cantilever bridge

[marimo]

what r the indication of cantilever bridge?

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[doc toothache]

what r the indication of cantilever bridge?

A good indication for a cantilever bridge is when planing to assure failure of the abutment(s).

 

[charlestweed]

When it is not possible to place implants in the posterior part of the completely edentulous dental arch (due to low sinus floor or severely resorbed ridge), the cantilever bridge can be used. The larger the AP spread, the further you can extend the bridge posteriorly.

http://thecuriousdentist.com/how-far-can-i-cantilever-from-implants-a-p-spread-explained/

 

[DentinBond]

what r the indication of cantilever bridge?

Posterior cantilevers are often problematic. The forces are extremely high. For an example, assume two premolar abutments and a premolar-sized molar pontic, a common occurence. The repetitive forces of occlusion exceed the ability of the periodontal ligament to dampen them out. The bridge rocks over the distal abutment, the one next to the pontic. At the least, this fractures the cement (microfractures all throughout) and leakage and caries ensue. At worst, the underlying tooth fractures horizontally.

This isn't to say never do a cantilever. There may be clinical situations where it is a valid treatment option. Generally speaking though, an implant is far more favorable. And these days the site can almost always be engineered to allow for implant placement.

Anterior cantilevers are different, however. Here, they often make sense. Consider a missing #7. And now consider the force magnitudes and vectors on anterior teeth. Fremitus gives us a clue about this.

The force vector on the canine is towards the buccal in most excursive movements; the magnitude of the force is very high and the movement of these long-rooted teeth is minimal. The force vector on the central is towards the labial; the magnitude is usually lower and the movement is far higher than with the canine. Different directions, different degrees of movement.

If we do a conventional anterior bridge, the mismatch can again be responsible for cement failures and caries, even in well-fitting bridges. Plus, unless these teeth are severely weakened by caries or restorations, who wants to prep more anteriors than we have to? Yet placing an abutment on the canine and a pontic on the lateral solves the case beautifully. Except in severe bruxers, the extra rotational forces on the big-rooted canine are well-tolerated, and the cement on what amounts to a large single crown is unlikely to fail.

For bonded bridges, the situation is even more dramatic. Those differing force vectors and magnitudes have been responsible for massive numbers of debonds. Yet- Place a wing on a canine and a lateral pontic (leaving the central out of the restoration entirely) and they almost never debond. I believe that some of the best studies on this have been done by Charles Cox DMD PhD.

Having said that, the last time I did an anterior RBR was back in the Pleistocene Era and I'd much prefer to do an implant in these situations. The cost is close to the same--higher cost on one tooth, but only one tooth, not three. Building out the buccal plate is a fun challenge, gaining acceptable papillae is even more fun, and, as my tombstone just might say someday, "Titanium does not decay."

 

[jay47]

A good indication for a cantilever bridge is when planing to assure failure of the abutment(s).

ALL bridges will eventually fail anyways, so that's not a good way to look at it, although I prefer the term, "cease to function".

The question is, when is it an indication?

The most common indication in my mind is missing laterals in the anterior, #7, #10, with a pontic cantilevered off of the canine tooth. With the right occlusal adjustment and person, this could last a long time. Then again, cantilevers should experience a higher failure rate due to their nature.

The second indication is a missing premolar, say #20 cantilevered of off a molar, or a molar cantilevered off of two premolars (http://www.toothiq.com/dental-information/page.aspx?id=0cd8b612-e1ef-4b5e-8e4c-1a2d4299d1dd) . A molar cantilevered off of two double abutted premolars should not be larger than the premolars it is abutted off of. These are not very common anymore due to the nature of implants however.

 

[doc toothache]

The question is, when is it an indication?

Actually the question was answered, but apparently not to your satisfaction.