Christian Lampson presents a case study and shares some tips and tricks on how to make the cementation process as simple as possible.
Albert Einstein once said: ‘Everything should be made as simple as possible, but not simpler’, and it applies to dentistry; bringing back the necessary work to the essentials without losing focus on a qualitative outcome.
Case study
This patient needed dental treatment after a hoof strike with trauma of the upper front teeth as a result. The UL1 could not be preserved and UL2 required endodontic treatment and a core build-up with a glass fibre post. It was planned to restore the UR1, UR2, UL2 and UL3 with zirconia crowns, an implant at the site of UL1 and a direct restoration on UR3.
Treatment planning
It is best to select the cement during the treatment planning. Patient factors and the restorative design may influence the choice.
Self-adhesive resin cements simplify the placement of indirect restorations by eliminating the need for separate etchants and primers. Precious time can be saved because fewer steps are required. However, as with any cement system, be sure that it’s indicated in the specific case. Always use it according to the manufacturer’s instructions to ensure optimal performance and longevity.
A long-term temporary restoration from UR1 to UL2 was made chairside with Tempsmart DC (GC). To optimise the alveolar bone and soft tissue prior to implant insertion, UL1 was orthodontically extruded before extraction. Thereafter, the implant (diameter 4.1mm, length 14mm) was placed according to an immediate placement protocol followed by immediate insertion of a laboratory fabricated milled long-term temporary restoration (shade A3).
Preparations
The UR1, UR2, UL2 and UL3 were prepared with a circumferential chamfer and rounded edges. The implant impression was taken using the pick-up technique, which was applied for the exact transfer of the implant positions after four months of healing time.
Thereafter, the placement of the definitive zirconia restorations was planned (Figure 1). The temporary restorations were removed (Figure 2) and the field was isolated with cotton rolls.
The implant crown was placed and the screw channel was closed with universal bond and composite after having covered the screw with Teflon tape. The preparations were cleaned with a pumice slurry (Figure 3). Thereafter, they were thoroughly rinsed and dried (Figures 4a and 4b).
After the try-in, the intaglio surfaces of the zirconia crowns were ultrasonically cleaned, dried and sandblasted with Al2O3 to remove all contaminants. To have a good bond strength, it is important that both surfaces – the tooth abutment and the intaglio surface of the crown – are clean before cementation.
Zirconia has phosphate-based bonding sites, which attract the phospholipids in saliva; these should be removed prior to cementation. Simply rinsing off with water won’t do the trick. Specific cleaning solutions could also be used.
Restoration
The self-adhesive resin cement G-Cem One (GC; shade A2) was used (Figure 5) because of its excellent dark-cure properties (as zirconia does not effectively penetrate the crown, this is very important), good handling and easy excess removal. It was not necessary to use the G-Cem One adhesive enhancing primer (AEP) as the restorations were sufficiently retentive.
With the tack-curing option, the excess cement reaches a rubbery consistency very fast (Figure 6), which is the best moment to remove the excess: it can be peeled off easily with a scaler (Figure 7).
The contact points were flossed to remove leftover debris and to ensure that all excess was thoroughly removed from the interproximal areas (Figure 8). Once all debris was removed, the margins were light-cured again to reach complete setting. If needed, the margins can still be polished (Figure 9).
At the follow-up appointment a few months later, the gingiva showed a healthy aspect (Figures 10a-c).
Summary
Thinking of the appropriate steps and materials before the actual cementation is already half the work. Some steps, such as cleaning the surfaces, require extra attention to ensure good quality and to avoid problems at a later stage.
In other steps, time can be saved by selecting a self-adhesive resin cement and tack-cure before excess removal. This is beneficial in terms of cost. Also, when the cementation can be done faster, there is less risk of moisture in the working field.
References
For a list of references email siobhan.hiscott@fmc.co.uk.
Products used
Tempsmart DC, G-Cem One – GC.
This article first ran in Clinical Dentistry magazine. You can subscribe to receive the latest issue here.
