Connectors –in fpd/ dentistry schools

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Connectors –in fpd/ dentistry schools

  1. 1. 1 INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. 2 Connectors are those parts of a fixed partial denture orsplint that join the individual Retainers and Pontics together.  Usually this is accomplished with -"Rigid connectors” although nonrigid connectors are used occasionally.  The latterare usually indicated when it is impossible to prepare a common path of insertion forthe abutment preparations foran FPDwww.indiandentalacademy.com
  3. 3. 3 CONNECTOR The portion of an FPDthat unites the retainer(s) and pontic(s). RIGIDCONNECTOR A cast, soldered, orfused union between the retainer(s) and pontic(s). NON RIGIDCONNECTOR Any connectorthat permits limited movement between otherwise independent members of an FPD.www.indiandentalacademy.com
  4. 4. 4www.indiandentalacademy.com
  5. 5. 5www.indiandentalacademy.com
  6. 6. 6www.indiandentalacademy.com
  7. 7. 7 RIGID CONNECTORS Rigid connections in metal can be made by casting, soldering, or welding. Cast connectors  are shaped in wax as part of a multiunit wax pattern. Cast connectors are convenient and minimize the numberof stepswww.indiandentalacademy.com
  8. 8. 8 The fit of the individual retainers may be adversely affected because distortion more easily results when a multiunit wax pattern is removed from the die system. www.indiandentalacademy.com
  9. 9. 9 Soldered connectors involve the use of an intermediate metal alloy whose melting temperature is lowerthan that of the parent metal The parts being joined are not melted during soldering but must be thoroughly wettable by liquefied solder. www.indiandentalacademy.com
  10. 10. 10 Dirt orsurface oxides on the connectorsurfaces can reduce wetting and impede successful soldering; forexample, the soldermay melt but will not flow into the soldering gap. www.indiandentalacademy.com
  11. 11. 11www.indiandentalacademy.com
  12. 12. 12 WeldingWelding is anothermethod of rigidly joining metal parts. Here the connection is created by melting adjacent surfaces with heat orpressure. A fillermetal whose melting temperature is about the same as that of the parent metal can be used during welding.www.indiandentalacademy.com
  13. 13. 13 In industrial metalworking, a distinction is made between soldering, in which the fillermetal has a melting point below 450 º C (842º F), and brazing, in which the fillerhas a melting point above 450 º C Rigid connections in dentistry are generally fabricated above 450 º C, but the process has almost always been referred to in the dental literature as soldering.  A proposed international standard uses the term brazing.www.indiandentalacademy.com
  14. 14. 14 NONRIGID CONNECTORSNONRIGID CONNECTORS Nonrigid connectors are indicated when it is not possible to prepare two abutments for an FPDwith a common path of placement. Segmenting the design of large, complex FPDs into shortercomponents that are easierto replace orrepairindividually is advisable. This can be helpful if there is uncertainty about an abutment's prognosis. If the abutment fails, only a portion of the FPDmay need to be remade.www.indiandentalacademy.com
  15. 15. 15 In the mandibulararch, nonrigid connectors are indicated when a complex FPDconsists of anteriorand posterior segments.  During the mandibularopening and closing stroke, the mandible flexes mediolaterally.'  Rigid fixed partial dentures have been shown to inhibit mandibularflexure, and extensive splints have been shown to flex during forced opening The associated stresses can cause dislodgment of complex FPDs. Segmenting complex mandibularFPDswww.indiandentalacademy.com
  16. 16. 16 Nonrigidconnectors aregenerated throughincorporationof prefabricated inserts inthewaxpatternorthrough custommillingprocedures afterthefirst castinghas beenobtained.  Thesecondpartis thencustom-fittedto themilledretainerandcast. Theyareoftenmadewithprefabricated plastic patterns.  Theretainers arethencastseparately andfittedtoeachotherinmetal.www.indiandentalacademy.com
  17. 17. 17 CONNECTOR DESIGN The size, shape, and position of connectors all influence the success of the prosthesis. Connectors must be sufficiently large to prevent distortion or fracture during function but not too large; otherwise, they will interfere with effective plaque control and contribute to periodontal breakdown overtime.www.indiandentalacademy.com
