September 28, 2011

Recement Crowns or Bridges: Why Did It Come Off in the First Place?

It is simple.  If a crown or bridge comes off, it has  failed.  Now why it failed is the real question.  Not every crown or bridge that fails can be recemented and if they are recemented, the reason why it failed in the first place is usually still there.

Reasons Why most Crown/Bridgework Fails:

  • Recurrent decay- Most people who have a crown/bridge don’t understand that they can still get a cavity on that tooth/teeth.  Crown/bridges are placed over a tooth and usually some of that tooth is exposed to the oral fluids (saliva, beverages and juices of foods). This exposure can be attacked by bacteria and can re-decay.
  • Trauma- Most crown/bridgework are not bionic!  They are as weak or weaker that your natural teeth.  Using them like a tool can cause fracturing of porcelain or the underlying tooth structure.
  • Occlusion- If you bite incorrectly on the tooth over a long enough period of time, this may cause a crown/bridge to get loose and/or fracture.
  • Hole in Restoration- If a hole has been chewed into the restoration or opened by over adjustments, saliva can erode the cement and cause the seal to fail.
  • Sticky Foods- Jolly Ranchers are great for removing crowns!
  • Inadequate preparation- If the tooth was either not prepared properly or there wasn’t enough tooth structure left to prepare it correctly, then the tooth/teeth may not be able to support crown/bridgework in the first place.

Cape Dental Care Recementation Protocol:

  1. We always take an X-ray of the tooth to make sure there isn’t anything hidden inside the bone
  2. We check to see if the tooth is restorable.  Sometimes the tooth is completely rotten under the failed restoration and cannot be recemented
  3. The tooth is inspected under high magnification to see if there is any decay not detected with the x-ray.  This decay is removed and the left over tooth structure is re-evaluated.
  4. The inside of the crown/bridge is micro-etched with a sand blaster to remove all the old cement and to increase retention.
  5. The crown/bridge is adjusted to fit.  This could require no adjustments if the restoration had just fallen off, to massive adjustments if the restoration had been off a long time (> 1 week)
  6. Address any overgrown gums.  If the tooth/teeth have been off for any period of time the gums may have fallen/tightened over the crown margins making it impossible to seat without first removing some of the gums.  We do this with local anesthetic and a diode laser.  It is a very simple procedure which is included in the recementation of the crown/bridge fee.
  7. The tooth is scrubbed thoroughly with hydrogen peroxide inside a syringe and a brush tipped needle.
  8. The choice of cements can vary from aluminum glass ionomer, to a total etch/bond cement.
  9. The cement is removed and the occlusion is adjusted.
  10. Oral hygiene instructions are given including floss threading of bridges and splinted together crowns
  11. The patient is given a prognosis and told what the next treatment plan is for that tooth, e.g. it is fine, to it needs to be remade or extracted.
Alternatives to Recementation (if it is non-restorable)
  • Extraction and no further restoration
  • Extraction and possible bone grafting (for possible future implant placement or to support a denture)
  • Extraction and implant/crown replacement (it is like growing your tooth back)
  • Extraction and removable partial denture (something you take in and out of your mouth at night)
  • Extraction and possible bridge (this is damaging to the two teeth on either side of the lost tooth/teeth)