Easy hygiene maintenance • Enhanced crown/root ratio

  24. Dalla BonaThe Ball Attachment A spherical, resilient, adjustable stud attachment with vertical and rotational movement for retaining partial and complete overdentures

  25. Advantages • Low Profile - limited space • Easy path of insertion • Adjustable female • All adjustments done in prostheses • Can be rigid – vertical movement only • Can be resilient – vertical and rotational • Easy fabrication • Hygienically maintainable

  26. Accessory Attachments Plunger Screw Type Frictional

  27. Magnetic Attachments • Processing magnet- in denture • Intraradicular keeper All magnetic attachments should be processed chairside in the denture

  28. Magnetic Indications • Overdentures • Implant restorations

  29. Magnetic Realities • Provide little lateral stability • Used in limited applications • Heat curing will weaken magnets • Corrosion

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