Article by Chris Hussey as featured in Implant Dentistry Today (July 2016)
In this article I hope to encourage thought regarding the future-proofing of certain implant cases. There may be times when you are in two minds whether or not to extract a singular tooth adjacent to an implant site to be restored that may already have a questionable future ahead of it. Zirconia may be your new ally in addressing this circumstance with a view to giving the lone survivor a fighting chance as well as saving your valued patient money in the long run.
I fully acknowledge that the techniques discussed here may not be suitable to all cases. The overall success will depend upon your expert judgement as to whether you believe that the retaining implant placement is clinically apt.
The freedom afforded to zirconia-based restorations can allow the clinician and technician to formulate a long-term contingency plan for subsequent loss of a tooth adjacent to a sound implant site. Such forethought will ensure that “Plan B” can be executed as simply as possible with the highest chance of success and minimal impact on the patient.
Let’s say that you have a patient with implants to be restored at sites 34 and 36, yet the 35 presents itself with an uncertain future. Your patient wants you to leave the 35 alone as he or she cannot afford an implant bridge at this stage and said patient certainly does not wish to undergo any future implant surgery. Time to call the technician.
In this circumstance, it may be possible to offer the patient a future-proofed solution at an additional cost. The technique I have been working on allows the dentist to issue the 34 and 36 as usual, be it cement-on or screw-retained, and have nothing further to do unless the 35 is later extracted.
My solution is to have a pre-prepared inlay-type recess at the mesial of the 36 restoration that may later serve as a connector to a future pontic. This pontic may also be supported by either an equivalent design on the distal of the 34, or a deep rest seat at the marginal ridge, or remain unsupported.
The design of this connector is of paramount importance. A successful cross-section should be deep and as wide as is practicable with regard to embrassures. Notwithstanding the impressive technology of cements containing MDP (worth looking up) and fantastic applicants such as 3M™ ESPE™ Rocatec™, solid mechanical retention should not be overshadowed in the absence of long-term clinical research for this circumstance.
The preferred design of this connector can be best explained by example. Recently, we manufactured the following case for Dr Brendan Moore of Doncaster Dental in Victoria. Dr Moore opted for a future-proofed solution for his patient who required implants to be restored at sites 23, 24 and 26 (Figure 1). The agreed solution was to have an inlay recess at the mesial of the 26 (Figure 2) and a smaller rest-seat recess at the distal of the 24 by his request. This provided an ideal foundation for a bridging restoration down the track should the 25 require extraction.
The chosen material for each implant restoration was a high strength translucent monolithic zirconia that was to be enhanced with GC Lustre Pastes. Once the designs were milled and sintered, they were seated on the model and re-scanned again for the purposes of fabricating an inlay for the screw-retained 26 (Figure 3). This was done in the same material for aesthetic reasons then cemented in the laboratory.
As the 24 was a cement-on, I opted to fill the rest-seat void with porcelain rather than making a separate inlay. The rationale for this remains in the practical steps which must be taken to prepare the fitting surfaces for a future bridge design. The following is an example of such steps (post extraction and healing):
- Appointment 1: Chairside retrieval of the screw-retained 26 then laboratory removal of the inlay by the application of low heat;
- Appointment 2: Replacement of the re-prepared 26 and chairside removal of the porcelain within the rest-seat of the 24. PVS impression then fill rest-seat with temporary material for comfort. The 26 can be again retrieved or the inlay can be re-affixed with temporary cement.
Lab to manufacture bridge restoration.
- Appointment 3: Issue of bridge restoration.
I acknowledge that there are other approaches to how “Plan B” may be executed, however the aforementioned steps were provided as a guide. The digitally-minded may suggest that the bridge restoration could be fabricated at the laboratory instantly from previous scans and contacts can be checked on a printed model. This is true, however this approach does not accommodate the state of the newly-healed soft tissue unless an alginate impression is taken of this which is then digitally superimposed over those original scans.
With future-proofing in general, don’t feel that you have to come up with the perfect game plan alone. Your technician is your partner in all of this and he or she is likely to be a great source of knowledge. With the plethora of materials now available, there will hence be an abundance of options for a given case so part of the fun is coming up with the best plan of attack.
A well-future-proofed solution may be more expensive if additional layers of restorations are required but this should not be altogether dissuading. The whole point of this is insurance which always comes at a cost. Paying a little extra in the short-term may be quite attractive to a patient if it means that he or she may save more in the long term. As such, this could be offered as a second-tier purchase.
Future-proofing is a topic that extends far beyond the scope of this brief article and its examples but I hope that this discussion has served to provoke further thought. It is worth considering that the concept is not only restricted to implants, but could come in handy for crown and bridge restorations also. If you ever find yourself wondering if something can be done to save your patient money down the line, then please feel free to call me at the laboratory and we will see what we can come up with.
Dental Ceramist & CAD/CAM Specialist
Shop 3 / 49 Ash Road
Leopold VIC 3224
(03) 5250 3170