Cementing Crowns and Bridges on Implants: Problem of Excess Cement?

Use one of the implant specific cements such as Premier , where it sets to a soft consistency yet breaks of as an entire section hence you easily remove all the excess before it sets hard . Another benefit is it allows for retrieval. Peter

I have seen many cases of recalcitrant peri -implantitis as the result of cement. Especially glass ionomer. The viscosity of this stuff is dangerous around implants and it is difficult to clean. I have seen cases by good dentists using microscopes with huge cement retention problems. Glass ionomer seems to work well when you have a PDL, but around an implant, it can be trouble. As stated above by dr fairbaum, I recommend screw retention or premier, zop, even temp bond.

Dr. K, Anybody that has done Implant Prosthodontics for any length of time has encountered this problem, sometimes to the detriment of the restoration. there is a solution. Never use a custom abutment if you can help it. The only reason that you must use one is to correct for a surgical malposition in placement. Alwqays use a "stock" abutment. Pick a gingival height that leaves the crown margin deep in the tissue (do not encroach on any soft tissue attaschment that may have developed). The deep margin allows you to develop the soft tissue contour with the crown restoration. Since you are using an "off the shelf" abutment, you can use an exact duplicate abutment to pre-cement the crown or bridge onto. Simply wipe away the excess cement that is expressed and immediately transfer the restoration to the mouth. Studies show that the retention is not significantly different than if you did a direct cementation. And use a slightly soluable cement such as ZOP or Polycarboxylate. Although you will have difficulty reaching the final margin for clean-up, the minmimal expression of cementthat might occur will be removed by the body. Also, lubricate the intaglio surface of bridges under the pontic(s)and pre-wrap floss there before cementation placement if you want to ensure excess cement removal.

I will offer my opinion in contrast to that of Dr. Hoffman for discussion purposes and to help solve the cement problem. After having taught hundreds of implant courses and restoring implants since 1985, I will give you the protocol and rationale that we use. Do rarely now do stock abutments for a number of reasons. Stock abutments are round. Custom CAD-CAM abutments such as Atlantis abutments are shaped like teeth. We use the shape of the abutment to form the emergence profile, not the round shape of a stock abutment. A wider custom abutment will always leave smaller gaps mesially and distally to prevent food entrapment. And the margin placement of a custom abutment can always be controlled to be at tissue level or just slightly below. Cementing a deep crown margin near an implant leaves the possibility of leaving cement on the implant. However, cementing a crown on a custom abutment at or slightly below tissue, allows cement to be cleaned of a very smooth, highly polished abutment, not a rough threaded implant. Almost all implant procedures performed in our office now are fixture level impressions and custom abutments. There is no stock abutment that will ever allow the practitioner the opportunity to place the crown margin exactly where it should be. As far as cements, whatever you are comfortable with. They all work and the standard is a good crown and bridge cement by any of the reputable manufacturers. We begin cleaning immediately before the cement begins to set as opposed to cementing to a tooth. In cementing to teeth, we want the cement to fully set before cleaning because it is highly soluble until set and highly insoluble after the set. The object here is to prevent bacterial leakage for as many years as possible to prevent decay. In implants, the cement is used as a luting agent. There are no decay issues. We seat the crowns, keep occlusal pressure while 'shoe shining' the interproximals with floss to begin the removal process before the set occurs. In Europe this discussion doesn't happen as frequently because the majority of their crowns are screw retained while in North America we cement retain crowns. Whatever works best for you and the patient. In our office it is almost always a custom abutment.

Use the abutment most ideal for the situation, custom or stock. This is a problem frequently seen in the anterior. Use minimal cement, unlike crowns on natural teeth and our tendency is to fill the crown w cement when seating. Do not do this with implants. Use your best judgement, but do not fill the restoration with cement, and seat it w axial force and wait for cement to dry. If you are concerned about cement induced peri-implantitis or you have seen this in your practice try packing cord prior to seat. As more implants are being placed and treatment planned, this is becoming more of a problem.

Screw retained when possible

I'm agree with you in using the zinc phosphate cement in implant dentistry is better than other types in regard to excess cement removing. in implant restoration the luting bonds the metal to metal and the resulted retention is enough. in cases the abutment height are not enough for retention the screw-retained restorations are indicated.

