Do You Have a Patient Needing Comprehensive Implant Treatment?

CASE SUMMARY: Extending a prosthesis posteriorly without additional grafting
By Caroline C. Eskow, DDS, MS

 

This is a patient who was referred from another dental professional for evaluation of his missing posterior teeth.

If you have a patient with multiple implants or several missing or broken teeth, they may be a candidate for an oral rehabilitation with a full-arch splinted implant restoration.

Patient “Elmer” was referred to me by another dental professional in the area. Elmer was concerned about a fractured mandibular anterior tooth and also complained that he “couldn’t chew” because he was missing most of his posterior teeth. His diagnosis included: partially edentulous, limited available bone due to pneumatized maxillary sinuses and anatomic position of inferior alveolar nerves, dental caries on all remaining natural teeth, and existing restored dental implants.

He was given options to restore his posterior teeth, either by sinus augmentation and new implants in the posterior maxilla, or by splinting his existing implants and extending the prostheses posteriorly with cantilevers. He chose to move forward with full-arch implant-retained FDPs that extended posteriorly with cantilevers. In order to restore his posterior function, I would refer him for placement of two additional implants at #12 and #25. Then I would remove his existing implant-retained crowns, and connect the implants across the entire arch. By splinting the implants across the arch, we would be able to extend his occlusion by 2 teeth bilaterally, without additional bone grafting or sinus lifts. This would provide him with a greater chewing efficiency. You can see the before and after photos below.

 

Let’s Talk Occlusion….

Elmer was thrilled to be able to chew again. I was able to extend Elmer’s occlusion posteriorly, by 1-2 teeth on either side, after splinting the implants across the arch. So…how far can you cantilever off of an implant supported FDP? This depends on many factors, including the span of the implants (AP spread), the functional and parafunctional forces of the patient, the opposing arch, the restorative material, etc. A parameter that has been discussed in the prosthodontic literature states that you can cantilever 1.4x the AP spread of the implants. This parameter oversimplifies this concept because it does not take into account the other factors that I mentioned above. In general, it is best to minimize (or eliminate) cantilevers, but we know this is not always possible or practical. In Elmer’s case, I extended each cantilever 1-2 teeth. He had no signs of parafunctional activity, the frame was made of chrome cobalt, and this cantilever was well within the 1.4x parameter.