Excess Cement and Dental Implant Failure: Thoughts?

You can check the osseonews archives for prevention of excess cement when placing an implant crown. Now for my opinion, the only time an implant crown need be cemented is when there is an issue with where the screw hole would be, ie incisal edge or facial due to constraints of placement. This can be solved with good treatment planning and grafting. An implant is not a tooth it has no PDL and a cord should not be packed. Cement in the long attachment will cause an implant to fail. As a doctor who knows this and is concerned it is your decision not the patients and it is not up for negotiation. Perhaps you could have a waiver for the patient to sign after you you have tactfully explained this. It doesn't seem logical to me that your patients won't let you do a screw retained crown when it is your judgement and risk! A good spin is that "screw retained crowns are retrievable and do not expose you to the risk of cement causing the implant to fail etc. I think that if it is presented in a way the patient can understand there will be better compliance. Follow your gut, and do what you feel is best, instead of letting the tail wag the dog. The only reason implant crowns are cemented is that is what we were taught in dental school on natural teeth and that is what we are comfortable with. I have seen a lot of cement and even impression material cause implants to fail it is not pretty. An implant is not a tooth!! Thanks for reading!

You are right to be concerned about this issue. The cause for it comes largely because people are using stock titanium abutments. These are generally undersized and the crown preparation margins are usually located sub-gingivally to avoid a metal display. The solution is to provide custom Zirconia emergences. These can generate a natural emergence from the gingiva with a "proper" tooth form, provided the implant platform is located deep enough and the emergence profile is correctly developed. These days with the color of zirconia improving it's really no problem to bring the margins supra gingival, especially on the interproximal and palatal. When you get used to using these, you will never go back. The future for abutments is to get away from stock abutments and into custom. The best systems are based on a metal connection, then there is no concern about zirconia abrading the inside of the implant or for fracture of the zirconia when tightening the retaining screw.

I completely agree with the above reply! As a periodontist, I am often asked to treat perimplantitis and I can't tell you how many times I have found cement under the crown, along the abutment and below the implant platform. Usually it does not show on a radiograph unless it is on the mesial or distal of the implant and the radiopacity of the cements can vary greatly. Plus, it can actually take years for the bone loss to show on an x-ray and by that time you have lost a significant amount of attachment. I just returned from the ITI North American Congress and it was a hot topic of discussion. There is an excellent paper by Thomas Wilson (which I don't have the reference in front of me) on the subject and another study by Chandur Wadhwani (also don't have the reference with me) about the ability of certain cements to actually promote the growth of bacteria. Bottom line is don't use cement unless you have to and avoid the whole problem. The only thing I would add to the previous comment is that you can avoid some of the problems with subgingival margins by using custom milled abutments with the crown margins either at the tissue level or no more that 1 mm below, so that you can access the cement to remove it. I have seen that work very well.

bone loss is multifactorial and cement retention is just one of the factors. We have been cementing crowns to implants for 30 years so no need to throw out one restorative method of retaining crowns in a panic. There are several things that need to be addressed to successfully cement a crown. first, use a custom abutment (Atlantis abutments work great and their titanium abutment is very reasonably priced) and make sure the finish line is within a millimeter of the free gingival margin. Second, use a radioopaque cement that is white. Any cement with zinc will be radioopaque. I use either a temporary cement or zinc phospate (flecks cement) for more permanent cementation. These cements are easy to clean, easy to see and are radioopaque. If there is a small fragment left behind, these cements are also water soluble. Lastly, zinc is bacteriostatic and can help with the crevicular bacteria. The main lesson is, no more resin cements. These cements form a tough, thin film that is difficult to detect and remove. They are also radiolucent. Moral of the story, quit panicking. Dont' let the lecturers freak you out. They have a good message which, simply put, can be easily followed. No more stock abutments. Custom or CADCAM abutments to position the finish line in a cleansable area. Use zinc containing cement and get it all off. Any questions?

An excellent article by Prosthodontist Alfonso Piniero from Seattle Washington reviews excess cement effects on implants. Google it and read it...he has multiple techniques to help prevent this problem...JohnB

Here's a cementation technique that has worked well for me. I use the same technique for traditional crown and bridge too. I make a custom die out of a PVS bite registration material. Simply inject s ome bite reg into the crown, extrude a little excess so you can remove it Mix your cement and load the crown, place the die gently into the loaded crown. Set the die 90 percent down, remove the die and wipe off extruded cement. Seat your restoration. You'll find you have very little clean up. I also take a digital image to check that all the excess cement is removed. I think the radiation dose is well justified. Hope this helps

Just addressing your main concern, you can place a retraction cord into the sulcus big enough to prevent the cement from running,after the cement set just remove the cord If any cement went into sulcus believe me it will come out with the cord. SIMPLE BUT WORKS EVERY TIME.

Dr Cain, I appreciate your comments. I have also found excess cement under crowns on natural teeth to cause similar problems. Dr Johnson the PVS die tip sounds like a good idea. I will give it a try.

Very good discussion from my guys in the trenches, good tips thanks for reading!

Dr MV Johson, really appreciate your sharing of your experiences and observations. The best part I like most " don't let the lecturers freak you out . Quit panicking." And Dr Campos's " Simple but works all the Time ". is a gem . Thanks Guys for willing to share. You make life Simple.

