Approximately 25 years ago, Per Branemark burst onto the dental scene—bringing his implant system with him. He brought a system that was proven with over 25 years of credible scientific study and yielded unusual looking prosthetics that, despite their appearance, offered a reliable alternative to full dentures for the first time. Since those early days, implants have improved to the point that they should be routinely offered as restorative options in every dental practice. In fact, dental implants are often one of the most successful and predictable restorative options we have in our armentarium. We have the capacity today to offer single or multiple unit prosthetics, as well as full or partial denture options. The relative ease of placement of dental implants, along with advances in implant design, has made the process largely routine, save for one aspect—restoration. Because of the fact that implants require certain volumes of bone in both horizontal and vertical components, the placement of an implant in an edentulous space often results in challenging restoration fabrication.
To accommodate these challenges, implant companies, dentists, and dental labs have partnered to manage these situations with angled abutments, two-piece abutment systems, and customized abutments. Each of these solutions has its own issues and offers additional complications.
The angled abutments are limited by the amount of angulation offered by the implant company, which may or may not be sufficient for the restoration in question—or may be more angulation than needed. In addition, because of the widespread use of internal and external locking systems, placement of the angled abutment at the desired angulation can be awkward. Two-piece abutment systems are typically more complicated and offer an additional failure point, the connection point of the two implant restorative pieces. Customized abutments usually start out with a plastic cone screwed into the implant body analog after the implant transfer. The lab then waxes to the plastic cone to achieve the desired abutment shape and casts the assembly in one piece conventionally. In some cases, the lab will take a titanium abutment and cast to the abutment with precious metals. The problem with the latter techniques is that, theoretically, because of the dissimilar metals, the metals could separate at some future point; in practice this rarely seems to be a problem. Inherent in all of these compromised solutions are the issues of occlusal stresses, cost, and time.
In particular for the angled abutments and the two-piece abutment systems, the issue of occlusal stresses is certainly as critical as it is in the natural dentition. For some reason, it has been assumed that it is unimportant to have the crown portion of the implant center occlusal forces along the long axis of the implant body, and this simply isn’t true. All too often, the resultant restoration may appear cosmetically acceptable, while simultaneously creating extensive cantilever forces that ultimately doom the prosthesis. Implants are subject to the same vagaries as the natural dentition, in that they are subject to periodontal disease, and when placed in excessive force situations, cause bone loss or prosthesis failure. Screws can break, abutments can unscrew, and restorations can break. Customized abutments can mitigate some of these problems but there still is the issue of fastening the abutment to the implant via a screw. This may result in the placement of a screw access hole that compromises the final restoration cosmetically or affects retention. In all of these solutions we must make compromises, which in increasing cost in the time required for the dentist to effect restoration, and increased lab costs as well. These costs should not be overlooked, since the time required for each implant restoration may vary as much as several hours, and combined with the extra lab costs and component costs, the total cost may exceed a $1,000 or more. Awareness of these costs and the time frame required must be factored into the fee charged, and if a doctor is not careful, may actually result in an expensive restoration that has little or no profit margin. Clearly, a more predictable alternative would be preferable—one that would result in less cost, less stress and finally a better restoration. I believe that I have been introduced to just such an alternative and it is called the Atlantis Abutment.
The Atlantis Abutment offers a cad/cam solution to the construction of a dental implant abutment. From a single block of titanium, a customized abutment is cut to mimic the crown preparation in a natural tooth. Thus the abutment can be constructed and customized to the dentist’s preferences, to be symmetrical within the tissue space and permit for the natural, cosmetic appearance of a finely crafted porcelain crown. The software adjusts for the screw placement and incorporates the screw access into the design. In addition, if employed from the time of placement, the proprietary software not only provides you with the abutment, it accounts for tissue maturation to mitigate the need for any chair side customization.
The technique is as follows:
The restoring dentist will provide Atlantis with full arch preoperative study models, along with a VPS bite registration and a shade for provisional fabrication. At the time of implant placement, once the implant has been placed and the tissue is still retracted, the surgeon will place a Fixture Mount that acts as a transfer post (it can also be used to fabricate provisionals chair side). A VPS index is taken and the post in the index is then also sent to Atlantis. At this point all materials can be sent to Atlantis for model fabrication or your lab can pour a model with the transfer posts in place, leaving room for a soft tissue model around the implants. If Atlantis pours the models, they can then begin the fabrication of customized abutments. If so desired, they can also fabricate an additional duplicate abutment and a provisional restoration as well (more on this point later).
After healing at the second surgical stage where the implants are uncovered, the surgeon can then install the abutment and place the provisional restoration. This provides for speedier tissue adaptation around the appropriate contours of a tooth, rather than a healing cap. Atlantis reports that in 87% of their cases no further modification of the abutment is necessary and thus once second stage healing has occurred, the case is ready for an impression—or you can send the duplicate abutment to the lab for crown fabrication along with an implant body analog, eliminating the need for an impression altogether.
Advantages
In my view, while implants offer an excellent restorative option, all too often there can be a lack of predictability with respect to the ultimate restoration. This causes stress, increases cost, reduces profitability, can compromise treatment results, and may result in a negative experience for both the doctor and the patient. If we can find a system that reduces or eliminates these problems, we must avail ourselves of that system. I believe the Atlantis abutment is just such a system. Let us review what the Atlantis Abutment does for us.
- It eliminates the need for abutment selection either by the doctor or the lab, which eliminates the need for either stocking or ordering of parts or reduces the mark-up expense of these parts by the lab.
