We are dedicating a portion of this blog to clinicians in an Ask the Expert format. If you have a question which you would like answered, we would be happy to forward it to an expert in the field and post his or her answer in this blog. Recently we were asked the following questions:
Q. You have 4 posterior crowns. The two premolars and second molar are prepped teeth. The first molar is an implant crown. In what order would you cement them?
A. As far as cementation of implant crowns, natural teeth have a Periodontal ligament which allows for movement both immediately and long term. However, implants do not move. Hence, it is always best to seat the implant crown first since it will stay in a static position and allow the adjacent natural teeth to accommodate any pressure. Once the implant crown is seated the contacts can be adjusted, if needed, to seat the natural teeth. If the natural tooth crowns are seated first there is no ability for the implant to accommodate unless the implant crown contacts are “overbuilt” and adjusted until the crown is fully seated. I always prefer a slightly snug contact on my implant restorations so some minor adjustment can be done if needed. Also, due to the nature of bone remodeling around implants which often leads to open embrasures I always want my implant crown contacts to be Long (to close the embrasure space) and Flat (to aid in anti-rotation as well). So, posterior implant contacts should be long and flat and full in the gingival third to prevent open embrasures and food impaction.
Q. How would you approach the cementation of 3 posterior implant crowns?
A. As far as multiple implant crowns: I always seat the middle one first and then adjust the implant to implant contacts as needed to seat the adjacent crowns since the middle implant has no resilient neighbours. Again, the implant to implant contacts should be long, flat and slightly snug. Once the adjacent implant crowns are seated the natural teeth will accommodate while the middle implant cannot.
These questions were answered by Dr. Robert C. Vogel, DDS, who is a fellow of the International Team for Implantology. He lectures internationally on implant dentistry with an emphasis on simplification, confidence, and predictability of implant prosthetics through ideal treatment planning and team interaction. He maintains a private practice focused on implant prosthetics and reconstructive dentistry in Palm Beach Gardens, Florida. He may be reached at firstname.lastname@example.org.