Dr Johnson, I used the PVS die tip two times yesterday on two separate patients. It did reduce the amount of cement to remove from the margins. Time will tell the story as per retention. Still a simplemtipmthat will help to avoid a lot of problems.

Agree some nice comments , agree with Dr Johnson , the desire to achieve a desirable "emergence profile" has led to some cemented junctions being moved too deep . Whether stock or custom the key is to select abutments where the cement margin is where we can control the cement as we would with a normal crown . Keep calm and watch the Masters . Peter

Screwing them in is still a problem because of microgaps that allow microorganisms to proliferate give rise to peri-implantitis. Excess cement in the transmucosal passage of dental implants, its dangers and the different possible solutions were discussed at some length in the osseonews link below. Device a method in which you can eyeball the excess cement and remove them is the surest way. Any other way cannot be guaranteed. Every dental implant ever placed has created a periodontal pocket and with excess cement will increase the chances of peri-implantitis. So, if we have to create a pocket, it makes sense to make a small one as far as possible. http://www.osseonews.com/excess-cement-penetrating-deep-into-gingival-tissue-do-specific-implant-fixtures-prevent-this/

Screwmentable!....For posterior implant crowns, I have had good success with: 1. Atlantis custom titanium abutment (gold hue or standard) with a. margins 1mm supragingival where it does not show b. margins 1mm subgingival where it does show 2. A Zirconia crown a. Full-contour where esthetics are not a concern (e.g. Bruxzir) b. Layered porcelain on zirconia where esthetics are a concern (e.g. Lava) The lab puts a screw access hole through the occlusal of the crown and delivers to me the abutment and crown (separate items). Then: 1. Try in the abutment (a try-in jig from the lab often helps) 2. Try the crown on the abutment in the mouth, adjust contacts & occlusion as needed 3. In the lab, cement the zirconia crown to the abutment with an opaque resin cement a. stuff teflon (plumbers) tape into the abutment access hold to keep cement out b. dual cure cement (such as RelyX Ultimate + speeds up this process) c. EASY to remove all excess cement! d: freshen access hole zirc/porc 4. Torq in the 'Screwmentable' crown a. have the patient chew on a cotton roll for 2 min, then re-torq 5. Plug access hold with sponge or plumbers tape and plug/seal with an opaque white composite. Note: if a lab tries to make an PFM all-in-one abutment crown you will 1. have a lot of metal cost 2. the mass of metal will not cool in a matched sync with the porcelain and lead to fractures. 3. zirconia as suggested above is stronger than PFM yet has good wear/opposing characteristics Practical Note: When I cannot place a 'screwmentable' because an access hole would be in an unacceptable place, I have had success using: 1. minimal cement techniques mentioned in previous posts 2. USE cord, small 00 or 00, and place a piece 'like flossing it into place', one at the mesial and one at the distal, without packing. 3. pull the cord when the crown is down and the cement is not yet set 4. take a radiograph--you want to be the first to know if you have a problem! Best Wishes, Jim

I can see some of the benefits of screw retained prosthesis. I prefer to use cement retained prosthetics. It's very difficult for laboratories to offer the degree of accuracy necessary for multiple unit screw retained prosthetics to fit correctly. I have had my major head aches with screw retained prosthetic cases that have appointed with my office for retightening of the prosthetics. Yes, these are cases that I did not restore. Now I'm going to make a big contradiction. Those cases which repeadly become dislodged, I have fabricated prosthetics that are cement able with screw access holes. This is for those with severe occlusal parafunction. This has been and will continue to be a debate for years. Basically it's what one believes!

I like this too.

There are three critical margins that can give rise to peri-implantitis, bone resorption and failure of the dental implant. The first is the abutment-fixture margin. This margin used to cause bone resorption 1-2mm away from it due to microbes in the microgap. The problem has been largely solved using the conical aka Morse taper connection which effectively cold welds the abutment with the fixture. The second critical margin is the crown-abutment margin. This is the margin at issue in this discussion... whether to screw it tight or fill it with cement. Screwing it leaves a microgap for microbes which produces toxins that enters into the periodontal pocket around the implant that extends all the way to the bone level. These toxins cause peri-implantitis. This margin can be at the level of the connective tissue interface with the implant or preferably at the gingival interface with the implant. Whether it is above the long gingival fibres running parallel to the implant surface or not does not make it less harmful because there is no such thing as a long gingival fibre attachment to the surface of the implant! It is totally different from the fibres that attach perpendicularly to the surface of the cementum or the epithelial attachment to the surface of a natural tooth. Screw retained will have microbes in the micro-gap and cement retained will have the problem of excess cement that cannot be seen and therefore often cannot be removed. I will still prefer cement retained because there are different techniques to eliminate most if not all the excess cement. If retrievability is such a critical issue, we should never have cemented our conventional bridges in the past but screw them all in..... it is a matter of which is the lesser evil, i guess. The third critical margin is the emergence margin of the dental implant and since it is the entrance to the iatrogenic perio pocket of all dental implants, keep it as small as possible.

After placing cement in crown place back on analog on the cast. This will get rid of any flash.