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Non-Ideal Positions and Angulations

Last Updated: Sep 20, 2005

There are times when dental implants are not placed in ideal positions with ideal angulations. Suppose you intend to restore an edentulous mandible with a dental implant supported fixed partial denture.

You have taken accurate records, mounted your diagnostic casts, waxed-up the case, made your surgical stent, etc. The patient is wearing a maxillary complete denture. Your treatment plan is based on the placement of 5 regular platform dental implants in the classic A-B-C-D-E positions. The patient has a narrow, atrophic mandible which you split and grafted. Unfortunately there is sufficient bone width for the placement of narrow platform implants. The implants in A and E positions are angulated 15 degrees to the distal to accommodate the anterior loop of the mental foramen nerve. The implant in C position is angulated to the lingual to avoid perforation of the buccal cortical plate.

What would be your technique for restoring this case with a fixed partial denture? How would you make your dental implant level impressions? What design would you use for the abutments? What design would you use for the metal framework? Feel free to leave your comments below.

5 Comments on Non-Ideal Positions and Angulations

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Alejandro Berg

9/20/2005

Certainly is a problem to face this situation (poorly placed implants) but in most cases one can overcome this problem with personalized abutments like procera abutments made of zirconia or with overcasted gold/plastic ucla abutments. It is clear that in some cases one can use prefabricated angulated abutments. It is also clear that almost everybody has seen almost horizontal implants that are so far of the place that they should be that the only real choice is to remove them or to let them sleep forever. greetings

Daren Rosen

9/20/2005

I think it is safe to assume that every one of us imagines the case described slightly differently. Nevertheless, if applicable, what I would suggest is to try repositioning the middle fixture by cutting out a block of bone around it and then anchoring it to a prefabricated rigid splint from above and a monocortical bone plate from below. When possible, this will usually result in a more favorable soft tissue response near the emerging abutment and better vector distribution of the forces applied during function.

JXA

9/21/2005

For external hex implants distal angulated implants are a biomechanical advantage, and well documented. placement of angulated multiunit abutments in accord solves the prosthetic problem and reduces cantilever length. Although I prefer angulation in from buccal to lingual direction as not to invade the lingual clearance, in case of thin remanent bone I like to only angulate mesio-distally and not bucco-distally.

Michael Johnson

9/22/2005

The posterior angled implants are easy to deal with. Simply use pickup impression copings so draw is not an issue. Use either a multiunit type of abutment or wax the framework to the implant aka the "UCLA" style. Also, the hybrid prosthesis should be screw retained since access hole orientation and position are no big deal. The toughy is the anterior implant. Implants positioned too far lingual impinge on the lingual frenum and salivary gland ducts and can cause difficulty with hygiene. If the implant is too poorly positioned, simply put it to sleep with a cover screw and retain the hybrid with 4 implants. If the A-P spread is reasonable, and the opposing arch is a complete denture, then there should not be unreasonable forces on the retaining screws. I am a big fan of the kiss principle and there is no reason to get too technical with a simple case like this where only one implant is technically "poorly positioned" that could cause soft tissue problems.

Dr.Ejaz Khawer khawaja

10/3/2005

it is a excellent topic on the position and angulation of implant posted by michael johnson.

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