Since becoming involved with the use of small-diameter implants (SDIs) to assist in retaining complete dentures, I’ve found that patients take a shine to the prospect of having their full upper dentures created without palatal coverage. This approach keeps the prosthetic closer to the partial that they may have worn prior to the need for the denture. There’s also the reduced bulk and the ability to better sense taste and thermal conditions in the mouth when soft tissue is not covered up, as is the case with full palatal coverage. When bone is adequate, 4 to preferably 6 SDIs in the maxilla, anterior to the sinus cavity, can do a bang-up job of retaining one’s denture, palatefree, without the need to use denture adhesive. Like anything else we do in dentistry, there’s an easy way to do this and a corresponding hard way to do it. A shout out to Dr. Joe Santelli for mentoring me on the “easy way” that I am going to share with you in this clinical case report article.
The Hard Way
Simply put, the “hard way” consists of making the denture first, subsequently placing the SDIs, and then retrofitting the new denture to your implant placements. Maybe they will situate just right relative to the denture acrylic above them, or maybe they won’t; in which case you could be faced with breaching the surface of the denture to accommodate one or more of the o-ring housings. Of course, this would necessitate a modicum of laboratory intervention to right the ship. The same risks are incurred when retrofitting someone’s existing denture to a new set of SDIs. At least, in this instance, patients can be prepared for this possibility and be willing to accept it, as long as they aren’t required to purchase a new denture. They can be made to understand the trade-off. The “hard way” is anxiety producing for the clinician; labor intensive as one toils away in the laboratory, grinding acrylic holes in the base of the denture while hoping not to perforate it. The more SDIs, the more grinding, and the greater the chance of poking through the surface of the denture acrylic or, worse yet, a denture tooth.
The Easy Way
This approach depends upon the nature of the case (immediate versus already edentulous) but assumes in both instances that SDI retention is desired upon case completion. Let’s focus on the already edentulous case that is deemed to have adequate bone for the SDIs following case evaluation, and has a serviceable pre-existing denture that will become the “transitional appliance.”
The overall strategy consists of first placing the SDIs in the most suitable sites, accommodating their position within the existing denture by relieving the denture over each implant. (This constitutes far less grinding than is needed to accommodate a full o-ring housing). When the existing denture can be fully seated over the SDIs, a new border-molded final impression is taken, using that denture as a “custom tray.” What happens next is what renders the process très elegant!
Enter the Solution
In your past readings of continuing education selections, you may have once run across the Celara (3M ESPE) technique for denture fabrication. To refresh your memory, the Celara technique involves taking an impression of one’s existing denture (inside and out) via the supplied plastic flasks, alginate, and stone found in each self-contained Celara kit. This allows one to record the newly impressed denture, pour the model, and subsequently remove the patient’s denture, clean it up, and return it to the patient at the same visit. The Celera impression and model are then sent to the lab for wax injection and a trial setup. You also supply a counter model, tooth shade, and bite registration. In the case to be demonstrated, the sweet wrinkle consists of placing 6 SDI analogs in the denture impression before pouring the stone.
Let’s walk through the case in stepwise fashion.
In Figures 1 and 2, you will see the panoramic and clinical images of 6 freshly placed SDIs (Intra-Lock [Shatkin First Dental Lab]). All 6 were torqued to well above 40 Ncm and were deemed suitable for loading upon denture completion (or even that day if it was a “retrofit” case).
In Figure 3, you’ll see that space for the SDIs has been created, and border molding was begun with Futar (Kettenbach LP) vinyl polysiloxane (VPS), fast set, heavy body. Following a final impression (Splash medium and light body [DenMat]), 6 SDI analogs have been seated in the impression in preparation for model pouring (Figure 4).
Figure 5 demonstrates that the denture has been placed in the Celara flask that has first been filled with the Celera alginate. It is nestled so that borders of the denture remain slightly above the level of the alginate. Note: To “avoid a void,” it is helpful to preload the deepest depth of the palate with alginate before submerging the denture.
Once the alginate is set, the top of the plastic flask is placed on the base and then stone is poured into the waiting final impression, contained by the top of the flask that snaps into place (Figures 6 and 7).
|Figure 1. Panoramic film demonstrating placement of six 2.5 Intra-Lock small-diameter implants (SDIs) from Shatkin First Dental Lab.||Figure 2. Intraoral view of the SDIs on the day of the surgery.|
|Figure 3. Denture has been relieved to seat over SDIs, and border molding with Futar (Kettenbach LP) has been initiated.||Figure 4. Final impression taken with a heavy and light body vinyl polysiloxane (Splash [DenMat]) and SDI analogs seated in impression.|
|Figure 5. Denture seated in Celera (3M ESPE) alginate, awaiting setting of alginate.||Figure 6. Upper half of Celara flask has been snapped into place.|
|Figure 7. Celara stone has been poured into tissue-side impression so as to create the master model.|
When the stone has set, the flask is separated, having generated an impression of the dentulous side of the denture in alginate (Figure 8) and a stone model of the arch, complete with SDI analogs imbedded in stone in their respective locations, revealed once the denture is gently pried off of the stone model (Figures 9 to 11). Note: When pouring the model in stone, moderate to severe undercuts on the tissue surface of the denture should be blocked out with base plate wax or impression material. Do not pour stone into a denture that has not been relined with impression material for obvious reasons. (Hint: you won’t be able to remove it without breaking the denture or model.)
