Abandon cement retention?

There is nothing wrong with cement retention if you follow simple guidelines: 1. Make sure your finish line is no deeper than 1.5mm from the FGM 2. Clean your cement If you follow these simple steps, you should not have any issues. Chuck

I learned a great technique in a CE course to cement crowns with minimal cement left over. Prior to cementing inject Bite reg into the prep and let it set up. When you go to cement inject cement and have asst or doc place the bite reg into the cement extruding all the excess. Wipe off anywhere but the intaglio of the crown and carry to mouth for cementation. Follow cement clean up still for the little that remains. This should help all to keep cement to a minimum. Aloha Jeff

I am very happy to see someone concerned about the issues of placing and removing cement retained implant restorations..... if there are two units soldered together....no problem.....put a C & B remover under the joint, and tap it out gently... The problem is the well fitted single crown where there is nothing to grip on to for the C & B remover, or when the crown is built on an angled abutment and there is no access to the screw by drilling a hole through the cingulum..... ..........but I have answered your prayers in an article that I published in the January/February 2015 issue of Implant News & Views entitled " BAILOUT PROCEDURE FOR CEMENT RETAINED IMPLANT SUPPORTED CROWNS" Contact the editor, Dr. Keith Rossein and I am sure he will send you the publication when you mention my name. You will be amazed how easy it is to remove a cement retained crown on a loose abutment, without any damage to the crown...... Another tip you the reader might be interested in is...... before cementing an implant crown ( preferably with a temporary cement) put retraction cords in the sulcus around the implant, followed by a piece of ordinary Teflon tape rolled into a rope, and placed on top of the cord..... this will prevent excess cement from being trapped in the soft tissue......... when you take out the Teflon and the retraction cord, any trapped or hidden excess cement will come out completely, and no surprizes later on. Dr. Gerald Rudick MONTREAL, CANADA

Nobel recently introduced ASC the cement free angulated abutment. With advances like this we Should be doing more screw retained implant supported restorations. Predictable retrievability with no concern about cement retention . I have only had to deal with 2 cases of fractured abutment screws where the restorative dentist could not remove the cemented crown. That was two to many.

Editors note: If anyone is interested in following up on Dr. Rudick's article, simply go to the website of Implant News and View: http://www.implantnewsandviews.com and inquire there. Thanks.

Totally Agree with Chuck , there are issues with screw retained as well just different issues . Premier cement seems good and removal easy with crown remover. Peter

While no method is perfect I would like to share my thoughts. When an implant is placed in an ideal position with adequate bone and soft tissue and a surgical guide so that screw retention is possible then the restoration is retrievable. I learned cement placement for natural teeth since that was all that was possible, it is a paradigm shift. I think that screw retention is the first choice but corners can't be cut. Even with good technique cement retention seems to be the most common cause of implant failure. If I were a patient and knew that the screw retained option was available and the dentist is cutting off a crown and compromising my implant I would not feel that I was receiving the best care.

Also using a crown remover or various other traumatic techniques on a natural tooth with a periodontal ligament is different from placing such forces on an integrated implant. The natural tooth has some tolerance and healing capability. There is less tolerance in an inert implant especially with the delicate internal threads. Think of the biology and the delicate technical skill. Gentle is best.

I always value CRS's opinions....and yes....... when tapping off a crown on an implant, extreme caution must be exercised.....when I refer to a crown and bridge remover, what comes to my is the spring loaded type, and now therer are air driven types as well........... as a dental implant patient myself, I always bring my personal spring loaded C & B remover to the dentist...... and I know that the bridge will be easily tapped off....with no after affects. It does not take much force to dislodge a cemented crown........ and there are some spring loaded types that are adjustable.....just be gentle and you will succeed.

