ERA Complications with Implants: Can’t Get Any Retention?

Dear Dr. R: I am Jim Ellison from Sterngold. I hold two patents on the ERA Implant that you have used in this case and I am one of the inventors of the ERA attachment system. With four ERA attachments you can achieve far too much retention of the overdenture, but that would not be a good thing. There are only two reasons why there would not be more that enough retention for this overdenture. The first would be if someone has polished or ground out the inside of the female part of the attachment on top of the implant. I doubt if that is the case. The second is if the males are not snapping correctly into the females. It sound like you did a chairside pickup procedure, but even if the males were processed into the denture in the lab the largest source of error in these procedures comes from tissue displacement. Back in the 1950s Steiger and Boitel demonstrated that tissue in the edentulous areas can be displaced by firm impression material or when a patient closes too firmly, by up to 2 mm. If this does occur, the patient must push hard to displace the tissue every time they insert the denture. Then the tissue rebounds and unseats the attachments. My guess is that this is playing a part in the lack of retention in this case. To solve this you should remove the metal jacketed males from the denture. Remove whatever colored final male is in the metal and seat black males completely inside the metal jackets. Snap the males onto each female being sure they seat all the way. The micro attachments are the smallest attachments on the market, which is good for placing into a denture, but that means you don’t have a lot of surface area to push on. You can see if they are seated because the black nylon sits right down onto the flat land areas just occlusal to the hex you used to drive in the implants. You will need to block out any undercuts and make sure no acrylic or composite touches the exposed metal areas of the implant, such as the tissue cuff. The simplest way to do this is to use a small piece of thin rubber dam into which you have punched a small hole. Stretch it over the metal jacket until only the metal jacketed male is exposed. It is best to use a bisacryl composite to pick up attachments; you may have one that you use to make temporary crowns with. I think Sterngold is the only company with a pink colored composite for picking up attachments. You need to prime the holes in the denture with an unfilled resin, like our Varnish so that the composite will chemically bond to the acrylic of the denture. You can use self curing acrylic, but the patients don’t like the taste, odor, or heat, but the big problem is shrinkage. Typically a self curing acrylic will shrink 7 – 8%, but the composites will shrink less than 1% and they are denser. The key is making sure the patient does not close too firmly. You want the denture base to just sit on the tissue, not to displace it. Patients often have a difficult time sensing light contact, therefore, you may want to have them close into centric and then open and you can then hold the denture in light tissue contact during the setting time. Core out the black males and snap in the white or maybe the orange and you will get very good retention. If you would like to discuss this further, you can call me at 800-243-9942 or e-mail at James.Ellison@Sterngold.com. I hope this helps. Jim Ellison Sterngold Dental Director of Technical and Educational Services

JimEllison-I have a case where I have placed three Biohorizons one piece overdentures in the maxilla and mandible. They have a 3.0mm diameter, I had to graft to gain more bone on the right side of both arches. I just saw the sterngold ERA attachments in the Implant Tribune in a 2.2 mm diameter. This slightly smaller diameter would have worked on the right side of the arches. Would there be a problem if I used the ERA's on the right side of the arches to complete the case?

No, there would be no problem using the 2.2 mm ERA Implant to complete the right side of your case. There are actually two diameters of the ERA Implants; the 2.2 mm diameter screw for narrow ridges, such as you describe, and the 3.25 mm when you have more width of bone. Each has the micro ERA attachment on top. But, there are a couple of things to consider. If you are going to use the one piece ERA Implant, just as with the ball attachment on the Biohorizons implant, the implants will need to be fairly parallel, within about 7 degrees of each other. With any of the attachments, if you exceed this you may be changing attachment parts more often than you like. We do have an angle correction implant, but only in the 3.25 size at the moment. Not only is the screw diameter of the 2.2 ERA Implant smaller, the attachment part on top is also smaller than the ball of the Biohorizons overdenture attachment. This may or may not be an advantage in your case. The other major difference is that the ERA is a resilient attachment and the ball attachments just hinge but are not resilient. This means that the ERA will move vertically, slightly (0.4 mm) and allow the tissue to absorb some of the occlusal load. This is why studies have show the ERA to be the gentlest attachment. But, given these considerations, they will both work to retain the patient's overdenture. Hope this helps. Call if you have more questions (800)243-9942. Jim Ellison

I just seated an ERA micro attachment today with the same technique stated by Jim above. If the metal housings are completely seated as suggested, you should have more than adequate retention. The only other item to be considered might be divergence in angulation of the implants which could prevent proper withdrawal and reseating. Using the ERA angled abutments will solve this problem. Call Jim Ellison and have him walk you through this technique.

Jim-Thanks for your response.

Dr.R. There is a couple of issues here that have not been addressed by the Posters 1. You state that the patient can dislodge the denture with her tongue, this is common with any attachment and a bad habit of denture patients. Break this habit and the attachments will be fine. 2. You also stated that you tried the male on a single female and got no retention. ERA's females can wear out but I doubt this is the case in only a month, the only way to tell is to see if the gold coating is worn on the inside of the attachment if so you will need to remove the implants.

Dr. R As Jim Ellison stated, lab processing or compressing the tissue when you pick up the attachments is the main problem when you do not have retention. If you are going to reuse the Stainless Steel housings, be sure to core out the colored attachments prior to removing the housings. An almost impossible task to remover the attachments from the housing once they are removed. Make sure that you have the black males in the housings when picking up the attachments or you will lose the vertical resilency feature of the attachment. As stated, do not have the patient close on the denture during pick up, otherwise, you will compress the tissue and have retention problems. You can contact me if you have any other problems @ 313-530-8833