  18. 18. 18 Adequate access (i.e., embrasure space) must be available fororal hygiene aids cervical to the connector If a connectoris too large incisocervically, hygiene is impeded and overtime periodontal failure will occurForesthetic FPDs, a large connectororinappropriate shaping of the individual retainers may result in display of the metal connector. www.indiandentalacademy.com
  19. 19. 19 TYPES OF CONNECTORS RIGIDCONNECTORS Rigid connectors must be shaped and incorporated into the wax pattern afterthe individual retainers and pontics have been completed to final contourbut before reflowing of the margins forwww.indiandentalacademy.com
  20. 20. 20 Cast Connectors Connectors to be cast are also waxed on the mastercast before reflowing and investing of the pattern. The presence of a cast connector makes the pattern somewhat more awkward. Access to the proximal margin is impeded, and the pattern cannot be held proximally during removal from www.indiandentalacademy.com
  21. 21. 21 Restricting cast connectors to complete coverage restorations is therefore advisable, which can be gripped buccolingually. Partial-coverage wax patterns are easily distorted when they are part of a single-cast FPD.www.indiandentalacademy.com
  22. 22. 22 Soldered Connectors.  As with cast connectors, connectors to be soldered are waxed to final shape but are then sectioned with a thin ribbon saw therefore, when the components are cast, the surfaces to be joined will be flat, parallel, and a controlled distance apart.  This allows accurate soldering with a minimum of distortion.www.indiandentalacademy.com
  23. 23. 23www.indiandentalacademy.com
  24. 24. 24 Molten solderwill flow toward the location where the temperature is highest. In metal, the two flat surfaces previously created in wax retain heat, ensuring that the highest temperature is in the www.indiandentalacademy.com
  25. 25. 25 Soldering Gap Width. As gap width increases, soldering accuracy decreases .  Extremely small gap widths can prevent propersolderflow and lead to an incomplete or weak joint. www.indiandentalacademy.com
  26. 26. 26 An even soldering gap of about 0.25 mm is recommended. If a connectorarea has an uneven soldering gap width, obtaining a connectorof adequate cross-sectional dimension without resulting distortion is more difficultwww.indiandentalacademy.com
  27. 27. 27 Loop Connectors Although they are rarely used, loop connectors are sometimes required when an existing diastema is to be maintained in a planned fixed prosthesis. The connectorconsists of a loop on the lingual aspect of the prosthesis that connects adjacent retainers and/orpontics. www.indiandentalacademy.com
  28. 28. 28 The loop may be cast from sprue wax that is circularin cross section orshaped from a platinum-goldpalladium (Pt- Au-Pd) alloy wire. Meticulous design is important so that plaque control will not be impeded www.indiandentalacademy.com
  29. 29. 29www.indiandentalacademy.com
  30. 30. 30 NON RIGID CONNECTORS The design of nonrigid connectors that are incorporated in the wax pattern stage consists of a mortise (also referred to as the female component) prepared within the contours of the retainerand a tenon (male) attached to the ponticwww.indiandentalacademy.com
  31. 31. 31 The mortise is usually placed on the distal aspect of the anteriorretainer. Accurate alignment of the dovetail orcylindrically shaped mortise is critical; it must parallel the path of withdrawal of the distal retainerwww.indiandentalacademy.com
  32. 32. 32www.indiandentalacademy.com
  33. 33. 33 Paralleling is normally accomplished with a dental surveyor. When aligning the cast, the path of placement of the retainerthat will be contiguous with the tenon is identified. www.indiandentalacademy.com
  34. 34. 34 The mortise in the other retaineris then shaped so its path of insertion permits concurrent seating of the tenon and its corresponding retainer.  The mortise can be prepared freehand in the wax pattern or with a precision milling machine. www.indiandentalacademy.com
  35. 35. 35www.indiandentalacademy.com
  36. 36. 36 Anotherapproachis to useprefabricatedplastic components forthemorti andtenonof anonrigid connector www.indiandentalacademy.com
  37. 37. 37 As analternative, aspecial mandrelcanbeembeddedin thewaxpatternandthe abutmentretainercanbecast, withrefinementof thefemale componentas necessary; the malekeyis thenfabricatedof autopolymerizingacrylic resin andattachedtothepontic. www.indiandentalacademy.com
  38. 38. 38 For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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