Following removal of the denture, the alginate flask and stone model are then re-opposed, placed in the included, sealable plastic packing sleeve and readied to send to a Celera qualified dental laboratory (this case was sent to RTG Dental Lab, located in Rochester, NY). As was mentioned, a counter model bite registration and shade are included in the package. The patient’s existing denture is then relined with soft denture liner in the voids created for the heads of the SDIs (COE-SOFT Soft Denture Reline Material [GC America]), affording the patient some newfound stability owing to the freshly placed SDIs (Figure 12). Reassure the patient that the retention to be had from the soon-to-be-experienced o-ring housings far exceeds that provided by the temporary liner.
Fast-Forward Two Weeks
Figures 13 to 15 demonstrate the model with o-ring housings and green blockout shims in place as well as the waxed-up denture try-in. The denture’s inner surface is fully relieved by the lab to accommodate the housings. Note also that the denture is chrome reinforced, featuring an open palate not unlike that of a partial denture. After a successful try-in, the wax-up/try-in is returned to RTG labs for final processing. RTG was instructed not to lute the housings, as I prefer to pick them up chairside. The finished denture was returned to me as shown in Figure 16, readied for a chairside pickup.
|Figure 8. Upon removing upper half of flask and set stone within, the alginate impression of the “tooth side” of the denture is revealed.|| |
Figure 9. The stone model is ready to be separated from the lower half of the Celera flask.
|Figure 10. The denture is now ready to be gently pried off of the model.||Figure 11. The separated model reveals the master model with SDI analogs in place.|
|Figure 12. The patient’s cleaned up denture has been relined with a denture liner (COE-SOFT Soft Denture Reline Material [GC America]).||Figure 13. The master model, shown with Intra-Lock o-ring housings over the SDI analogs.|
|Figure 14. Wax try-in of new upper denture with relief for o-ring housings.||Figure 15. Tooth side of wax-up ready for try-in.|
|Figure 16. Processed acrylic open palate denture ready for housing |
|Figure 17. O-ring housings with green blockout shims ready for pickup with Quick Up (VOCO America).|
|Figure 18. O-ring housings withdrawn (Quick Up).||Figure 19. Seated open palate denture in place.|
|Figure 20. Delighted patient!|
Figure 17 demonstrates the o-ring housings in place awaiting denture pickup as shown in Figure 18. A product that I have found to be a good one to accomplish the denture conversion is Quick Up (VOCO America). This product features an automix pick-up resin possessing the ideal viscosity needed for pickups as well as a light-cured, syringe-delivered matching resin for patching small air bubbles or other surface irregularities. If needed (primarily for retrofit cases), the kit includes a VPS paste aimed at disclosing locations in the denture base where the housings are “hanging up.”
Figures 19 and 20 demonstrate the finished product. Note: this case took but 3 visits to deliver with the second and third visits taking 30 minutes each.
The “easy way” was made easy in several ways.
Be assured that the freedom to choose the most robust SDI locations, minus the concerns of conforming to an already existing denture base, is a notable plus.
Most will also agree that in the majority of instances, there is no better “custom tray” than a patient’s existing denture, and as long as the denture isn’t ancient, there’s an excellent chance that the teeth and vertical may be in shouting distance of where you want them to be. They need only be tweaked by your instructions to the lab and the way that you record your bite registration during that first visit. Remember, this first visit includes implant placement, final impression, counter, shade, and bite registration. The rest is downhill. Note: If the implants do not torque above 30 Ncm, you may wish to soft reline the old denture only and wait for osseointegration before proceeding to the final denture. If, however, 4 or 5 SDIs of the 6 exceed the 30 Ncm benchmark, you may wish to load the “good ones” and leave the o-ring out of the housings of the ones that need to “mature.” I have had success with this approach. All housings are placed at the time of delivery, but the o-rings are plucked from those housings atop those you do not wish to load and are then replaced at a later date.
It’s worth mentioning at this juncture that some operators choose to deliver the denture with a covered palate inclusive of the cast frame. This may be done as a safeguard for added retention if the SDIs aren’t ready to load. The acrylic palate is then removed upon full osseointegration some months down the road. The cast frame is especially important for those patients who have a natural dentition on the lower arch due to the increased forces applied to the upper denture. If opposing an acrylic lower denture, then the need for cast reinforcement is less critical.
Keep in mind also that the overall process was also enhanced by not having to carry out the onerous task of grinding out 6 holes in the base of your patient’s new denture. The joy of the elimination of this part of the process cannot be overstated.
The Immediate Denture Scenario
Should your patient be an immediate case that will require multiple extractions and possible grafting, best to build a temporary denture into the fee of the case. Your patient will wait 6 months before proceeding with the SDIs unless he or she is fortunate enough to have 6 sites available that are already edentulous and ready to go. Again, this will afford you the opportunity to select the best implant sites when the arch has fully healed. The temporary denture will become the custom tray when you are ready to take the final impression as described above.
Getting Back to the “Hard Way”
The “hard way,” that is, the “seat-of-your-pants way,” does have a place in the world of SDI denture stabilization. Much, however, is dependent upon your judgment regarding the existing denture’s capacity to be retrofitted. Some will work seamlessly. Others will put you in an awkward position when it becomes necessary to “relocate” an SDI a bit more labial or lingual than you had planned. Choose carefully!
The process described herein, as taught to me by Dr. Joseph Santelli, will offer extreme satisfaction to your patients as you free them from the need to use denture adhesive and in essence, liberate their palates. You will also liberate their bank accounts as SDI retained dentures can be delivered at significantly lower cost than that offered by their bigger brothers. On a professional level, you will be thrilled at being able to provide this service in a time efficient and predictable method. I also encourage you to check out the Celera approach to fabricating dentures, even if you aren’t involved yet with SDI placement. RTG lab is an excellent source of information on this time saving approach to denture fabrication.
Here’s to better retention! Over and out!
Disclosure: Dr. Goldstein reports no disclosures.