If you have restored implants for a long enough period of time, you most likely have experienced the following scenario and scratched your head wondering what happened. Imagine you’re about to seat an implant restoration on tooth #30. You try the restoration in and go through your checklist.
- Is the abutment seated?
- Is the crown seated?
- Are the margins good?
- Are the proximal contacts correct?
- How is the occlusion?
- How is the color?
After everything checks out, you cement the restoration, or torque it into place if it is screw-retained. A few years go by and you are checking the patient during a regular hygiene appointment when you notice that the mesial proximal contact is open.
How can this be? It was perfect when the restoration was seated ...
You know that the implant couldn’t have moved (since it is osseointegrated), so that must mean the teeth anterior to the implant restoration have moved. But where could they go? The lower anteriors still couple with the upper anteriors, so that prevents them from moving forward. So what is going on?
Believe it or not, the presence of diastemas developing around implant restorations is not that uncommon. The loss of interproximal contact between fixed implant restorations and adjacent natural teeth was evaluated in a 2010 paper from Koori and colleagues.(1) Evaluation ranging from one to 123 months (10.5 years) showed that out of the 146 restorations that were placed, 43 percent developed an open interproximal contact, most commonly on the mesial. It appears from this paper that the greatest incidence of developing an open contact was in patients with an opposing dentition that was natural teeth or implants - AND where the teeth adjacent to the implant restoration were non-vital and non-splinted.
What is the mechanism for the development of these open contacts? It is hypothesized that this is the result of mesial drift - wearing of the interproximal contacts as a result of attrition of the contacts over time.(1)(2)
Given that nearly half of the patients in this study developed an open interproximal contact, it is important for us to continually monitor our implant patients at follow-up visits; an open contact may induce food impaction and have an adverse effect on the peri-implant bone/soft tissue. When it is present, either the implant restoration needs to be replaced or the tooth anterior needs to be restored to close the contact. The downside is that if the contact opened once, there is always the chance that it can open again in the future ... if you wait long enough.
- Statistical analysis of the diachronic loss of interproximal contact between fixed implant prostheses and adjacent teeth. Hidehiro K., et al. Int J Prosthodont 2010:23:535-40
- Implant prostheses and adjacent tooth migration: Preliminary retrospective survey using 3-dimensional occlusal analysis. Wei H. et al. Int J Prosthodont 2008:21:302-304
(For more articles by Dr. Greggory Kinzer, click here.)
Greggory Kinzer, D.D.S., M.S., Spear Faculty and Contributing Author