Repairing fractured pfm


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Repairing fractured pfm

  1. 1. Repairing FracturedPorcelain-Fused-to-MetalBridge Pontics<br />By: JehanneCalinga<br />
  2. 2. Repairing Fractured PFM<br />This procedure is:<br /> less costly <br />less invasive <br />requires much less chair time than does total bridge replacement<br />
  3. 3. Porcelain<br />The porcelain of a porcelain-fused-to-metal bridge:<br />is brittle in nature and<br />It is susceptible to fracture<br />
  4. 4. Porcelain<br />porcelain has roughly 2.5 times less compressive strength than does enamel<br /> not surprisingly it can and does fracture occasionally.<br />
  5. 5. Fracture can result from: <br />excessive forces in function,<br />interferences from malocclusion, <br />Parafunctional habits<br />
  6. 6. Fracture can result from: <br />Impact trauma.<br /> <br />Poor case selection or inadequate design <br />also result in the overlaid porcelains being unable to withstand the physiological stresses placed on the bridge. <br />
  7. 7. Replacing fractured PFM<br />When a fracture occurs, one solution is to replace the bridge.<br />In the case of a three-unit bridge, this option is costly and requires a lot of time in the dental chair. <br />
  8. 8. Disadvantage of Replacing <br />every time a tooth is manipulated to remove and reprepare a bridge, it increases the risk of:<br /> <br />abutment fracture,<br /> root fracture<br />or irreversible pulpal damage<br />caused by mechanical trauma.<br />
  9. 9. Disadvantage of Replacing PFM<br />In the case of bridges on periodontally compromised teeth, the trauma of removing a bridge can lead to the loss of an abutment tooth.<br />
  10. 10. Numerous solutions to theproblem of pontic fracture:<br />1) It is possible to remove the bridge intact and have the porcelain refired.<br />This presents the possibility of damage to an abutment tooth, <br />damage to the metal framework of the bridge<br />further damage to the porcelain.<br />More often than not, it is impossible to remove the bridge without damaging or destroying it.<br />
  11. 11. Numerous solutions to theproblem of pontic fracture:<br />2) Another option is to repair the damaged pontic with resin-based composite.<br />Problems encountered with this option:<br />Retention always has been the problem,<br />Most of these repairs were temporary.<br />
  12. 12. Repairing the damaged pontic with resin-based composite.<br />This is done by bonding resin to:<br />exposed metal <br />exposed porcelain<br />
  13. 13. Bonding on exposed metal<br />
  14. 14. Bonding on Exposed Metal<br />bonding on exposed metal involves achieving macromechanical retention by:<br />Making grooves<br /> Making notches<br />Abrading<br />
  15. 15. Bonding on exposed Porcelain<br />
  16. 16. Bonding on exposed porcelain involves:<br />Abrading<br />Hydrofluoric acid etching<br />Silanating<br />Conventional bonding procedure<br />
  17. 17. Disadvantages<br />Howeverbest composite repairs were not predictable in longevity, <br />They are not as color-stable as the porcelain repairs<br />The patient must be informed, however, that the prognosis of such a repair is guarded, but hopeful.<br />
  18. 18. case example:<br />there was one case in which the overlay was dislodged and recemented twice with zinc phosphate cement in a relatively short time,<br /> <br />but, with the use of a resin cement, the overlay crown has remained in place since the second recementation.<br />
  19. 19. Technique for repairing PFM:<br />The key to success lies less with:<br />the cement than with careful case selection <br /> knowing the cause of the previous fracture<br /> <br />
  20. 20. Technique for repairing PFM:<br />maintain the adequate metal coping thickness for strength<br />It is important not to compromise the strength of the original substructure<br /> <br />
  21. 21. Causes of fracture that would not be ideal candidates for this repair procedure are:<br />Patients with a deep overbite,<br />Occlusal interferences,<br /> <br />Heavy protrusive guidance,<br /> <br />Bruxing<br /> <br /> Other parafunctional habits <br />
  22. 22. The fracture as viewed from the labial aspect.<br />
  23. 23. The slide shows a typical anterior three-unit bridge that was fractured in an altercation (in which the injured patient allegedly was an innocent bystander).<br />
  24. 24. The patient came to the dentist with limited funds, requesting a repair. <br />She reported that the bridge was more than 15 years old and that she had been happy with its appearance and function until it was fractured and the entire incisal edge was destroyed.<br />