- Via the custom milling of abutment, the screw hole placement can be incorporated into the design, thus removing a headache for the lab and eliminating a potential cosmetic or functional concern. In the anterior esthetic zones, if the screw hole is too far labial, the esthetics may be compromised, too far lingually and you have area for a constant source of tongue irritation. If the screw hole is too far mesially or distally, the abutment may be too thin for adequate retention, and in all of these cases, excessive forces may be created causing premature screw failure and subsequent loosening of the abutment and restoration. The Atlantis Abutment cannot correct for poor implant placement but it can correct for most restorative concerns when the implant is placed properly.
- Assuming that the implant surgeon and restoring dentist are different clinicians, one of the major advantages is that while the Atlantis Abutment adds a small amount of chair time for the surgeon, it can greatly reduce the chair time of the restorative dentist. Theoretically, the Atlantis Abutment System can eliminate the need for provisional fabrication as well as the impression step. Even if at the time of patient presentation to the restorative dentist for fabrication of the prosthetics, the abutment requires some customization (remember, Atlantis reports that chair side modification occurs only 13% of the time), you still have the duplicate abutment and thus at most you may have to take a pick up impression that should not require retraction. The abutment can then be unscrewed from the implant and then screwed into the tissue model or an implant body analog and placed in the new impression. I believe the less we have to touch the gingiva in contact with the abutment margin, the better. In addition, most labs prefer a machined titanium surface to build their restoration, so there are no impression inaccuracies conveyed. Thus the total chair time required of the restorative dentist may be under 45 minutes inclusive of the initial study model, centric records, shade taking, impression, and seating steps. This is likely less chair time than for conventional porcelain fused to metal restorations. For greater esthetics, the abutment can be coated to provide a gold color, and, in January 2006, Atlantis is coming out with a Zirconium milled abutment.
Other Systems
The Atlantis abutment system is also compatible with most of the major implant brands, such as Lifecore, Sterngold-Implamed, Nobel Biocare, 3i, Straumann, Astra, and, of course, Zimmer. The system can also be utilized if the patient has had the first stage of surgery, but this will require that a transfer post be taken either at the second stage surgery appointment or shortly thereafter.
Cost
On a per unit basis, the cost of using this system is approximately $450-$500 in addition to the laboratory cost of prosthetic fabrication, if you take advantage of all the services the system offers. (Each dentist may select some or all of these services, resulting in a lower fee if fewer services are selected.) On the surface this cost seems high, but this raw total ignores the chair time and component cost.
For conventional crown fabrication, the steps include anesthesia, preparation, and provisionalization, and probably require approximately one hour of chair time. Obviously this will vary from clinician to clinician; however, let us assume that for a dental implant crown, the time frame will be the same. Obviously there are additional steps: the healing cap has to be removed, abutment installed and then prepared, or perhaps you may elect to utilize a transfer post and have the laboratory perform the preparation. Both of these methods are suitable, each has its advantages and disadvantages. The transfer method requires less time but is also less predictable esthetically, has a higher lab cost, and presupposes a likely non-fixed provisional. The first method is more like a conventional approach and thus both more familiar and more predictable, and has lower lab costs.
The total cost involved, regardless of the method employed, will be the sum of the cost of implant parts, chair time, and lab costs. In the conventional approach, this will likely mean $100 to $150 in implant parts, $300 for the chair time, and approximately $150 in lab cost, for a total of $550 to $600. The transfer method is likely take about a half hour of chair time at the initial appointment and then another 10-15 minutes in seating because the abutment will have to be installed, verified by x-ray, and then the restoration seated. If a fixed provisional is contemplated, obviously there must also be time allotted for provisional fabrication. For this example we will assume about $200 in chair time. Implant parts should be the same if the doctor purchases the parts himself, but the lab costs will be considerably higher, perhaps two to three times that of a conventional crown, especially if some customization through casting is required. So the total costs will likely be similar to that of the conventional method.
Let us review the cost of the Atlantis abutment system. The cost of first abutment is $266, a duplicate abutment is $97, lab services are $50, and a provisional is $72, for a total of $485. Lab cost will be the same $150, but chair time should be reduced to perhaps 15-30 minutes or less. Atlantis reports that 87% of their abutments require no additional preparation or adjustment. If some adjustment or repreparation is needed, the abutment can be unscrewed, and then replaced into the duplicate abutment placed in the mouth, and the provisional recemented. Thus there would be no need for an impression, just any appropriate occlusal records needed. To minimize chair time, or at least predict how much time you will need, you can have the patient come in for a brief visual check of the abutment with the provisional in place. If the patient is happy and the clinician is satisfied then no changes are needed and you can then send the case directly to the lab for fabrication. If there are some repreparations needed, schedule the needed time and proceed, but clearly, you will have far less time invested than in either of the aforementioned methods of restoration. And the less time you need for one patient means more time for another patient, which means more revenue.
Additional Benefits
If no impression is required and no provisionalization is required, there is far less chance of tissue trauma from either cord packing or the fabrication of the provisional. This means no anesthesia, no foul tastes from acrylic, and likely a happier patient. This also means that the marginal integrity can be maintained and the cosmetics can be more predictable. The provisional also provides an opportunity for both the patient and doctor to see the final result or make changes. This can provide a template for the lab to duplicate, which makes the whole process simpler and more predictable.
Conclusion
Since the cost of the Atlantis system is actually comparable to the cost of fabricating a conventional implant crown, and the final result is much more likely to be better, there really is no reason not to use this system. After all, what could be better than an excellent result, a satisfied patient, and a happy, less stressed doctor?
Review Synopsis
Product
The Atlantis Abutment
The Good
The Atlantis abutment system provides a reliable method of implant crown and bridge restoration, minimizing time and stress.
The Bad
The system is pricey in terms of raw cost, but may actually be less expensive or comparable to conventional implant restoration methods.
The Bottom Line
The Atlantis Abutment system offers a more predictable, less stressful alternative to implant crown restoration. Despite the cost, it is definitely worth considering when performing implant crown restorations.