Implant Frustration and Dilemma

Last Updated: Sep 11, 2013

I am in the process of getting 2 implants for teeth # 29 and 30 at a dental school. The implants are installed, and (as the x-ray below shows), posts temporarily placed in the implants when impressions were taken for the abutments and crowns.

After having a bridge for a decade, I was looking forward to having separate teeth that I could floss between. My doctor prefers to splint the 2 abutments / crowns together, and possibly go with a molar and 2 pre-molars with a pontic given the 20 mm spacing between teeth # 28 and 31 in the picture.

However, he is willing to make 2 molars (each ~10 mm) and not splint them together â€“ my preference. I understand that with no ligaments to absorb the pressure from chewing, and no distribution of this pressure as with a splint, that there is some risk of premature failure. But the question is how much?

Before making a final decision, I would appreciate input from professional folks.

Questions:

1. Why the implants were not spaced more evenly between teeth # 28 and 31 is unknown to me. As installed, the crown for tooth # 29 will not be directly over the implant. Arg! For learning purposes at the dental school, and for my own interest, I plan to ask why they were installed as they were.

Other than removing them and starting over (not realistic), is there anything else that can be done with them given their location?

Assuming the implants are â€œit is what it isâ€, the alternatives are:

â€¢ 2 molar crowns non-splinted,
â€¢ 2 molar crowns splinted, or
â€¢ 1 molar crown and 2 pre-molars with a pontic to fill the 20 mm gap.

Iâ€™m concerned that regardless of the alternative, the crown for tooth # 29 is the weak link. That is, given the placement of the implants, there is a high risk that this crown will fail 1 or more times over the next 30 years.

2. Given the space between tooth # 28 and the implant tooth # 29, is a pontic needed regardless of the alternative chosen?

3. Is the risk any greater with alternative 1, my preferred alternative?

4. Alternative 3 was suggested because of the large space that needed to be filled. Is alternative 2 (2 molars each ~10mm) okay? Or is 10 mm too large for a crown, so alternative 3 would be better?

7 Comments on Implant Frustration and Dilemma

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Maximplante

09/12/2013

All alternatives are ok.. However it is possible to try on the crowns before. You may ask for a temporary crown to be done which has a lower cost. Although many Dental software can simulate the final aesthetics crown. Anyway, I believe that you should approve the final contour by trying on the temporary crown on your mouth. Should you not happy with it, just give your feedback. Your dentist should redone the crowns if the result is not satisfactory.

Samuel Barr, DMD

09/12/2013

As to what lasts longer, splinted, vs non-splinted, there is no real consensus of opinion in the profession. It used to be felt that splinting was essential for long term implant survival, whenever possible. Lately, I have read research that shows no difference. From a theoretical standpoint, you should get better stress distribution if the implants are splinted. If any aspect of the restoration involves any sort of cantilever, then, in my opinion, splinting becomes more important. When the question is what may last better over 30 years, I don't think anyone has a clue, because the implants done 30 years ago are a different beast than the ones being done today.

Carlos Boudet, DDS DICOI

09/12/2013

I will try to answer your concerns. 1- The reason the implants are not in the ideal position with respect to the crowns is probably that they may not have been placed using a surgical guide, where the doctor waxes up the teeth in the ideal position and makes a surgical guide made of acrylic that he or she uses to guide the drill in the ideal location and angulation. 2- From the radiograph you provide, it looks like you do not have space for a pontic. You have the implants placed in a manner that would require a molar that is smaller than normal and a premolar that is larger than normal due to the placement of the implants. I guess the crown on #29 may look fine as a molar instead of an oversized premolar. 3- I believe the only risk involved is in the design of the restorations. I don't think you have to worry about failure if you restore the implants with two individual crowns. PFM crowns with properly supported porcelain or solid zirconia crowns will do very well. Please be aware that this has happened to all of us. We have all placed implants in less than ideal positions and have learned how to manage these situations. Having them placed at a dental school sometimes does not guarantee results. Try not to worry and I am sure you will have successful, long lasting restorations. Good Luck!

toofdoc

09/12/2013

It is obvious that you are well educated on implants and what is happening in your mouth. Much more than most. Well done! I would say that I think all three of the above comments are great advice and information. So I will not repeat them! I will add a comment about the implant placement. The Inferior Alveolar Nerve runs under the posterior (back) teeth and turns superiorly (up) in the #29 area. That nerve comes out a hole in the bone (mental foramen) in that area..... that is why your lip gets so numb when they do anesthesia on the mandible. Hitting that nerve with an implant or damaging it when it comes out of the bone can cause permanent numbness. Working near and "uncovering" that nerve can give a surgeon some pause. It is very common to work in that area and uncover it.... but in the hands of an inexperienced dental student..... I for one would be very glad that the student (and staff they are working with) are wise enough to not push limits so early in their learning curve! Since there is a cantilever to the anterior (front) in this situation.... I would personally lean towards splinting the two implants together. All the best! It will be fine!

George Felt, DDS, Perio,

09/12/2013

You attach too much importance to the little stuff in this case (implant positioning is adequate); a little knowledge is a dangerous thing (leads to misunderstandings and specious worries). These implants are "good enough" to support a fixed prosthesis. What really matters now is simple: you need a well-fitted (passive) fixed prosthesis (could have one, two, or three teeth - NO MATTER - let the doc decide what works best) with contours that are cleansable (open gingival embrasures) and a good bite (occlusion optimized for axial loading and minimal lateral stress). If these issues are managed well your chances of a 20 year or better positive outcome are above 90% (assuming good maintenance and otherwise good health). BTW, the issues mentioned here WILL be managed well because anybody in a teaching environment knows this stuff and will routinely get it right. Find something else to think about and let them do their job - surely you have better things to do, or maybe not - in which case maybe YOU should go to dental school ;) BTW you need to splint those teeth for long term prosthetic stability. Good luck - relax - enjoy your excellent new teeth and move on..

John Dentist

09/14/2013

Dr. Felt's comments are 100% correct. Although the implant in the #29 location could have been placed a little closer to the #28 bicuspid, the reality is that the implants were extremely well done and the prosthesis (which should be splinted in my opinion), will outlive you. You're way too concerned about trivial issues in this case. Leave well enough alone.

Walter Mick DDS

09/19/2013

Place 2 molar crowns....splinted, not for stabliliy,but for interproximal control. Because of the lack of PDL, fitting the sides of the teeth together in a matter that doesn't become a foodtrap can be difficult to achieve well. Is there any aversion to replacing the crown immediately anterior to the edentulous space and slightly (1.5mm) overcontouring distally. BTW the edentulous space appears quite large for just 29 & 30...Is this really 29-31 with a partially drifted 3rd molar?

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