  25. 25. Procedures in Repairing Porcelain Repair <br />
  26. 26. Procedure:<br />1)Without administering anesthetic, use coarse diamonds from the labial approach to remove all the porcelain from the broken tooth pontic.<br /> <br />2) Extend the preparation into metal to gain as much surface area as possible on the incisal and gingival walls and thus maximize resistance form.<br />
  27. 27. Procedure:<br />3) keep the incisal and gingival planes as parallel as possible to increase retention form<br />The dentist can achieve additional retention and antirotational:<br />the prepped margins of the pontic,<br />the incisal and proximal surfaces of the retainers,<br />and the tissue surface of the edentulous ridge<br />
  28. 28. 4)the clinician in this procedure used resin cement for its adhesive strength<br /> <br /> the additional micromechanical retention of a roughened surface was desirable.<br />( the clinician made no attempt to smooth the rough surface of the prepared pontic)<br />
  29. 29. 5) To perform the procedure, use a modified sectional custom tray, with an open lingual area and sufficient length to cover the labial and incisal surfaces of the bridge retainers.<br />
  30. 30. 6) Take the impression with a low-viscosity polyvinylsiloxane impression material, to have adequate rigidity and flexibility to disengage from the minor undercuts. <br />
  31. 31. Impression taking<br />The impression must draw to the labial aspect, and care must be taken to prevent the impression material from flowing lingually and locking in around the pontic.<br /> To achieve this, a gloved finger or cotton roll should be held in place on the lingual surface as a barrier to prevent excessive overflow of the impression material.<br />
  32. 32. Impression taking<br />The crucial areas that need to be captured in the impression are:<br />the prepped margins of the pontic<br />the incisal and proximal surfaces of the retainers,<br />and the tissue surface of the edentulous ridge<br />No opposing cast was needed in this case as the practitioner finalized the occlusion intraorally. <br />
  33. 33. Procedure<br />7) select a shade to match the rest of the bridge.<br /> Note that the metal coping design should replace the ideal form of the original pontic substructure with adequate room for porcelain.<br />
  34. 34. Procedure<br />8) Send the impression and shade information to the dental laboratory, along with adequate drawings and a good description of the properties desired in the finished product. <br />Detailed instructions are important, as this sort of repair is a bit unusual and few laboratories will have performed this before.<br />
  35. 35. Procedure<br />9) Fabricate a temporary restoration of acrylic and cement it with zinc oxide eugenol.<br />keep the incisal edge of the temporary restoration short enough to be out of occlusion<br />
  36. 36. Procedure<br />10) The laboratory fabricated an overlay crown that had:<br /> a metal coping with extensions into the incisal<br />  gingival porcelain and proximal boxes to slot into the connectors, like a jigsaw puzzle <br />
  37. 37. Procedure<br />The surfaces that would contact cement were left unfinished and were sandblasted for additional micromechanical retention.<br />
  38. 38. Procedure<br />The surfaces that would contact cement were left unfinished and were sandblasted for additional micromechanical retention.<br />
  39. 39. Procedure<br />11) When receiving the overlay pontic from the laboratory, Take it to the patient’s mouth, insert it and adjusted it for fit and occlusion.<br />12) Prepare both metal surfaces for cementation with primers and bonding agents according to adhesive cementation protocols.<br />
  40. 40. Procedure<br />13) cement the overlay crown pontic with the corresponding resin cement.<br />
  41. 41. Conclusion<br />Repairing a porcelain-fused-to-metal bridge pontic is clinically acceptable and has served well as an alternative to replace a completely new bridge <br />clinician must attain a labial lingual shelf as wide as possible on the incisal portion of the preparation.<br />
  42. 42. Fractured PFM<br />Prepared PFM<br />
  43. 43. Overlay Crown<br />Finished product<br />
  44. 44. Reference<br />Fred C. Quarnstrom, Tar C. AW. Repairing fractured porcelain-fused-to-metal bridge pontics. The Journal of the American Dental Association 2010.<br />
  45. 45. END<br />