Dental Implants: 3-Unit Fixed Denture

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Dr. Croll asks us:

I just inherited a patient with a 3-unit fixed partial denture on 3 well integrated dental implants #19, 20, 21 positions.

All of the porcelain has shattered off #21.  The FPD is intact and the porcelain is intact on #19, 20.  It is cement retained.  I am planning on doing an overcoping to replace the porcelain on #21.  How much space do I need for an overcoping with metal framework and porcelain surface?  Any recommendations for luting medium?  I am planning on using a base metal alloy for increased strength and ridigity and a high fusing porcelain.  Any recommendations on any aspect of my intended treatment plan?

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10 Responses to “ Dental Implants: 3-Unit Fixed Denture ”

• Gary D. Kitzis, DMD March 28th, 2006

  
  

  It’s times like this where a screw retained prosthesis comes in handy! I would try to get the same amount of thickness as in a new PFG crown–1.5mm. Hopefully since it is an implant bridge, the lab left more room between the abutment and the opposing arch than would have been there if you had prepared #21 if it were a tooth. Measure it with feeler gauges and/or a wax bite and boley gauge. If there isn’t that much room available, get what you can. I can’t tell you to get “X” amount of clearance because we don’t know what is available. I don’t think this is an insurmountable problem. Good luck!

• Mark Adams, DDS, MS March 28th, 2006

  
  

  Echoing Dr. Kitzis, you’ll need the same room as for pfm - so some ‘preping’ of the fractured unit is necessary - especially some ‘retention/resistance form - slot/groove/box. As for cementation, micro-etch (sandblast) the metal surfaces, cement with Panavia F - it’s a dual cure resin - follow Panavia directions. Good Luck.

• Anonymous March 28th, 2006

  
  

  If you have 3 units on top of 3 implants simply remove the unit from 21 and remake it. Telescope crowns are not all they are cracked up to be. Otherwise remake the FPD.

• Anonymous March 28th, 2006

  
  

  How would you suggest removing the prosthesis or even the single cemented crown?

• Anonymous March 28th, 2006

  
  

  What type of implants are they (brand and length)? If it looks like 21 can stand on its own, I’d consider sectioning it and leaving 20/19 as two units. Cut like you would to remove a bridge where you want to save an abutment as a single crown. The cut 21 like you are cutting off a crown. If you damage the abutment, replace it. Then go back and polish the connector area on 20. Take a new impression and replace it as a single unit.

• Anonymous March 28th, 2006

  
  

  Why not either section the case and replace the single unit or just replace the 3 units? it will be less work and more predictable in the long run. The porcelain probably fractured due to insufficient material thickness of either metal or porcelain in the first place.

• Anonymous March 28th, 2006

  
  

  Porcelain fractures due to tension stresses ie., lateral interferences not due to “insufficient…thickness of porcelain”

• Anonymous March 29th, 2006

  
  

  Thought from a periodontist who doesnt restore implants but constantly picks the brains of some very fine prosthodontist. Dont waste your’s and the patient’s time and money to do the repair. Why did the procelain break? Was it functional or parafunctional forces? Was it the quality of the restoration and its structural limatations? If you have three well integrated consecutive implants, they should all be able to stand on their own. The fact that the porcelain fractured means that it has taken some amout of excess force. First go back to basics and completely equilibrate the case. Address the occlusion early in treatment, not as a last resort. Next seperate the single unit and make a new crown screw retained so that should this happen in the future the change and repair will be easier.

• DR.M.ALI DDS.MS. March 29th, 2006

  
  

  you con do over coping or sectioning #21 crown and redo one unit, hawever, desession is yours.space needed for overcoping is 1.5 mm,with a fresh bur and a lot of cooling water, then impression.any resin bonded cement and micro etch metal of coping,as well as the abutment frame. use resin cement as panavia or nexus ,or any othr resin cement .other option is to redo #21crown by sectioning between #21 and 20 ,take a new imp.this option is more secure for long term. as a general protocol to retreive cemented crowns : lab. should make a box in lingual surfsce of abutment as well as metal coping ,temp.cement should be used. in case of retreiving needed insterment will be put in the box and twist between the coping and the abutment to break the seal of the cement for any repair or modifications.good luck .from DR.ALI

• Jay C. Resnick DDS April 9th, 2006

  
  

  The easiest way of repairing the prosthesis is with an overcoping. Prepare to allow as much space as possible. I have successfully repaired several fixed bridges, both tooth and implanted supported. As Dr. Adams recommended, I have used Panavia F as a luting agent.

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