I have thousands of Implants permanently cemented to Implants. Before after and recall XR without any problem. An screw retained crown will allow for bacterial infiltration and stinking odor periimplantitis and other gum disease. Most of the Implnt companies are pushing the screw in crowns for the purpose of selling more components to the doctors. Any one interested in seeing the results of long term cemented crowns is welcome to my office, and I will share with them. By the way didn't we learn how to cement crowns with permanent cement to natural dentition and to remove calculus in Dental School? This is my humble opinion on the matter. Raul

I agree with Roul Mena on this issue. Infiltration of bacteria around screw-retained prosthesis is indeed a very malodorous problem. I have seen it and it is very unpleasant for the patient. Worst of all, it can mean an exasperated patient. Only cement seals well enough to prevent it. Furthermore -- and inasmuch as I always respect CRS's opinion immensely -- I personally feel that screw-retained is actually to be avoided whenever and wherever possible. If I were a patient and I received a restoration that actually gave me bad breath, no matter how well I maintained oral hygiene, I would feel I didn't receive good care at all. (We must remember most patients are laypeople and judge these issues in a superficial, simplistic manner. Expanations often don't interest them, only results do, and rightfully so. I have seen the grossly unsatisfied reactions of these patients.) I have seen a few cases (not mine) where the screws actually broke, and removing them becomes a real head-ache. To me, even one such case is one too many. I have been able to avoid all such problems by using temporary cement, or even Dykal, which is in many cases better than a temporary cement. It's no big deal if the crown comes off and it needs recementation. It is actually beneficial to the patient, because it "forces" him to periodically return to the office for follow-up. I find that too many implant patients tend to forget about follow up and go about their lives without paying attention to periodic professional implant hygiene. Not leaving any excess cement in the peri-implant sulcus is simply a matter of a very thorough yet gentle clean-up (with fine periodontal curettes when needed) and paying close attention to the minutest details, with loupes. With the advent of the latest cements specifically designed for implant-supported restorations this is easier than ever. BUT, having said all of that, the single most important factor by far which affects the ease of removing a cemented crown is a completely passive crown fit over the abutment. I personally feel this is paramount. Indeed, for those who wish to leave themselves an additional safety valve, a small access hole can be drilled into the occlusal of the crown and covered with composite, for future ease of access to the abutment screw. As for tapping off implant supported crown and bridge, I prefer the manual sliding crown remover to the spring loaded one, because it affords me the possibility of applying the absolute lightest and gentlest tap, which in most cases proves sufficient if very very gently repeated, if the crown fit is completely passive. And when I say the lightest tap, I do mean the absolutely lightest of taps, with no shock at all! On this point I agree wholeheartedly with CRS that traumatic crown removal on implants is to be avoided at all costs, as implants have neither the resilience nor the healing capacity of natural teeth.

I agree with Matt Helm and CRS....go gentle on the tapping..... if Matt has a better and softer device for removing the cemented crown....wonderful....my suggestion was basically to provide a way to have a lever on the smooth crown in order to get a grip on it without damaging it......

@Dr. Gerald Rudick: Thanks. I would be very curious how you provide a lever on a single, stand-alone crown. Can you briefly describe it? As for a softer device to obtain purchase on the crown, the only one I know of is a forceps (similar to a lower bicuspid extraction forceps) with 360 degree rotating rubber inserts in the jaws. However, I personally don't see any need for removing implant supported crowns unless there is a problem. Routine implant hygiene can be done with fine, slender, perio curettes without removing the crown, unless it's a bridge with extremely tight gingival embreasures. if the crown is loose it should come off easily anyway. And if the abutment is loose but the crown won't come off there is always the option of drilling through the occlusal of the crown to gain access to the abutment retaining screw. Keeping things simple goes a long way towards avoiding complicated problems, in my view.

