Stainless steel crown


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Stainless steel crown

  1. 1. 1st in a relatively small deciduous teeth neglected carious can destroy tooth’s integrity faster than in large teeth in permanent dentition.  2nd the deciduous teeth pulp is larger than permanent pulp whereas the enamel and dentin is less in thickness, thus it is difficult to make dentinal stump for a gold casting or to use a pin system of retention for more extensive amalgam restoration. 
  2. 2. 1. 2. 3. It has respect to life span, replacement, retention and resistance. They are acceptable by both patient &dentist. They are also more cost effective because of comparatively simple procedures in restoring.
  3. 3. To achieve biological compatible ,competent for mastication .  To maintain the form and function and when possible the vitality of the teeth to be maintained . 
  4. 4. Untrimmed crowns: e.g. Rocky mountain 2. Pretrimmed crown: straight, non contoured sides but are festooned to follow a line parallel to the gingival crest, e.g. (Unitek stainless steel crowns, 3M Co., and Denvo crowns, Denvo Co. Arcadia, CA). 3. Precontoured crown : festooned and precontoured, (e.g. Ni-Chro Ion crowns and Unitek stainless steel crowns and 3M Co.). 1.
  5. 5.  Stainless Steel Crowns 17-19% chromium 10-13% nickel 67% iron 4% minor element • These crowns are available in various sizes. • Mostly these crowns are used in posterior teeth which undergone pulp therapy.
  6. 6.  Nickel – base Crowns 72% nickel 14%chromium 6-10% Iron 0.04% carbon 0.35% manganese 0.2% silicon • The alloys have good formability and ductility necessary for clinical adaptation of crowns and wear resistance to resist opposing occlusal forces.
  7. 7. Extensive decay in primary & young permanent teeth. 2. For teeth deformed by developmental defects or anomalies. 3. For teeth with hypoplastic defects. 4. Following pulp therapy. 5. As preventive restoration. 6. As an abutment. 7. Temporary restoration of a fractured tooth. 8. In sever cases of bruxism. 9. Single tooth crossbite. 10. For replacing prematurely lost anterior teeth. 1.
  8. 8. Dental age of the patient. 2. Cooperation of the patient. 3. Motivation of the parents. 4. Medically compromised/disabled child. 1.
  9. 9.  • • • Evaluate the preoperative occlusion Take the alginate impression of U/L jaws. Pour the cast with dental stone Note the dental midline and the cusp fossa relationship bilaterally  Selection of crown • The correct size crown is selected by the M-D dimensions of the tooth to be restored using Boley gauge. To produce steel crown margins of similar shape examine the contour of gingiva of the buccal & lingual marginal gingiva. •
  10. 10.  L.A. should be administrated  Isolation by rubber dam or cotton rolls  Remove the decay
  11. 11.  Occlusal reduction A 69L or 169L bur is used to reduce the occlusal surface by 1.5-2.0mm .  Proximal slices place the wooden wedges in the interproximal embrasures, the 69L bur is moved B-L acrossthe proximal surface. Buccolingual reduction  Round off all the line angles  It is done by using side of bur.
  12. 12.     Two principles related to SSC length and margin shape that are based on an understanding of the tooth morphology and gingival tissue contours were presented by Spedding 1984 The crown should be of a correct length and its margins should be adapted closely to the tooth. For shaping the crown margins mark 3 light points on the metal at the (mesiolingual, lingual and distolingual)and at (mesiobuccal, buccal, distobuccal) surfaces at the crest of respective marginal gingiva without compressing the marginal gingiva. Final finished margins are placed approximately 1mm below these marks.
  13. 13. Now the crown is tried on the preparation by seating the lingual first and applying pressure in a buccal direction so that the crown slides over the buccal surface into the gingival sulcus.  Resistance should be felt as the crown slips over the buccal bulge. 
  14. 14.   Initial crown contouring is performed with a 114 plier in the middle 1/3rd of the crown to produce a belling effect. This will give the crown a more even curvature. Crown crimping The tight marginal fit aids in: 1. Mechanical retention of the crown. 2. Maintenance of gingival health. 3. Protect of cement from exposure to oral fluids. 
  15. 15. The crown should be replaced on the preparation after the contouring procedure to see that it snaps securely into place.  The occlusion should be checked at this stage to make sure that the crown is not opening the bite or causing a shifting of mandible into an undesirable relationship with opposing teeth. 
  16. 16. Accumulation of plaque and inflammation of gingiva is commonly seen in practice of restorative dentistry due to rough and unpolished restoration.  To avoid these complications crown should be polished prior t o cementation with rubber wheel to remove all scratches. 
  17. 17.  Before cementation a bitewing is taken to verify proximal marginal integrity
  18. 18. SSC should be cemented only on clean dry mouth, isolation of teeth with cotton roll is recommended.  Rinse and dry the crown inside & out side and prepare to cement it.  A zinc phosphate, polycarboxylate or GIC is preferred. 
  19. 19. Before the cements set ask the patient to close into centric occlusion by applying pressure through a cotton roll and confirm that the occlusion has not been altered.  Remove the excess cement by an explorer or scaler & for interproximal area can be cleaned by passing dental floss through them. 
  20. 20.  Quadrant dentistry ( Nash, 1981) -Prepare the occlusal reduction of one tooth completely before beginning the other as there is tendency to under reduce both when reduction on them is done at the same time. -Reduce the adjacent proximal surface of the teeth being restored more than when only one tooth is restored. -Both crown should be trimmed, contoured and prepared before cementation simultaneously to allow for adjustment in inter proximal space and establish proper contact area.  Crown in area of space loss(Mc - Evoy 1977)  Preparing a SSC adjacent to a class II amalgam (Mc - Evoy 1985)
  21. 21.  1. 2. 3. 4. 5. In 1971, Mink & Hill report several way of modifying the SSC when they are either too large or too small Undersize tooth or the oversize crown. Oversize tooth or undersize crown. Deep subgingival caries. Open contact. Open-faced stainless steel crown.
  22. 22. Interproximal ledge.  Crown tilt.  Poor margins.  Inhalation or ingestion of crown. 
  23. 23. Shoba Tandon, 2nd edition  McDonald . Avery . Dean, 8th edition 