Anyone who wants to provide their patient with the best outcome and longevity for the implant should read the above section by Mark P Miller. He has provided an excellent method for restoration and cementing. I wouldn't be doing it any other way.

http://www.osseonews.com/excess-cement-penetrating-deep-into-gingival-tissue-do-specific-implant-fixtures-prevent-this/ Excess cement in the transmucosal passage of dental implants, its dangers and the different possible solutions were discussed at some length in the above osseonews discussion. Device a method in which you can eyeball the excess cement and remove them is the surest way. Any other way cannot be guaranteed. Screwing them in is still a problem because of microgaps that allow microorganisms to proliferate and may still give rise to peri-implantitis. 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.

As a periodontist I do not restore implants, but I encourage restoring dentists to attend one of Dr Wadwani's and Dr Pineyro's lectures, two prosthodontists from Seattle. They recommend using a radiopaque type of cement and-if I recall correctly-placing two venting holes in the custom abutment so that any excess cement will be diverted into the abutment space rather than along the margin. For me as the implant surgeon the problem lies in the fact that when an implant fails down the road the patient is sent back to me to replace it, often in a compromised ridge due to the periimplantitis. And, with all due respect to my restorative colleagues, it is implied that it was the surgeon's fault.

What a great forum and many great posts! Thank you everyone for the great input. This is a great problem we see and this is fantastic information I wish all could read. It is nice to see a post without people ripping into other people from questions posed due to surgical inexperience. This is the meaning behind these forums. Does anyone know of a good lecturer in the midwest for this subject for a large study group?

CPG (omfs): Check out nwprosthodontics.com I've seen these guys speak, they're excellent and they travel around the country. They'd be happy to set something up for you in the midwest.

These are all excellent comments. I have placed implants for 20 of my 30 years as a periodontist and I see this as a significant and emerging problem. Although I do not restore implants, I believe I have an excellent feel for restorative dentistry as the son a dentist and the husband of another. The key lies in understanding the biotype of the bone and soft tissue surrounding the implant and the adjacent teeth. The margins on the abutment must follow the scallop of the tissue 360 degrees around the implant. I often see situations where the position of the margin is at the same level on the facial as on the interproximal. This rarely happens in nature. If the margin is left more than 2mm subgingival, it becomes almost impossible to detect extruded cement. Some cements are worse than others, but subgingival cement is a problem whether around teeth or implants. The other important point is following the emergence profile developed by the surgeon. The labs will often try to have an implant crown that follows the contours of a natural crown and some times that just creates and overhang. The restorative doctor is immediately in a compromised position. The labs need to be guided with respect to margin position and emergence profile. I will usually evaluate the patient after the restoration and have missed the cement a number to times only to be surprised a year or two later with a problem. If you pay attention to the biology throughout the process, you will rarely be surprised. A good surgeon will communicate this to the restorative doc. Sorry to be so long winded, but I think this is a very important topic. Thank you for bringing it up. PC

Hi everyone.I think there are two simple ways to avoid periimplantitis caused by cement excess. 1- Use Bicon implants,especially in single tooth implantation, therefore you can use IAC material ,ie. lab. can place the ceramic material directly on the abutment , thus there will be no need to any cementation. When there is no screw in such systems , everything in prosthetic phase will be much more easier. 2 - Use one of routine temporary cements , why not? If there is any need to retrieve the crown/bridge for any reason , it would be very easier to do so. Combining two above mentioned methods result in this problem solution.

I'd like to know if you know of any studies that might verify my thought that an appropriate amount of time should lapse between the placement of the implant and the cementation, allowing for some maturation of the tissues around the new implant prior to introducing cement. Has the "time after placement" variable been studied with respect to the cement inclusion down the threads of the implant that is suffering from cement induced failure? What I am getting at is that if we don't allow some maturation of the tissue, and if there is poor osseointegration prior to cementation due to immediate extraction and placement, poor boney architecture, inadequately grafted site, or rushing through the process, it does not appear that the cementation protocol is the problem, but rather there is a lack of resistance of the circum-implant tissues to resist the hydrostatic pressure of the cement during the cementation. Can't this be avoided just by slowing down the process a bit???

Dr. O'Conner the answer to your questions are in the books.