CRS, I agree that the implant surgeon should place the implant in adequate bone and adequate soft tissue, but they also have to be in the proper position and at the proper height. If that is the case either screw retained or cement retained should work properly. One extra point, there is not such a thing as a pure screw retained crown since some sort of temporary cement or sealant should be place to try to prevent bacterial infiltration between the implant the abutment and the crown. If properly done bridges do not need to be removed from the abutments. What is the difference from removing cement from a crown placed on natural dentition versus a crown cemented to an abutment. As a practicing implantologist and president of an implant company that also has screw retained abutment, I can say that implant companies are pushing the screw retained abutment because it adds a 25 % profit margin to their annual sales. Raul

CRS, i am aware that there is no PDL around dental implants, but it is a fact that PDl like Bone doesn't like Cement either. As a surgeon and as a restorative implantologist, if the case is properly treated both in the surgical as well as the restorative phases there should be no reason to retrieve the case. Basically what we are going over is a choice of treatment, you prefer screw retained and I prefer cemented retained. Respectfully, Raul

The value of professional dialog is informational. Sub gingival cement is more of a problem with an implant supported restoration because there are no circumferential fibers around implants. This makes it easy for cement to be pushed to the level of bone. There have been many case reports describing peri implant bone loss resulting from excess cement. As a dentist who regularly serves as an expert in malpractice cases related to implants I can tell you that I recently reviewed a case where the patient experienced recession in the esthetic zone after the excess cement was removed. Additionally, complete removal of excess cement, where inflamation becomes a problem, is facilitated by removal of the crown. This provides better access and visibility. Saying that retrievability is not necessary, is short sighted.Of course so many cases have been done with cement without complications. Just be careful. This is an important step. Use a technique to eliminate excess cement and use a cement that allows removal of the crown.

Raul Mena wrote......." if the case is properly treated in both in the surgical as well as the restorative phases, there should be no reason to retrieve the case". If the implant has an abutment, there is always the possibility of screw loosening or fracturing under a cemented crown...or a porcelain fracture may dictate the removal in order to repair it...so the option of removing a cemented crown should always be there......

I direct my comment to Alex Corsair's very important comments above :- Another tip you the reader might be interested in is…… before cementing an implant crown ( preferably with a temporary cement) put retraction cords in the sulcus around the implant, followed by a piece of ordinary Teflon tape rolled into a rope, and placed on top of the cord….. this will prevent excess cement from being trapped in the soft tissue……… when you take out the Teflon and the retraction cord, any trapped or hidden excess cement will come out completely, and no surprizes later on.

Gentlemen, gentlemen, why all the arguing? My my how we professonals can become heated, even as we are all on the same page. We are all obviously in agreement that retrievability is paramount and that tissues don't like excess cement. In fact, no tissue likes excess cement, be it peri-implant or natural dentition marginal gingiva. I think we've all seen at some point the ill-effects of excess cement even in natural dentition restorations. How many times in your careers have you seen inflamed marginal gingiva secondary to a super-tiny spec of retained excess cement, so acute that it resembled a perio abcess at first glance? Having said that, I will now add another monkey wrench into this heated discussion: one of the -- to me important -- reasons I prefer cemented over screw retained is because the cement adds a layer of shock absorbtion, albeit a very small one. I personally feel that screw retained is too rigid resulting in all the masticatory forces being fully and directly transmitted into the implant 100%. If, perchance, there is the slightest bit of imperfection in an occlusal contact this will transmit more force into the implant than a cemented restoration and cause marginal peri-implant crestal bone resorption sooner in the long run. And although this has not been scientifically substantiated, it makes simple logical sense that a layer of cement -- specially a temporary cement -- will add a layer of very slight resiliency... a sort of additional "shock absorption", if you will. You may argue the point, but in our world of teeth, where things are measured in microns, even a few additional microns of "shock absorption" provided by the layer of cement -- I feel -- can help make a difference in the long run. Of course, it will not make the difference when there is a clear and grossly premature (or poorly placed) occlusal contact. But overall and, considering an implant only has 50-100 microns of delayed movement afforded it by the viscoelasticity of bone -- as opposed to the 56-108 microns of primary movement of a natural tooth PDL -- I personally feel that any additional microns of shock absorption (albeit unknown, and unmeasured as yet) provided by the temporary cement is helpful in the long run and, is welcome.

Did not know that cement has this property I do know that some implant systems are designed to break at the screw interface to save the implant body. Actually I think this is a very good thread vs an argument. I have zero experience with restoring an implant and like the imput from those more experienced. I have broader surgical experience and like to share. I actually think about these comments when treating patients. Nothing is absolute. Peanut butter vs chocolate!

