The Combo cementation. A dual-consistency composite approach.
Combo is a new approach to adhesive cementation. The idea behind it, is to combine composite consistencies to make cementation of indirect restorations easier. In the Combo approach, a small amount of paste composite is positioned on the proximal-cervical margins of the preparation, while ﬂowable composite is spread to cover the rest of the preparation.
Today the limit between partial indirect restorations and full crowns is blurred, so we often choose to restore with an overlay teeth that we would have covered with a full crown just a few years ago. We might also ﬁnd ourselves removing old crowns and replacing them with large overlays.
In this illustration, you can see the shape of an extensive overlay preparation. The paste composite is placed on the proximal preparation margins (lime green), and ﬂowable composite is spread all over the preparation (dark green).
The restoration is positioned. Once you start pushing it, the paste composite will come out from the proximal areas, the ones where we need the most control, and it will be easy to remove. The ﬂowable composite will come out from the buccal and lingual, leaving a thin layer in between the preparation and the overlay.
So, at the end of the cementation, we will have most of the surface covered in a thin layer of ﬂowable composite, and paste composite only in the proximal cervical margins.
Let’s see a clinical case. First step is isolation with the rubber dam. Then sandblasting and selective enamel etching are carried out. The composite you can see in the picture, outside the margins of the preparation, is a ﬂowable wing.
A universal adhesive is used to bond the surface.
Paste composite is placed on the margins. These increments will prevent the ﬂowable composite from leaking in that area.
The areas where the paste composite is placed are highlighted in lime green.
Then the ﬂowable composite in the central area of the preparation.
The area where the ﬂowable composite is placed is highlighted in dark green.
Lateral view of the tooth just before the placement of the restoration.
The restoration is positioned, and the excess material leaks exactly how we want it to.
Detail of the leakage. Note how only paste composite is in the proximal area.
Occlusal view of the excess composite distribution.
The restoration is pushed to perfectly ﬁt the preparation. It’s now easy to remove the paste composite with a sharp instrument. If a thin layer were used, it wouldn’t go inside the contact point. The thinner, the better. A brush makes it easy to remove the ﬂowable.
Final picture, buccal view.
Final picture, occlusal view.
The Combo cementation combines the advantages of paste and ﬂowable composites. The dual-consistency approach guides the leakage of the ﬂowable, thus making it easier to clean the proximal areas.
1. Oglakci B, Kazak M, Donmez N, Dalkilic EE, Komen SS. The use of a liner under diﬀerent bulk-ﬁll resin composites: 3D GAP formation analysis by x.ray micro-computed tomography. J App Oral sci. 2020;28:e20190042.
2. Sousa SJL, Poubel DLDN, Rezende LVML, Almeida FT, de Toledo IP, Garcia FCP. Early clinical performance of resin cements in glass-ceramic posterior restorations in adult vital teeth: A systematic review and meta-analysis. J Prosthet Dent. 2020 Jan;123(1):61-70.
3. da Mota-Martins V, Silva CF, Almeida LM, de Paula MS, Menezes MS, SantosFilho PCF. Bond strength of glass ﬁber posts cemented with bulk-ﬁll ﬂowable composite resin. Appl Adhes Sci. 2019;7:3.
4. Almeida LJDS Junior, Penha KJS, Souza AF, Lula ECO, Magalhães FC, Lima DM, Firoozmand LM. Is there correlation between polymerization shrinkage, gap formation, and void in bulk ﬁll composites? A μCT study. Braz Oral Res. 2017 Dec 18;31:e100.
5. Baptista PJ, Amorim AT, Carpinteiro I, Belbut M, de Melo TP, Pinto A. Comparative study of the bond strength of composite resins in the cementation of indirect restorations, Annals of Medicine. 2019;51:sup1, 147-148.
6. Reis AF, Vestphal M, Amaral RC, Rodrigues JA, Roulet JF, Roscoe MG. Eﬃciency of polymerization of bulk-ﬁll
7. composite resins: a systematic review. Braz. Oral Res. 2017;31(suppl):e59