Fig.1
Initial situation, the 65 y.o. patient presented old amalgam restorations (performed by myself 40 years earlier). The extensive amalgam restoration at tooth 16 was replaced with an indirect restoration in order to maintain and preserve the integrity of the tooth, while teeth 14 and 15 were later restored directly.

Fig.2
After rubber dam application, the old restoration was removed and sclerotic dentin was exposed.

Fig.3
Once the surface was cleaned, a selective enamel etching was carried out with 37% orthophosphoric acid for 30 seconds.

Fig.4
After the application of the adhesive procedures, a flowable composite was used to seal the dentin and to elevate the deep distal margin.

Fig.5
A high viscosity bulk-fill composite was used to build the tooth up.

Fig.6
After that, an overlay preparation was designed and performed to quickly and easily obtain a correct digital impression that exactly reproduced the final shape of the tooth. At this point, the digital impression could be taken.

Fig.7
The final scan of the preparation taken with Helios 600 (Eighteeth, China).

Fig.8
The antagonist was also scanned for bite registration.

Video.1
This video demonstration highlights how quick and easy it is to take a digital impression with the Helios 600 intra-oral scanner.

Fig.9
Once the intra-oral scan was completed, a temporary restoration was placed to cover the entire preparation, waiting to receive the overlay restoration from the lab.

Fig.10
Moving on to the laboratory, the final design of the indirect overlay was created, checking the correct contact points and the finish line of the restoration.

Fig.11
From digital to analogical, the wax-up of the indirect restoration was performed.

Fig.12
As for the digital workflow, also for the analogical one the contact points and the finish line were checked. After that, the lithium-disilicate restoration was fabricated from the wax-up model.

Fig.13
The finished lithium-disilicate restoration is ready to be cemented.

Fig.14
After removing the temporary restoration, the surface of the preparation was sandblasted and cleaned.

Fig.15
Orthophosphoric acid was applied on the entire bonding surface for 30 seconds.

Fig.16
Scotchbond Universal Plus was applied on the surface, rubbing and scrubbing the brush accurately. After air-blowing, the bonding agent was polymerized for 40 seconds.

Fig.17
A resin cement was applied on the internal surface of the indirect restoration and then the overlay was fitted with a constant pressure. A 5 second tag-curing was used to harden the excess cement in order to remove it easily with the Eccesso tool of LM Arte kit (LM Dental).

Fig.18
Glycerine was applied to prevent oxygen inhibition of the superficial resin cement layer, and the curing was completed with another 1 minute cycle.

Fig.19
Final result after rubber dam removal. The two amalgam restorations will be replaced in a following session with direct composite restorations.

Conclusions

In an ever-evolving world we should really implement the tools we’re offered by contemporary technology in our everyday practice. Once protocols are adapted and set to standard, digital instruments make our work easier and more predictable.

Bibliography

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Hasanzade M, Aminikhah M, Afrashtehfar KI, Alikhasi M. Marginal and internal adaptation of single crowns and fixed dental prostheses by using digital and conventional workflows: A systematic review and meta-analysis, J Prosthet Dent. 2021 Sep;126(3):360-368. Epub 2020 Sep 12.