The ideal composite build-up in posterior indirect restorations

Build-up of cavities in posterior direct restorations, is a technique (also called block-out) invented by Dr. R.V.Tucker and has as one of its key points the aim of being more conservative in removing undercuts during the preparation for indirect restorations.

Speaking about indirect restorations, one of the best materials in term of longevity and biocompatibility is gold. In well trained hands, gold inlays, onlays and overlays are incredibly long-lasting and precise. The disadvantages of this material are the high operator variable and the “yellow” aesthetic, so nowadays it’s unfortunately really uncommon to perform a gold indirect restoration.

Adhesive restorations are the first choice in a lot of cases. The “silent revolution” of adhesive dentistry described by J.F. Roulet is nowadays the present and the future of the daily clinical practice.

With the new available technologies, many techniques are changing, but some principles are still very important.

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Fig.1
Just imagine to have this carious lesion. If you want to prepare a cavity for an indirect restoration, you must remove all the undercuts, just to let the inlay passively sit.

The quantity of sound tissue you’d need to remove is very big (red line).

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Fig.2
The build-up technique is really simple. Once you removed the carious tissue, you only need to fill everything with a restorative material, so you can prepare a more conservative cavity.
You are actually filling most of the undercuts, instead of removing sound tissue, and lifting up the cavity floor.
Nowadays the ideal material for build-up is obviously composite. In this picture you can notice the smaller cavity (red line), the build-up composite (light blue) and the absence of undercuts.
If you only fill up the undercuts, then you immediately prepare the indirect cavity, you’re making a “block-out”.
If you make a complete filling, you’re making a real build-up.
Sometimes making a complete build-up can be necessary for many reasons. For example, you might want to wait for a certain period, just to be sure about the pulp health, or maybe you just don’t have enough time to perform the complete treatment because the patient came as an emergency.

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Fig.3
In this case we have a fractured lower first molar with an infiltrated amalgam restoration. The tooth is highly sensitive, but the pain is very short lasting. The patient came as an emergency, because of the fracture, so we need to do something that’s fast, easy and reliable.

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Fig.4
After rubber dam isolation we start removing the old restoration and the carious tissue.

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Fig.5
The cavity is actually extended very to the pulp. Dentin in the distal area appears very dark but, after caries removal, it’s hard and sound. The distal margin is quite deep, but easily isolated by rubber dam.
We decided together with the patient to make a build-up in order to wait and see if the symptoms were gone. Going immediately with an indirect restoration could have been dangerous, in case of an irreversible pulpitis.
Endodontic treatment can be, at least, postponed!

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Fig.6
After properly finishing the cavity, putting a circumferential matrix and performing dentin-enamel adhesion, a complete build-up was made with a dual-cure zirconia reinforced composite (DMG LuxaCore Z). This kind of material is very easy to use, fast and allows you to create a strong and stable temporary filling, that could become in the near future the base for an indirect restoration. In case of irreversible pulpitis, this restoration could be a very efficient pre-treatment for the endodontic procedure.

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Fig.7
The build-up is finished and polished.
The tooth will be monitored in order to evaluate if a root canal treatment is needed, or if a indirect restoration can be performed keeping it vital.

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Fig.8
In this case the patient has two infiltrated old fillings on lower first and second molars. She’s complaining about a non effective contact point.

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Fig.9
The view after rubber dam isolation.

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Fig.10
The situation after decay removal.

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Fig.11
After performing dentin-enamel adhesion, a dual cure composite reinforced with zirconia (DMG LuxaCore Z) was used to make two build-ups.
Than teeth has been prepared for two indirect restorations.
After the finishing procedures, a silicon impression was taken using a check bite tray and an addition silicon (DMG Honigum), then a temporary restoration was applied (DMG Luxatemp Inlay).

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Fig.12
The two restorations were waxed by the dental technician (CDT Pasquale Casaburo).

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Fig.13
And then fused in Lithium Disilicate.

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Fig.14
In the second appointment, the temporary restorations were removed and the onlays were tried in, in order to verify appropriateness of sitting and the contact area.

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Fig.15
The rubber dam was applied.

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Fig.16
Then the restorations were tried again after putting the rubber dam on.

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Fig.17
After isolating the second molar, adhesive procedures were performed.

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Fig.18
The onlay was etched with hydrofluoric acid for 20 seconds, well rinsed and completely dried. Then silane was applied and heated (DMG Vitique Silane). A layer of adhesive was then applied.

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Fig.19
A dual-cure resin cement was applied (DMG PermaCem) and the onlay was cemented.

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Fig.20
The same procedure was repeated with the first molar.

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Fig.21
The view after rubber dam removal.

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Fig.22
The situation 4 months after the cementation.

Conclusions

Adhesive indirect restorations are a great source to manage frequent clinical situations.
Using the build-up or block-out technique can be an important help to be more conservative and save a lot of sound structure. It’s also very useful in all the cases with uncertain pulp prognosis: making a strong, stable and perfectly sealing temporary restoration can be a versatile solution that can turn from a build-up for an indirect restoration into a pre-endodontic restoration, if needed.
A fast, easy to use, strong and reliable material can be really important to properly manage this kind of situations.

Bibliography

Roulet JF. Adhesion: the silent revolution. 2nd European Symposium on Adhesive Dentistry: 7-9 May 1999. J Adhes Dent. 1999 Autumn;1(3):285-7.
Tucker RV. Why gold castings are excellent restorations. Oper Dent. 2008 Mar-Apr;33(2):113-5.

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