Cantilever Bridge with Dental Implants: Does This Work?

Question:

Marland asks:

In 2002, I had 5 implants put in on the bottom. A bridge was made to span this area with teeth cantilevered past the outer implants. 2 to 3 years later one area broke just inside the last implant. About the same time the porcelain came off the last implant on the other side.

This week the cantilevered teeth on that side broke off. I went back to the implant dentist and he said the the pressure was not evenly distributed and that is why they broke. The dentist that did the other work said this was not true and and that cantilevered are no longer the way to go.

I'm caught in the middle. Does cantilevering work or are they doomed to fail with implants?



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Expert Advice and Comments
cboudet's picture

Cantilever Bridge with Dental Implants: Does This Work?

Answered By: Dr. Carlos Boudet - West Palm Beach , FL

Dear Marland:
There is no absolute yes or no answer to your question.
Cantilevers have been used for decades in implant dentistry with success, but this success depends on the particulars of the case in question.
When cantilevers are considered, the prosthesis needs to be designed with special attention to engineering principles such as anterio-posterior spread of the implants, thickness and strength of the metal framework in the interproximal which is the weakest area, opposing dentition, parafunctional habits, etc...
Cantilevers are not the ideal solution, but sometimes are used to avoid complicated grafting or risk of nerve injury in the posterior mandible.
However, if implants can be placed with reasonable safety, then cantilevering is not the best way to go.
Thanks for asking such a good question.


Carlos A. Boudet, DDS, DICOI
http://boudetdds.com/

drjbdmd's picture

Cantilevers

Answered By: Dr. Jeffrey Brook - Massapequa , NY

Dear Marland:
I agree with Dr. Boudet. It is preferred not to have a situation utilizing a cantilever, but if the ultimate prosthesis is engineered properly, cantilevers can work well. I usually try to over-engineer the case to maximize the long-term chances for success. Good luck wtih your case.
Dr. Jeffrey Brook


Dr. Jeffrey Brook
http://www.periowellness.com/

cgrobins's picture

Cantilever Bridge with Dental Implants: Does This Work?

Answered By: Dr. Cheryl Goren Robins - Millburn , NJ

The comments above were both excellent, but I thought that I would expand further just to clarify a few of the issues.

There is a term called "anterio-posterior spread of the implants." This refers to the distance from the implant which is furthest back in the mouth to the implant which is furthest forward in the mouth provided that they will all be connected together in the final restoration. Barring any of the other issues mentioned in previous commentaries, it is generally acceptable for the amount of the cantilever to be limited to 1/2 or less of the anterio-posterior spread. Also, the more implants that are present, the safer it is to get to the 1/2 distance. Anything more than that sets up stress in the design of the restoration that can result in breakage of the implant bridge and even breakage of the implants themselves.

If you are someone who generates a lot of force when you bite down, then a cantilever becomes a riskier treatment plan because there is less support in an area of higher stress. This is especially true the further back in the mouth that the cantilever is located because the forces on the bite also increase the further back you go.

In my practice, I see patients on a yearly basis to continually evaluate the "bite" or occlusion on their implants as this can change over time. The hope is that if there is an area that has excessive force that can contribute to a fracture or problem, it can be treated prior to any major issues.

For your particular situation, you may want to attempt to find out why your implant restoration had the problems that it did. Was it a problem in the original design? Was it related to the strength of the materials used? Was it the occlusion? While eliminating a cantilever all together is probably the safest thing to do (if possible), it doesn't always prevent porcelain from chipping, etc. as there are other factors (some mentioned above) to consider. If you can eliminate the risk factors, then you may still be able to consider the use of a cantilever for your implants.


Dr. Cheryl Goren Robins
Suburban Periodontics and Implants

drkazemi's picture

cantilever off dental implants

Answered By: Dr. H. Ryan Kazemi - Bethesda , MD

Hello,

Likewise, in agreement with other doctors above, it is best to avoid cantilever design as from mechanics stand point, it can receive non-physiologic forces that can result in damage. When they are used, it requires careful design to make sure the positioning of the implants and cantilever prosthesis have proper dimensions. Once suggestion I have, if it has happened once, then it is probably will happen again and maybe best to avoid the similar design in your case.


Dr. H. Ryan Kazemi
http://www.facialart.com/

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