Dear friends, I hope that all these postings are of some scientific value and are taken as an exchange of different opinions. WE have seen the pendulum from cementing to non-cementing to cementing to now going to non-cementing. There are circumferential fibers around the implanto-abutment connection but these fibers lack hemidsmosomal connections. Another important factor in the healthy maintnence of the implanto gingival junction is the abutment design. Must abutments lack CERVICALITY, they are manufactured with flat gingival area, and that allows for food to be trap and dislodged toward the apical. Raul

Hi Matt- If I correctly recall, after many years, the purpose of dental cement was to fill the micro-discrepancies between the internal (intaglio) surface of the restoration and that of the prepped tooth, or in these discussions, the implant abutment. The interface tolerance of the internal surface of the crown to the implant abutment surface must be minimal to ensure that a mechanical lock, aided with a cement media, resists vertical and lateral occlusal forces. To my knowledge, there is no "shock absorber effect" and if there is excess interface space, the cement will break down with loosening of the implant crown to the abutment. Applying only a very thin layer of cement will aid the mechanical locking effect and reduce excess cement escaping into the gingival crevicular space. Anyone have comments confirming my memory is now rapidly fading or if I was bored and could not wait until Dental School's dental materials class was over for the day? Ivan

Dr. Rudick, I have no problem with screw loosening since I use True Morse Taper Abutment. My cases go back over 30 years without the need to retrieve them. TaperLock Implanto-Abutment connections have a real advantage over screw retained abutments. Raul

Answer to Raul Mena Any student beginning his/her education, is taught to beware of the words "never" and "always" when answering an exam question...... and this should also apply to screw loosening or screw breakage when considering the security of an abutment connection to a dental implant. A Morse taper connection is certainly superior to an external hex implant system, which relies most heavily on the screw itself...........the "never" had a screw loosening or it "always" works....may one day surprize you....and this is why you need a back up solution should you be faced with this problem..... a very simple solution.......

Answer to Dr.Gerald Rudick Dear Dr. Rudick, I was also taught to be ware of the words "never" and "always" when answering an exam question. I was also taught to read the question and think of the proper answer before answering the question. I didn't use the word never on my posting, please read my comment carefully so it is not taken out of context. (I have no problem with screw loosening since I use True Morse Taper Abutment). If I din't use screws in those cases then there are no screws to come lose. At the same time I am glad that you like TaperLocking abutments. Raul

Answer to CRS Dear CRS I also had foreign instructors some with accents and others spoke as if they were born in the USA. I was lucky enough that since I am a Cuban American and understand a few languages, my classmates in many occasions use to aks me “Raul what did he say”. Neither I nor anyone else has said that there is only one right way. What I have posted is that I like cemented retention over screw retention. Of course that implants need to be placed in the proper position and if there is lack of hard or soft tissue then it needs to be corrected before proceeding with implant placement. You always mention that you use screw retained implants. Does your referring base have a choice of implant that you place when they refer you their patients? Do you fallow their treatment plan or do you treatment plan their cases? These questions are just to figure out your statement regarding the Implants cowboys of the west “Who is the Cowboy and Who are the Indians”? With all my respects Sincerely Raul

Regarding comments about bacterial infiltration with screw retained restorations - whether you screw retain or have a cement retained abutment there will always be a microgap between the abutment and the implant connection interface so either way bacteria get in. With a cement retained unit - when you remove the prosthesis there may be no smell but when you remove the abtument there will be. Screw retention alone will not stop prei-implant problems if the prosthesis design is poor (access to hygien aides). I the anterior aesthetic zone screw retention can be difficult in cases where tooth loss occurred years ago. Again its all "Top Down" - accept that you have have to graft and modify the implant bed for screw retention to be an option. Screw retention using adhesive base abutments can resolve most aesthetic complications but if you are restoring a single tooth and the patient has opalescent teeth then a pfm restoration (or zirconia) may not be an option.